HT3402S

3/11

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

www.hotchip.com.cn

Ver1.1

Cable Resistance Compensation



The longer cable of car charger reduces output voltage. Add voltage compensation function will

increase the output voltage and make the output of cable is remained to be the design value. An

external resistor will be connected to the VCABLE pin to match the immanent resistor of cable. In the

cable compensation circuit, the voltage of the VCABLE pin will be raised as the load current increase;

the reference voltage of voltage loop will be raised to an appropriate value, and finished the

compensation function. If there is no load, no compensation resistors or output current is zero,

the

output voltage will not rise. Set VCABLE pin in floating state to turn off this function off. Selection of

external compensation resistor is based on the equivalent resistance of cable. Compensating voltage

can be determined by equation:

sen

out

cable

cable

R

I

R

K

V







2000

Over Voltage protection

When the output voltage of HT3402S is 10% higher than the targeting voltage, the PMOS will be turned off.

Thermal Shutdown (OTP)

preset value of approximately 120℃, HT3402S stops output

Short- circuit protection



At the beginning of enable HT3402S, system charges the load

for about 100ms. If the short circuit

protection module detect the output voltage is fallen down to 1.5V, it sends a single to Logic Circuit to

turn off IC. When shor-t circuit happens, a current of about 2 mA will charge the load.

If the short circuit state is aligned, charge voltage will raise above 1.5V and being detected,

system is

resumed to normal