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19-1358; Rev 0; 4/98
Force-Sense Switches
General Description
The MAX4554/MAX4555/MAX4556 are CMOS analog ICs configured as force-sense switches for Kelvin sensing in automated test equipment (ATE). Each part contains high-current, low-resistance switches for forcing current, and higher resistance switches for sensing a voltage or switching guard signals. The MAX4554 contains two force switches, two sense switches, and two guard switches configured as two triple-pole/single-throw (3PST) normally open (NO) switches. The MAX4555 contains four independent single-pole/single-throw (SPST) normally closed (NC) switches, two force switches, and two sense switches. The MAX4556 contains three independent single-pole/double-throw (SPDT) switches, of which one is a force switch and two are sense switches. These devices operate from a single supply of +9V to +40V or dual supplies of 4.5V to 20V. On-resistance (6 max) is matched between switches to 1 max. Each switch can handle Rail-to-Rail(R) analog signals. The off-leakage current is only 0.25nA at +25C and 2.5nA at +85C. The MAX4554 is also fully specified for +20V and -10V operation. All digital inputs have +0.8V and +2.4V logic thresholds, ensuring both TTL- and CMOS-logic compatibility.
Features
o 6 Force Signal Paths (15V Supplies) 1 Force Signal Matching (15V Supplies) o 60 Sense-Guard Signal Paths (15V Supplies) 8 Sense-Guard Signal Matching (15V Supplies) o Rail-to-Rail Signal Handling o Break-Before-Make Switching (MAX4556) o tON and tOFF = 275ns (15V Supplies) o Low 1A Power Consumption o >2kV ESD Protection per Method 3015.7 o TTL/CMOS-Compatible Inputs
MAX4554/MAX4555/MAX4556
Ordering Information
PART MAX4554CPE MAX4554CSE MAX4554C/D MAX4554EPE MAX4554ESE TEMP. RANGE 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C PIN-PACKAGE 16 Plastic DIP 16 Narrow SO Dice* 16 Plastic DIP 16 Narrow SO
Applications
Automated Test Equipment (ATE) Calibrators Precision Power Supplies Automatic Calibration Circuits Asymmetric Digital Subscriber Line (ADSL) with Loopback
Ordering Information continued at end of data sheet. *Contact factory for availability.
Rail-to-Rail is a registered trademark of Nippon Motorola Ltd.
Pin Configurations/Functional Diagrams/Truth Tables
TOP VIEW
MAX4554
NOG1 1 NOS1 2 NOF1* 3 V- 4 GND 5 NOF2* 6 NOS2 7 NOG2 8 16 COMG 15 COMS 14 COMF* 13 V+ 12 VL 11 IN1 10 IN2 9 EN EN 1 0 0 0 0 IN1 X 0 0 1 1 MAX4554 IN2 COMG X OFF 0 OFF 1 NOG2 0 NOG1 NOG1 1 & NOG2 COMS OFF OFF NOS2 NOS1 NOS1 & NOS2 COMF* OFF OFF NOF2* NOF1* NOF1* & NOF2*
NOTE: SWITCH POSITIONS SHOWN WITH IN_ = LOW *INDICATES HIGH-CURRENT, LOW-RESISTANCE FORCE SWITCH X = DON'T CARE
DIP/SO
MAX4555/MAX4556 shown at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
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Force-Sense Switches MAX4554/MAX4555/MAX4556
ABSOLUTE MAXIMUM RATINGS
(Voltages referenced to GND) V+ ...........................................................................-0.3V to +44V V- ............................................................................-25V to +0.3V V+ to V-...................................................................-0.3V to +44V All Other Pins (Note 1) ..........................(V- - 0.3V) to (V+ + 0.3V) Continuous Current into Force Terminals .......................100mA Continuous Current into Any Other Terminal....................30mA Peak Current into Force Terminals (pulsed at 1ms, 10% duty cycle).................................300mA Peak Current into Any Other Terminal (pulsed at 1ms, 10% duty cycle).................................100mA ESD per Method 3015.7 ..................................................>2000V Continuous Power Dissipation (TA = +70C) Plastic DIP (derate 10.53mW/C above +70C) ...........842mW Narrow SO (derate 8.7mW/C above +70C) ...............696mW Operating Temperature Ranges MAX455_C_ E ......................................................0C to +70C MAX455_E_ E ...................................................-40C to +85C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10sec) .............................+300C
Note 1: Signals on analog or digital pins exceeding V+ or V- are clamped by internal diodes. Limit forward diode current to maximum current rating.
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS--MAX4554 (+20V, -10V Supplies)
(V+ = +20V, V- = -10V, VL = 5V, GND = 0V, VIN_H = 2.4V, VIN_L = 0.8V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER SYMBOL CONDITIONS TA MIN TYP (Note 2) MAX UNITS
6 ANALOG SWITCH (FORCE) Analog Signal Range On-Resistance On-Resistance Match (Note 4) On-Resistance Flatness (Note 5) NOF_ Off-Leakage Current COMF Off-Leakage Current COMF On-Leakage Current Charge Injection VCOMF, VNOF_ RON RON RFLAT(ON) INOF_(OFF) ICOMF(OFF) ICOMF(ON) Q VCOMS, VCOMG, VNOS_, VNOG_ RON RON (Note 3) VCOMF = 10V, ICOMF = 10mA VCOMF = 10V, ICOMF = 10mA VCOMF = +5V, 0V, -5V; ICOMF = 10mA V+ = 22V, V- = -11V, VCOMF = 10V, VNOF_ = 10V V+ = 22V, V- = -11V, VCOMF = 10V, VNOF_ = 10V V+ = 22V, V- = -11V, VCOMF = 10V VCOMF = 0, Figure 13 C, E +25C C, E +25C C, E +25C C, E +25C C, E +25C C, E +25C C, E C, E -0.25 -2.5 -0.5 -2.5 -0.5 -10 80 0.06 0.03 0.03 0.5 0.4 V3.5 V+ 6 7 1 1.5 1.5 2.0 0.25 2.5 0.5 2.5 0.5 10 V nA nA nA pC
60 ANALOG SWITCH (SENSE-GUARD)
Analog Signal Range
(Note 3)
On-Resistance On-Resistance Match (Note 4)
VCOM_ = 10V, ICOM_ = 1mA VCOM_ = 10V, ICOM_ = 1mA
2
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C, E
V-
V+
V
+25C C, E +25C C, E
34 5
60 70 8 10

Force-Sense Switches
ELECTRICAL CHARACTERISTICS--MAX4554 (+20V, -10V Supplies) (continued)
