Datasheet

ENABLE
SOFT START
SHORT-CIRCUIT PROTECTION
THERMAL SHUTDOWN
TPS62250
SLVS842 – SEPTEMBER 2008 .......................................................................................................................................................................................... www.ti.com
The device is enabled setting EN pin to high. During the start up time t
Start Up
the internal circuits are settled and
the soft start circuit is activated. The EN input can be used to control power sequencing in a system with various
DC/DC converters. The EN pin can be connected to the output of another converter, to drive the EN pin high and
getting a sequencing of supply rails. With EN = GND, the device enters shutdown mode in which all internal
circuits are disabled. In fixed output voltage versions, the internal resistor divider network is then disconnected
from FB pin.
The TPS62250 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 = I
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
J
, 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.
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Product Folder Link(s): TPS62250