Datasheet

V
ENABLE
V
COMP
V
OUT
SC Threshold
Configured
(1 ms)
Soft Start Time (4 ms)
Compensation
Network Zeroed
(1 ms)
UDG-06062
TPS40192, TPS40193
www.ti.com SLUS719E –MARCH 2007–REVISED MAY 2013
Startup Sequence and Timing
The TPS40192/3 startup sequence is as follows. After input power is applied, the 5-V onboard regulator comes
up. Once this regulator comes up, the device goes through a period where it samples the impedance at the
COMP pin and determines the short circuit protection threshold voltage, by placing 400 mV on the COMP pin for
approximately 1 ms. During this time, the current is measured and compared against internal thresholds to select
the short circuit protection threshold. After this, the COMP pin is brought low for 1 ms. This ensures that the
feedback loop is preconditioned at startup and no sudden output rise occurs at the output of the converter when
the converter is allowed to start switching. After these initial two milliseconds, the internal soft-start circuitry is
engaged and the converter is allowed to start. See Figure 13.
Figure 13. Startup Sequence
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