(V+ = +20V, V- = -10V, VL = 5V, GND = 0V, VIN_H = 2.4V, VIN_L = 0.8V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER On-Resistance Flatness (Note 5) NOS_, NOG_ Off-Leakage Current COMS, COMG Off-Leakage Current COMS, COMG On-Leakage Current Charge Injection LOGIC INPUT IN_, EN Input Logic Threshold High IN_, EN Input Logic Threshold Low IN_, EN Input Current Logic High or Low VIN_H, V ENH VIN_L, V ENL IIN_H, IIN_L, I ENH , I ENL VIN_ = V EN = 0 or VL C, E C, E C, E 0.8 -0.5 1.6 1.6 0.03 0.5 2.4 V V A SYMBOL RFLAT(ON) INOS_(OFF), INOG_(OFF) ICOMS(OFF), ICOMG(OFF) ICOMS(ON), ICOMG(ON) Q CONDITIONS VCOM_ = +5V, 0V, -5V; ICOM_ = 10mA V+ = 22V; V- = -11V; VCOM_ = 10V; VNOS_, VNOG_ = 10V V+ = 22V; V- = -11V; VCOM_ = 10V; VNOS_, VNOG_ = 10V V+ = 22V, V- = -11V, VCOM_ = 10V VCOM_ = 0, Figure 13 TA +25C C, E +25C C, E +25C C, E +25C C, E +25C MIN TYP (Note 2) 3.5 -0.25 -2.5 -0.25 -2.5 -0.5 -5.0 0.02 0.02 0.04 6 MAX 9 10 0.25 2.5 0.25 2.5 0.5 5.0 UNITS nA nA nA pC
MAX4554/MAX4555/MAX4556
SWITCH DYNAMIC CHARACTERISTICS Turn-On Time (Force) Turn-On Time (Sense-Guard) Turn-Off Time (Force) Turn-Off Time (Sense-Guard) Enable Time On Enable Time Off NOF_ Off-Capacitance NOS_, NOG_ Off-Capacitance COMF Off-Capacitance COMS, COMG Off-Capacitance COMF On-Capacitance COMS, COMG On-Capacitance Total Harmonic Distortion (Force) Off Isolation (Force) tON tON tOFF tOFF tEN tEN COFF COFF COFF COFF CON CON THD VISO RIN_ = 50, ROUT = 50, f = 1MHz, VCOM_ = 100mVRMS, Figure 15 VCOMF = 3V, RL = 300, Figure 10 VCOMS, VCOMG = 10V; RL = 1k; Figure 10 VCOMF = 3V, RL = 300, Figure 10 VCOMS, VCOMG = 10V; RL = 1k; Figure 10 VCOM_ = 10V, Figure 11 VCOM_ = 10V, Figure 11 VNOF = GND, f = 1MHz, Figure 14 VNOS_, VNOG_ = GND; f = 1MHz; Figure 14 VCOMF = GND, f = 1MHz, Figure 14 VCOMS, VCOMG = GND; f = 1MHz; Figure 14 VCOMF = GND, f = 1MHz, Figure 14 VCOMS, VCOMG = GND; f = 1MHz; Figure 14 +25C C, E +25C C, E +25C C, E +25C C, E +25C C, E +25C C, E +25C +25C +25C +25C +25C +25C +25C +25C 150 150 130 130 375 170 22 7 50 15 130 30 0.007 -30 300 350 300 350 300 350 300 350 500 600 275 350 ns ns ns ns ns ns pF pF pF pF pF pF % dB
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3
Force-Sense Switches MAX4554/MAX4555/MAX4556
ELECTRICAL CHARACTERISTICS--MAX4554 (+20V, -10V Supplies) (continued)
(V+ = +20V, V- = -10V, VL = 5V, GND = 0V, VIN_H = 2.4V, VIN_L = 0.8V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER POWER SUPPLY Power-Supply Range V+ Supply Current V- Supply Current VL Supply Current Ground Current V+, VL, VI+ IIL+ IGND VL 4.5V V+ = 22V; V- = -11V; V EN, V IN_ = 0 or VL V+ = 22V; V- = -11V; V EN, V IN_ = 0 or VL V+ = 22V; V- = -11V; V EN, V IN_ = 0 or VL V+ = 22V; V- = -11V; V EN, V IN_ = 0 or VL C, E +25C C, E +25C C, E +25C C, E +25C C, E 4.5 -1.0 -5.0 -1.0 -5.0 -1.0 -5.0 -1.0 -5.0 20 1.0 5.0 1.0 5.0 1.0 5.0 1.0 5.0 V A A A A SYMBOL CONDITIONS TA MIN TYP (Note 2) MAX UNITS
ELECTRICAL CHARACTERISTICS--MAX4554 (15V Supplies)
(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, VIN_H = 2.4V, VIN_L = 0.8V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER SYMBOL CONDITIONS TA MIN TYP (Note 2) MAX UNITS
6 ANALOG SWITCH (FORCE) Analog Signal Range On-Resistance On-Resistance Match (Note 4) On-Resistance Flatness (Note 5) NOF_ Off-Leakage Current COMF Off-Leakage Current COMF On-Leakage Current Charge Injection VCOMF, VNOF_ RON RON RFLAT(ON) INOF_(OFF) ICOMF(OFF) ICOMF(ON) Q VCOMS, VCOMG, VNOS_, VNOG_ RON (Note 3) VCOMF = 10V, ICOMF = 10mA VCOMF = 10V, ICOMF = 10mA VCOMF = +5V, 0V, -5V; ICOMF = 10mA C, E +25C C, E +25C C, E +25C C, E +25C -0.25 -2.5 -0.5 -5.0 -0.5 -10 100 0.06 0.03 0.03 0.1 0.5 V4 V+ 6 7 1 1.5 1 1.5 0.25 2.5 0.5 5.0 0.5 10 V nA nA nA pC
V+ = 16.5V, V- = -16.5V, VCOMF = 10V VCOMF = 0, Figure 13
60 ANALOG SWITCH (SENSE-GUARD)
Analog Signal Range
(Note 3)
On-Resistance
VCOM_ = 10V, ICOM_ = 1mA
4
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V+ = 16.5V, V- = -16.5V, VCOMF = 10V, VNOF_ =
V+ = 16.5V, V- = -16.5V, VCOMF = 10V, VNOF_ =
10V 10V
C, E +25C C, E +25C C, E +25C
C, E
V-
V+
V
+25C C, E
38
60 70
Force-Sense Switches
ELECTRICAL CHARACTERISTICS--MAX4554 (15V Supplies) (continued)
(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, VIN_H = 2.4V, VIN_L = 0.8V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER On-Resistance Match (Note 4) On-Resistance Flatness (Note 5) NOS_, NOG Off-Leakage Current COMS, COMG Off-Leakage Current COMS, COMG On-Leakage Current Charge Injection LOGIC INPUT IN_, EN Input Logic Threshold High IN_, EN Input Logic Threshold Low IN_, EN Input Current Logic High or Low VIN_H, V ENH VIN_L, V ENL IIN_H, IIN_L, I ENH , I ENL V EN = 0 or VL C, E C, E C, E 0.8 -0.5 1.6 1.6 0.03 0.5 2.4 V V A SYMBOL RON RFLAT(ON) INOS_(OFF), INOG_(OFF) ICOMS(OFF), ICOMG(OFF) ICOMS(ON), ICOMG(ON) Q CONDITIONS VCOM_ = 10V, ICOM_ = 1mA VCOM_ = +5V, 0V, -5V; ICOM_ = 1mA V+ = 16.5V; V- = -16.5V; VCOM_ = 10V; VNOS_, VNOG_ = V+ = 16.5V; V- = -16.5V; VCOM_ = 10V; VNOS_, VNOG_ = V+ = 16.5V, V- = -16.5V, VCOM_ = 10V VCOM_ = 0, Figure 13 TA +25C C, E +25C C, E +25C 10V 10V -0.25 -2.5 -0.25 -2.5 -0.5 -5.0 4 0.02 0.01 0.01 C, E +25C C, E +25C C, E +25C 1.5 MIN TYP (Note 2) 5 MAX 9 10 5 6 0.25 2.5 0.25 2.5 0.5 5.0 UNITS nA nA nA pC
MAX4554/MAX4555/MAX4556
SWITCH DYNAMIC CHARACTERISTICS Turn-On Time (Force) Turn-On Time (Sense-Guard) Turn-Off Time (Force) Turn-Off Time (Sense-Guard) Enable Time On Enable Time Off NOF_ Off-Capacitance NOS_, NOG_ Off-Capacitance COMF Off-Capacitance COMS, COMG Off-Capacitance tON tON tOFF tOFF tEN tEN COFF COFF COFF COFF VCOM_ = 10V, RL = 300, Figure 10 VCOM_ = 10V, RL = 1k, Figure 10 VCOM_ = 10V, RL = 300, Figure 10 VCOM_ = 10V, RL = 1k, Figure 10 VCOM_ = 10V, RL = 300, Figure 11 VCOM_ = 10V, RL = 300, Figure 11 VNOF = GND, f = 1MHz, Figure 14 VNOS_, VNOG_ = GND; f = 1MHz; Figure 14 VCOMF = GND, f = 1MHz, Figure 14 VCOMS_, VCOMG _= GND; f = 1MHz; Figure 14 +25C C, E +25C C, E +25C C, E +25C C, E +25C C, E +25C C, E +25C +25C +25C +25C 22 9 29 9 170 310 135 170 135 135 275 325 225 275 275 325 225 275 500 600 300 400 ns ns ns ns ns ns pF pF pF pF
