HT77S10/HT77S11 -- High Efficiency Synchronous Step-up DC/DC Converter

General Description

The HT77S11 and HT77S10 are high efficiency PFM synchronous step-up DC-DC converters. The two devices although functionally similar are different in their output drive current capabilities. Synchronous rectification operation is uesed to increase device efficiency and to reduce the external component resulting in reduced product costs. The converter switching frequency, which can have a value up to 500KHz, will vary according to the load demands and according to the input voltage to keep the output voltage at the required level.

The HT77S11 and HT77S10 have 0.7V start-up voltage, and will consume a typical quiescent current of 20uA. A shutdown mode is provided whereby the operating current will be reduced a very low value. The output voltage has two fixed voltage of 3.3V by setting FB to OUT pin and 5V by setting FB to GND pin, but can also be adjusted between a value of 1.8V~5.5V using two external resistors. With internal voltage detector function, the detected voltage can be set by using dividing resistor.