STR3A400 Series

STR3A400-DSE Rev.2.1

SANKEN ELECTRIC CO.,LTD.

2

Sept. 18, 2015

http://www.sanken-ele.co.jp/en/

© SANKEN ELECTRIC CO.,LTD. 2014

CONTENTS

Description ------------------------------------------------------------------------------------------------------ 1

CONTENTS ---------------------------------------------------------------------------------------------------- 2

1. Absolute Maximum Ratings----------------------------------------------------------------------------- 3

2. Electrical Characteristics -------------------------------------------------------------------------------- 4

3. Performance Curves -------------------------------------------------------------------------------------- 5

3.1

Derating Curves ------------------------------------------------------------------------------------- 5

3.2

MOSFET Safe Operating Area Curves --------------------------------------------------------- 6

3.3

Ambient Temperature versus Power Dissipation Curves ----------------------------------- 7

3.4

Transient Thermal Resistance Curves ---------------------------------------------------------- 8

4. Block Diagram --------------------------------------------------------------------------------------------- 9

5. Pin Configuration Definitions--------------------------------------------------------------------------- 9

6. Typical Application ------------------------------------------------------------------------------------- 10

7. External Dimensions------------------------------------------------------------------------------------ 11

8. Marking Diagram --------------------------------------------------------------------------------------- 11

9. Operational Description ------------------------------------------------------------------------------- 12

9.1

Startup Operation--------------------------------------------------------------------------------- 12

9.2

Undervoltage Lockout (UVLO) ---------------------------------------------------------------- 12

9.3

Bias Assist Function------------------------------------------------------------------------------- 12

9.4

Soft Start Function -------------------------------------------------------------------------------- 13

9.5

Constant Output Voltage Control-------------------------------------------------------------- 13

9.6

Leading Edge Blanking Function -------------------------------------------------------------- 14

9.7

Random Switching Function -------------------------------------------------------------------- 14

9.8

Automatic Standby Function ------------------------------------------------------------------- 14

9.9

Step Drive Control -------------------------------------------------------------------------------- 15

9.10 Overcurrent Protection (OCP) ----------------------------------------------------------------- 16

9.10.1

OCP Operation ------------------------------------------------------------------------------ 16

9.10.2

OCP Input Compensation Function ----------------------------------------------------- 16

9.11 Overload Protection (OLP)---------------------------------------------------------------------- 17

9.12 Overvoltage Protection (OVP) ------------------------------------------------------------------ 17

9.13 Thermal Shutdown (TSD) ----------------------------------------------------------------------- 18

10. Design Notes ---------------------------------------------------------------------------------------------- 18

10.1 External Components ---------------------------------------------------------------------------- 18

10.1.1

Input and Output Electrolytic Capacitor----------------------------------------------- 18

10.1.2

S/OCP Pin Peripheral Circuit ------------------------------------------------------------ 19

10.1.3

VCC Pin Peripheral Circuit--------------------------------------------------------------- 19

10.1.4

FB/OLP Pin Peripheral Circuit ---------------------------------------------------------- 19

10.1.5

Snubber Circuit------------------------------------------------------------------------------ 19

10.1.6

Peripheral Circuit of Secondary-side Shunt Regulator ------------------------------ 19

10.1.7

Transformer ---------------------------------------------------------------------------------- 19

10.2 PCB Trace Layout and Component Placement --------------------------------------------- 20

11. Pattern Layout Example ------------------------------------------------------------------------------- 22

12. Reference Design of Power Supply ------------------------------------------------------------------ 23

OPERATING PRECAUTIONS -------------------------------------------------------------------------- 25

IMPORTANT NOTES ------------------------------------------------------------------------------------- 26