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5
Force-Sense Switches MAX4554/MAX4555/MAX4556
ELECTRICAL CHARACTERISTICS--MAX4554 (15V Supplies) (continued)
(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, VIN_H = 2.4V, VIN_L = 0.8V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER COMF On-Capacitance COMS, COMG On-Capacitance Total Harmonic Distortion (Force) Off Isolation (Force) POWER SUPPLY Power-Supply Range V+ Supply Current V- Supply Current VL Supply Current Ground Current SYMBOL CON CON THD VISO RIN_ = 50, ROUT = 50, f = 1MHz, VCOM_ = 100mVRMS, Figure 15 VL 4.5V V+ = 16.5V; V- = -16.5V; V EN, V IN_ = 0 or V+ V+ = 16.5V; V- = -16.5V; V EN, V IN_ = 0 or V+ V+ = 16.5V; V- = -16.5V; V EN, V IN_ = 0 or V+ V+ = 16.5V; V- = -16.5V; V EN, V IN_ = 0 or V+ CONDITIONS VCOMF = GND, f = 1MHz, Figure 14 VCOMS, VCOMG_ = GND; f = 1MHz; Figure 14 TA +25C +25C +25C +25C MIN TYP (Note 2) 107 29 0.007 -30 MAX UNITS pF pF % dB
V+, VL, VI+ IIL+ IGND
C, E +25C C, E +25C C, E +25C C, E +25C C, E
4.5 -1.0 -5.0 -1.0 -5.0 -1.0 -5.0 -1.0 -5.0
0.001 0.001 0.001
20 1.0 5.0 1.0 5.0 1.0 5.0 1.0 5.0
V A A A A
ELECTRICAL CHARACTERISTICS--MAX4555 (15V Supplies)
(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, VIN_H = 2.4V, VIN_L = 0.8V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER SYMBOL CONDITIONS TA MIN TYP (Note 2) MAX UNITS
6 ANALOG SWITCH (FORCE) Analog Signal Range On-Resistance On-Resistance Match (Note 4) On-Resistance Flatness (Note 5) NC_ Off-Leakage Current COM_ Off-Leakage Current COM_ On-Leakage Current Charge Injection VCOM_, VNO_ (Note 3) RON RON RFLAT(ON) INC_(OFF) ICOM_(OFF) ICOM_(ON) Q VCOM_ = 10V, ICOM_ = 10mA VCOM_ = 10V, ICOM_ = 10mA VCOM_ = +5V, 0V, -5V; ICOM_ = 10mA V+ = 16.5V, V- = -16.5V, VCOM_ = 10V, VNO_ = 10V V+ = 16.5V, V- = -16.5V, VCOM_ = 10V, VNO_ = 10V V+ = 16.5V, V- = -16.5V, VCOM_ = 10V VCOM_ = 0, Figure 13 C, E +25C C, E +25C C, E +25C C, E +25C C, E +25C C, E +25C C, E +25C -0.25 -2.5 -0.5 -5.0 -0.5 -10 100 0.06 0.03 0.03 0.05 0.3 V3.8 V+ 6 7 1 1.5 1 1.5 0.25 2.5 0.5 5.0 0.5 10 V nA nA nA pC
6
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Force-Sense Switches
ELECTRICAL CHARACTERISTICS--MAX4555 (15V Supplies) (continued)
(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, VIN_H = 2.4V, VIN_L = 0.8V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER SYMBOL CONDITIONS TA MIN TYP (Note 2) MAX UNITS
MAX4554/MAX4555/MAX4556
30 ANALOG SWITCH (SENSE-GUARD) Analog Signal Range On-Resistance On-Resistance Match (Note 4) On-Resistance Flatness (Note 5) NC_ Off-Leakage Current COM_ Off-Leakage Current COM_ On-Leakage Current Charge Injection LOGIC INPUT IN_ Input Logic Threshold High IN_ Input Logic Threshold Low IN_ Input Current Logic High or Low VIN_H VIN_L IIN_H, IIN_L VIN_ = 0.8V or 2.4V C, E C, E C, E 0.8 -0.5 1.6 1.6 0.03 0.5 2.4 V V A VCOM_, VNO_ (Note 3) RON RON RFLAT(ON) INC_(OFF) ICOM_(OFF) INC_(ON) Q VCOM_ = 10V, ICOM_ = 10mA VCOM_ = 10V, ICOM_ = 10mA VCOM_ = +5V, 0V, -5V; ICOM_ = 10mA V+ = 16.5V, V- = -16.5V, VCOM_ = 10V, VNO_ = 10V V+ = 16.5V, V- = -16.5V, VCOM_ = 10V, VNO_ = 10V V+ = 16.5V, V- = -16.5V, VNC_ = 10V VCOM_ = 0, Figure 13 C, E +25C C, E +25C C, E +25C C, E +25C C, E +25C C, E +25C C, E +25C -0.3 -2.5 -0.3 -2.5 -0.6 -5.0 4 0.02 0.01 0.01 0.6 0.6 V15 V+ 30 45 4 5 5 6 0.3 2.5 0.3 2.5 0.6 5.0 V nA nA nA pC
SWITCH DYNAMIC CHARACTERISTICS Turn-On Time (Force) Turn-On Time (Sense-Guard) Turn-Off Time (Force) Turn-Off Time (Sense-Guard) COM_ Off-Capacitance (Force) COM_ On-Capacitance (Sense-Guard) COM_ On-Capacitance (Force) COM_ Off-Capacitance (Sense-Guard) tON tON tOFF tOFF COFF CON CON COFF VCOM_ = 3V, RL = 300, Figure 10 VCOM_ = 10V, RL = 1k, Figure 10 VCOM_ = 3V, RL = 300, Figure 10 VCOM_ = 10V, RL = 1k, Figure 10 VCOM_, VNO_ = GND; f = 1MHz; Figure 14 VCOM_, VNO_ = GND; f = 1MHz; Figure 14 VCOM_, VNO_ = GND; f = 1MHz; Figure 14 VCOM_, VNO_ = GND; f = 1MHz; Figure 14 +25C C, E +25C C, E +25C C, E +25C C, E +25C +25C +25C +25C 29 9 107 29 125 190 125 155 275 325 225 275 275 325 225 275 ns ns ns ns pF pF pF pF
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7
Force-Sense Switches MAX4554/MAX4555/MAX4556
ELECTRICAL CHARACTERISTICS--MAX4555 (15V Supplies) (continued)
(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, VIN_H = 2.4V, VIN_L = 0.8V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER NC_ Off-Capacitance (Force) NC_ Off-Capacitance (Sense-Guard) Total Harmonic Distortion (Force) Off Isolation (Force) (Note 6) POWER SUPPLY Power-Supply Range V+ Supply Current V- Supply Current VL Supply Current Ground Current SYMBOL COFF COFF THD VISO RIN = 50, ROUT = 50, f = 1MHz, VCOM_ = 100mVRMS, Figure 15 CONDITIONS VCOM_, VNO_ = GND; f = 1MHz; Figure 14 VCOM_, VNO_ = GND; f = 1MHz; Figure 14 TA +25C +25C +25C +25C MIN TYP (Note 2) 22 9 0.007 -38 MAX UNITS pF pF % dB
V+, VL, VI+ IIL+ IGND V+ = 16.5V; V- = -16.5V; V EN, V IN_ = 0 or V+ V+ = 16.5V; V- = -16.5V; V EN, V IN_ = 0 or V+ V+ = 16.5V; V- = -16.5V; V EN, V IN_ = 0 or V+ V+ = 16.5V; V- = -16.5V; V EN, V IN_ = 0 or V+
C, E +25C C, E +25C C, E +25C C, E +25C C, E
4.5 -1.0 -5.0 -1.0 -5.0 -1.0 -5.0 -1.0 -5.0
0.001 0.001 0.001 0.001
20 1.0 5.0 1.0 5.0 1.0 5.0 1.0 5.0
V A A A A
ELECTRICAL CHARACTERISTICS--MAX4556 (15V Supplies)
(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, VIN_H = 2.4V, VIN_L = 0.8V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER SYMBOL CONDITIONS TA MIN TYP (Note 2) MAX UNITS
