TPS54341_15 datasheet(24/48 Pages) TI

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REF

COMP

Type 2A

Type 2B

Type 1

OUT

ESR

OUT

Adc = gm

OUT

Adc

p ´

TPS54341

SLVSC61 – NOVEMBER 2013

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DETAILED DESCRIPTION (continued)

(14)

(15)

(16)

(17)

Small Signal Model for Frequency Compensation

The TPS54341 device uses a transconductance amplifier for the error amplifier and supports three of the

commonly-used frequency compensation circuits. Compensation circuits Type 2A, Type 2B, and Type 1 are

shown in Figure 44. Type 2 circuits are typically implemented in high bandwidth power-supply designs using low-

ESR output capacitors. The Type 1 circuit is used with power-supply designs with high-ESR aluminum-

electrolytic or tantalum capacitors. Equation 18 and Equation 19 relate the frequency response of the amplifier to

the small signal model in Figure 44. The open-loop gain and bandwidth are modeled using the RO and CO shown

in Figure 44. See the APPLICATION INFORMATION section for a design example using a Type 2A network with

a low-ESR output capacitor.

Equation 18 through Equation 27 are provided as a reference. An alternative is to use WEBENCH software tools

to create a design based on the power-supply requirements (go to www.ti.com/WEBENCH for more information).

Figure 44. Types of Frequency Compensation

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