Datasheet Texas Instruments UCC28704DBVR-1

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SLUSCA8A – FEBRUARY 2016 – REVISED FEBRUARY 2016 UCC28704 High-Efficiency Off-Line CV and CC Flyback Controller
with Primary-Side Regulation (PSR)
1 Features 3 Description The UCC28704 Off-line flyback controller is a highly
integrated, 6-pin primary-side regulated PWM
controller for designing high efficiency AC-to-DC
power supplies with low standby power consumption
to comply with global efficiency standards. The
controller has ultra-low current consumption at startup to enable designs with 4.85 V, the device operates in constant current mode. When load is in step-down
transient demanding frequency lower than 4 kHz, first, the device stays at 4 kHz for up to 500 ms, or the output
voltage reaches about 10% over the VOCV within 500 ms, then the device adjusts the switching frequency to be
lower than 4 kHz as needed. More details can be found in Load Transient Response. Submit Documentation Feedback Copyright В© 2016, Texas Instruments Incorporated Product Folder Links: UCC28704 15 UCC28704
SLUSCA8A – FEBRUARY 2016 – REVISED FEBRUARY 2016 www.ti.com Feature Description (continued)
7.3.4 Primary-Side Constant Current (CC) Regulation
Timing information at the VS pin and current information at the CS pin allow accurate regulation of the secondary
average current. The control law dictates that as power is increased in CV regulation and approaching CC
regulation the primary-peak current is at IPP(max). Referring to Figure 16 below, the primary peak current (IPP), …