ZL2008

2

Data Sheet Revision 2/19/2009

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Table of Contents

1. Electrical Characteristics...............................................................................................................................................4

2. Pin Descriptions ............................................................................................................................................................8

3. Typical Application Circuit.........................................................................................................................................10

4. ZL2008 Overview .......................................................................................................................................................11

4.1 Digital-DC Architecture ......................................................................................................................................................... 11

4.2 Power Conversion Overview.................................................................................................................................................. 12

4.3 Power Management Overview ............................................................................................................................................... 13

4.4 Multi-mode Pins..................................................................................................................................................................... 13

5. Power Conversion Functional Description..................................................................................................................15

5.1 Internal Bias Regulators and Input Supply Connections........................................................................................................ 15

5.2 High-side Driver Boost Circuit .............................................................................................................................................. 15

5.3 Output Voltage Selection ....................................................................................................................................................... 15

5.3.1. Standard Mode..............................................................................................................................................15

5.3.2. SMBus Mode.................................................................................................................................................16

5.3.3. POLA Voltage Trim Mode ............................................................................................................................16

5.3.4. DOSA Voltage Trim Mode............................................................................................................................17

5.4 Start-up Procedure.................................................................................................................................................................. 17

5.5 Soft Start Delay and Ramp Times .......................................................................................................................................... 18

5.6 Power Good............................................................................................................................................................................ 19

5.7 Switching Frequency and PLL ............................................................................................................................................... 20

5.8 Power Train Component Selection......................................................................................................................................... 21

5.8.1. Design Goal Trade-offs ................................................................................................................................22

5.8.2. Inductor Selection.........................................................................................................................................22

5.8.3. Output Capacitor Selection ..........................................................................................................................23

5.8.4. Input Capacitor.............................................................................................................................................23

5.8.5. Bootstrap Capacitor Selection......................................................................................................................23

5.8.6. QL Selection..................................................................................................................................................23

5.8.7. QH Selection.................................................................................................................................................24

5.8.8. MOSFET Thermal Check .............................................................................................................................24

5.8.9. Current Sensing Components .......................................................................................................................24

5.9 Current Limit Threshold Selection......................................................................................................................................... 25

5.10 Loop Compensation ............................................................................................................................................................. 26

5.11 Non-linear Response (NLR) Settings................................................................................................................................... 28

5.12 Efficiency Optimized Driver Dead-time Control ................................................................................................................. 28

5.13 Adaptive Diode Emulation................................................................................................................................................... 28

5.14 Adaptive Frequency Control ................................................................................................................................................ 28

6. Power Management Functional Description ...............................................................................................................30

6.1 Input Undervoltage Lockout .................................................................................................................................................. 30

6.2 Output Overvoltage Protection............................................................................................................................................... 30

6.3 Output Pre-Bias Protection..................................................................................................................................................... 30

6.4 Output Overcurrent Protection ............................................................................................................................................... 32

6.5 Thermal Overload Protection ................................................................................................................................................. 32

6.6 Voltage Tracking.................................................................................................................................................................... 32

6.7 Voltage Margining ................................................................................................................................................................. 34

6.10 Digital-DC Bus..................................................................................................................................................................... 35

6.11 Phase Spreading ................................................................................................................................................................... 35

6.12 Output Sequencing ............................................................................................................................................................... 36

6.13 Fault Spreading .................................................................................................................................................................... 36

6.14 Temperature Monitoring Using the XTEMP Pin ................................................................................................................. 36

6.15 Active Current Sharing......................................................................................................................................................... 37

6.16 Phase Adding/Dropping ....................................................................................................................................................... 39