6 ANALOG SWITCH (FORCE) Analog Signal Range On-Resistance On-Resistance Match (Note 4) On-Resistance Flatness (Note 5) NO1, NC1 Off-Leakage Current COM1 Off-Leakage Current COM1 On-Leakage Current Charge Injection 8 VCOM1, VNO1, VNC1 RON RON RFLAT(ON) INO1(OFF), INC1(OFF) ICOM1(OFF) ICOM1(ON) Q (Note 3) VCOM1 = 10V, ICOM1 = 10mA VCOM1 = 10V, ICOM1 = 10mA VCOM1 = +5V, 0V, -5V; ICOM1 = 10mA C, E +25C C, E +25C C, E +25C C, E +25C -0.25 -2.5 -0.5 -5.0 -0.5 -10 100 0.06 0.03 0.03 0.05 0.3 V3.8 V+ 6 7 1 1.5 1 1.5 0.25 2.5 0.5 5.0 0.5 10 V nA nA nA pC
V+ = 16.5V, V- = -16.5V, VCOM1 = 10V, VNO1 = 10V V+ = 16.5V, V- = -16.5V, VCOM1 = 10V VCOM1 = 0, Figure 13
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V+ = 16.5V; V- = -16.5V; VCOM1 = 10V; VNO1, VNC1 =
10V
C, E +25C C, E +25C C, E +25C
Force-Sense Switches MAX4554/MAX4555/MAX4556
ELECTRICAL CHARACTERISTICS--MAX4556 (15V Supplies) (continued)
(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, VIN_H = 2.4V, VIN_L = 0.8V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER SYMBOL CONDITIONS TA MIN TYP (Note 2) MAX UNITS
60 ANALOG SWITCH (SENSE-GUARD) Analog Signal Range On-Resistance On-Resistance Match (Note 4) On-Resistance Flatness (Note 5) NO_, NC Off-Leakage Current COM_ Off-Leakage Current COM_ On-Leakage Current Charge Injection LOGIC INPUT IN_ Input Logic Threshold High IN_ Input Logic Threshold Low IN_ Input Current Logic High or Low VIN_H VIN_L IIN_H, IIN_L VIN_ = 0 or VL C, E C, E C, E 0.8 -0.5 1.6 1.6 0.03 0.5 2.4 V V A VCOM_, VNO_, VNC_ RON RON RFLAT(ON) INO_(OFF), INC_(OFF) ICOM_(OFF) ICOM_(ON) Q (Note 3) VCOM_ = 10V, ICOM_ = 10mA VCOM_ = 10V, ICOM_ = 10mA VCOM_ = +5V, 0V, -5V; ICOM_ = 10mA C, E +25C C, E +25C C, E +25C C, E +25C C, E +25C C, E +25C C, E +25C V36 5 0.6 -0.25 -2.5 -0.25 -2.5 -0.5 -5.0 0.01 0.01 0.02 5 V+ 60 70 9 10 5 6 0.25 2.5 0.25 2.5 0.5 5.0 V nA nA nA pC
V+ = 16.5V, V- = -16.5V, VCOM_ = 10V VCOM_ = 0, Figure 13
SWITCH DYNAMIC CHARACTERISTICS Transition Time (Force) Transition Time (Sense-Guard) Break-Before-Make Time NO1, NC1 Off-Capacitance (Force) COM1 On-Capacitance (Force) NO_, NC_ Off-Capacitance (Sense-Guard) COM_ On-Capacitance (Sense-Guard) Total Harmonic Distortion (Force) Off Isolation (Force) tTRANS tTRANS tBBM COFF CON COFF CON THD VISO RIN = 50, ROUT = 50, f = 1MHz, VCOM_ = 100mVRMS, Figure 15 VCOM_ = 10V, RL = 300, Figure 10 VCOM_ = 10V, RL = 1k, Figure 10 VCOM_ = 10V, RL = 1k, Figure 12 VNO1, VNC1 = GND; f = 1MHz; Figure 14 VCOM1 = GND, f = 1MHz, Figure 14 VNO_, VNC_ = GND; f = 1MHz; Figure 14 VCOM_ = GND, f = 1MHz, Figure 14 +25C C, E +25C C, E +25C +25C +25C +25C +25C +25C +25C 1 150 125 15 21 137 7 30 0.007 -30 250 300 225 275 ns ns ns pF pF pF pF % dB 9
_______________________________________________________________________________________
V+ = 16.5V; V- = -16.5V; VCOM_ = 10V; VNO_, VNC_ =
V+ = 16.5V; V- = -16.5V; VCOM_ = 10V; VNO_, VNC_ =
10V 10V
Force-Sense Switches MAX4554/MAX4555/MAX4556
ELECTRICAL CHARACTERISTICS--MAX4556 (15V Supplies) (continued)
(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, VIN_H = 2.4V, VIN_L = 0.8V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER POWER SUPPLY Power-Supply Range V+ Supply Current V- Supply Current VL Supply Current Ground Current Note 2: Note 3: Note 4: Note 5: SYMBOL VL 4.5V V+ = 16.5V, V- = -16.5V, VIN_ = 0 or VL V+ = 16.5V, V- = -16.5V, VIN_ = 0 or VL V+ = 16.5V, V- = -16.5V, VIN_ = 0 or VL V+ = 16.5V, V- = -16.5V, VIN_ = 0 or VL CONDITIONS TA MIN TYP (Note 2) MAX UNITS
V+, VL, VI+ IIL+ IGND
C, E +25C C, E +25C C, E +25C C, E +25C C, E
4.5 -1.0 -5.0 -1.0 -5.0 -1.0 -5.0 -1.0 -5.0
0.001 0.001 0.001 0.001
20 1.0 5.0 1.0 5.0 1.0 5.0 1.0 5.0
V A A A A
The algebraic convention is used in this data sheet; the most negative value is shown in the minimum column. Guaranteed by design. RON = RON(MAX) - RON(MIN). Resistance flatness is defined as the difference between the maximum and the minimum value of on-resistance as measured over the specified analog signal range.
10
______________________________________________________________________________________
Force-Sense Switches
__________________________________________Typical Operating Characteristics
(V+ = +15V, V- = -15V, GND = 0V, TA = +25C, unless otherwise noted.)
SWITCH ON-RESISTANCE vs. VCOM (DUAL SUPPLIES)
MAX4554/5/6-01
MAX4554/MAX4555/MAX4556
MAX4554 FORCE SWITCH ON-RESISTANCE vs. VCOM AND TEMPERATURE
MAX4554/5/6-02
SENSE/GUARD SWITCH ON-RESISTANCE vs. VCOM AND TEMPERATURE
55 50 45 RDS(ON) () 40 35 30 25 20 15 TA = -40C TA = +25C TA = +85C
MAX4554/5/6-03
40 35 SWITCH ON-RESISTANCE () 30 25 20 MAX4555 SENSE 15 10 5 0 -15 -10 -5 0 VCOM (V) 5 10 FORCE MAX4554/MAX4556 SENSE & GUARD
6 5 4 3 TA = +25C 2 TA = -40C 1 0 TA = +85C
60
RDS(ON) ()
10 -10 -5 0 5 VCOM (V) 10 15 20 -15 -10 -5 0 VCOM (V) 5 10 15
15
SWITCH ON-RESISTANCE vs. VCOM (SINGLE +15V SUPPLY)
MAX4554/5/6-04
ON-LEAKAGE CURRENT vs. TEMPERATURE
V+ = 15V, V- = -15V, VCOM = 10V FORCE
MAX4554/5/6-05
100
100 10 ON-LEAKAGE (nA) 1 0.1 0.01 0.001
SWITCH ON-RESISTANCE ()
MAX4554/MAX4556 SENSE & GUARD
10
MAX4555 SENSE
SENSE & GUARD
FORCE
1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 VCOM (V)
0.0001 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
OFF-LEAKAGE CURRENT vs. TEMPERATURE
V+ = 15V, V- = -15V, VNC OR VNO = 10V VCOM = 10V
MAX4554/5/6-06
MAX4554 CHARGE INJECTION vs. VCOM (+20V, -10V SUPPLIES)
FORCE
MAX4554/5/6-07
100 10 OFF-LEAKAGE (nA) 1 0.1 0.01 0.001 0.0001 -50
100 80 60 Q (pC) 40 20
FORCE SENSE & GUARD
0 -20 -40
SENSE & GUARD
-25
0
25
50
75
100
125
-10
-5
0
5 VCOM (V)
10
15
20
TEMPERATURE (C)
______________________________________________________________________________________
11
Force-Sense Switches MAX4554/MAX4555/MAX4556
____________________________________Typical Operating Characteristics (continued)
(V+ = +15V, V- = -15V, GND = 0V, TA = +25C, unless otherwise noted.)
