ANALOG DEVICES ADM1172 Service Manual
2.7 V to 16.5 V Hot Swap Controller
V
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with Power-Fail Comparator
FEATURES GENERAL DESCRIPTION
Controls supply rails from 2.7 V to 16.5 V
Allows protected board removal and insertion to a live
backplane
External sense resistor provides adjustable analog current
limit with circuit breaker
Peak fault current limited with fast response
Charge pumped gate drive for external N-FET switch
Power-fail comparator
Automatic retry or latch-off during current fault
Undervoltage lockout
8-lead, TSOT package
APPLICATIONS
Hot swap board insertion: line cards, raid systems
Industrial high-side switches/circuit breakers
Electronic circuit breakers
The ADM1172 is a hot swap controller that safely enables a
printed circuit board to be removed and inserted to a live
backplane. This is achieved using an external N-channel power
MOSFET with a current control loop that monitors the load
current through a sense resistor. An internal charge pump is
used to enhance the gate of the N-channel FET. When an overcurrent condition is detected, the gate voltage of the FET is
reduced to limit the current flowing through the sense resistor.
During an overcurrent condition, the TIMER pin capacitor
determines the amount of time the FET remains at a current
limiting mode of operation until it is shut down. The ON
CLR
(ON-
) pin is the enable input for the device and can be
used to monitor the input supply voltage. The ADM1172
operates with a supply voltage ranging from 2.7 V to 16.5 V.
The ADM1172 also features a power-fail comparator. The
voltage on the PFI pin is compared with an internal 0.6 V
reference, and the output of this comparator is presented on
the PFO pin. This device is available in two options: the
ADM1172-1 with automatic retry for overcurrent fault and the
ADM1172-2 with latch-off for an overcurrent fault. Toggling
the ON (ON-
CLR
) pin resets a latched fault. The ADM1172 is
packaged in an 8-lead TSOT.
ADM1172
FUNCTIONAL BLOCK DIAGRAM
= 5V V
IN
GND GND
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
LONG
SHORT
LONG
R
ON1
R
ON2
R
SENSE
SENSE
V
CC
ON
ADM1172-1
TIMER
C
TIMER
Figure 1.
GATE
PFI
PFO
GND
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 www.analog.com
Fax: 781.461.3113 ©2006 Analog Devices, Inc. All rights reserved.
Q
1
R
PR1
R
PR2
C
OUT
LOAD
= 5V
05126-001
ADM1172
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TABLE OF CONTENTS
Features.............................................................................................. 1
UVLO........................................................................................... 12
Applications....................................................................................... 1
General Description ......................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 4
Thermal Characteristics .............................................................. 4
ESD Caution.................................................................................. 4
Pin Configurations and Function Descriptions ........................... 5
Typical Performance Characteristics ............................................. 6
Theory of Operation ...................................................................... 12
Overview...................................................................................... 12
REVISION HISTORY
7/06—Revision 0: Initial Version
ON (ON-
GATE ........................................................................................... 12
Current Limit Function............................................................. 12
Calculating the Current Limit.................................................. 12
Circuit Breaker Function........................................................... 12
Timer Function........................................................................... 13
Power-Up Timing Cycle............................................................ 13
Circuit Breaker Timing Cycle................................................... 13
Automatic Retry or Latched Off............................................... 14
Power-Fail Comparator ............................................................. 14
Outline Dimensions....................................................................... 15
Ordering Guide .......................................................................... 15
CLR
) Pin..................................................................... 12
Rev. 0 | Page 2 of 16
ADM1172
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SPECIFICATIONS
VCC = 2.7 V to 16.5 V, TA = −40°C to +85°C, typical values at TA = 25°C, unless otherwise noted.
Table 1.
