2007 Portable Power Design Seminar. Topic 3. Battery Charging Design Considerations. Charles Mauney and Jinrong Qian. Battery Management Applications

Transcription

1 2007 Portable Power Design Seminar Topic 3 Battery Charging Design Considerations Charles Mauney and Jinrong Qian Battery Management Applications 1

2 Portable Power Device Market Hideo Takeshita Institute of Information Technology, Ltd THE 23rd International battery seminar, Cellular Phone Unit (Million) Notebook PC Unit (Million) 02CY 03CY 04CY 05CY 06CY Others 50 LGE S Ericsson 40 Siemens Samsung 30 Motorola 20 Nokia DSC Unit (Million) 20 02CY 03CY 04CY 05CY 06CY Others Lenovo Acer Toshiba HP Dell Digital Camcorder Unit (Million) Others Fujifilm Nikon Olympus Kodak Sony Canon Others Hitachi Samsung Canon JVC Pana Sony CY 03CY 04CY 05CY 06CY 0 02CY 03CY 04CY CY 06CY 3-2

3 Portable Power Management for Portable Electronics Longer Battery Life Safety and fast charging Battery Charging Management Safety Longer battery cycle life Longer battery usable time Shorter battery charge time Smaller size Lighter weight 3-3

4 Outline Battery charging voltage vs. capacity and cycle life, Battery charge front end (CFE) safety protection Power path management battery charging Voltage based DPPM Input current based DPM 3-4

5 Charging Voltage versus Cycle Life 4.2 V 4.35 V 4.3 V 4.25 V Low Charging voltage accuracy: Over Charging Over charging get higher initial capacity Over charging shortens battery cycle life 3-5

6 Capacity versus Battery Charging Voltage Capacity versus Charging Voltage Capacity Loss versus Undercharge 10% Capacity - mah Capacity Loss - % 8% 6% 4% 2% Charging Voltage V / Cell 0% 0.0% -0.5% -1.0% -1.5% Under charge voltage Under charge decrease battery capacity Charge voltage accuracy is very important 3-6

7 Li-Ion Charge CC-CV Profile Pre-charge Constant Current Fast-charge Constant Voltage 4.2 V/Cell Battery Voltage I CHARGE 3.0 V/Cell Taper Current I PRECHARGE Pre-charge Timer Safety Timer I TERMINATION Constant Current: 20-30% charging time, 70-80% capacity Constant Voltage: 70-80% charging time, 20-30% capacity 3-7

8 Battery Charging System Requirements Safety and Reliability Hot Plug-in Reverse Input to the charger Short Circuit and Overcharging Protection 3-8

9 Cellular Phone Charger Interface AC V 50/60 Hz DC 5 V, 0.31 A USB 5V Data Clock GND V D D- GND USB type A connector from adapter output Terminal to the portable device could be different 3-9

10 Causes of System Failure Due to Input Power ADAPTER V INCIN Battery Charger SYSTEM Voltage (V) 5-V/500-mA UNREGULATED 5-V/500-mA REG Input Over Voltage Current (A) Wrong or After-Market Transformer Rectifier s (un-regulated) Hot Plug Event 3-10

11 Hot Plug In Test Setup and Equivalent Circuit 120 AC 220 AC V i - 1-m Cable C IN V IN CHARGER Charge Controller Battery R ESR > 2 i L C i IN V i Damping conditions: How ESR and C IN affect the Over-voltage? Ri I IN Li ESR C IN V IN CHARGER Charge Controller Battery 3-11

12 Reducing Overshoot by Increasing C IN 5V V IN bq2406x System I IN C IN Battery Charger R ESR > i 2 L C i IN C IN = 2 1 μf (0805, X7R) Overshoot: 50.4% to 7.52 V C IN = 8 1 μf (0805, X7R) Overshoot: 45.6%, 7.28 V 7.52 V V IN 5 V 7.28 V V IN I IN 2.95 A I IN 5.7 A C IN, Overshoot can not be reduced significantly. 3-12

13 Reducing Overshoot by Increasing ESR 5V R C C IN V IN bq2406x Battery Charger System R ESR > i 2 L C i IN C IN = 2 1 μf (0805, X7R) Overshoot: 50 % to 7.5 V C IN = 2 1 μf (0805,X7R) 1 Ω overshoot: 20%, 6.08 V 7.5 V V IN 5 V 6.0 V 5 V V IN I IN 2.95 A I IN 2 A High ESR or external resistor can help reduce voltage overshoot. 3-13

