Rev. S 12/07

2

DPA422-426

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Section List

Functional Block Diagram ....................................................................................................................................... 3

Pin Functional Description ...................................................................................................................................... 3

DPA-Switch Family Functional Description ............................................................................................................ 4

CONTROL (C) Pin Operation .................................................................................................................................... 4

Oscillator and Switching Frequency.......................................................................................................................... 5

Pulse Width Modulator & Maximum Duty Cycle........................................................................................................ 5

Minimum Duty Cycle and Cycle Skipping ................................................................................................................. 6

Error Amplifier .......................................................................................................................................................... 6

On-chip Current Limit with External Programmability ................................................................................................ 6

Line Under-Voltage Detection (UV)............................................................................................................................ 6

Line Overvoltage Shutdown (OV).............................................................................................................................. 6

Line Feed-Forward with DC

Remote ON/OFF ...................................................................................................................................................... 7

Synchronization........................................................................................................................................................ 7

Soft-Start ................................................................................................................................................................. 8

Shutdown/Auto-Restart ........................................................................................................................................... 8

Hysteretic Over-Temperature Protection ................................................................................................................... 8

Bandgap Reference ................................................................................................................................................. 8

High-Voltage Bias Current Source ............................................................................................................................ 8

Using Feature Pins ..................................................................................................................................................... 8

FREQUENCY (F) Pin Operation ................................................................................................................................ 8

LINE-SENSE (L) Pin Operation ................................................................................................................................. 9

EXTERNAL CURRENT LIMIT (X) Pin Operation......................................................................................................... 9

Typical Uses of FREQUENCY (F) Pin ...................................................................................................................... 11

Typical Uses of LINE-SENSE (L) and EXTERNAL CURRENT LIMIT (X) Pins ....................................................... 11

Application Examples .............................................................................................................................................. 14

Key Application Considerations .............................................................................................................................. 16

DPA-Switch Design Considerations........................................................................................................................ 16

DPA-Switch Layout Considerations ........................................................................................................................ 18

Quick Design Checklist .......................................................................................................................................... 19

Design Tools .......................................................................................................................................................... 20

Product Specifications and Test Conditions .......................................................................................................... 21

Typical Performance Characteristics

.................................................................................................................. 27

Part Ordering Information ....................................................................................................................................... 30

Package Outlines .................................................................................................................................................... 31