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TPS54200, TPS54201

SLUSCO8A – NOVEMBER 2016 – REVISED MARCH 2017

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7 Detailed Description

7.1 Overview

The TPS5420x is a 1.5-A synchronous buck LED driver up to 28-V input. Current-mode operation provides fast

transient response. The optimized internal compensation network minimizes the external component counts and

simplifies the control loop design.

Fixed 600-kHz switching frequency is chosen for a good tradeoff between efficiency and size.

The integrated 150-mΩ high-side MOSFET and 70-mΩ low-side MOSFET allow for the high-efficiency LED driver

with continuous output currents up to 1.5 A.

The TPS5420x supports deep dimming in both analog and PWM dimming mode. In analog dimming mode, the

internal reference voltage is changed proportional to the duty cycle of PWM signal in 1% to 100% range. In PWM

dimming mode, LED will be turn on and off according to PWM duty cycle periodically. For higher efficiency, the

internal reference will be halved to 100 mV.

Cycle-by-cycle current limit in high-side MOSFET protects the converter in over-load condition and is enhanced

by a low-side MOSFET freewheeling current limit which prevents current runaway. There is a low-side MOSFET

sinking current limit to prevent excessive reverse current.

For safety and protection the TPS5420x includes LED open and short protection, sense resistor open and short

protection, and device thermal protection. TPS54200 implements shutdown-and-latch mode protection, while

TPS54201 adopts hiccup up mode protection.