Improved Error Amplifier

REF

VSENSE

+

-

COMP

4.95V

C

Z

R

Z

C

P

+

+

COMP

VSENSE

Soft Start

6V

5.75V

6.45V

OV

PWM

Shutdown

160mA

g

m

+

R

Q

Q

S

+

0.5V

Brownout

EN

UV

OV

(UCC28061)

UCC28060

www.ti.com .................................................................................................................................................... SLUS767E – MAY 2007 – REVISED NOVEMBER 2008

The voltage error amplifier is a transconductance amplifier. Voltage loop compensation is connected from the

error amplifier output, COMP, to analog ground, AGND. The recommended compensation network is shown in

Figure 28.

Figure 28. Typical Error Amplifier Compensation

To improve the transient response, the error amplifier output current is increased by 100

µA when the error amp

input is below 5.815 V, as shown in Figure 29. This increase allows faster charging of the compensation

components following sudden load current increases (also refer to Figure 4 in the Typical Characteristics).

Figure 29. Error Amplifier Block Diagram Showing Speed-Up and Latched Soft-Start

Copyright © 2007–2008, Texas Instruments Incorporated

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