AD ADM869LARQ

a
2 A, High-Side P-Channel Switch with
Current Limit and Thermal Shutdown
ADM869L
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
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 µA and shutdown current of typically 10 nA.
APPLICATIONS
Desktop Computers
Palmtop Computers
Notebook Computers
Hand-Held Instruments
Universal Serial Bus (USB)
FUNCTIONAL BLOCK DIAGRAM
MAIN FET
IN
(2.7V TO 5.5V)
OUT
MIRROR
AMPLIFIER
MIRROR FET
ON
22␮F
0.1␮F
SET
ADM869L
CURRENT
LIMIT
AMPLIFIER
ON
VPULLUP
0 TO 5.5V
1.24V
BANDGAP
REFERENCE
RSET
ON
RPULLUP
10k⍀ TO 100k⍀
ON
ON
TEMPERATURE
SENSOR AND
CONTROL
OVERTEMP
CIRCUITRY
FAULT
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
© Analog Devices, Inc., 2000
ADM869L–SPECIFICATIONS (V
= 3.0 V, TA = –40ⴗC to +85ⴗC1, unless otherwise noted.)
Parameter
Min
Typ
Max
Unit
Operating Voltage Range
Quiescent Current
2.7
12
5.5
20
V
µA
12
25
µA
0.01
0.04
2.3
38
45
2
2
2.6
70
90
2.4
1.302
1100
0.8
µA
µA
V
mΩ
mΩ
A
V
A/A
V
V
V
µA
µA
V
µA
µs
µs
µs
µs
µs
CC
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
2.0
0.4
1.178
810
2.0
2.4
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
1.240
955
±1
±3
0.4
1
0.01
0.05
1
0.05
10
4
100
200
2
300
30
Test Conditions/Comments
VIN = 5 V, ON = GND, IOUT = 0 A,
0°C to 85°C
VIN = 5 V, ON = GND, IOUT = 0 A,
–40°C to +85°C
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
NOTES
1
Specifications to –40°C 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) 艌 0.8 V.
Specifications subject to change without notice.
–2–
REV. A
ADM869L
ABSOLUTE MAXIMUM RATINGS*
PIN CONFIGURATION
(TA = 25°C unless otherwise noted)
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 = 70°C) . . . . . . . 667 mW
QSOP (Derate 8.3 mW/°C above 70°C)
Operating Temperature Range
Industrial (A Version) . . . . . . . . . . . . . . . . –40°C to +85°C
Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C
Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . . 300°C
ESD Rating (Outputs) . . . . . . . . . . . . . . . . . . . . . . . . . . 15 kV
(Other Pins) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 kV
16 IN
IN 1
OUT
2
15 OUT
OUT
3
14 OUT
IN
4
IN
5
13 IN
TOP VIEW
(Not to Scale) 12 IN
ADM869L
OUT
6
11 OUT
ON
7
10 FAULT
GND
8
9
SET
*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.
THERMAL CHARACTERISTICS
16-Lead QSOP Package:
θJA = 50°C/W, θJC = 10°C/W
ORDERING GUIDE
Model
Temperature
Range
ADM869LARQ –40°C to +85°C
Package
Description
Package
Option
16-Lead QSOP RQ-16
PIN FUNCTION DESCRIPTIONS
Pin
Mnemonic
Function
1, 4, 5, 12, 13, 16
IN
2, 3, 6, 11, 14, 15
7
9
OUT
ON
SET
10
FAULT
Input to P-Channel MOSFET Source and Supply to Chip Circuitry. Bypass IN with a 22 µF
capacitor to ground.
Output from P-Channel MOSFET Drain. Bypass OUT with a 0.1 µF 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 135°C. During startup, FAULT remains low for the turn-on time + 50 µs.