14 Reducing Overshoot by TVS Diode I IN V IN Bq2406x V IN Zener C IN Charger System 5.6 V 6.3 V I V C IN = 2 1 μf (0805, X7R) Overshoot: 50 % to 7.5 V 7.5 V 5V V IN C IN = 2 1 μf 5.6-V TVS Zener overshoot: 26%, 6.3 V V IN 6.3 V 5 V I IN 2.95 A 3 A I IN TVS Zener diode can marginally clamp voltage spike 3-14

15 TI Solution: Charge Front End (CFE) Improves Safety 120V 220V AC AC C IN V IN bq243xx Charge Front End (CFE) bq2408x Low Voltage Charger Without CFE If Charger fails due to any reason System will be in over-voltage condition and Fail Battery will be over-charged, and may explode or burn CFE Provide System Level Protections Input Transient Over-Voltage Steady state over voltage Over-Current Protection, Latch or Hiccup Reverse Polarity Battery Over-voltage Low Voltage System 3-15

16 Reverse Input Voltage to the System Forward-biased ESD diode, short the adapter output High current injected into the substrate V CC D ESD Diode Battery Charger System GND Power dissipation across the Diode D V CC ESD Diode Battery Charger System GND 3-16

17 TI Solution: Multiple Protection Levels IN Bq24300/4 or USB Q2 PGATE V SS Comparators and Control CE Q1 V BAT Battery Charger Disable Enable System Protections Input Over-Voltage Protection Over-Current Protection: Hiccup or Latch Battery Over-Voltage Protection Reverse Input Voltage Protection bq24300: V O(REG) = 5.5 V 2x2 8-pin DSG package V OVP = 10.5 V OCP = 300 ma, current limiting BATOVP = 4.35 V bq24304: V O(REG) = 4.5 V 3-17

18 Bq2430x OCP Performance IN or USB Q2 PGATE Q1 bq24300/4 V BAT Battery Charger System V SS CE 300 ma 64 ms V IN Curren t OCP Hiccup 3-18

19 bq2431x OCP-Hiccup-Latch or USB IN CE I LIM Q1 bq24314/16 V BAT bq24080 Battery Charger System R SET V SS FAULT 1 A Current 176 µs 15 times OCP, Latch Current FAULT Regulated Over-Current threshold for 3-19

20 Bq2430x Battery OVP (Hiccup) IN or USB Q2 PGATE Q1 bq24300/4 V BAT Battery Charger System V SS CE 4.35 V 176 µs V BAT Battery OVP Hiccup V BAT Battery OVP is 4.35 V with 6% hysteresis 3-20

21 bq2431x Battery OVP (Latch) or USB IN CE I LIM Q1 bq24314/16 V BAT bq24080 Battery Charger System R SET V SS FAULT V BAT V BAT BOVP is hiccup 15 times and then latch mode for bq2431x POR or toggle /CE pin to reset BOVP latch FAULT 3-21

22 Summary of bqcfe Protection Features INPUT OVP OCP Battery OVP Part # Package V OVP V O(REG) t BLANK(OVP) I OCP t BLANK(OCP) BV OVP Counter bq x2 mm μs 300 ma 5 ms 4.35 HICCUP bq x2 mm μs 300 ma 5 ms No HICCUP bq x2 mm μs 300 ma 5 ms 4.35 HICCUP bq x2 mm 10.5 PROG 64 μs 300 ma 5 ms 4.35 HICCUP bq x2 mm PROG 0 PROG 5 ms 4.35 LATCH bq x2 mm PROG 0 PROG 176 μs 4.35 LATCH bq24314 bq x2 mm 4x3 mm 2x2 mm 4x3 mm PROG 176 μs 4.35 LATCH PROG 176 μs 4.35 LATCH Latch: After 15 times OCP or OVP, then latch 3-22

23 Power Path Management Charging 3-23

24 Charging with an Active System Load: Issues or USB Charger I CHG I SYS I BAT System Charger output current is shared: I CHG = I BAT I SYS Issues: Safety Timer False Expiration Termination Detection 3-24

25 Issue 1: Pre-charge and Safety Timer Fault or USB Charger I CHG I SYS 100 ma 80 ma I BAT 20 ma System Pre-Charge Mode: Battery voltage may not reach the fast charge voltage threshold Pre-charge timer may expire Solution: keep system off or in low-power mode in pre-charge mode Drawback: Can not operate the system while charging a deeply discharged battery simultaneously 3-25

