REG

VDD

VD

START

TSD

VG

VS

Adaptive TOFF

& DCM ring rejection

VTHVGON

S

Q

Q

R

VTHVGOFF

VTHREG

Prop-DRV

threshold

9.5-V Linear

Regulator

REG

UVLO

POWER & FAULT

MANGEMENT

PROPORTIONAL

GATE DRIVE

CONTROL

GATE

DRIVER

+

±

+

±

Turn On

Blanking

Copyright © 2018, Texas Instruments Incorporated

10

UCC24612

SLUSCM5A – AUGUST 2017 – REVISED FEBRUARY 2018

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Copyright © 2017–2018, Texas Instruments Incorporated

7 Detailed Description

7.1 Overview

The UCC24612 synchronous rectifier (SR) controller uses drain-to-source voltage sensing to determine the SR

MOSFET conduction interval. The SR MOSFET is turned on when VDS exceeds turn-on threshold VTHVGON, and

is turned off when VDS falls below VTHVGOFF. The SR conduction voltage drop is continuously monitored and

regulated to minimize the conduction loss while allowing the SR to pre-turn-off when operating in continuous

conduction mode (CCM) . The extremely fast turn-off comparator and driving circuit ensures the fast turn-off of

the SR MOSFET, even in CCM condition. Fixed minimum on-time (tON(min) ) allows the controller to operate up to

1-MHz switching frequency (1 MHz for UCC24612-1, 800 kHz for UCC24612-2). The adaptive minimum off-time

control simplifies the design, making the controller suitable for a wide range of applications and switching

frequencies, with good immunity to noise caused by parasitic ringing. To minimize the standby power, automatic

light-load mode disables the VG pulses when the average switching frequency of the converter becomes lower

than fSLEEP (12 kHz typical). When the load increases such that the average switching frequency increases above

fWAKE (15 kHz typical), the controller resumes normal SR operation. The wide VDD range and gate driver clamp

make the controller ideal for wide output voltage range applications such as USB Power Delivery (USB-PD)

adapters, for example.

7.2 Functional Block Diagram