Datasheet



SLUS610 − JULY 2004
12
www.ti.com
TYPICAL CHARACTERISTICS
Figure 21.
T
A
− Ambient Temperature − °C
UVLO PIN PULL-UP CURRENT
vs
AMBIENT TEMPERATURE
I
SRC_UV
− Sourced Current − µA
−40 10−15 35 8560
−10.3
−10.1
−9.9
−9.7
−9.5
−9.3
V
I(UVLO)
= 2.5 V
V
I(RTN)
= 20 V to 48
V
DETAILED DESCRIPTION
When a plug-in module or printed circuit card is inserted into a live chassis slot, discharged supply bulk
capacitance on the board can draw huge transient currents from the system supplies. Without some form of
inrush limiting, these currents can reach peak magnitudes ranging over 100 A, particularly in high-voltage
systems. Such large transients can damage connector pins, PCB etch, and plug-in and supply components.
In addition, current spikes can cause voltage droops on the power distribution bus, causing other boards in the
system to reset.
The TPS2393A is a hot swap power manager that limits current peaks to preset levels, as well as controls the
slew rate (di/dt) at which charging current ramps to the programmed limit. This device uses an external
N-channel pass FET and sense element to provide closed-loop control of current sourced to the load. Input
undervoltage lockout (UVLO) and overvoltage lockout (OVLO) functions control automatic turn-on when the
input supply voltage is within the specified operational window, otherwise inhibiting card operation by turning
off the pass FET. In addition, load power can be controlled with a system logic command via the EN input,
allowing electrical isolation of faulty cards from the power bus. Two active-low inputs can be connected to
provide card insertion detection. An internal overload comparator provides circuit breaker protection against
short-circuits occurring during steady-state (post-turn-on) operation of the card. Load power status is
continuously monitored and reported via the PG
(powergood) and FAULT outputs.