1.6 V to 16.5 V Hot Swap Controller
Data Sheet
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FEATURES
Controls supply rails from 1.6 V to 16.5 V
Supply voltage range 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
Soft start controls inrush current profile
Peak fault current limited with fast response
Charge pumped gate drive for external N-FET switch
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 ADM1170 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.
The ADM1170 operates with a supply voltage ranging from
2.7 V to 16.5 V. By using independent SENSE pins from V
CC
,
the ADM1170 allows for the hot swap of supplies ranging down
to 1.6 V. 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 ADM1170 also
features soft start to provide the user with a capacitor program-
mable ramping reference to the internal current sense comparator.
This provides a linearly increasing current limit at startup at a
rate set by C
SS
. This helps to reduce and limit large inrush
currents.
This device is available in two options: the ADM1170-1 with
automatic retry for overcurrent fault and the ADM1170-2 with
latch-off for an overcurrent fault. Toggling the ON (ON-
CLR
)
pin resets a latched fault. The ADM1170 is packaged in an
8-lead TSOT.
FUNCTIONAL BLOCK DIAGRAM
LONG
V
IN
= 1.8V V
OUT
= 1.8V
SENSE+
R
SENSE
Q
1
C
TIMER
LONG
SHORT
LONG
SENSE–
GATE
ON
V
CC
TIMER
SS
ADM1170-1
GND
GND GND
V
IN
= 3.3VAUX
R
ON1
R
ON2
C
LOAD
C
SS
05124-001
Figure 1.
