TPS77633DR

The Open Drain Power-On Reset feature in the TPS775xx and TPS776xx devices is used to drive power-on reset circuitry or as a low-battery indicator .

The Power Good (PG) output in the TPS776xx device is used to monitor the status of the regulator. When the output voltage drops to between 92% and 98% of its nominal regulated value, the PG output transistor turns on, taking the signal low. This feature can be utilized to drive power-on reset circuitry or as a low-battery indicator. The PG output is an open-drain output that requires a pullup resistor, but if not used, it can be left floating.

The TPS775xx and TPS776xx devices achieve a fast transient response by being stable with a 10 μF low ESR capacitor, providing high performance at a reasonable cost. The PMOS device behaves as a low-value resistor, resulting in a very low dropout voltage of typically 169mV at an output current of 500mA. The dropout voltage is directly proportional to the output current, and the PMOS pass element's tendency to saturate when the device goes into dropout forces an increase in IB to maintain the load. This increase in IB translates to large start-up currents during power up, which can be problematic in certain systems. However, the TPS775xx and TPS776xx devices have low quiescent currents even when the regulator drops out, eliminating these issues. Additionally, these families feature a shutdown mode that reduces quiescent current to 2 μA and places the output in a high-impedance state if not used. The devices are stable at zero load, requiring no minimum load for operation .