April 2015

DocID027705 Rev 1

1/4

www.st.com

STEVAL-ISA169V1

Evaluation board: SRK2001L adaptive synchronous rectification

controller for LLC resonant converters with STL140N4LLF5

Data brief

Features



Synchronous rectifier for LLC resonant

converter, with adaptive turn-on and turn-off





Max frequency: 500 kHz



Dual gate drive for N-channel MOSFETs

(logic level driver)



SR MOSFET type: STL140N4LLF5 (40 V

–

3.1 mΩ) PowerFlat

Description

The STEVAL-ISA169V1 is a product evaluation

board designed to demonstrate the performance

of the SRK2001L synchronous rectification

controller. The SRK2001L implements a control

scheme specific for secondary-side synchronous

rectification in LLC resonant converters that use

a transformer with center-tap secondary winding

for full-wave rectification. It provides two high-

current gate-drive outputs (for driving N-channel

power MOSFETs). Each gate driver is controlled

separately and an interlock logic circuit prevents

the two synchronous rectifier (SR) MOSFETs

from conducting simultaneously. Device

operation is based on adaptive algorithms for

both turn-on and turn-off of SR MOSFETs. During

fast load transitions or during above resonance

operation, a further turn-off mechanism is

provided, based on a ZCD_OFF comparator that

triggers the gate drive circuit for very fast

MOSFET turn-off. The board includes two SR

MOSFETs (PowerFlat package) and can be

easily implemented in an existing converter as a

substitute for rectifier diodes.