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19-2743; Rev 1; 5/03
High-Accuracy, 76V, High-Side Current Monitors in SOT23
General Description
The MAX4007/MAX4008 precision, high-side, high-voltage current monitors are specifically designed for monitoring photodiode current in fiber applications. They offer a connection point for the reference current and a monitor output that produces a signal proportional to the reference current. The monitor output of the MAX4007 is a current proportional to the reference current. The monitor output of the MAX4008 is a voltage proportional to the reference current. The current monitors have six decades of dynamic range and monitor reference currents of 250nA to 2.5mA with better than 5% accuracy. The photodiode current can be monitored from 10nA to 10mA with reduced accuracy. The MAX4007/MAX4008 accept a supply voltage of +2.7V to +76V, suitable for APD or PIN photodiode applications. Internal current limiting (20mA, typ) protects the devices against short circuit to ground. A clamp diode protects the monitor output from overvoltage. Additionally, these devices feature thermal shutdown if the die temperature reaches +150C. The MAX4007/MAX4008 are available in tiny, spacesaving 6-pin SOT23 packages, and operate over the extended temperature range of -40C to +85C.
Features
o Wide Reference Current Dynamic Range Guaranteed 250nA to 2.5mA with 5% Monitor Accuracy Extended 10nA to 10mA with 10% Monitor Accuracy o Current (MAX4007) or Voltage (MAX4008) Monitor Outputs o Reference Current-Limit Protection (20mA, typ) o Voltage Clamp Protects Subsequent Output Circuitry o +2.7V to +76V Wide Voltage Range Operation o 6-Pin SOT23 Packages
MAX4007/MAX4008
Ordering Information
PART TEMP RANGE PIN-PACKAGE 6 SOT23-6 6 SOT23-6 TOP MARK ABNM ABNO
Applications
Photodiode Current-Monitoring Systems Portable Instrumentation Medical Instrumentation Laboratory Instrumentation Consumer Electronics Current-to-Voltage Conversion Level Translation
MAX4007EUT-T -40C to +85C MAX4008EUT-T -40C to +85C
Pin Configuration Selector Guide
TOP VIEW
CLAMP 1 6 BIAS
PART MAX4007EUT-T MAX4008EUT-T
PINPACKAGE 6 SOT23-6 6 SOT23-6
INTERNAL TYPICAL RESISTOR ACCURACY (%) None 10k 5 1
GND 2
MAX4007 MAX4008
5
N.C.
OUT 3
4
REF
Typical Operating Circuit appears at end of data sheet.
SOT23
________________________________________________________________ Maxim Integrated Products
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High-Accuracy, 76V, High-Side Current Monitors in SOT23 MAX4007/MAX4008
ABSOLUTE MAXIMUM RATINGS
CLAMP to GND ......................................................-0.3V to +80V BIAS, REF to GND ..................................................-0.3V to +80V OUT to GND .........................................-0.3V to (VCLAMP + 0.6V) Short Circuit, REF to GND ..........................................Continuous Current into Any Pin..........................................................30mA Continuous Power Dissipation (TA = +70C) 6-Pin SOT23 (derate 8.7mW/C above +70C)............696mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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
(VBIAS = 40V, GND = 0V, REF = open, VOUT = 0V (MAX4007), CLAMP = open, -40C to +85C. Typical values are at TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER Bias Voltage Range Bias Quiescent Current Reference Voltage Thermal Shutdown Engage Temperature Trip-Point Temperature Hysteresis Input Current Limit MAX4007 Output Current Noise SYMBOL VBIAS IBIAS VREF TSHDN THYS ILIM CONDITIONS Inferred from power-supply rejection test IREF = 250nA IREF = 2.5mA IREF = 2.5mA REF shorted to GND, junction temperature rising REF shorted to GND, junction temperature falling VREF = VBIAS - 5V f = 0.1Hz to 10Hz