MAX4555/MAX4556 CHARGE INJECTION vs. VCOM (+15V SUPPLIES)
MAX4554/5/6-08
MAX4554 ON/OFF/ENABLE TIMES vs. TEMPERATURE (+20V, -10V SUPPLIES)
MAX4554/5/6-09
MAX4555/4556 ON/OFF/TRANSITION TIMES vs. TEMPERATURE (+20V/-10V SUPPLIES)
160 140 120 TIME (ns) 100 80 60 MAX4556 tTRANS MAX4555 tON/tOFF
MAX4554/5/6-10
100 80 60 Q (pC) 40 20 0 -20 -40 -15 -10 -5 0 VCOM (V) 5 10 SENSE & GUARD
500 450 400 350 TIME (ns) 300 250 200 150 100 50 0 tOFF -40 -15 10 35 60 tON tEN(OFF) tEN(ON)
180
FORCE
40 20 0 85 -40 -15 10 35 60 85
15
TEMPERATURE (C)
TEMPERATURE (C)
SUPPLY CURRENT vs. TEMPERATURE
A: I+ = 16.5V B: I- = -16.5V 10 C: IL = 5.5V 1 0.1
A
MAX4554/5/6-11
LOGIC-LEVEL THRESHOLD vs. LOAD VOLTAGE
MAX4554/5/6-12
100
6 5 4 3 2 1
0.01 0.001
B
C
LOGIC-LEVEL THRESHOLD (V)
I+, I-, IL (A)
0.0001 -75 -55 -50 -25
0 0 25 50 75 85 100 0 5 10 VL (V) 15 20 25
TEMPERATURE (C)
FORCE SWITCH FREQUENCY RESPONSE
0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 0.1 1 10 FREQUENCY (MHz) 100 1000
MAX4554/5/6-13
FORCE SWITCH TOTAL HARMONIC DISTORTION vs. FREQUENCY
V+ = +15V V- = -15V 5Vp-p, 600 IN & OUT
MAX4554/5/6-14
ON LOSS
180 150 120 90 60 30 0 -30 -60 -90 -120 -150 -180
100
10 PHASE (degrees)
SWITCH LOSS (dB)
OFF LOSS
THD (%)
1
0.1
ON PHASE
0.01
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
12
______________________________________________________________________________________
Force-Sense Switches
Pin Description
PIN MAX4554 1 -- 2 -- 3* -- -- 4 5 6* -- 7 -- 8 9 11, 10 12 13 14* 15 16 MAX4555 -- -- -- 2, 15*, 10*, 7 -- 3, 14, 11, 6 -- 4 5 -- -- -- -- -- -- 1, 16, 9, 8 12 13 -- -- -- MAX4556 -- 1, 2 -- 14*, 15, 16 -- -- 3* 4 5 -- 6* -- 7, 8 -- -- 9, 10, 11 12 13 -- -- -- NAME NOG1 NO3, NO2 NOS1 COM1, COM2 COM3, COM4 NOF1* NC1, NC2, NC3, NC4 NO1* VGND NOF2* NC1* NOS2 NC2, NC3 NOG2 EN IN1, IN2, IN3, IN4 VL V+ COMF* COMS COMG FUNCTION Analog Guard Channel 1 Normally Open Terminal Analog Signal Normally Open Terminals Analog Sense Channel 1 Normally Open Terminal Analog Signal Common Terminals. COM2 and COM3 are low-resistance (force) switches on the MAX4555. COM1 is a low-resistance (force) switch on the MAX4556. Analog Force Channel 1 Normally Open Terminal Analog Signal Normally Closed Pins. NC2 and NC3 are low-resistance (force) switches. Analog Force Signal Normally Open Terminal Negative Analog Supply Voltage Input. Connect to GND for singlesupply operation. Ground. Connect to digital ground. (Analog signals have no ground reference; they are limited to V+ and V-.) Analog Force Channel 2 Normally Open Terminal Analog Force Signal Normally Closed Terminal Analog Sense Channel 2 Normally Open Terminal Analog Signal Normally Closed Terminal Analog Guard Channel 2 Normally Open Terminal Enable Logic-Level Digital Input. Connect to GND to enable all switches. Logic-Level Digital Inputs. See Truth Tables. Logic-Level Positive Supply Input. Connect to logic (+5V) supply. Can be connected to V+ for single-supply operation. Positive Analog Supply Voltage Input. Internally connected to substrate. Analog Force Channel Common Terminal Analog Sense Channel Common Terminal Analog Guard Channel Common Terminal
MAX4554/MAX4555/MAX4556
* Indicates high-current, low-resistance (force) switch terminal. Note: NO_, NC_, and COM_ pins are identical and interchangeable. Any may be considered as an input or output; signals pass equally well in either direction.
______________________________________________________________________________________
13
Force-Sense Switches MAX4554/MAX4555/MAX4556
______________Force-Sense Philosophy
When a precise voltage must be applied to a load that draws appreciable current, the resistance of the conductors connecting the source and the load can degrade the load voltage. The resistance of the conductors forms a voltage divider with the load, so that the load voltage is lower than the source voltage. The greater the distance between the source and the load, and the greater the current or conductor resistance, the greater the degradation. The resulting signal reduction can be overcome and the signal at the load guaranteed by using a 4-wire technique known as Kelvin sensing, or force-sense. The basic idea behind the force-sense philosophy is to use four wires, forcing a voltage or current through two high-current wires to the load, and measuring (sensing) the voltage with two separate wires that carry very low or negligible current. One of two basic configurations is used, depending on whether or not feedback is employed: 1) The sensed voltage can be completely independent of the forced voltage or current, as in the case of a 4-wire ohmmeter, where a constant current is forced through one pair of wires and the voltage at the resistor is measured by another pair. 2) The sensed voltage can be part of a feedback circuit to force the load voltage to the desired value, as in the case of a 4-wire power supply. (In rare cases, this method is also used to measure resistance; the source is forced to produce a desired voltage in the resistor, and the source current required to achieve this voltage is measured.) In all cases, the resistance of the high-current conductors can be ignored and the sensed voltage is an accurate measure of the load (or resistor's) voltage, despite appreciable voltage loss in the wires connecting the source and load. There are two limitations to this scheme. First, the maximum source voltage (compliance) must be able to overcome the combined voltage loss of the load and the connecting wires. In other words, the conductors in the force circuit can have significant resistance, but there is a limit. Second, the impedance of the sensing circuit (typically a voltmeter, A/D converter, or feedback amplifier) must be very high compared to the load resistance and the sense wire resistance. These limitations are usually simple to overcome. The source compliance is usually required to be only a volt more than the load voltage, and the sense circuit usually has a multimegohm impedance. Typical 4-wire force-sense configurations are shown in Figure 1.
14
4-WIRE RESISTANCE MEASUREMENT (CONSTANT CURRENT) FORCE CURRENT VOLTAGE MEASUREMENT V SENSE VOLTAGE FORCE CURRENT CURRENT SOURCE WIRE AND TERMINAL RESISTANCE SENSE VOLTAGE MEASURED RESISTANCE
4-WIRE POWER SUPPLY FORCE CURRENT VOLTAGE MEASUREMENT FEEDBACK V SENSE VOLTAGE LOAD SENSE VOLTAGE FORCE CURRENT CURRENT SOURCE WIRE AND TERMINAL RESISTANCE
4-WIRE RESISTANCE MEASUREMENT (CONSTANT VOLTAGE)
V FORCE VOLTAGE FEEDBACK V SENSE VOLTAGE VOLTAGE MEASUREMENT VOLTAGE SOURCE WIRE AND TERMINAL RESISTANCE FORCE VOLTAGE SENSE VOLTAGE MEASURED RESISTANCE
ARROWS INDICATE SIGNAL DIRECTION, NOT POLARITY
Figure 1. 4-Wire Force-Sense Measurements
______________________________________________________________________________________
Force-Sense Switches
__________________Guard Philosophy
When measuring a precise voltage from a high-resistance source, or when measuring a very small current or forcing it into a load, unwanted leakage currents can degrade the results. These leakage currents may exist in the insulation of wires connecting the source and the measuring device. Higher source voltages, higher source impedances, longer wires, lower currents, and higher temperatures further degrade the measurement. The effect has both DC and low-frequency AC components; AC signals are generally capacitively coupled into the high-impedance source and wiring. The AC and DC effects are hard to separate, and are generally grouped under the designation "low-frequency noise." This signal degradation can be overcome and the measured signal guaranteed by using a 3-wire technique known as guarding. A "guard," "guard channel," or "driven guard" is formed by adding a third wire to a 2-wire measurement. It consists of a physical barrier (generally the surrounding shield of a coaxial cable) that is actively forced to the same voltage as is being measured on its inner conductor. The forcing of the driven guard is from the output of a low-impedance buffer amplifier whose high-impedance input is connected to the source. The idea is not just to buffer or shield the signal with a low-impedance source but, by forcing the shield to the same potential as the signal, to also force the leakage currents between the signal and the outside world to extremely small values. Any unwanted leakage current from the source must first go through the coaxial-cable insulation to the shield. Since the shield is at the same potential, there is virtually no unwanted leakage current, regardless of the insulation resistance. The shield itself can have significant leakage currents to the outside world, but it is separated from the measured signal. The physical positioning of the guard around the signal is extremely important in maintaining low leakage. Since the guard can be at potentials far from ground, conventional coaxial cable is often replaced by triaxial cable (i.e., cable with a center conductor and two separate inner and outer shields). The signal is the center conductor, the inner shield is the guard, and the outer shield is the chassis ground. The outer shield isolates the inner driven guard from ground, physically protects the driven guard, and acts as a secondary Faraday shield for external noise. The physical guard must be maintained continuously from the source to the measuring device, including paths on printed circuit boards, where the guard becomes extra traces surrounding the signal traces on both sides (and above and below the signal traces on multilevel boards.) This is one case where a ground plane is not appropriate. In extreme cases, such as with nano-voltmeters and femto-ammeters, printed circuit boards cannot be adequately shielded and are eliminated from the guarded signal paths altogether. Figure 2 shows both the basic 3-wire guarded measurement and a 5-wire variation, used for balanced signals that are elevated from ground potential. The 5-wire configuration is really two 3-wire circuits sharing a common ground. Figure 2 also shows the configuration using triaxial cable.
