7 Detailed Description

7.1 Overview

The TPS92201 is a high-efficiency 1.5A synchronous buck-type LED driver with 2.5V to 5.5V input range. The

device operates at typically 1.5MHz pulse width modulation (PWM) mode in full current range. In additional,

TPS92201A can support Power Save Mode, the device operates in pulse width modulation (PWM) mode with

1.5MHz switching frequency at heavy load, similar as TPS92201. But at light load, the device automatically

enters pulse frequency modulation (PFM) to maintain high efficiency over the entire load current range. In Power

Save Mode, the converter reduces switching frequency and minimizes current consumption, the output voltage

rises slightly above the nominal output voltage. This effect is minimized by increasing the output capacitor.

The integrated switches for both deivces have the capability to deliever up to 1.5A constant current and no need

for external Schottky diode. Analog dimming is achieved by adjusting the duty cycle of the PWM in 1% to 100%

range. Full protection methods are implemented including LED open, LED short, FB resistor open, FB resistor

short and thermal shutdown.

7.2 Functional Block Diagram

UVLO

Modulator

SW

Soft

Startup

Gate

Driver

-

+

VREF

Control Logic

EA

VIN

GND

FB

Dimming Control

Peak

Current

Detect

EN

Thermal

Shutdown

PWM

Zero

Current

Detect

TOFF

VIN

VSW

Figure 7-1. TPS92201 Functional Block Diagram

7.3 Feature Description

7.3.1 Adaptive Off-time Control

Adaptive off-time with peak current control scheme is used in the device. The device operates at typically

1.5MHz pulse width modulation (PWM) mode in full current range. At medium to heavy load, the device operates

in pulse width modulation (PWM) mode with 1.5MHz switching frequency. At light load, the device automatically

enters pulse frequency modulation (PFM) to maintain high efficiency over the entire load current range. Based

on the VIN/VOUT ratio, a simple circuit sets the required off time for the low-side MOSFET. The switching

frequency relatively constant regardless of the variation of input voltage, output voltage, and load current.

7.3.2 Power Save Mode

TPS92201A automatically enters Power Save Mode to improve efficiency at light load when the inductor current

becomes discontinuous. In Power Save Mode, the converter reduces switching frequency and minimizes current

consumption. In Power Save Mode, the output voltage rises slightly above the nominal output voltage. This

effect is minimized by increasing the output capacitor.

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TPS92201, TPS92201A

SLVSH40B – NOVEMBER 2023 – REVISED AUGUST 2024

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Product Folder Links: TPS92201 TPS92201A