I

L

t

200mA

(typ.)

ContinuousCurrentOperation

DiscontinuousCurrentOperation

200mA

(typ.)

Current

Sensor

Gate

Driver

Device

Control

GND

EN

FB

VOUT

L

VREF

VIN

Device

Control

StartUp

VIN

VOUT

Current

Sensor

Gate

Driver

Device

Control

GND

EN

FB

VOUT

L

VREF

VIN

Device

Control

StartUp

VIN

VOUT

TPS61220, TPS61221, TPS61222

www.ti.com

SLVS776B – JANUARY 2009 – REVISED NOVEMBER 2014

10 Detailed Description

10.1 Overview

The TPS6122x is a high performance, high efficient family of switching boost converters. To achieve high

efficiency, the power stage is realized as a synchronous-boost topology. For the power switching, two actively-

10.2 Functional Block Diagrams

Figure 23. Functional Block Diagram (Adjustable

Figure 24. Functional Block Diagram (Fixed Output

Version)

Voltage Version)

10.3 Feature Description

10.3.1

Controller Circuit

The device is controlled by a hysteretic current mode controller. This controller regulates the output voltage by

keeping the inductor ripple current constant in the range of 200 mA and adjusting the offset of this inductor

current depending on the output load. If the required average input current is lower than the average inductor

current defined by this constant ripple current, the inductor current becomes discontinuous to keep the efficiency

high under low-load conditions.

Figure 25. Hysteretic Current Operation

To regulate the output voltage, the voltage error amplifier compares this feedback voltage to the internal voltage

reference and adjusts the required offset of the inductor current accordingly. In fixed output voltage devices, an

internal feedback network is used to program the output voltage. In adjustable versions an external resistor

divider is required.

The self-oscillating hysteretic current mode architecture is inherently stable and allows fast response to load

variations. This architecture also allows using a wide range of inductor and capacitor values.

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Product Folder Links: TPS61220 TPS61221 TPS61222