Datasheet

TPS2044, TPS2054
QUAD POWER-DISTRIBUTION SWITCHES
SLVS174B – JULY 1998 – REVISED FEBRUARY 1999
23
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
generic hot-plug applications (see Figure 34)
In many applications it may be necessary to remove modules or pc boards while the main unit is still operating.
These are considered hot-plug applications. Such implementations require the control of current surges seen
by the main power supply and the card being inserted. The most effective way to control these surges is to limit
and slowly ramp the current and voltage being applied to the card, similar to the way in which a power supply
normally turns on. Due to the controlled rise times and fall times of the TPS2044 and TPS2054, these devices
can be used to provide a softer start-up to devices being hot-plugged into a powered system. The UVLO feature
of the TPS2044 and TPS2054 also ensures the switch will be off after the card has been removed, and the switch
will be off during the next insertion. The UVLO feature guarantees a soft start with a controlled rise time for every
insertion of the card or module.
Power
Supply
Block of
Circuitry
0.1 µF
1000 µF
Optimum
2.7 V to 5.5 V
PC Board
Overcurrent Response
TPS2044
GND1
IN1
EN1
OC1
OUT1
OUT2
OC2
EN2
GND2
EN3
IN2
EN4
OC3
OUT3
OUT4
OC4
Block of
Circuitry
Block of
Circuitry
Block of
Circuitry
Figure 34. Typical Hot-Plug Implementation
By placing the TPS2044 and TPS2054 between the V
CC
input and the rest of the circuitry, the input power will
reach these devices first after insertion. The typical rise time of the switch is approximately 2.5 ms, providing
a slow voltage ramp at the output of the device. This implementation controls system surge currents and
provides a hot-plugging mechanism for any device.