HT3402S

2/11

40V/2A Constant Voltage & Constant Current Buck Converter IC

www.hotchip.com.cn

Ver1.1

Application Circuit

Operation

General Introduction



HT3402S utilizes a constant current and constant voltage circuit to manage charging current by an

external sensing Resistor via Pins of SEN and VOUT . The preset Output Voltage is internally built

@ 5.1V, with internal amplifier and resistor divider to ensure <±3% regulation accuracy.

Automatic Start- Up



When a > 4V signal being inputted and sensed by HT3402S, it starts up automatically.

CC and CV Circuitry



In regular operation, the constant current charge loop starts- up at first, and will be taken over by the

constant voltage loop when the output voltage is higher than preset value of 5V. In the constant current

loop, the average current of inductor is set to be followed the external Sensing Resistor. This constant

current function is well controlled by an Error- amplifier, I-EA, and which ensures current accuracy



range within 5%. In voltage loop, system regulates SEN voltage by switching at a fixed frequency

transferring power to Load in each cycle by adopting a slope circuit, and Voltage mode PWM Controlled

A simplified function diagram of charge current and charge voltage is shown as: