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FEATURES 2 A Load Current 45 m On Resistance User-Settable Current Limit 12 A Typical Quiescent Current 10 nA Typical Shutdown Current 40 nA Typical Switch Off Leakage Short-Circuit Protection Thermal Shutdown FAULT Output Small, 16-Lead QSOP Package APPLICATIONS Desktop Computers Palmtop Computers Notebook Computers Hand-Held Instruments Universal Serial Bus (USB)
2 A, High-Side P-Channel Switch with Current Limit and Thermal Shutdown ADM869L
GENERAL DESCRIPTION
The ADM869L is a logic controlled P-channel switch with low on resistance, capable of sourcing up to 2 A from supply voltages between 2.7 V and 5.5 V. A user-settable current limit allows the trip current to be set between 400 mA and 2 A with an accuracy of 21%. This allows the system power supply to be protected against short circuits and surge currents in peripheral loads powered via the ADM869L. Over-current and overtemperature conditions are signalled by a FAULT output. The ADM869L also offers low quiescent current of typically 12 A and shutdown current of typically 10 nA.
FUNCTIONAL BLOCK DIAGRAM
MAIN FET OUT
IN (2.7V TO 5.5V)
MIRROR AMPLIFIER MIRROR FET ON 22 F SET CURRENT LIMIT AMPLIFIER ON VPULLUP 0 TO 5.5V 1.24V BANDGAP REFERENCE ON ON ON TEMPERATURE SENSOR AND CONTROL OVERTEMP CIRCUITRY FAULT 0.1 F
ADM869L
RSET
RPULLUP 10k TO 100k
GND
REV. A
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 World Wide Web Site: http://www.analog.com Fax: 781/326-8703 (c) Analog Devices, Inc., 2000
ADM869L-SPECIFICATIONS (V
Parameter Operating Voltage Range Quiescent Current Min 2.7
CC
= 3.0 V, TA = -40 C to +85 C1, unless otherwise noted.)
Typ 12 12 Max 5.5 20 25 2 2 2.6 70 90 2.4 1.302 1100 0.8 1 3 0.4 1 Unit V A A A A V m m A V A/A V V V A A V A s s s s s Test Conditions/Comments VIN = 5 V, ON = GND, IOUT = 0 A, 0C to 85C VIN = 5 V, ON = GND, IOUT = 0 A, -40C to +85C ON = VIN = VOUT = 5.5 V ON = VIN = VCC, VOUT = 0 V Rising Edge, 1% Hysteresis VIN = 4.75 V VIN = 3.0 V RSET = 1% Tolerance2 VSET Required to Turn Off Switch3 IOUT = 1 A, VOUT > 1.6 V VIN = 2.7 V to 5.5 V VIN = 2.7 V to 3.6 V VIN = 4.5 V to 5.5 V VON = 5.5 V VSET = 1.24 V, IOUT = 0 A ISINK = 1 mA, VSET = 1.4 V VFAULT = 5.5 V, VSET = 1 V 20% Current Overdrive, VIN = 5 V VIN = 5 V, IOUT = 500 mA VIN = 3 V, IOUT = 500 mA VIN = 5 V, IOUT = 500 mA
Shutdown Supply Current Off-Switch Current Undervoltage Lockout On Resistance Nominal Current-Limit Setting Range Current-Limit Amplifier Threshold IOUT/ISET Current Ratio ON Input Low Voltage, VIL ON Input High Voltage, VIH ON Input Leakage Current-Limit Amplifier Input Bias Current FAULT Logic Output Low Voltage FAULT Output High Leakage Current Slow Current-Loop Response Time Fast Current-Loop Response Time Turn-On Time Turn-Off Time
2.0
0.01 0.04 2.3 38 45 1.240 955
0.4 1.178 810 2.0 2.4
0.01 0.05 0.05 10 4 100 200 2
300 30
1
NOTES 1 Specifications to -40C are guaranteed by design, not tested. 2 Guaranteed by design. Derived from the I SET current ratio, current-limit amplifier and external set resistor accuracies. 3 Tested with IOUT = 200 mA and VSET adjusted until (V IN - VOUT) 0.8 V. Specifications subject to change without notice.
-2-
REV. A
ADM869L
ABSOLUTE MAXIMUM RATINGS*
(TA = 25C unless otherwise noted)
PIN CONFIGURATION
IN 1 OUT OUT IN IN OUT ON GND 2 3 4 5 6 7 8 16 IN 15 OUT 14 OUT 13 IN TOP VIEW (Not to Scale) 12 IN
IN to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 V to +6 V ON, FAULT to GND . . . . . . . . . . . . . . . . . . . -0.3 V to +6 V SET, OUT to GND . . . . . . . . . . . . . . -0.3 V to (VIN + 0.3 V) Maximum Continuous Switch Current . . . . . . . . . . . . . . . 3 A Continuous Power Dissipation (TA = 70C) . . . . . . . 667 mW QSOP (Derate 8.3 mW/C above 70C) Operating Temperature Range Industrial (A Version) . . . . . . . . . . . . . . . . -40C to +85C Storage Temperature Range . . . . . . . . . . . . -65C to +150C Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . . 300C ESD Rating (Outputs) . . . . . . . . . . . . . . . . . . . . . . . . . . 15 kV (Other Pins) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 kV
*This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.
ADM869L
11 OUT 10 FAULT 9 SET
THERMAL CHARACTERISTICS
16-Lead QSOP Package: JA = 50C/W, JC = 10C/W
ORDERING GUIDE
Model
Temperature Range
Package Description
Package Option
ADM869LARQ -40C to +85C
16-Lead QSOP RQ-16
PIN FUNCTION DESCRIPTIONS
Pin 1, 4, 5, 12, 13, 16 2, 3, 6, 11, 14, 15 7 9 10
Mnemonic IN OUT ON SET FAULT
Function Input to P-Channel MOSFET Source and Supply to Chip Circuitry. Bypass IN with a 22 F capacitor to ground. Output from P-Channel MOSFET Drain. Bypass OUT with a 0.1 F capacitor to ground. Digital Input. Active-low switch enable (logic 0 turns the switch on). Current Limit Setting Input. A resistor from set to ground sets the current limit. Refer to Current Limit section. Open-Drain Digital Output. FAULT goes low when the current limit is exceeded or the die temperature exceeds 135C. During startup, FAULT remains low for the turn-on time + 50 s.
REV. A
-3-
ADM869L-Typical Performance Characteristics
60 55 50
45 40 35
CURRENT - nA
QUIESCENT CURRENT - A
45 40 35 30 25 20 15 10 5 0 -5 0 1 2 3 4 INPUT VOLTAGE - Volts 5 6
30 25 20 15 10 5 0 -40 -20 0 20 40 TEMPERATURE - C 60 80 OFF-SWITCH CURRENT
TPC 1. Quiescent Current vs. Input Voltage
TPC 4. Off-Switch Current vs. Temperature
13.0
1.3
12.5
1.2
A
12.0
NORMALIZED RON
1.1 RESISTANCE 1.0
CURRENT -
11.5
11.0
0.9
10.5
0.8
10.0 -40
-20
0
20 40 TEMPERATURE - C
60
80
0.7 -40
-20
0
20 40 TEMPERATURE - C
60
80
TPC 2. Quiescent Current vs. Temperature
TPC 5. Normalized On Resistance vs. Temperature
9
1300 1250
7
CURRENT - nA
1200 1150
IOUT/ISET RATIO
5
1100 1050 VIN = 5V 1000 950 900 850 VIN = 3V
3 CURRENT 1
-1 -40
-20
0
20 40 TEMPERATURE - C
60
80
800 0.4
0.6
0.8
1.0
1.2 1.6 1.4 ISWITCH - A
1.8
2.0
2.2
2.4
TPC 3. Off-Supply Current vs. Temperature
TPC 6. IOUT/ISET Ratio vs. Switch Current
-4-
REV. A
ADM869L
1.4 1.2 1.0 0.8 0.6
tON - s
350 VIN = 3V 300 250 200 150 100 50 0 -40
NORMALIZED OUTPUT CURRENT
VIN = 5V
0.4 0.2 0 0.5
1.0
1.5
2.0 2.5 3.0 3.5 OUTPUT VOLTAGE
4.0
4.5
5.0
-20
0
20 40 TEMPERATURE - C
60
80
TPC 7. Normalized Output Current vs. Output Voltage
TPC 8. Turn-On Time vs. Temperature
5
4
tOFF - s
3
2 VIN = 3V OR 5V 1
0 -40
-20
0
20 40 TEMPERATURE - C
60
80
TPC 9. Turn-Off Time vs. Temperature
REV. A
-5-
ADM869L
VFAULT, 5V/DIV 1
VON 1 VOUT 2
VOUT, 5V/DIV 2 CIN = 100 F COUT = 0.1 F RLOAD = 1.0
IOUT, 4A/DIV 3 VIN, 5V/DIV 4
IOUT, 0.5A/DIV 3
4
CH1 5.00V CH2 5.00V M 20.0 s CH3
120mV
CH1 5.00V CH3 50.0mV
BW
CH2 5.00V M 50.0 s CH1 CH4 5.00V
VFAULT 2.2V
TPC 10. Fast Current-Limit Response
TPC 13. Switch Turn-On Time
VON
VFAULT, 5V/DIV 1 T VOUT, 5V/DIV 2
T 1 T 2 VOUT
IOUT, 2A/DIV T 3 VIN, 5V/DIV 4 T
T 3 T 4
CH2 5.00V M 50.0 s CH3
BW
IOUT, 0.5A/DIV
CH1 5.00V CH3 100mV
64mV
CH4 5.00V
CH1 5.00V CH2 5.00V M 1.00 s CH1 CH3 100mV CH4 5.00V
VFAULT 2.5V
TPC 11. Slow Current-Limit Response
TPC 14. Switch Turn-Off Time
VON
T IOUT = 0mA TO 1A, 0.5A/DIV 3
1
T VOUT
2 3
VOUT RIPPLE, 100mV/DIV, 2 AC COUPLED T
T T IOUT, 0.5A/DIV
4
CH2 100mV BW M 10.0 s CH2 CH3 50.0mV BW -52mV
T CH1 5.00V CH2 2.00V M 500 s CH1 CH3 100mV CH4 2.00V
VFAULT 3.1V
TPC 12. Load Transient Response
TPC 15. USB Circuit Output Rise Time
VON 1 T T 2 3 T IOUT, 0.5A/DIV VOUT
4 5.00V CH2 2.00V M 500 s CH1 CH3 100mV CH4 2.00V CH1
VFAULT 3.1V
TPC 16. USB Circuit Output Fall Time
-6-
REV. A
ADM869L
FUNCTIONAL DESCRIPTION
The ADM869L comprises a high-current P-channel switch controlled by an active-low logic input ON (Pin 7). When ON is low, the internal circuitry of the ADM869 is powered up and the output of the current-limit amplifier is low, providing gate drive to the switching FET. When ON is high, the internal circuitry is powered down and the current consumption is typically 100 nA. It should be noted that the ADM869L is not a bidirectional switch, so VIN must always be higher than VOUT.
