Datasheet

LTC4364-1/LTC4364-2
8
436412f
PIN FUNCTIONS
TMR: Fault Timer Input. Connect a capacitor between this
pin and ground to set the times for fault warning, fault
turn-off, and cool down periods. Either voltage regulation
or current regulation starts pulling up the TMR pin. The
current charging up this pin during the fault conditions
increases with the voltage difference between V
CC
and OUT
pins (see Applications Information). When TMR reaches
1.25V, the F LT pin pulls low to indicate the detection of a
fault condition. If the condition persists, the pass device
controlled by HGATE turns off when TMR reaches the
threshold of 1.35V. As soon as the fault condition disap-
pears, a cool down interval commences while the TMR
pin cycles 32 times between 0.15V and 1.35V with 2μA
charge and discharge currents. When TMR crosses 0.15V
the 32nd time, the HGATE pin is allowed to pull high turn-
ing the pass device back on if the OV pin voltage is below
its threshold for the LTC4364-2 version. The HGATE pin
latches low after fault time-out for the LTC4364-1.
UV: Undervoltage Comparator Input. When the UV pin
falls below its 1.25V threshold, the HGATE pin is pulled
down with a 1mA current. When the UV pin rises above
1.25V plus the hysteresis, the HGATE pin is pulled up by
the internal charge pump. For LTC4364-1, after HGATE
is latched off, pulling the UV pin below 0.6V resets the
latch and allows HGATE to retry. If unused, connect to
the SHDN pin.
V
CC
: Positive Supply Voltage Input. The positive supply
input ranges from 4V to 80V for normal operation. It can
also be pulled below ground potential by up to 40V during
a reverse battery condition, without damaging the part.
Shutting down the LTC4364 by pulling the SHDN pin to
ground reduces the V
CC
current to 10μA.