UCC28C53_V01 datasheet(22/48 Pages) TI

22 / 48 page

8.4 Device Functional Modes

8.4.1 Normal Operation

During normal operating mode, the controller can be used in peak current mode or voltage mode control.

When the converter is operating in peak current mode, the controller regulates the converter's peak current and

duty cycle. When used in voltage mode control, the controller regulates the power converter's duty cycle. The

regulation of the system's peak current and duty cycle can be achieved with the use of the integrated error

amplifier and external feedback circuitry.

8.4.2 UVLO Mode

During the system start-up, VDD voltage starts to rise from 0 V. Before the VDD voltage reaches its

corresponding turn-on threshold, the IC is operating in UVLO mode. During UVLO mode operation, the VREF

pin voltage is not generated. When VDD is above 1 V and below the turn-on threshold, the VREF pin is actively

pulled low. This behavior allows VREF to be used as a logic signal to indicate UVLO mode. If the bias voltage to

VDD drops below the UVLO-OFF threshold, the PWM switching stops and VREF returns to 0 V. The device can

be restarted by applying a voltage greater than the UVLO-ON threshold to the VDD pin.

UCC28C53, UCC28C54, UCC28C55

UCC28C56H, UCC28C57H, UCC28C57L, UCC28C59

SLUSER8 – JUNE 2022

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UCC28C53 Datasheet(PDF) 22 Page - Texas Instruments