Undervoltage

Lockout

Bias Supply

_

+

+

–

REF

Current Limit Comparator

+

–

REF

P-Channel

Power MOSFET

N-Channel

Power MOSFET

Driver

Shoot-Through

Logic

+

–

Load Comparator

Control

Logic

+

–

1.21 V

Soft Start

850 kHz

Oscillator

+

–

S

R

Comparator High

Comparator Low

Comparator High2

+

–

Compensation

R2

See Note

R1

Comparator Low

Comparator Low2

Comparator High

Saw Tooth

Generator

V

I

Comparator

SW

PG

LBO

GND

PGND

LBI

FB

EN

SKIP Comparator

Error Amp

SYNC

TPS62050, TPS62051, TPS62052, TPS62054, TPS62056

www.ti.com

SLVS432F – SEPTEMBER 2002 – REVISED JUNE 2015

9 Detailed Description

9.1 Overview

The TPS6205x family of devices are synchronous step-down converters that operate with a 850-kHz fixed-

frequency pulse width modulation (PWM) at moderate to heavy load currents and enters the power save mode at

light load current.

During PWM operation, the converter uses a unique fast response voltage mode control scheme with input

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

capacitors. At the beginning of each clock cycle initiated by the clock signal (S), the P-channel MOSFET switch

is turned on and the inductor current ramps up until the voltage comparator trips and the control logic turns the

switch off. Also the switch is turned off by the current limit comparator if the current limit of the P-channel switch

is exceeded. After the dead time preventing current shoot through, the N-channel MOSFET rectifier is turned on

and the inductor current ramps down. The next cycle is initiated by the clock signal again, turning off the N-

channel rectifier and turning on the P-channel switch.

The error amplifier as well as the input voltage determines the rise time of the saw tooth generator; therefore,

any change in input voltage or output voltage directly controls the duty cycle of the converter giving a very good

line and load transient regulation.

9.2 Functional Block Diagram

NOTE: For the adjustable versions (TPS62050, TPS62051 devices), the internal feedback driver is disabled and the

FB pin is directly connected to the GM amplifier.

Copyright © 2002–2015, Texas Instruments Incorporated

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Product Folder Links: TPS62050 TPS62051 TPS62052 TPS62054 TPS62056