TPS1663 datasheet(14/30 Pages) TI1

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ILIM

TPS1663

SLVSET9A – SEPTEMBER 2018 – REVISED OCTOBER 2018

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Feature Description (continued)

(1)

RPLIM = 100 kΩ

RILIM = 3 kΩ

Figure 6. Output Power Limiting Response of TPS16632

8.3.6 Overload and Short Circuit Protection

The device monitors the load current by sensing the voltage across the internal sense resistor. The FET current

is monitored during start-up and normal operation.

8.3.6.1 Overload Protection

The TPS1663x devices feature accurate over load current limiting and fast short circuit protection feature. If the

load current exceeds the programmed current limit IOL, the device regulates the current through it at IOL

eventually reducing the output voltage. The power dissipation across the device during this operation will be

(VIN–VOUT) x IOL and this could heat up the device and eventually enter into thermal shutdown. The maximum

duration for the over current through the FET tCL(dly). If the thermal shutdown occurs before this time the internal

FET turns OFF and the subsequent operation (auto-retry or latch OFF) will depend on the MODE pin

configuration. Set the current limit using Equation 5

where

•

I(OL) is the overload current limit in Ampere

•

R(ILIM) is the current limit resistor in kΩ

(5)

8.3.6.2 Short Circuit Protection

During a transient output short circuit event, the current through the device increases rapidly. As the current-limit

amplifier cannot respond quickly to this event due to its limited bandwidth, the device incorporates a fast-trip

comparator. The fast-trip comparator architecture is designed for fast turn OFF tFASTTRIP(dly) = 300 ns (typical) with

I(SCP) = 40 A of the internal FET during an output short circuit event. The fast-trip threshold is internally set to

I(FASTTRIP). The fasttrip circuit holds the internal FET off for only a few microseconds, after which the device turns

back on slowly, allowing the current-limit loop to regulate the output current to I(OL). Then the device functions

similar to the overload condition. Figure 7 illustrates output hot-short performance of the device.

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