MAX4554/MAX4555/MAX4556
____Force-Sense-Guard Philosophy
Force-sense measurements are combined with guarded measurements when a wide range of voltages and currents are encountered, or when voltage and current must be accurately measured or controlled simultaneously. This frequently occurs in automatic test equipment (ATE) and in some critical physical or chemical sensor applications where voltage and/or current measurements can span many decades. Two techniques are used: 8-wire and 12-wire.
8-Wire Measurements
Figure 3 shows an 8-wire guarded force-sense power supply. A precise voltage is forced to the load, and load current is sensed without interacting with the output voltage, and without unwanted leakage currents. Separate twin-axial, or "twinax" cable is used for each of the positive and negative wires. Each cable has a twisted-pair of wires surrounded by a common shield, which is connected as the driven guard. Since the force and sense wires are at approximately the same potential, they can be protected by the same driven guard. In critical applications, two special 4-wire cables and connectors are substituted for the two twinax cables and separate ground wire. These cables add a second shield, which replaces the chassis-to-chassis ground wire and reduces noise. Figure 3 shows current sensing with a fixed precision resistor and voltmeter, but other methods (such as op amps with feedback) are frequently employed, particularly if current limiting is required. One of the advantages of Figure 3's circuit is that leakage in the current-sensing path has no effect on the output voltage. The two diodes in the force-sense feedback path protect the force-sense amplifier from operating open loop if either the force or sense wires are disconnected from the load. These diodes must have both lower forward voltage and lower reverse leakage than the current being measured.
______________________________________________________________________________________
15
Force-Sense Switches MAX4554/MAX4555/MAX4556
BASIC 3-WIRE GUARD CIRCUIT
DRIVEN GUARD (COAX CABLE SHIELD)
BALANCED 5-WIRE GUARD CIRCUIT
DRIVEN GUARD (COAX CABLE SHIELD)
GUARD AMPLIFIER
GUARD AMPLIFIER
SENSE VOLTAGE OR CURRENT LEAKAGE CURRENT
LEAKAGE CURRENT VOLTAGE OR CURRENT SOURCE
VOLTAGE OR CURRENT SOURCE
SENSE VOLTAGE OR CURRENT
LEAKAGE CURRENT
3-WIRE GUARD CIRCUIT USING TRIAX
TRIAX CABLE SIGNAL GUARD GROUND GUARD AMPLIFIER SENSE VOLTAGE OR CURRENT LEAKAGE CURRENT GUARD AMPLIFIER
DRIVEN GUARD (COAX CABLE SHIELD)
TRIAX CABLE/CONNECTOR VOLTAGE OR CURRENT SOURCE CENTER WIRE INNER SHEILD OUTER SHEILD
Figure 2. 3-Wire and 5-Wire Guarded Measurements
16
______________________________________________________________________________________
Force-Sense Switches MAX4554/MAX4555/MAX4556
8-WIRE PRECISION SOURCE-MONITOR
FORCE-SENSE AMPLIFIER V+ CURRENT SENSE V VV+ +FORCE +SENSE +DRIVEN GUARD TWINAX CABLE
GUARD AMPLIFIER VV+ LEAKAGE CURRENT VOLTAGE SOURCE LEAKAGE CURRENT V+ VLOAD
GUARD AMPLIFIER V+V V CURRENT SENSE VFORCE-SENSE AMPLIFIER -DRIVEN GUARD -SENSE -FORCE TWINAX CABLE
Figure 3. 8-Wire Guarded Force-Sense Measurements
Note that although the positive and negative circuits are identical, they are not redundant. Both are always used, even when one side of the load is grounded, because maintaining a precision output voltage requires losses in the ground leads to be corrected by a force-sense amplifier. If more than one power supply and load are operated together, and they have a common connection, this requirement becomes even more critical. Separate 8-wire connections prevent current changes in one load from changing voltage in the other load.
12-Wire Measurements
Figure 4 shows a 12-wire circuit, which is an elaboration of the 8-wire system using separate driven guards for the force and sense wires. Four sets of triaxial
cables and connectors are used. The extra wires are used for two reasons: 1) They provide better shielding by having separate chassis grounds on each cable, rather than separate ground wires external to the signal cables; 2) In test equipment, where connection changes are frequent, it is very convenient to use four triax connectors or two quadrax (dual triax) connectors for each load. In addition, this method is slightly better for power supplies or measurements that switch between constant voltage and constant current, since separate driven guards reduce circuit capacitance. Also, when troubleshooting, it is convenient to be able to interchange force and sense leads.
17
______________________________________________________________________________________
Force-Sense Switches MAX4554/MAX4555/MAX4556
12-WIRE PRECISION SOURCE-MONITOR
+ FORCE-SENSE AMPLIFIER V+ CURRENT SENSE V VV+ TRIAX CABLE +FORCE +GUARD GROUND
V+ FORCE-GUARD AMPLIFIER V+ TRIAX CABLE +SENSE +GUARD GROUND
LEAKAGE CURRENT
+SENSE GUARD AMPLIFIER VLEAKAGE CURRENT
V+ VOLTAGE SOURCE (OPTIONAL GROUND) LOAD
VLEAKAGE CURRENT V+
- SENSE-GUARD AMPLIFIER V- FORCE-GUARD AMPLIFIER V+
GROUND - GUARD -SENSE TRIAX CABLE LEAKAGE CURRENT
+V V CURRENT SENSE V- FORCE-SENSE AMPLIFIER
Figure 4. 12-Wire Guarded Force-Sense Measurements
18 ______________________________________________________________________________________
+V VGROUND - GUARD - FORCE TRIAX CABLE TRIAX CABLE/CONNECTOR CENTER WIRE (FORCE/SENSE) INNER SHEILD (GUARD) OUTER SHEILD (GROUND)
Force-Sense Switches
Switching Guarded and Force-Sense Signals
When a precision source or measurement must be connected sequentially to several circuits, all sense and guard connections must be switched simultaneously, and at least one of the force connections must be switched. To maintain safety and low noise levels, the ground (or chassis) connection should never be disconnected. The force circuit switch should have low-resistance, high-current capability, but the sense and guard circuit switches require only moderate resistance and current capability. The sense and guard switches should have lower leakage than the lowest measured current. CMOS switches should also be operated from power supplies higher than the highest circuit voltage to be switched.
Switch Resistances
Each IC contains four internal switches: four low-current sense-guard switches and two high-current force switches. Each sense-guard switch has an on-resistance of approximately 60, while each force switch has an on-resistance of approximately 6. The MAX4555's two low-current sense-guard switches are connected in parallel to produce lower on-resistance and allow higher current.
MAX4554/MAX4555/MAX4556
Power-Supply Considerations
Overview The MAX4554/MAX4555/MAX4556's construction is typical of most CMOS analog switches. They have four supply pins: V+, V-, VL, and GND. V+ and V- are used to drive the internal CMOS switches and set the analog voltage limits on any switch. Reverse ESD protection diodes are internally connected between each analog and digital signal pin and both V+ and V-. If any signal exceeds V+ or V-, one of these diodes will conduct. During normal operation these reverse-biased ESD diodes leak, forming the only current drawn from the signal paths.
Virtually all the analog leakage current comes through the ESD diodes to V+ or V-. Although the ESD diodes on a given signal pin are identical, and therefore fairly well balanced, they are reverse biased differently. Each is biased by either V+ or V- and the analog signal. This means their leakages vary as the signal varies. The difference in the two diode leakages from the signal path to the V+ and V- pins constitutes the analog-signal-path leakage current. All analog leakage current flows to the supply terminals, not to the other switch terminal. This explains how both sides of a given switch can show leakage currents of either the same or opposite polarity. There is no connection between the analog signal paths and GND or VL. The analog signal paths consist of an N-channel and P-channel MOSFET with their sources and drains paralleled, and their gates driven out of phase to V+ and V- by the logic-level translators. VL and GND power the internal logic and logic-level translator and set the input logic threshold. The logiclevel translator converts the logic levels to switched V+ and V- signals for driving the gates of the analog switches. This drive signal is the only connection between GND and the analog supplies. V+ and V- have ESD-protection diodes to GND. The logic-level inputs (IN_, and EN) have ESD protection to V+ and V-, but not to GND; therefore, the logic signal can go below GND (as low as V-) when bipolar supplies are used. The logic-level threshold VIN is CMOS and TTL compatible when VL is between 4.5V and 36V (see Typical Operating Characteristics).
