HIGH PERFORMANCE SYNCHRONOUS RECTIFIER

DESCRIPTION

UTC USR5V10X is a high performance and tightly integrated

secondary side synchronous rectifier for switch mode power supply

system. It combines a much lower voltage drop N-channel

MOSFET to emulate the traditional diode rectifier at the secondary

side of Flyback converter, which can reduce heat dissipation,

increases output current capability and efficiency and simplify

thermal design.

It is suitable for multiple mode applications including

discontinuous conduction mode and quasi-resonant mode. With its

versatility and optimization, UTC USR5V10X can be used in

various  switch  mode  power  supply  topologies  including

secondary-side control topology and primary-side control topology.

From the information on the secondary side of the isolation

transformer, UTC USR5V10X generates a driving signal with dead

time with respect to the primary side PWM signal to turn the

integrated N-channel SR switch on and off in proximity of the zero

current transition. It is optimized for 5V output voltage. In

primary-side control topology, UTC USR5V10X can detect the

output voltage and feed back a series of warning pulses to primary

side controller when the output voltage is lower than an

inner-determined threshold to awaken the primary-side power

switch to improve dynamic response.

The externally adjustable minimum on time and internally off

time control scheme effectively avoid the ring impact induced by

parasitic elements so that a reliable and noise free operation of the

SR system is insured.

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FEATURES

* Low cost small size CC/CV mode support

* Accurate secondary side MOSFET V DS sensing

* Secondary-side synchronous rectifier optimized for 5V output system

* Output voltage over-shoot control and under-shoot control

* Suitable for DCM, QR operation

* Up to 150kHz operation frequency

* V DD UVLO protection