Zero-Pole

AMP.

Integrator

Error Amp

PFMComp

PWM

Comp .

VREF

Control

Stage

GateDriver

Anti

Shoot-Through

Current

LimitComparator

Current

LimitComparator

VREF

FB

VIN

GND

MODE

SW

EN

VIN

Softstart

VOUT RAMP

CONTROL

Thermal

Shutdown

Reference

0.6VVREF

Undervoltage

Lockout1.8V

HighSide

LowSide

Sawtooth

Generator

FB

MODE

GND

2.25MHz

Oscillator

TPS62590

www.ti.com

SLVS897C – JANUARY 2009 – REVISED DECEMBER 2015

7 Detailed Description

7.1 Overview

The TPS62590 step-down converter operates with typically 2.25-MHz fixed frequency pulse width modulation

(PWM) at moderate to heavy load currents. At light load currents, the converter can automatically enter power

save mode and operates then in pulse frequency modulation (PFM) mode.

During PWM operation, the converter use a unique fast response voltage mode controller scheme with input

voltage feed-forward to achieve good line and load regulation allowing the use of small ceramic input and output

capacitors. At the beginning of each clock cycle initiated by the clock signal, the high-side MOSFET switch is

turned on. The current flows now from the input capacitor through the high-side MOSFET switch through the

inductor to the output capacitor and load. During this phase, the current ramps up until the PWM comparator trips

and the control logic turns off the switch. The current limit comparator also turns off the switch if the current limit

of the high-side MOSFET switch is exceeded. After a dead time preventing shoot through current, the low-side

MOSFET rectifier is turned on and the inductor current ramps down. The current flows now from the inductor to

the output capacitor and to the load. It returns to the inductor through the low-side MOSFET rectifier.

The next cycle is initiated by the clock signal again turning off the low-side MOSFET rectifier and turning on the

high-side MOSFET switch.

7.2 Functional Block Diagram

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Product Folder Links: TPS62590