TPS40180 Datasheet, PDF (21/52 Pages) Texas Instruments – SINGLE PHASE STACKABLE CONTROLLER

TPS40180
www.ti.com
SLVS753B – FEBRUARY 2007 – REVISED NOVEMBER 2007
Hiccup Fault Recovery
To reduce the input current and component dissipation during on overcurrent event, a hiccup mode is
implemented. Hiccup mode refers to a sequence of 7 soft-start cycles where no MOSFET switching occurs, and
then a re-start is attempted. If the fault has cleared, the re-start results in returning to normal operation and
regulation. This is shown in Figure 26.
V_VDD
SS
1.5 V
(A)
0.5 V
GND
VIN
(B)
GND
SW NODE
(C)
GND
VOUT, REG
VOUT
ILIM
(D)
COMP
t0 t1 t2
t3
Figure 26. Hiccup Recovery From Faults
UDG-07024
Normal operation is occurring between t0 and t1 as shown by VOUT at the regulated voltage, (C) and normal
switching on the SW NODE (B) and COMP at its nominal level, (D). At t1, an overcurrent load is experienced.
The increased current forces COMP to increase to the ILIM level as shown in (D). If the COMP voltage is above
the ILIM voltage for 7 switching cycles, the controller enters a hiccup mode at t2. During this time the controller is
not switching and the power MOSFETs are turned off. The SS pin goes through 7 cycles of charging and
discharging the soft-start capacitor. At the end of the 7 cycles the controller attempts another normal re-start. If
the fault has been cleared, the output voltage comes up to the regulation level as shown at time t3. If the fault
has not cleared, the COMP voltage again rises above the ILIM voltage and a fresh hiccup cycle starts. This
condition may continue indefinitely.
The pre-bias circuitry is reset at this time and the restart does not discharge an output pre-bias condition if it
exists.
Copyright © 2007, Texas Instruments Incorporated
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