VOUT pin

IDS

CT pin

FLTB pin

2.4V

0.4V

10µA

20µA

1

2

3

14

15 16

FAULT Timeout

peroid

Discharge

to 0V

Fault and Restart Sequence

OVER TEMPERATURE PROTECTION

LP14040P has over temperature protection. While the temperature exceeds the over temperature

threshold, the device will enter the over temperature protection, the power MOSFET will be turned off

and output will be discharged by the internal pull down resistor. After the temperature drop below the

over temperature recover threshold, the system tries to restart again.

FAULT FUNCTION INDICATOR

LP14040P has an open drain FLTB pin to indicate the fault condition. When the device is in the

fault conditions, such as over temperature, input over voltage, input under voltage or fault timer time

out, the FLTB pin will be pulled down to GND by the internal open drain MOSFET. The fault will be

cleared after the system finish hiccup timer, toggle VIN or EN, or device temperature drop to OTP

recover threshold. FLTB pin is high impedance when the WP14040P is disabled.

INPUT RIPPLE REJECTION

LP14040P has implemented an input ripple rejection circuit. When input goes high, which make

LP14040P works under current limit condition, the fault timer will start to work, 10μA (typ.) current

charge CT pin cap; when input goes low, which make WP14040P out of current limit ,the fault timer

start to discharge the CT pin cap with 20μA (typ.) current. In such a case, there never have input ripple

causes over current protection happen.

TEMPERATURE FOLD BACK

To increase device’s reliability, a temperature fold back feature is integrated in to WP14040P.

The basic idea is, when the device’s temperature is higher than temperature fold back threshold, the

current limit value decrease with temperature increase.

LP14040P

Rev :

www.leiditech.com

01.06.2015

9/13