Analog Integrated Circuit Device Data

Freescale Semiconductor

13

34726

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

OVER-TEMPERATURE PROTECTION

To limit its operating temperature, the 34726 shuts down if

the junction temperature of the switching MOSFET

surpasses 140°C. If the junction temperature subsequently

drops to 130°C, the 34726 re-starts.

SOFT-START OPERATION

To limit the in-rush current, an internal timer controls the

output voltage ramp after the part is enabled. The start-up

time is internally set to approximately 2.0ms and is

independent of input voltage, output voltage, or load current.

The soft-start sequence also occurs upon recovery from any

fault condition.

UNDER-VOLTAGE LOCK-OUT

reached.

If the UVLO falling threshold is met, the part shuts down

and will power up again with soft-start, when the UVLO rising

threshold is surpassed.