iNOUT
MIN 2.7
TYP
MAX 76
UNITS V A mA V C C mA
90 3.6 VBIAS - 1.1 VBIAS - 0.8 150 5 20 IREF = 250nA IREF = 2.5mA IREF = 250nA IREF = 2.5mA IREF = 250nA IREF = 2.5mA IREF = 250nA IREF = 2.5mA IREF = 250nA IREF = 2.5mA 0.3 63 9.2 1240 0.041 0.63 1.3 12.5 50 5 10 1 0 to VBIAS - 1.5 0 to VBIAS - 0.85 0.6
200 4
pARMS
f = 0.1Hz to 10kHz f = 0.1Hz to 10Hz MAX4008 Output Voltage Noise eNOUT f = 0.1Hz to 10kHz MAX4007 MAX4008 Output Leakage Output Voltage Range VOUT VOUT VCLAMP REF = open
VRMS
G M k pA V
Output Resistance
ROUT
VBIAS = 2.7V to 76V, IREF = 0 to 1mA, MAX4007: IOUT/IOUT = 1%, MAX4008: VOUT/IOUT = 1%
Output Clamp Voltage
V
2
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High-Accuracy, 76V, High-Side Current Monitors in SOT23
ELECTRICAL CHARACTERISTICS (continued)
(VBIAS = 40V, GND = 0V, REF = open, VOUT = 0V (MAX4007), CLAMP = open, -40C to +85C. Typical values are at TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER Output Clamp Leakage MAX4007 Current Gain IOUT/IREF SYMBOL CONDITIONS VCLAMP = 0 to 76V IREF = 250nA IREF = 2.5mA IREF = 10mA, VBIAS = 12V MAX4008 Transimpedance Gain IREF = 250nA VOUT/IREF (IOUT/IOUT) /VBIAS (VOUT/VOUT) /VBIAS IREF = 2.5mA IREF = 10mA, VBIAS = 12V Power-Supply Rejection Ratio (PSRR) IREF = 250nA MAX4007: VBIAS = 2.7V to 76V IREF = 1mA MAX4008: IREF = 1mA VBIAS = 2.7V to 76V IOUT settles within 0.1%, CIN = 10nF between REF and GND IREF = 250nA IREF = 2.5mA 0.9 0.95 0.09 0.094 MIN TYP 1 0.0999 0.095 0.0997 0.992 0.998 1.00 50 50 50 7.5 90 1000 1000 1000 ms s ppm/V 1.1 1.05 V/mA 0.11 0.106 mA/mA MAX UNITS pA
MAX4007/MAX4008
Power-Up Settling Time
tS
Note 1: All devices are 100% tested at room temperature (TA = +25C). All temperature limits are guaranteed by design.
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High-Accuracy, 76V, High-Side Current Monitors in SOT23 MAX4007/MAX4008
Typical Operating Characteristics
(TA = +25C, unless otherwise noted.)
BIAS CURRENT vs. SUPPLY VOLTAGE
MAX4007/08 toc01
BIAS CURRENT vs. REFERENCE CURRENT
MAX4007/08 toc02
BIAS CURRENT vs. TEMPERATURE
IREF = 2.5mA
MAX4007/08 toc03
10 IREF = 2.5mA
100.00 VBIAS = 40V 10.00
10
BIAS CURRENT (mA)
BIAS CURRENT (mA)
BIAS CURRENT (mA)
1
1
1.00
0.1 IREF = 250nA
0.1
IREF = 250nA
0.10 VBIAS = 40V
0.01 2 8 14 SUPPLY VOLTAGE (V) 20 26
0.01 10n 100n 1 10 IREF (A) 100 1m 10m
0.01 -40 -15 10 35 60 85 TEMPERATURE (C)
GAIN ERROR vs. REFERENCE CURRENT
MAX4007/08 toc04
GAIN ERROR vs. TEMPERATURE
MAX4007/08 toc05
GAIN ERROR vs. BIAS VOLTAGE
0 -0.2 GAIN ERROR (%) -0.4 -0.6 -0.8 -1.0 -1.2 -1.4 IREF = 250nA IREF = 25A IREF = 2.5mA IREF = 5mA
MAX4007/08 toc06
5 4 3 GAIN ERROR (%) 2 1 0 -1 -2 -3 -4 -5 10n 100n 1 10 IREF (A) 100 1m VBIAS = 40V
9 8 7 GAIN ERROR (%) 6 5 4 3 2 1 0 -1
VBIAS = 40V IREF = 10nA
0.2
IREF = 250nA IREF = 2.5A IREF = 250A IREF = 2.5mA IREF = 10mA
10m
-40
-15
10
35
60
85
2.0
20.5
39.0 VBIAS (V)
57.5
76.0
TEMPERATURE (C)
TRANSIENT RESPONSE (VBIAS = 40V)
MAX4007/8 toc07
STARTUP DELAY (VBIAS = 40V, IREF = 250nA)
MAX4007/8 toc08
STARTUP DELAY (VBIAS = 40V, IREF = 2.5mA)
MAX4007/8 toc09
A
CH1
VBIAS BIAS D.U.T. REF OUT R1 CH2
CH1
40V BIAS D.U.T. REF OUT CH1 6.3k CH2 12.1k
RREF 13pF RTEST
CH1
CH1 VBIAS BIAS D.U.T. REF OUT R1 CH2 RREF 13pF
B
0V CH2 0V 20ms/div
0V CH2 0V 20ms/div
BGND AGND
10k
RTEST
400ns/div A: CH2, 5V/div, IREF = 0 TO 2.5mA B: CH1, 1V/div, IOUT = 0 TO 0.25mA
RREF = 158m R1 = 118m RTEST = 1.67m CH1: 10V/div CH2: 20mV/div
RREF = 15.8k R1 = 0 RTEST = 140k CH1: 10V/div CH2: 10V/div
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High-Accuracy, 76V, High-Side Current Monitors in SOT23
Typical Operating Characteristics (continued)
(TA = +25C, unless otherwise noted.)
