9.3 Feature Description

9.3.1 Hot Plug-In and In-Rush Current Control

The devices are designed to control the in-rush current upon insertion of a card into a live backplane or

other hot power source. This design limits the voltage sag on the backplane’s supply voltage and prevents

unintended resets of the system power. The controlled start-up also helps to eliminate conductive and radiative

interferences. An external capacitor connected from the dVdT pin to GND defines the slew rate of the output

voltage at power-on. The fastest output slew rate of 24 V/500 µs can be achieved by leaving dVdT pin floating.

The inrush current can be calculated using Equation 1.

u

t

u

(IN)

(INRUSH)

(OUT)

dVdT

dV

V

I

C

I

C

dT

t

(1)

where

tdVdT = 20.8 × 103 × V(IN) × C(dVdT)

(2)

Figure 9-1 illustrates in-rush current control performance of the device during Hot Plug-In.

TPS1663

SLVSET9F – SEPTEMBER 2018 – REVISED FEBRUARY 2023

www.ti.com

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