Parameter Symbol Min Typ Max Unit Conditions
VCC PIN
Operating Voltage Range VCC 2.7 16.5 V
Supply Current ICC 0.65 0.8 mA
Undervoltage Lockout V
Undervoltage Lockout Hysteresis V
ON (ON-CLR) PIN
Input Current
Threshold VON 1.22 1.3 1.38 V ON rising
Threshold Hysteresis V
SENSE PIN
Hot Swap Operating Range 2.7 16.5 V
Input Current
Circuit Breaker Limit Voltage VCB 44 50 56 mV VCB = (VCC – V
GATE PIN
Drive Voltage V
6.0 8 12 V V
8.75 10 12 V V
7.5 9 12 V V
5.56 8 12 V V
Pull-Up Current −6.5 −12 −14.5 A V
Pull-Down Current 4 mA
Pull-Down Current
TIMER PIN
Pull-Up Current I
−25 −60 −100 µA During current fault, V
Pull-Down Current I
100 µA Normal operation, V
Threshold High V
Threshold Low V
PFI PIN
Threshold Rising 0.58 0.6 0.62 V
Threshold Hysteresis 10 mV
Input Current −1 0 +1 µA
PFO PIN
Pull-Up Current −5 µA
Output Low Voltage 0.4 V I
t
OFF
Turn-Off Time (TIMER Rise to GATE Fall) 2 µs V
Turn-Off Time (ON Fall to GATE Fall) 40 µs VON = 5 V to 0 V step, VCC = 5 V
Turn-Off Time (VCC Fall to IC Reset) 40 µs VCC = 5 V to 2 V step, VON = 5 V
2.4 2.525 2.65 V VCC rising
UVLO
40 mV
UVLOHYS
I
−1 0 +1 µA
INON
50 mV
ONHYST
I
5 10 15 µA
INSENSE
4.6 7.5 10 V V
GATE
25 mA V
− VCC, VCC = 3.0 V
GATE
− VCC, VCC = 3.3 V
GATE
− VCC, VCC = 5 V
GATE
− VCC, VCC = 12 V
GATE
− VCC, VCC = 15 V
GATE
= 0 V
GATE
= 3 V, VCC = 5 V, ON (ON-CLR) = low
V
GATE
= 3 V, VCC < UVLO
GATE
−2 −5 −8.5 µA Initial cycle, V
TIMERUP
2 3.5 µA After Cct breaker tip, V
TIMERDN
1.22 1.3 1.38 V TIMER rising
TIMERH
0.15 0.2 0.25 V TIMER falling
TIMERL
= 200 µA
LOAD
= 0 V to 2 V step, VCC = VON = 5 V
TIMER
SENSE
TIMER
)
= 1 V
TIMER
TIMER
TIMER
= 1 V
= 1 V
= 1 V
Rev. 0 | Page 3 of 16
ADM1172
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ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Rating
VCC Pin −0.3 V to +20 V
SENSE Pin −0.3 V to +20 V
VCC − SENSE ±5 V
TIMER Pin −0.3 V to (VCC + 0.3 V)
ON (ON-CLR
PFI Pin −0.3 V to +20 V
PFO Pin −0.3 V to +20 V
GATE Pin −0.3 V to (VCC + 11 V)
Storage Temperature Range −65°C to +125°C
Operating Temperature Range −40°C to +85°C
Lead Temperature (10 sec) 300°C
Junction Temperature 150°C
) Pin
−0.3 V to +20 V
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
THERMAL CHARACTERISTICS
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 3. Thermal Resistance
Package Type θ
8-Lead TSOT 152.9 °C/W
Unit
JA
Rev. 0 | Page 4 of 16
ADM1172
A
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PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
ADM1172-1AUJ
TIMER
GND
PFO
ON
1
2
TOP VIEW
(Not to Scale)
3
4
8
7
6
5
V
CC
SENSE
PFI
GATE
Figure 2. Pin Configuration, 1AUJ Model Figure 3. Pin Configuration, 2AUJ Model
Table 4. Pin Function Descriptions
Pin No. Mnemonic Description
1 TIMER
Timer Input Pin. The initial and circuit breaker timing cycles a
delay is 272.9 ms/F, and 21.7 ms/µF for a circuit breaker delay. When the TIMER pin is pulled beyond the upper
threshold, the GATE turns off.
2 GND Chip Ground Pin.
3 PFO
4
ON (ON-CLR) Input Pin. The ON (ON-CLR) pin is an input to a comparator that has a low-to-high threshold of 1.3 V with 80 mV
Power-Fail Comparator Output. Digital output from the power-fail comparator.
hysteresis and a glitch filter. The ADM1172 is reset when the ON (ON-CLR) pin is low. When the ON (ON-Error!)
pin is high, the ADM1172 is enabled. A rising edge on this pin has the added function of clearing a fault and
restarting the device on the latched off model, the ADM1172-2.
5 GATE
Gate Output Pin. An internal charge pump provides a 12 µA pull-up current to drive the gate of an N-channel
MOSFET. In an overcurrent condition, the ADM1172 controls the external FET to maintain a constant load
current.
6 PFI
7 SENSE
Power-Fail Comparator Input. Comparator threshold = 0.6 V.
Current Limit Sense Input Pin. The current limit is set via a sense resistor between the V
overcurrent condition, the gate of the FET is controlled to maintain the SENSE voltage at 50 mV. When this limit is
reached, the TIMER circuit breaker mode is activated. The circuit breaker limit can be disabled by connecting the
V
pin and SENSE pin together.
CC
8 V
CC
Positive Supply Input Pin. The ADM1172 operates between 2.7
circuit with a glitch filter resets the ADM1172 when the supply voltage drops below the specified UVLO limit.
DM1172-2AUJ
TIMER
1
2
GND
PFO
05126-006
ON-CLR
TOP VIEW
(Not to Scale)
3
4
8
7
6
5
V
CC
SENSE
PFI
GATE
re set by this external capacitor. The initial timing
and SENSE pins. In an
CC
V to 16.5 V. An undervoltage lockout (UVLO)
05126-007
Rev. 0 | Page 5 of 16
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