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