STARTUP DELAY (VBIAS = 5V, IREF = 250nA) STARTUP DELAY (VBIAS = 5V, IREF = 2.5mA) SHORT-CIRCUIT RESPONSE (VBIAS = 40V)
TA = +85C
MAX4007/MAX4008
MAX4007/8 toc10
MAX4007/8 toc11
MAX4007/8 toc12
CH1 0V
CH1 A
CH1 VBIAS BIAS D.U.T. REF OUT R1
B
C
D
0V
CH1
VBIAS BIAS D.U.T. REF OUT
CH1
CH2
CH2 0V
CH2 RREF 13pF RTEST
CH2
RREF 13pF
R1
0A
0V 40ms/div RREF = 16.8m R1 = 118m RTEST = 1.67m CH1: 2V/div CH2: 10V/div RREF = 1.68k R1 = 0 RTEST = 14.0k CH1: 2V/div CH2: 1V/div 4ms/div
RTEST
20ms/div CH1: IBIAS, 10.0mA/div A: REF SHORTS TO GND B: CURRENT LIMIT ACTIVE C: THERMAL SHUTDOWN D: POST COOL-DOWN RETRY
SHORT-CIRCUIT RESPONSE (VBIAS = 76V)
TA = +85C
VOLTAGE DROP vs. REFERENCE CURRENT
VBIAS = 2.7V 1.20 1.00
MAX4007/08 toc14
MAX4007/8 toc13
1.40
A
B
C
D
VBIAS - VREF (V)
0.80 0.60 0.40 0.20
A B C D 1 10 100 A: TA = -40C B: TA = +25C C: TA = +85C D: TA = +100C 1m 10m
CH1 0A
40ms/div CH1: IBIAS, 10.0mA/div A: REF SHORTS TO GND B: CURRENT LIMIT ACTIVE C: THERMAL SHUTDOWN D: POST COOL-DOWN RETRY
0 100n
REFERENCE CURRENT (A)
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High-Accuracy, 76V, High-Side Current Monitors in SOT23 MAX4007/MAX4008
Pin Description
PIN MAX4007 1 2 3 4 5 6 -- MAX4008 1 2 -- 4 5 6 3 NAME CLAMP GND OUT REF N.C. BIAS OUT FUNCTION Clamp Voltage Input. External potential used for voltage clamping of VOUT. Ground Current-Monitor Output. OUT sources a current of 1/10th IREF. Reference Current Output. REF provides the source current to the cathode of the photodiode. No Connection. Not internally connected. Bias Voltage Input. Bias voltage for photodiode. Current-Monitor Output. OUT presents a voltage proportional to IREF at 1V/mA. An internal 10k resistor connects OUT to GND (see Functional Diagram).
Functional Diagrams
BIAS BIAS
MAX4007
CURRENT MONITOR CURRENT MONITOR
MAX4008
10x
1x CLAMP
10x
1x CLAMP OUT
CURRENT CLAMP REF GND
OUT
CURRENT CLAMP REF 10k GND
Detailed Description
The MAX4007/MAX4008 are versatile current monitors intended for monitoring DC photodiode current in fiber applications (see Functional Diagram). The MAX4007 output is a current that is exactly one-tenth the reference current. The MAX4008 outputs a voltage that is proportional to the reference current with a transimpedance gain of 1V/mA achieved by a factory-trimmed, internal 10k resistor.
