LD5523T

04/08/2021

1

Leadtrend Technology Corporation

www.leadtrend.com.tw

LD5523T-DS-00 April 2021

Multi-Mode PWM Controller of Flyback with

MOSFET Integrated

REV. 00

General Description

The LD5523T is built in a multi-mode PWM controller.

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 LD5523T 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 LD5523T 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).

Features



Secondary-side feedback control with

quasi-resonant + CCM operation



Low Startup Current (<1

A)



Ultra-low operating current at light load



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 (Over Voltage Protection) on FB pin.



Adj. UVP (Under Voltage Protection) on FB pin.



OLP (Over Load Protection)



Internal OTP (Over Temperature Protection)

Applications



Switching AC/DC Adaptor



Open Frame Switching Power Supply

Typical Application