CURRENT LIMIT
VPULLUP
RPULLUP INT FAULT FAULT FAULT
ADM869L
ADM869L
ADM869L
Figure 2. Wire Or'ing FAULT Outputs
When the switch is turned on, a smaller mirror switch passes a proportionate current equal to IOUT/955. The mirror amplifier maintains this relationship by keeping the drain of the mirror FET at the same voltage as the main FET, and drives the mirror current through the current-limit resistor RSET, which is connected between the noninverting input of the current limit amplifier and ground. An on-chip bandgap reference of 1.24 V is connected to the inverting input of the current-limit amplifier. When the load current exceeds the preset limit, the voltage across RSET exceeds 1.24 V, and the output voltage of the current-limit amplifier rises, reducing the gate drive to the FETs. If, for example, a 1 A current limit is required, RSET = 1.24 V/ 1.047 mA = 1.184 k. Note that IOUT/ISET varies depending on current so please refer to TPC 6.
ILIMIT 955 SET RSET
During startup, the FAULT output goes low for the turn-on time plus 50 s.
APPLICATIONS INFORMATION
INPUT FILTERING
To prevent the input voltage being pulled below the minimum operating voltage under transient short-circuit conditions, before the current limit has had time to operate, a reservoir capacitor should be connected from IN to GND. This does not need to be large, but should have a low ESR. A 22 F ceramic type is suitable. Larger values will reduce the voltage drop still further.
OUTPUT CAPACITANCE
ADM869L
1.24V
A 0.1 F capacitor should be connected between OUT and GND to prevent the back e.m.f. of parasitic inductance from pulling OUT below ground during turn-off. For Universal Serial Bus (USB) applications, COUT should be at least 120 F. This causes the output rise and fall times to be longer, as shown in the typical operating characteristics, but does not affect the turn-off time of the ADM869L itself.
LAYOUT CONSIDERATIONS
Figure 1. Setting the Current Limit
THERMAL SHUTDOWN
The thermal shutdown operates when the die temperature exceeds 135C, turning off the switch. The thermal shutdown circuit has built-in hysteresis of 10C, so the switch will not turn on again until the die temperature falls to 125C. If the fault condition is not removed, the switch will pulse on and off as the temperature cycles between these limits.
FAULT OUTPUT
Printed circuit board tracks to and from the ADM869L should be as thick and as short as possible to minimize parasitic inductance and take full advantage of the fast response time of the switch. It is recommended that all input lines be connected together, close to the device. This ensures equal current distribution in all legs. If this is not possible, then all traces should be of equal width and length. The same rules apply for all output lines. Input and output capacitors should be placed as close to the device as possible (less than 5 mm).
THERMAL CONSIDERATIONS
If either the current limit or the thermal shutdown is activated, FAULT will pull low. This is an open-drain output and requires a pull-up resistor of between 10 k and 100 k. Several FAULT outputs may be wire-OR'd to form a common interrupt line, as shown in Figure 2 or FAULT may be wire-OR'd to an existing interrupt line that has a resistive pull-up.
Under normal operating conditions, the worst-case power dissipation will be 518 mW with the highest specified on resistance and 3 V supply (W = 2.4 A x 0.9 V). The package is capable of handling and dissipating this power, but heat dissipation can further be improved by providing a large area of copper in contact with the device pins, particularly IN and OUT.
REV. A
-7-
ADM869L
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
16-Lead QSOP Package (RQ-16)
0.197 (5.00) 0.189 (4.80)
16
9
0.157 (3.99) 0.150 (3.81)
1 8
0.244 (6.20) 0.228 (5.79)
PIN 1 0.059 (1.50) MAX
0.069 (1.75) 0.053 (1.35)
0.010 (0.25) 0.004 (0.10)
0.025 (0.64) BSC
8 0.012 (0.30) 0 SEATING 0.010 (0.20) 0.008 (0.20) PLANE 0.007 (0.18)
0.050 (1.27) 0.016 (0.41)
-8-
REV. A
PRINTED IN U.S.A.
C01037-0-7/00 (rev. A)

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