Page 2 - Cell-Balancing Foundation; Equation 1; cellN; Equation 6
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 2 - Table 1. Specifications for Two-Cell Li-Ion/Li-Pol Battery Charger with Cell-Balancing Support Item Item Value Battery Charger Parameters Built-In Battery Charger Type Two-cell Li-Ion/Li-Pol battery charger Power Supply Voltage 10…14V Pow...
Page 3 - Equation 7; Amount of Imbalance
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 3 - Temperature gradient across the battery pack. Temperature mismatches of 15 degrees Celsius can cause up to 5- percent capacity differential among cells. Such a temperature gradient is relatively common in densely packed products, where ...
Page 4 - Cell Balancing Time; bal; Cell Capacity; mA; Two-Cell Battery Charger Hardware; constant current
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 4 - Cell Balancing Time : If C is the cell capacity and b V is the battery voltage, and the requirement is to eliminate the amount of imbalance (in percent) in one hour of balancing time, then the power dissipation on balancing circuit P ba...
Page 5 - Figure 3
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 5 - A two-cell battery charger structure with cell-balancing support is shown in Figure 3 . Similar battery charger structures are explained in detail in AN2258 , AN2294 , and AN2267 . Note that the fuel gauge function can easily be added to ...
Page 6 - Device Schematic; Figure 4; Error
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 6 - Device Schematic The schematics shown in Figure 4 on page 7 and Figure 5 on page 8 constitute a complete two-cell battery charger. A signal from the PWM goes to the RC-filter, which consists of resistor R4 and capacitor C4. A constant vol...
Page 8 - PSoC Device Internals; Figure
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 8 - Figure 5. Two-Cell Battery Charger Schematic – Power Supply and User Interface R 30 33 12 J 4 POW ER 12V D C PSoC C 12 0. 33u 16V I N 1 OU T 3 U 2 L78L05/ TO D 6 BAT54C Close to PSoC C 15 0. 1u D 8 BAS16 VC C R 29 1K VC C Vbias POW ER - +...
Page 9 - Battery Measurement; meas; max; ref
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 9 - Figure 6. PSoC Internal User Module Configuration Battery Measurement To provide a correct implementation of the charge and cell-balancing algorithms, the charge current, battery voltage and temperature must be measured accurately. These ...
Page 10 - Figure 7
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 10 - The voltage measurement also is performed by the INA on the corresponding resistor. The resistive dividers (R7, R6), (R13, R12), and (R18, R19) transform cell voltage into signals suitable for the PSoC device. It is very important to use...
Page 11 - Two-Cell Battery Charger Firmware; Two-Cell Battery Charger Algorithm; Figure 8
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 11 - Figure 7. Temperature Profile T HOT_STOP T HOT_RESTART T COLD_STOP T COLD_RESTART T BATT Charge in process Charge in Process No Charge T DISCH_COLD_STOP T DISCH_HOT_STOP No Discharge No Discharge Two-Cell Battery Charger Firmware The two...
Page 12 - Figure 9
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 12 - Figure 8. Two-Cell Battery Charger State Diagram Activation Initialization Rapid Error Charge Complete Wait For Temperature Full Discharge Discharge 1 7 4 5 8 3 2 12 11 9 10 6 13 Initially the charger is in the Initialization state. Afte...
Page 13 - Figure 9. Two-Cell Battery Charger Firmware Flowchart Part 1
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 13 - Figure 9. Two-Cell Battery Charger Firmware Flowchart Part 1 Start Init Device Measure V b1 , V b2 , I ch , T b Calc V bmin , V bmax State Activation Set I reg =I ACT ; Regulate State Initialization Yes Set Activation State Charge On Sta...
Page 14 - Figure 10. Two-Cell Battery Charger Firmware Flowchart Part 2; Cell-Balancing Algorithm; pulse charge technique
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 14 - Figure 10. Two-Cell Battery Charger Firmware Flowchart Part 2 State Charge Complete Charge Off Timers Off Yes No State Error Yes Charge Off Timers Off Check Charge Restart Condition Set Initialization State Yes No State Wait For Temperat...
Page 16 - Two-Cell Battery Charger Parameters; in the project folder. The header file
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 16 - Two-Cell Battery Charger Parameters All two-cell battery charger parameters are located in the header file globdefs.h in the project folder. The header file globdefs.h contains the following parameters: Table 2. Two-Cell Battery Charger ...
Page 17 - Cell-Balancing Parameters; All cell-balancing parameters are located in the header file; Conclusion; if users are interested in easily adding fuel
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 17 - Cell-Balancing Parameters All cell-balancing parameters are located in the header file globdefs.h in the project folder. The header file globdefs.h contains the following parameters: Table 3. Cell-Balancing Parameters Parameter Unit Desc...
Page 18 - Appendix; Charge/Discharge and Cell-Balancing Profile Examples; Figure 13. Charge/Discharge Manager Profile
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 18 - Appendix Charge/Discharge and Cell-Balancing Profile Examples Figure 13. Charge/Discharge Manager Profile Constant Current Charge Constant Voltage Charge Battery Discharge Cell Voltages Without Charge Interrupt Charger State Cell-Balanci...
Page 19 - Figure 14. Cell-Balancing Activity Profile
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 19 - Figure 14. Cell-Balancing Activity Profile Voltage Imbalance Value Cell Voltages With Charge Interrupt [+] Feedback
Page 20 - Figure 15. Cell-Balancing Parameter Profile Screen; About the Author; Oleksandr Karpin
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 20 - Figure 15. Cell-Balancing Parameter Profile Screen About the Author Name: Oleksandr Karpin Title: Application Engineer Background: Oleksandr received a PhD ’s degree in computer science in 2008 from Lviv Polytechnic National University (...
Page 21 - Document History; ECN; HMT
AN2309 November 25, 2007 Document No. 001-17394 Rev. *B - 21 - Document History Document Title: Power Management - Low-Cost, Two-Cell Li-Ion/Li-Pol Battery Charger with Cell-Balancing Support Document Number: 001-17394 Rev. ECN Orig. of Change Submission Date Description of change ** 1352043 HMT 08/...