VOUT

IIN

IMON

FLTb

VIN = 50 V

MODE = GND

RILIM = 18 kΩ

Figure 9-6. Overload Performance During Load

Step from 140 Ω to 40 Ω

VOUT

IIN

IMON

FLTb

VIN = 50 V

MODE = GND

RILIM = 18 kΩ

Figure 9-7. Coming Out of Overload With Load

Step from 40 Ω to 140 Ω

The TPS1663x devices features ILIM pin short and open fault detection and protection. The internal FET is

turned OFF when ILIM pin is detected short or open to GND and it remains OFF till the ILIM pin fault is removed.

9.3.4.2 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) = 1 µs (typical)

with I(SCP) = 45 A of the internal FET during an output short circuit event. The fast-trip threshold is internally

set to I(FASTTRIP). The fast-trip 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 9-8 illustrates output hot-short performance of the device.

VOUT

IIN

IMON

FLTb

VIN = 50 V

RILIM = 18 kΩ

Figure 9-8. Output Hot-Short Response

The fast-trip comparator architecture has a supply line noise immunity resulting in a robust performance in noisy

environments. This supply line noise immunity is achieved by controlling the turn OFF time of the internal FET

based on the overcurrent level, I(FASTTRIP), through the device. The higher the overcurrent, the faster the turn

TPS1663

SLVSET9F – SEPTEMBER 2018 – REVISED FEBRUARY 2023

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