UCC28951
www.ti.com.cn
ZHCSIQ7A –AUGUST 2018 –REVISED DECEMBER 2021
7 Detailed Description
7.1 Overview
The UCC28951 controller combines all the functions necessary to control a phase-shifted, full-bridge, power
stage in a 24-pin TSSOP package. The controller includes two synchronous-rectifier (SR), gate-drive outputs as
well as the outputs needed to drive all four switches in the full-bridge circuit. The dead times between the upper
and lower switches in the full bridge may be set using the DELAB and DELCD inputs. Further, this dead time
may be dynamically adjusted according to the load level using the ADEL pin. This adjustment allows the user to
optimize the dead time for their particular power circuit and to achieve ZVS over the entire operating range. In a
similar manner, the dead times between the full-bridge switches and the secondary SRs may be optimized using
the DELEF input. This dead time may also be dynamically adjusted according to the load, using the ADELEF
input to the controller. A DCM (discontinuous conduction mode) option disables the SRs at a user settable light
load to improve power circuit efficiency. The controller enters a light-load-burst mode if the feedback loop
demands a conduction time less than a user settable level (TMIN).
At higher-power levels, two or more UCC28951 controllers may be easily synchronized in a leader/follower
configuration. A SS/EN input may be used to set the length of the soft start process and to turn the controller on
and off. The controller may be configured for voltage mode or current mode control. Cycle-by-cycle current
limiting is provided in voltage mode and peak current mode. Users can set the switching frequency over a wide
range making this controller suited to both IGBT and MOSFET based designs.
Copyright © 2023 Texas Instruments Incorporated
Submit Document Feedback
19
Product Folder Links: UCC28951
English Data Sheet: SLUSDB2
TI [ TEXAS INSTRUMENTS ]
