AP3776 datasheet(13/17 Pages) DIODES

13 / 17 page

AP3776

Document number: DS36707 Rev. 4 - 2

13 of 17

www.diodes.com

February 2015

AP3776

A Product Line of

Diodes Incorporated

Function Description (Cont.)

VTH(ST)

VFB(SCP)

tOFF(MAX)

VCC

VFB

VOUT

VOUT(SCP)

Figure 6. Normal Start-up

VTH(ST)

VOPR(MIN)

VFB(SCP)

tOFF(MAX)

VCC

VFB

VOUT

Figure 7. Short Circuit Protection (SCP) and Hiccup Mode

RCS Short Protection

When the primary side current sense resistance is shorted, the primary side current rapidly increases, and the transformer saturates, which leads

to some components

’ damage. The AP3776 draws in the RCS short protection to avoid the damage. If the voltage of CS pin is smaller than 0.15V

at the primary side maximum on time tonp(MAX), the RCS short protection is triggered, and the AP3776 immediately shuts down, and then

restarts.

Over Temperature Protection (OTP)

When the IC junction temperature exceeds the thermal shutdown temperature threshold of +130ºC, the device shuts down immediately. Retry is

allowed if junction temperature reduces by hysteresis temperature value.

AP3776 数据表(PDF) 13 Page - Diodes Incorporated