Datasheet

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SOFT START

SHORT-CIRCUIT PROTECTION

THERMAL SHUTDOWN

TPS62240 , TPS62242 , TPS62243

SLVS762B – JUNE 2007 – REVISED SEPTEMBER 2007

The TPS62240 has an internal soft start circuit that controls the ramp up of the output voltage. The output

voltage ramps up from 5% to 95% of its nominal value within typical 250 µ s. This limits the inrush current in the

converter during ramp up and prevents possible input voltage drops when a battery or high impedance power

source is used. The soft start circuit is enabled within the start up time, t

Start up

The High Side and Low Side MOSFET switches are short-circuit protected with maximum switch current equal to

LIMF

. The current in the switches is monitored by current limit comparators. Once the current in the High Side

MOSFET switch exceeds the threshold of it's current limit comparator, it turns off and the Low Side MOSFET

switch is activated to ramp down the current in the inductor and High Side MOSFET switch. The High Side

MOSFET switch can only turn on again, once the current in the Low Side MOSFET switch has decreased below

the threshold of its current limit comparator.

As soon as the junction temperature, T

, exceeds 140 ° C (typical) the device goes into thermal shutdown. In this

mode, the High Side and Low Side MOSFETs are turned off. The device continues its operation when the

junction temperature falls below the thermal shutdown hysteresis.

Product Folder Link(s): TPS62240 TPS62242 TPS62243