REV. A
–3–
ADM869L–Typical Performance Characteristics
60
45
55
40
45
35
40
CURRENT – nA
QUIESCENT CURRENT – ␮A
50
35
30
25
20
30
25
20
15
15
10
OFF-SWITCH
CURRENT
10
5
5
0
–5
0
1
2
3
4
INPUT VOLTAGE – Volts
5
0
–40
6
13.0
1.3
12.5
1.2
12.0
11.5
11.0
10.5
10.0
–40
0
20
40
TEMPERATURE – ⴗC
60
80
TPC 4. Off-Switch Current vs. Temperature
NORMALIZED RON
CURRENT – ␮A
TPC 1. Quiescent Current vs. Input Voltage
–20
1.1
RESISTANCE
1.0
0.9
0.8
–20
0
20
40
TEMPERATURE – ⴗC
60
0.7
–40
80
TPC 2. Quiescent Current vs. Temperature
–20
0
20
40
TEMPERATURE – ⴗC
60
80
TPC 5. Normalized On Resistance vs. Temperature
9
1300
1250
1200
1150
IOUT/ISET RATIO
CURRENT – nA
7
5
3
CURRENT
1100
1050
VIN = 5V
1000
950
1
VIN = 3V
900
850
–1
–40
–20
0
20
40
TEMPERATURE – ⴗC
60
800
0.4
80
TPC 3. Off-Supply Current vs. Temperature
0.6
0.8
1.0
1.2
1.6
1.4
ISWITCH – A
1.8
2.0
2.2
2.4
TPC 6. IOUT/ISET Ratio vs. Switch Current
–4–
REV. A
1.4
350
1.2
300
1.0
250
VIN = 3V
tON – ␮s
NORMALIZED OUTPUT CURRENT
ADM869L
0.8
0.6
200
150
0.4
100
0.2
50
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
OUTPUT VOLTAGE
4.0
4.5
VIN = 5V
0
–40
5.0
TPC 7. Normalized Output Current vs. Output Voltage
–20
tOFF – ␮s
4
3
2
VIN = 3V OR 5V
1
–20
0
20
40
TEMPERATURE – ⴗC
60
80
TPC 9. Turn-Off Time vs. Temperature
REV. A
20
40
TEMPERATURE – ⴗC
60
80
TPC 8. Turn-On Time vs. Temperature
5
0
–40
0
–5–
ADM869L
VON
VFAULT, 5V/DIV
1
1
VOUT, 5V/DIV
2
2
VOUT
CIN = 100␮F
COUT = 0.1␮F
RLOAD = 1.0⍀
IOUT, 4A/DIV
3
IOUT, 0.5A/DIV
3
VIN, 5V/DIV
4
4
CH1 5.00V CH2 5.00V M 20.0␮s CH3
120mV
CH1 5.00V
CH3 50.0mV
TPC 10. Fast Current-Limit Response
BW
CH2 5.00V M 50.0␮s CH1
CH4 5.00V
VFAULT
2.2V
TPC 13. Switch Turn-On Time
VON
T
VFAULT, 5V/DIV
1
1
T
VOUT
T
VOUT, 5V/DIV
2
2
IOUT, 2A/DIV
T
IOUT, 0.5A/DIV
T
3
3
VIN, 5V/DIV
4
T
T
4
CH1 5.00V
CH3 100mV
CH2 5.00V M 50.0␮s CH3
BW
CH1 5.00V CH2 5.00V M 1.00␮s CH1
CH3 100mV CH4 5.00V
64mV
CH4 5.00V
VFAULT
2.5V
TPC 14. Switch Turn-Off Time
TPC 11. Slow Current-Limit Response
VON
T
T
1
IOUT = 0mA TO
1A, 0.5A/DIV
VOUT
3
VOUT RIPPLE,
100mV/DIV, 2
AC COUPLED
2
T
3
T
IOUT, 0.5A/DIV
T
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
TPC 12. Load Transient Response
VFAULT
3.1V
TPC 15. USB Circuit Output Rise Time
VON
1
VOUT
T
T
2
3
T
IOUT, 0.5A/DIV
4
CH1
5.00V CH2 2.00V M 500␮s CH1
CH3 100mV CH4 2.00V
VFAULT
3.1V
TPC 16. USB Circuit Output Fall Time
–6–
REV. A
ADM869L
FUNCTIONAL DESCRIPTION
VPULLUP
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.
RPULLUP
INT
FAULT
ADM869L
It should be noted that the ADM869L is not a bidirectional
switch, so VIN must always be higher than VOUT.
FAULT
ADM869L
FAULT
ADM869L
Figure 2. Wire Or’ing FAULT Outputs
CURRENT LIMIT
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 kΩ. Note that IOUT/ISET varies depending on
current so please refer to TPC 6.
ILIMIT
955
SET
ADM869L
1.24V
RSET
Figure 1. Setting the Current Limit
THERMAL SHUTDOWN
The thermal shutdown operates when the die temperature
exceeds 135°C, turning off the switch. The thermal shutdown
circuit has built-in hysteresis of 10°C, so the switch will not turn
on again until the die temperature falls to 125°C. If the fault
condition is not removed, the switch will pulse on and off as the
temperature cycles between these limits.
During startup, the FAULT output goes low for the turn-on time
plus 50 µs.
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 µF ceramic type is
suitable. Larger values will reduce the voltage drop still further.
OUTPUT CAPACITANCE
A 0.1 µF 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 µF. 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
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
FAULT OUTPUT
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 kΩ and 100 kΩ. 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.
REV. A
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 × 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.
–7–
ADM869L
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
C01037–0–7/00 (rev. A)
16-Lead QSOP Package
(RQ-16)
0.197 (5.00)
0.189 (4.80)
16
9
0.244 (6.20)
0.228 (5.79)
0.157 (3.99)
0.150 (3.81)
1
8
0.010 (0.25)
0.004 (0.10)
0.025
(0.64)
BSC
0.069 (1.75)
0.053 (1.35)
8ⴗ
0.012 (0.30)
0ⴗ
SEATING 0.010 (0.20)
0.008 (0.20) PLANE
0.007 (0.18)
0.050 (1.27)
0.016 (0.41)
PRINTED IN U.S.A.
PIN 1
0.059 (1.50)
MAX
–8–
REV. A