LTC4242_15 Datasheet, PDF (9/24 Pages) Linear Technology – Dual Slot Hot Swap Controller for PCI Express

LTC4242
PI FU CTIO S
AUXPGOOD1/AUXPGOOD2 (QFN): AUX Supply Power
Status Output. This open-drain pin is pulled high by an
internal 9µA pull-up when AUXOUTn is below power good
threshold, when ENn is high, during thermal shutdown,
AUXONn is low or when V_CC or AUXINn are in UVLO.
EN1/EN2: Card Presence/Slot Insert Detect Input. ENn
pin must be pulled below 1.235V to enable the system.
An internal 9µA pull-up current source is present on this
pin.
Exposed Pad (QFN): Power Ground. PCB electrical con-
nection is optional.
FAULT1/FAULT2: Main Supplies Fault Status Output.
FAULTn is pulled high by an internal 9µA pull-up. When an
overcurrent fault occurs at either the 12V or 3.3V supply,
FAULTn is latched low.
FON1/FON2: Force On Digital Input. For diagnostic pur-
poses, a high input overrides undervoltage and overcurrent
faults on 12V, 3.3V and AUX channels and input commands
on the ONn and AUXONn pins. However, UVLO on V_CC
would shut off the switches. Caution! There is no current
limit mechanism in this mode. Connect FONn to ground
to disable the fault override feature.
GND: Device Ground. Connect to a ground plane.
ON1/ON2: Main Supply On Control Input. A rising edge
turns on the external MOSFETs for the 12V and 3.3V sup-
plies, while a falling edge turns them off. Pull this pin below
0.6V to clear the faults on 12V and 3.3V channels.
PGOOD1/PGOOD2: Main Supply Power Status Output. This
open-drain pin is pulled high by an internal 9µA pull-up
when 12V_OUTn or 3V_OUTn is below power good threshold,
when ENn is high, ONn is low or when V_CC or any of the
main supplies are in UVLO.
V_CC: Device Supply Input. Operates from 2.7V to 6V. An
internal undervoltage lockout circuit disables the part until
the voltage at V_CC exceeds 2.45V.
4242f
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