Datasheet

V
CC
V
SW
V
ZCD
V
ZCD-ARM
V
ZCD-OVP
V
LED
25.6V
13V
Steady
state
Low freq
state
Low freq
state
t
t
t
t
TPS92310
www.ti.com SNVS792 –FEBRUARY 2012
Protection Features
Output Open Circuit Protection
If the LED string is disconnected, V
LED
increases and thus V
ZCD-PEAK
increases. When V
ZCD-PEAK
is larger than
V
ZCD-OVP
for 3 continues switching cycles, the Over Voltage Protection (OVP) feature is triggered such that the
TPS92310 becomes Over-Voltage (OV) state. In this case, the switching of Q
1
is stopped, and V
CC
decreases
owing to the power consumption of the internal circuits of the TPS92310. When V
CC
drops below the falling
threshold of V
CC-UVLO
, the TPS92310 restarts, and re-enter into startup state (Figure 20).
Output Short Circuit Protection
If the LED string is shorted, V
ZCD-PEAK
drops. If V
ZCD-PEAK
drops below V
ZCD-TRIG
, the TPS92310 will under low
frequency operation. In this case, the power supplied from L
AUX
is not enough to maintain V
CC
, then V
CC
decreases. If the short is removed during low frequency state, the TPS92310 will restore to steady state. If the
short sustains till VCC drops below the falling threshold of V
CC-UVLO
, the TPS92310 restarts, and becomes startup
state again. (Figure 19)
Figure 19. Output Short Circuit waveforms
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