LTC3723-1/LTC3723-2 UUPI DESCRIPTIO S (LTC3723-1/LTC3723-2)SS (Pin 14/Pin 14): Soft-Start/Restart Delay Circuitry threshold is exceeded, the LTC3723-1/LTC3723-2 com- Timing Capacitor. A capacitor from SS to GND provides a mences a soft-start cycle and a 10µA (nominal) current is controlled ramp of the current command (LTC3723-1) or fed out of UVLO to program the desired amount of system duty cycle (LTC3723-2). During overload conditions, SS is hysteresis. The hysteresis level can be adjusted by chang- discharged to ground initiating a soft-start cycle. SS ing the resistance of the divider. UVLO can also be used to charging current is approximately 13µA. SS will charge up terminate all switching by pulling UVLO down to less than to approximately 5V in normal operation. During a con- 4V. An open drain or collector switch can perform this stant overload current fault, SS will oscillate at a low function without changing the system turn on or turn off frequency between approximately 0.5V and 4V. voltages. UVLO (Pin 15/Pin 15): Input to Program System Turn-On SPRG (Pin 16/Pin 16): A resistor is connected between and Turn-Off Voltages. The nominal threshold of the UVLO SPRG and GND to set the turn off delay for the synchro- comparator is 5.0V. UVLO is connected to the main DC nous rectifier driver outputs. The nominal voltage on system feed through a resistor divider. When the UVLO SPRG is 2V. WUWTI I G DIAGRA PROGRAMMABLE PROGRAMMABLE SYNCHRONOUS DEAD-TIME TURN-OFF DELAY DRVA DRVB SDRA SDRB CURRENT SENSE OR CT RAMP PWM COMPARATOR 372312 TD01 (–) 372312f 7