ZHCSBP7C October 2013 – December 2018 TPS24750 , TPS24751
UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.
This pin provides gate drive to the internal MOSFET. A charge pump sources 30 µA to enhance the internal MOSFET. A 13.9 V clamp between GATE and VCC limits the gate-to-source voltage since VVCC is close to VOUT in normal operation. During start up, a transconductance amplifier regulates the gate voltage of the internal FET to provide inrush current limiting. The TIMER pin charges timer capacitor CT during the inrush. Inrush current limiting continues until the V(GATE – VCC) exceeds the Timer Activation Voltage 5.8 V for VVCC = 12 V. Then the TPS2475x enters into circuit breaker mode. In the circuit breaker mode, the current flowing in RSENSE is compared with the current limit threshold derived from the MOSFET power limit scheme (see the PROG definition). If the current flowing in RSENSE exceeds the current limit threshold, then the internal pass MOSFET will be turned off. The GATE pin is disabled by the following three mechanisms:
GATE remains low in latch mode (TPS24750) and attempts a restart periodically in retry mode (TPS24751).
Connect a capacitor from this pin to GND to control the slew rate of the output voltage at power-on. This pin can be left floating to obtain a predetermined slew rate on the output.
If used, any capacitor connecting GATE and GND must not exceed 1 μF and it must be connected in series with a resistor of no less than 1 kΩ. No external resistor must be directly connected from GATE to GND or from GATE to OUT.