ADM1172 Datasheet, PDF (1/16 Pages) Analog Devices – 2.7 V to 16.5 V Hot Swap Controller with Power-Fail Comparator

2.7 V to 16.5 V Hot Swap Controller
with Power-Fail Comparator
ADM1172
FEATURES
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
GENERAL DESCRIPTION
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 over-
current 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
(ON-CLR) 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.
V_IN = 5V
GND
FUNCTIONAL BLOCK DIAGRAM
LONG
R_SENSE
Q₁
SHORT ^RON1
R_ON2
LONG
V_CC SENSE
ON
GATE
ADM1172-1
PFI
TIMER
GND
C_TIMER
PFO
V_OUT = 5V
C_LOAD
R_PR1
R_PR2
GND
Figure 1.
Rev. 0
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