LD5523K

05/16/2018

1

Leadtrend Technology Corporation

www.leadtrend.com.tw

LD5523K-DS-00 May 2018

EMI

Filter

FB

OUT

CS

VCC

GND

COMP

LD5523K

photocoupler

AC

input

DC

Output

NTC

Multi-Mode PWM Controller of Flyback with

Integrated BNI/BNO and Bulk cap. OVP

REV. 00

General Description

In order to enhance the efficiency performance, the

LD5523K integrates the multi-mode PWM controller,

which consists of Quasi-Resonant (QR) PWM control for

light load condition and Continue Conduction Mode

(CCM) for heavy load condition. Moreover, the QR

controller not only gains the system performance, but

also brings the worse EMI capability, while the

frequency swapping function of LD5523K can reduce

the EMI emission of SMPS and helps the power circuit

designers to simply deal with EMI filter and saves

several component and developing time.

The LD5523K is implemented in SOT-26 package, and

includes the comprehensive protection function, such as

Over Load Protection (OLP), Over Voltage Protection

(OVP), Output Short Circuit Protection (OSCP) and

internal

Over

Temperature

Protection

(OTP).

Furthermore, the programmable brown-in/out and bulk

cap. OVP protection is built-in.

Features

 Secondary-side feedback control with

quasi-resonant + CCM operation

 Low Startup Current (<1

A)

 0.285mA Ultra-low operating current at light load

 Current Mode Control with Cycle-by-Cycle Current

Limit

 Green Mode Control

 UVLO (Under Voltage Lockout)

 LEB (Leading-Edge Blanking) on CS Pin

 VCC OVP (Over Voltage Protection)

 Adj. OVP / UVP on FB pin

 Adj. BNI/BNO, Bulk cap. OVP on FB pin

 OLP (Over Load Protection)

 External OTP (Over Temperature Protection) on

CS Pin

 Internal OTP (Over Temperature Protection)

 SDSP (Secondary Diode Short Protection)

 Gate Source/Sink Capability: 350mA/-355mA @

output pin with 33nF capacitor.

Applications

 Switching AC/DC Adaptor

Typical Application