26 Issue 2: Safety Timer Fault or USB Charger I CHG 800 ma I SYS 600 ma I BAT 100 ma System When in Fast Charge Mode: 1. Charger output current is limited to fast charge current 2. System current steals charger output current 3. Battery is charged at a lower rate! Charge safety timer may expire, turning off the charger Solution: Increase the safety timer timeout value Increase the fast charge current value 3-26

27 Issue 2: Charge Termination NOT Detected or USB Charger I CHG I BAT I SYS System Current (A) I CHG I BAT 0.2 I SYS Time I TAPER Voltage Regulation Mode: If I SYS > I TAPER, Termination is never detected Solution: current supplement circuit 3-27

28 Power Path Management Battery Charger - Q1 Controller Powering System Q2 C1 Charging Battery System System power supplied from adapter through Q1 Charge current controlled by Q2 Ideal topology when powering system and charging battery simultaneously is a requirement Separates charge current path from system current path No interaction between charge current and system current 3-28

29 Power Path Management: Potential Issues I ADP V System Current I SYS I CHG - Q1 Controller Q2 I BAT C1 Charging Battery I SYS System I SYS I CHG current limit I ADP Input current : I ADP = I BAT I SYS Issues: Input voltage collapses V voltage collapses Solution 1: Design the AC adapter at maximum I SYS I CHG, HIGH COST Time 3-29

30 Voltage Based Dynamic Power Path Management (DPPM) I ADP V I SYS I SYS DPPM Mode - or USB 1.15 V DPPM Q2 I CHG C1 System I ADP AC adapter current limit - Bus voltage drop causes system reset DPPM function : I CHG Reduces the charge current when the system voltage is V DPPM Finds maximum adapter power V VDPPM System Voltage V BAT Battery Supplement Mode Time 3-30

31 Voltage Based Dynamic Power-Path Management Charger AC Q1 System Load USB C1 C2 Vcc R4 R5 R6 R7 D1 D2 D3 D4 USB STAT1 STAT2 USBPG ACPG Q3 Q2 CE BAT BAT High Enable C3 10 µf 103AT RT1 High: 500 ma Low: 100 ma ISET2 ISET1 TMR VSS : 4.4 V for bq24032a; 6.0 V for bq24030 R1 R2 bq2403x TS LDO PSEL DPPM 3.3 V/20 ma High: AC Low: USB R3 C4 RT2 Dynamically reduces the charge rate to maximize adapter to system current Regulate junction temperature at 125 C by reducing charge current Dynamically increase the safety timer based on real charge current 3-31

32 Typical Output Characteristics Voltage (V) V 4.75 V Current (A) Current limited Voltage Source Ideal to use input current regulated battery charger 3-32

33 Input Current Regulated DPM Battery Charger I ADP R1 I SET R SET Current Regulation Loop R SNS REF - Q1 - Control Loops A1 A2 Q2 - REF2 I CHG I SYS BAT I SYS I ADP I CHG I SYS1 I CHG1 I SYS2 DPM Mode Current Limit Input Current Regulation I CHG2 Time Input current regulation to maximize use of the input current Current sharing between system and battery charger Minimize the AC adapter size and power rating Constant output voltage: Guarantee no system crash t1 t2 3-33

34 Input Current Regulated DPM Charger Example C1 D1 D2 Q1 IN CHG PGOOD EN1 System Load 10 µf R1 R2 R3 Termination disable CE TMR ILIM ISET TD Q2 bq24073 EN2 BAT BAT VSS TS RT 103AT Input current limiting Selectable charge termination Input over-voltage protection (6.6 V) Programmable charge current 3x3-mm QFN EN1 EN2 Maxim Input Current ma ma 1 0 Set by R2 1 1 Stand-by (USB suspend) 3-34

35 Comparisons Charging & System Operation Safety Timer Termi Detection Output Voltage Thermal Battery in system bus bq2401x,2x bq2406x Voltage DPPM bq2403x Current DPM bq2407x No May false expiration May Not V BAT Regulated at 125 C for bq2406x Yes Dynamic Yes Pulsating VDPPM V Regulated at 125 C Yes Dynamic Yes Fixed Regulated at 125 C 3-35

36 Summary Battery Charging System Safety Protection Battery Charging Front End (CFE) Voltage based Dynamic Power Path Management Charging Input Current regulated Dynamic Power management charging 3-36