Both current devices have six decades of dynamic range and monitor reference current ranging from 250nA to 2.5mA, the nominal operating range, with better than 5% accuracy across the entire reference current, bias voltage, and temperature ranges. The corresponding monitor outputs produce 25nA to 0.25mA (MAX4007) and 0.25mV to 2.5V (MAX4008). When the reference currents are extended to the broader range of 10nA to 10mA, an accuracy of less than 10% is maintained. Internal current limiting (20mA,
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High-Accuracy, 76V, High-Side Current Monitors in SOT23
typ) protects the device against short-circuit-to-ground conditions, and a thermal shutdown feature reduces both the reference current and the monitor current to zero if the die temperature reaches +150C. The MAX4007/MAX4008 accept a supply voltage of +2.7V to +76V, suitable for APD photodiode applications. A clamping diode, shown in the Functional Diagram, is provided to protect subsequent output circuitry from an overvoltage condition. photodiode, its voltage drop must also be considered. Leakage from the clamping diode is most often insignificant over nominal operating conditions, but grows with temperature. To maintain low levels of wideband noise, lowpass filtering the output signal is suggested in applications where only DC measurements are required. Determining the required filtering components is straightforward, as the MAX4007 exhibits a very high output impedance (>5M), while the MAX4008 exhibits an output resistance of 10k. In some applications where pilot tones are used to identify specific fiber channels, higher bandwidths are desired at OUT to detect these tones. Consider the minimum and maximum currents to be detected, then consult the frequency response and noise typical operating curves. If the minimum current is too small, insufficient bandwidth could result, while too high a current could result in excessive noise across the desired bandwidth. Refer to the MAX4009 family data sheet for devices intended for fiber applications using pilot tones.
MAX4007/MAX4008
Applications Information
Clamping the Monitor Output Voltage
CLAMP provides a means for diode clamping the voltage at OUT; thus, VOUT is limited to VCLAMP + 0.6V. CLAMP can be connected to either an external supply, to BIAS, or may be left floating if voltage clamping is not required.
Using APD or PIN Photodiodes in Fiber Applications
When using the MAX4007/MAX4008 to monitor APD or PIN photodiode currents in fiber applications, several issues must be addressed. In applications where the photodiode must be fully depleted, keep track of voltages budgeted for each component with respect to the available supply voltage(s). The current monitors require as much as 1.1V between BIAS and REF, which must be considered part of the overall voltage budget. Additional voltage margin can be created if a negative supply is used in place of a ground connection, as long as the overall voltage drop experienced by the MAX4007/MAX4008 is less than or equal to 76V. For this type of application, the MAX4007 is suggested so the output can be referenced to "true" ground and not the negative supply. The MAX4007's output current can be referenced as desired with either a resistor to ground or a transimpedance amplifier. Take care to ensure that output voltage excursions do not interfere with the required margin between BIAS and OUT. In many fiber applications, OUT is connected directly to an ADC that operates from a supply voltage that is less than the voltage at BIAS. Connecting the MAX4007/MAX4008s' clamping diode output, CLAMP, to the ADC power supply helps avoid damage to the ADC. Without this protection, voltages can develop at OUT that might destroy the ADC. This protection is less critical when OUT is connected directly to subsequent transimpedance amplifiers (linear or logarithmic) that have low-impedance, near-ground-referenced inputs. If a transimpedance amp is used on the low side of the
Bypassing and External Components
In applications where power-supply noise can interfere with DC diode measurements, additional filtering is suggested. Such noise is commonly seen when switching power supplies are used to generate the photodiode bias voltage. As shown in the Typical Operating Circuit, a pi filter (two 0.22F capacitors and one 2.2H inductor) greatly suppresses power-supply switching noise. If such a filter is already present in the bias generating circuit, only a simple bypass capacitor at the BIAS pin is suggested. The output lowpass filter, a 10k resistor and a 10nF capacitor, further reduce permeating powersupply noise, as well as other wideband noise that might otherwise restrict measurements at low-signal levels. Again, reducing the bandwidth of the OUT signal can affect performance of pilot-tone systems. To restrict high-frequency photodiode signals from affecting the current monitors and BIAS power supply, an RF choke and 10nF capacitor can be added. The capacitance presented to REF should not exceed 10nF; larger values increase startup time and could cause the thermal shutdown circuit to activate during startup.
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High-Accuracy, 76V, High-Side Current Monitors in SOT23 MAX4007/MAX4008
Typical Operating Circuit
+2.7V TO +76V 2.2H
0.22F
0.22F
BIAS
+5V
CURRENT MONITOR 10x 1x CLAMP
+5V
CURRENT CLAMP
OUT
ADC 10k
REF
MAX4007
GND
10nF
APD PIN PHOTODIODE TIA HIGH-SPEED DATA PATH TO LIMITING AMPLIFIER
Chip Information
TRANSISTOR COUNT: 195 PROCESS: BiCMOS
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High-Accuracy, 76V, High-Side Current Monitors in SOT23
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
6LSOT.EPS
MAX4007/MAX4008
PACKAGE OUTLINE, SOT-23, 6L
21-0058
F
1
1
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9 (c) 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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