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TPS2490

TPS2491

SLVS503 – NOVEMBER 2003

by the desired thermal stress on M1:

temperature prior to a start or restart.

A capacitor may be tied from PROG to ground to alter the natural constant power inrush current shape. If

properly designed, the effect is to cause the leading step of current in Figure 12 to look like a ramp.

PROG is internally pulled to ground whenever EN, POR, or UVLO are not satisfied or the TPS2490 is latched off.

This feature serves to discharge any capacitance connected to the pin. Do not apply voltages greater than 4 V to

PROG. If the constant power limit is not used, PROG should be tied to VREF through a 47-k

Ω resistor.

TIMER:

fault-time for both versions and the restart interval for the TPS2491. The timer charges at 25 µA whenever the

TPS2490/91 is in power limit or current limit and discharges at 2.5 µA otherwise. The charge-to-discharge current

ratio is constant with temperature even though there is a positive temperature coefficient to both. If TIMER

followed by 15 more charge and discharge cycles. The TPS2490 can be reset by either cycling the EN pin or the

UVLO (e.g. power cycling). TIMER discharges when EN is low or UVLO or POR are active. The TIMER pin

should be tied to ground if this feature is not used.

PG:

This open-drain output is intended to interface to downstream dc/dc converters or monitoring circuits. PG

2.5 V, or UVLO is active. PG can also be viewed as having an input and output voltage monitor function. The

9-ms deglitch circuit operates to filter short events that could cause PG to go inactive (low) such as a momentary

respect to ground.

GND:

This pin is connected to system ground.

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