This is one of the controller types.
Part Number : UP1589Q, UP1589QQKF
Function : High Efficiency, Main Power Supply Controller
Package : QFN-20 Pin Type
Manufacturers : UPI
See the preview image and the PDF file for more information.
The UP1589Q is a dual step down, Switch Mode Power Supply (SMPS) controller which generates logic supply voltages for battery powered systems. It includes two Pulse Width Modulation (PWM) controllers adjustable from 2V to 5.5V and also two fixed 5V/3.3V linear regulators. One of the controllers (LDO5) provides automatic switch over to the BYP1 input connected to the main SMPS1 output for maximized efficiency.
Pinout ( = RT8239B )
1. Notebook computers
2. System Power Supplies
3. 3- and 4- Cell Li+ Battery-Powered Device