259481A Marking, TPS259481AYWPR datasheet(22/56 Pages) TI

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While recovering from a OVLO event, the TPS25948xx bypasses the inrush control (dVdt) and starts up in

a current limited manner to provide faster turn ON and minimize power supply droop during supply transient

conditions.

Time

OUT

tOVLO

Input Overvoltage Event

Input Overvoltage Removed

OVLO

VOV(R)

VOV(F)

FLT(1)

VFLT

Current Limited

Start-up

VSPLYGD

SPLYGD(2)

tSWOV

(1) Applicable only to TPS259480x variants

(2) Applicable only to TPS259480x/2x variants

(3) Applicable only to TPS259481x variants

SPLYGD(3)

VSPLYGD

Figure 8-6. TPS25948xx Overvoltage Lockout and Recovery

8.3.3 Inrush Current, Overcurrent, and Short Circuit Protection

TPS25948xx incorporates four levels of protection against overcurrent:

1. Adjustable slew rate (dVdt) for inrush current control

2. Adjustable threshold (ILIM) for overcurrent protection during start-up or steady-state

3. Adjustable threshold (ISC) for fast-trip response to severe overcurrent during start-up or steady-state

4. Fixed threshold (IFFT) for fast-trip response to quickly protect against hard output short-circuits during steady-

state

8.3.3.1 Slew Rate (dVdt) and Inrush Current Control

During hot-plug events or while trying to charge a large output capacitance at start-up, there can be a large

inrush current. If the inrush current is not managed properly, it can damage the input connectors and/or cause

the system power supply to droop leading to unexpected restarts elsewhere in the system. The inrush current

during turn on is directly proportional to the load capacitance and rising slew rate.

Equation 3 can be used to find the slew rate (SR) required to limit the inrush current (IINRUSH) for a given load

capacitance (COUT):

IINRUSH (mA) = COUT (µF) × SRON (V/ms)

(3)

A capacitor can be connected to the dVdt pin to control the rising slew rate and lower the inrush current during

turn on. The required CdVdt capacitance to produce a given slew rate can be calculated using the equation:

TPS25948

SLVSGT9A – FEBRUARY 2023 – REVISED SEPTEMBER 2023

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