TPS2047, TPS2057

TRIPLE CURRENT-LIMITED POWER-DISTRIBUTION SWITCHES

SLVS194 – APRIL 1999

22

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

APPLICATION INFORMATION

generic hot-plug applications (see Figure 33)

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 TPS2047 and TPS2057, 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 TPS2047 and TPS2057 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

TPS2047

GND1

IN1

EN1

OC1

OUT1

OUT2

OC2

EN2

GND2

EN3

IN2

OC3

OUT3

Block of

Circuitry

Block of

Circuitry

Figure 33. Typical Hot-Plug Implementation

By placing the TPS2047 or TPS2057 between the VCC 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.