UC1875/6/7/8
UC2875/6/7/8
UC3875/6/7/8
APPLICATION INFORMATION (cont.)
Fault/Soft-Start
The fault control circuitry provides two forms of power
shutdown:
• Complete turn-off of all four output power stages.
• Clamping the phase shift command to zero.
Complete turn-off is ordered for an over-current fault or
a low supply voltage. When the SOFTSTART pin
reaches its low threshold, switching is allowed to pro-
ceed while the phase-shift is advanced from zero to its
nominal value with the time constant of the
SOFT-START capacitor.
The fault logic insures that a continuous fault will insti-
tute a low frequency “hiccup” retry cycle by forcing the
SOFT-START capacitor to charge through its full cycle
between each restart attempt.
UDG-95084
UDG-95085
10
TI [ TEXAS INSTRUMENTS ]
