ZHCSCK8G May 2014 – October 2017 LP8860-Q1
PRODUCTION DATA.
The gate driver for the external boost FET can be powered directly from the VDD input or from the charge pump integrated into the LP8860-Q1. When a 5-V rail is available in the system for VDD supply, it is typically a high enough voltage to drive the external FET, and the internal charge pump can be disabled. In this case, the VDD and CPUMP pins must be shorted together, and the fly cap can be removed. When the system VDD is not high enough to drive the gate of the boost FET (typical case is 3.3 V), the charge pump can be used to multiply the gate drive voltage to 2× VDD.
The SQW output provides a 100-kHz square wave signal (1 mA maximum) with amplitude equal to the charge-pump output voltage. When the charge pump is disabled, the amplitude of the SQW signal is equal to VDD. See Charge Pump and High Output Voltage Application sections for usage examples.