Micrel, Inc.

MIC7401

March 16, 2015

4

Revision 1.0

Table of Contents (Continued)

Timing Diagrams ................................................................................................................................................................... 35

Normal Power-Up Sequence for Outputs .......................................................................................................................... 35

Standby (STBY) Pin (Wake-Up)............................................................................................................................................ 36

Evaluation Board Schematic ................................................................................................................................................. 37

Bill of Materials ...................................................................................................................................................................... 38

PCB Layout Guidelines ......................................................................................................................................................... 39

General .............................................................................................................................................................................. 39

IC ....................................................................................................................................................................................... 39

Input Capacitor .................................................................................................................................................................. 39

Inductor.............................................................................................................................................................................. 39

Output Capacitor ............................................................................................................................................................... 39

Proper Termination of Unused Pins ...................................................................................................................................... 40

PCB Layout Recommendations ............................................................................................................................................ 41

Package Information

(17) and Recommended Landing Pattern.............................................................................................. 45

Via Layout Design and Layout Constraints ........................................................................................................................... 46

Appendix A ............................................................................................................................................................................ 47

I

2C Control Register........................................................................................................................................................... 47

Serial Port Operation ......................................................................................................................................................... 47

External Host Interface .................................................................................................................................................. 47

Special Host I

2C Commands ......................................................................................................................................... 48

Special Keys .................................................................................................................................................................. 48

Appendix B ............................................................................................................................................................................ 49

Register Settings Descriptions .......................................................................................................................................... 49

Power Good Register (00’h) .......................................................................................................................................... 49

EEPROM-Ready Register (01’h) ................................................................................................................................... 50

Fault Registers (02’h)..................................................................................................................................................... 51

Standby Register (03’h)..................................................................................................................................................... 52

Enable/Disable Register (04’h).......................................................................................................................................... 53

Regulator Output Voltage Setting NORMAL Mode (05’h

− 09’h) ...................................................................................... 54

Boost Regulator Output Voltage Setting NORMAL Mode (0A’h) ...................................................................................... 55

Regulator Voltage Setting STBY Mode (0B’h – 0F’h) ....................................................................................................... 56

Boost Regulator Output Voltage Setting STBY Mode (10’h)............................................................................................. 57

Sequence Register (11’h).................................................................................................................................................. 58

Delay Register (17’h) ......................................................................................................................................................... 61

Soft-Start Registers (18’h

− 1A’h)...................................................................................................................................... 62

Current-Limit (Normal Mode) Registers (1B’h

− 1D’h) ...................................................................................................... 63

Current-Limit (STBY Mode) Registers (1E

− 20’h) ............................................................................................................ 65

Power-on-Reset (POR) Threshold Voltage Setting Register (21’h and 22’h) ................................................................... 66

Pull-Down when Disabled Register (23’h)......................................................................................................................... 67