19
_______________Detailed Description
The MAX4554/MAX4555/MAX4556 are CMOS analog ICs configured as force-sense switches. Each part contains low-resistance switches for forcing current, and higher resistance switches for sensing a voltage or driving guard wires. Analog signals on the force, sense, or guard circuits can range from V- to V+. Each switch is completely symmetrical and signals are bidirectional; any switch terminal can be an input or output. The switches' open or closed states are controlled by TTL/CMOS-compatible input (IN_) pins. The MAX4555 and MAX4556 are characterized and guaranteed only with 15V supplies, but they can operate from a single supply up to +44V or non-symmetrical supplies with a voltage totaling less than +44V. The MAX4554 is fully characterized for operation from 15V supplies, and it is also fully specified for operation with +20V and -10V supplies. A separate logic supply pin, VL, allows operation with +5V or +3V logic, even with unusual V+ values. The negative supply pin, V-, must be connected to GND for single-supply operation. The MAX4554 contains two force switches, two sense switches, and two guard switches configured as two 3PST switches. The two switches operate independently of one another, but they have a common connection, allowing one source to be connected simultaneously to two loads, or two sources to be connected to one load. An enable pin, EN, turns all switches off when driven to logic high. The MAX4554 is also fully specified for operation with +20V and -10V supplies. The MAX4555 contains four independent SPDT, NC switches; two are force switches and two are sense switches. The MAX4556 contains three independent SPDT switches; one is a force switch and two are sense switches.
______________________________________________________________________________________
Force-Sense Switches MAX4554/MAX4555/MAX4556
Increasing V- has no effect on the logic-level thresholds, but it does increase the drive to the internal Pchannel switches, reducing the overall switch on-resistance. V- also sets the negative limit of the analog signal voltage. nected to GND. All of the bipolar precautions must be observed.
__________Applications Information
Switching 4-Wire Force-Sense Circuits
Figure 5 shows how to switch a single voltage or current source between two loads using two MAX4555s. A single CMOS inverter ensures that only one switch is on at a time. On each MAX4555, switches 2 and 3 are the high-current switches, so they should be used for force circuits. By interchanging loads and sources, the circuit can be reversed to switch two sources to a single load. Additional MAX4555s and loads or sources can be added to expand the circuit, but additional IN_ address decoding must be incorporated.
Bipolar-Supply Operation The MAX4554/MAX4555/MAX4556 operate with bipolar supplies between 4.5V and 18V. However, since all factory characterization is done with 15V supplies (and +20V, -10V for MAX4554), operation at other supplies is not guaranteed. The V+ and V- supplies need not be symmetrical, but their sum cannot exceed the absolute maximum rating of 44V (see Absolute Maximum Ratings). VL must not exceed V+. Single-Supply Operation The MAX4554/MAX4555/MAX4556 operate from a single supply between +4.5V and +44V when V- is con-
V+
V-
VL
FORCE SENSE FEEDBACK V SENSE FORCE VOLTAGE/CURRENT SOURCE
COM2 COM1
MAX4555
NC2 NC1 LOAD1
COM4 COM3 IN2 IN1 NC4 NC3 GND
LOGIC IN LOAD 0 1 2 1
CMOS INVERTER IN
IN4 IN3 V+ VVL
COM2 COM1
MAX4555
NC2 NC1 LOAD2
COM4 COM3 IN2 IN1 IN4 IN3
NC4 NC3
GND
Figure 5. Using the MAX4555 to Switch 4-Wire Force-Sense Circuits from One Source to Two Loads
20 ______________________________________________________________________________________
Force-Sense Switches
Figure 6 shows how to switch a single voltage or current source between two loads using the MAX4554 or MAX4556. By interchanging loads and sources, the circuits can be reversed so that they switch two sources to a single load. The two loads are electrically connected together at one point, but may be physically separated. This means that one force wire does not need to be switched, but the corresponding sense wires do. The MAX4554 has independent 3PST, NO switches driven out of phase by an external CMOS inverter, so that one switch is on while the other is off. If both switches were turned on at the same time, both loads would be connected, and the resulting voltage at either load would be close to (but not exactly equal to) the desired value; this would not cause any damage to the device.
MAX4554/MAX4555/MAX4556
Switching 3-Wire Guarded Circuits
Figure 7 shows how to switch a single guarded voltage or current source between two loads using the MAX4554 or MAX4556. By interchanging loads and sources, the circuits can be reversed to switch two sources to a single load. If the loads have a common connection, the switch to that node can be eliminated. Note that these circuits use sense (high-resistance) switches to switch the common wire. This is permissible only if the load currents are very low. If the currents are high, the common connection should not be switched unless another force switch is substituted.
V+
V-
VL
MAX4556
FORCE SENSE FEEDBACK V SENSE FORCE VOLTAGE/CURRENT SOURCE LOGIC IN LOAD 0 1 1 2 IN1 IN2 IN IN3 COM3 COM1 COM2
NC1 NO1 NC2 NO2 NC3 NO3 LOAD2 LOAD1
GND
V+
V-
VL
MAX4554
FORCE SENSE FEEDBACK V SENSE FORCE VOLTAGE/CURRENT SOURCE LOGIC IN LOAD 0 1 1 2 IN IN1 GCOM FCOM SCOM
NOF1 NOF2 NOS1 NOS2 LOAD2 NOG2 NOG1 GND EN LOAD1
IN2 CMOS INVERTER
Figure 6. Using the MAX4554/MAX4556 to Switch 4-Wire Force-Sense Circuits from One Source to Two Loads
______________________________________________________________________________________ 21
Force-Sense Switches MAX4554/MAX4555/MAX4556
V+ VVL
MAX4556
GUARD AMPLIFIER COM1 COM2 COM3
NC1 NO1 NC2 NO2 NC3 NO3 LOAD2 LOAD1
IN1 IN2 VOLTAGE OR CURRENT SOURCE LOGIC LOAD 1 2 IN IN3 GND
IN 0 1
V+
V-
VL
MAX4554
GUARD AMPLIFIER GCOM FCOM
NOG1 NOG2 NOF1 NOF2 LOAD2 NOS1 NOS2 GND EN LOAD1
SCOM
IN1
VOLTAGE OR CURRENT SOURCE LOGIC LOAD 1 2 IN IN2 CMOS INVERTER
IN 0 1
Figure 7. Using the MAX4554/MAX4556 to Switch 3-Wire Guarded Circuits from One Source to Two Loads
22
______________________________________________________________________________________
Force-Sense Switches
Figure 8 shows how to switch a single guarded voltage or current source between two grounded loads using a MAX4555. By interchanging loads and sources, the circuits can be reversed so that two sources are switched to a single load.
High-Frequency Performance
Although switching speed is restricted, once a switch is in a steady state it exhibits good RF performance. In 50 systems, signal response is reasonably flat up to 50MHz (see Typical Operating Characteristics). The force switches have lower on-resistance, so their insertion loss in 50 systems is lower. Above 20MHz, the on-response has several minor peaks that are highly layout dependent. The problem with high-frequency operation is not turning the switches on, but turning them off. The off-state switches act like capacitors and pass higher frequencies with less attenuation. At 10MHz, off-isolation between input or output signals is approximately -30dB in 50 systems, degrading (approximately 20dB per decade) as frequency increases. Higher circuit impedances also degrade offisolation.
MAX4554/MAX4555/MAX4556
Switching 8-Wire Guarded Circuits
Figure 9 shows how to switch a single 8-wire guarded force-sense voltage or current source between two loads using two MAX4556s or two MAX4554s. By interchanging loads and sources, the circuits can be reversed so that they switch two sources to a single load. The two loads are shown isolated from each another, but if they have a common connection then the circuit must remain as shown in order to maintain accurate load voltage.
