ADM1172 Datasheet, PDF (5/16 Pages) Analog Devices – 2.7 V to 16.5 V Hot Swap Controller with Power-Fail Comparator

ADM1172
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
ADM1172-1AUJ
TIMER 1
8 V_CC
GND 2 _{TOP VIEW} 7 SENSE
PFO 3 ^{(Not to Scale)} 6 PFI
ON 4
5 GATE
Figure 2. Pin Configuration, 1AUJ Model
ADM1172-2AUJ
TIMER 1
8 V_CC
GND 2 _{TOP VIEW} 7 SENSE
PFO 3 ^{(Not to Scale)} 6 PFI
ON-CLR 4
5 GATE
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 are set by this external capacitor. The initial timing
delay is 272.9 ms/μF, 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
Power-Fail Comparator Output. Digital output from the power-fail comparator.
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
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
Power-Fail Comparator Input. Comparator threshold = 0.6 V.
7
SENSE
Current Limit Sense Input Pin. The current limit is set via a sense resistor between the VCC and SENSE pins. In an
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
VCC pin and SENSE pin together.
8
VCC
Positive Supply Input Pin. The ADM1172 operates between 2.7 V to 16.5 V. An undervoltage lockout (UVLO)
circuit with a glitch filter resets the ADM1172 when the supply voltage drops below the specified UVLO limit.
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