Power Management AAC242/243

© Copyright 2010- ASIC Advantage, Inc. – AADS00012 / R127B

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Preliminary

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October 2010

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In cases where duty cycle exceeds 50% slope compensation is required. This can be implemented by adding a buffer

transistor to the oscillator circuit and using a resistive summing circuit to provide the ramp necessary for slope

compensation.

Shut down circuits depend on the desired function. A transistor can be used to allow control on and off of the PWM

or an SCR can be used to latch off the PWM.

Slope compensation

Ct

8

1

2

3

4

5

6

7

Vref

COMP

FB

Isense

R/C

GND

OUT

Vcc

C

2N3904

Rslope

Rt

Rsense

R

Shutdown circuits

shutdown

8

1

2

3

4

5

6

7

Vref

COMP

FB

Isense

R/C

GND

OUT

Vcc

2N3904

100K

2N3904

shutdown

100K

8

1

2

3

4

5

6

7

Vref

COMP

FB

Isense

R/C

GND

OUT

Vcc