V+
V-
VL
COM1 GUARD AMPLIFIER COM2
MAX4555
NC1 NC2 LOAD2
COM3 COM4 IN1 IN2 IN3 VOLTAGE OR CURRENT SOURCE LOGIC LOAD 2 1 IN IN4 NC3 NC4 GND LOAD1
IN 0 1
Figure 8. Using the MAX4555 to Switch 3-Wire Guarded Circuits from One Source to Two Loads
______________________________________________________________________________________
23
Force-Sense Switches MAX4554/MAX4555/MAX4556
FORCE-SENSE AMPLIFIER V+ CURRENT SENSE
MAX4556
V+
V-
VL NC1 NC2 NC3 NO1 NO2 NO3 GND IN3
TWINAX CABLE +FORCE +SENSE +DRIVEN GUARD
V+
V-
VL
V VV+ COM1 COM2 COM3 IN1 GUARD AMPLIFIER VVOLTAGE SOURCE V+ VV+ GND GUARD AMPLIFIER VV+ V CURRENT SENSE VFORCE-SENSE AMPLIFIER V+ LOGIC IN A,B LOAD 0 1 1 2 CURRENT SENSE
MAX4554
MAX4556
COM1 COM2 COM3 IN1 IN2 IN IN3
NC1 NO1 NC2 NO2 NC3 NO3 INA
IN2
V+
LEAKAGE CURRENT LEAKAGE CURRENT VVL LOAD 1 LOAD 2
MAX4556
COM1 COM2 COM3
NC1 NC2 NC3 NO1 NO2 NO3 GND IN2 IN3
IN1 INA V+
-DRIVEN GUARD -SENSE -FORCE TWINAX CABLE TWINAX CABLE +FORCE +SENSE +DRIVEN GUARD
V-
VL NC1 NC2 NC3 NO1 NO2 NO3 EN GND
V VV+ VVL V+ COMF COMS COMG
MAX4554
NOG1 COMG COMF COMS IN1 NOG2 NOF1 NOF2 NOS1 NOS2 EN GND IN2 LOGIC IN A,B LOAD 0 2 1 1 VV+ V-
GUARD AMPLIFIER V+
IN1 INB
IN2 LEAKAGE CURRENT LEAKAGE CURRENT LOAD 1 LOAD 2
VOLTAGE SOURCE V+ VV+ GUARD AMPLIFIER
V-
VL
MAX4554
COMG COMS COMF V CURRENT SENSE
IN
CMOS INVERTER
VFORCE-SENSE AMPLIFIER
LOGIC IN A,B LOAD 0 2 1 1
IN1 INB
NOG1 NOS1 NOF1 NOG2 NOS2 NOF2 EN GND IN2
-DRIVEN GUARD -SENSE -FORCE TWINAX CABLE
Figure 9. Switching 8-Wire Guarded Force-Sense Measurements from One Precision Source-Monitor to Two Loads
24 ______________________________________________________________________________________
Force-Sense Switches
______________________________________________Test Circuits/Timing Diagrams
V+ V+ VL VL NO_ OR NC_ VIN_ IN_ 50 EN V+ VIN_ 0V VL
MAX4554/MAX4555/MAX4556
50%
MAX4554 MAX4555 MAX4556 COM_
GND VV300
VOUT 35pF VOUT
V+ 90%
90% 0V tOFF tON
V- IS CONNECTED TO GND (0V) FOR SINGLE-SUPPLY OPERATION.
Figure 10. Address Transition Time
V+ VL ADDRESS SELECT IN_ V+ VL VL NO_ V+ VEN 0V VL 50%
MAX4554
VEN EN 50 GND COM_ VV0V tTRANS V- IS CONNECTED TO GND (0V) FOR SINGLE-SUPPLY OPERATION. tTRANS 300 VOUT 35pF VOUT 90% V+ 90%
Figure 11. Enable Transition Time
V+ VIN_ V+
VL VL VIN_ NO_ NC_ COM_ VOUT VOUT 300 35pF V+
V+ 50% 0V
t R < 5ns t F < 5ns
IN_
50
MAX4556
VNO_, NC_ 80%
GND
VV-
0V tOPEN
V- IS CONNECTED TO GND (0V) FOR SINGLE-SUPPLY OPERATION.
Figure 12. Break-Before-Make Interval
______________________________________________________________________________________ 25
Force-Sense Switches MAX4554/MAX4555/MAX4556
_________________________________Test Circuits/Timing Diagrams (continued)
V+ VIN_ 50 IN_ V+ VL VL NO_ OR NC_ VIN 0V VL
MAX4554 MAX4555 MAX4556 COM_
EN GND VVCL 1000pF
VOUT
VOUT
VOUT
VOUT IS THE MEASURED VOLTAGE DUE TO CHARGE TRANSFER ERROR Q WHEN THE CHANNEL TURNS OFF. Q = VOUT x CL
V- IS CONNECTED TO GND (0V) FOR SINGLE-SUPPLY OPERATION.
Figure 13. Charge Injection
V+ V+ VL VL NO_ NC_ COM_ GND VV1MHz CAPACITANCE ANALYZER
VL ADDRESS SELECT IN_ EN
MAX4554 MAX4555 MAX4556
Figure 14. COM_, NO_, NC_ Capacitance
V+ 10nF
VL 10nF NETWORK ANALYZER OFF ISOLATION = 20 log 50 50 ON LOSS = 20 log VOUT MEAS. REF CROSSTALK = 20 log 50 10nF 50 VOUT VIN VOUT VIN
V+
VL
COM_
VIN
VOUT VIN
VL ADDRESS SELECT IN_ EN
MAX4554 MAX4555 MAX4556
GND NO_, NC_ V-
VMEASUREMENTS ARE STANDARDIZED AGAINST SHORT AT SOCKET TERMINALS. OFF ISOLATION IS MEASURED BETWEEN COM_ AND "OFF" NO_ OR NC_ TERMINALS. ON LOSS IS MEASURED BETWEEN COM_ AND "ON" NO_ OR NC_ TERMINALS. CROSSTALK IS MEASURED BETWEEN COM_ TERMINALS WITH ALL SWITCHES ON. SIGNAL DIRECTION THROUGH SWITCH IS REVERSED; WORST VALUES ARE RECORDED. V- IS CONNECTED TO GND (0V) FOR SINGLE-SUPPLY OPERATION.
Figure 15. Frequency Response, Off-Isolation, and Crosstalk
26 ______________________________________________________________________________________
Force-Sense Switches MAX4554/MAX4555/MAX4556
__________Pin Configurations/Functional Diagrams/Truth Tables (continued)
TOP VIEW
MAX4555
IN1 1 COM1 2 NC1 3 V- 4 GND 5 NC4 6 COM4 7 IN4 8 16 IN2 15 COM2* 14 NC2* 13 V+ 12 VL 11 NC3* 10 COM3 9 IN3 NO3 1 N02 2 NO1* 3 V- 4 GND 5 NC1* 6 NC2 7 NC3 8
MAX4556
16 COM3 15 COM2 14 COM1* 13 V+ 12 VL 11 IN1 10 IN2 9 IN3
DIP/SO
MAX4555 IN_ SWITCH 0 1 ON OFF
DIP/SO
MAX4556 IN_ COM_ 0 1 NC_ NO_
SWITCH POSITIONS SHOWN WITH IN_ = LOW *INDICATES HIGH-CURRENT, LOW-RESISTANCE FORCE SWITCH
Ordering Information (continued)
PART MAX4555CPE MAX4555CSE MAX4555C/D MAX4555EPE MAX4555ESE MAX4556CPE MAX4556CSE MAX4556C/D MAX4556EPE MAX4556ESE TEMP. RANGE 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C PIN-PACKAGE 16 Plastic DIP 16 Narrow SO Dice* 16 Plastic DIP 16 Narrow SO 16 Plastic DIP 16 Narrow SO Dice* 16 Plastic DIP 16 Narrow SO
*Contact factory for availability.
______________________________________________________________________________________
27
Force-Sense Switches MAX4554/MAX4555/MAX4556
_________________________________________________________________________Chip Topographies
MAX4554
NOG1 COMG
MAX4555
IN1 IN2
NOS1 NOF1
COMS
COM1 NC1
COM2
COMF VV+ 0.190" (4.83mm)
NC2 VV+ 0.190" (4.83mm)
GND
GND
VL
VL
IN1 NOF2 NOS2 NOG2 0.086" (2.18mm) EN IN2
NC3 NC4 COM4 IN4 IN3 0.086" (2.18mm) COM3
MAX4556
NO3 COM3
NO2 NO1
COM2
COM1 VV+ 0.190" (4.83mm)
GND
VL
IN1 NC1 NC2 NC3 IN3 0.086" (2.18mm) IN2
TRANSISTOR COUNT: 197 SUBSTRATE IS INTERNALLY CONNECTED TO V+
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
28 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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