Instruction/ maintenance manual of the product CY8C24794 Cypress Semiconductor
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Power Management - L ow - Cost, Two-Cell Li -Ion/Li-Pol Battery Charge r with Cell-Balancing Support November 25, 2007 Document No. 001- 17394 Rev. * B - 1 - AN2309 Author : Oleksandr Karpin Associate.
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 Parameter.
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.
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 im.
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 .
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 co nsists of resistor R4 and capacitor C4.
AN2309 November 25, 2007 Document No. 001- 17394 Rev. * B - 7 - Figure 4. Two-Cell Battery Charger Schematic – CPU, Cell Balancing, and Measuring Equipment BAL2 Q1 IR LML6402 BAL1 CALIBRATION DR I V.
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 1 2 J4 POW ER 12V D C PSoC C 12 0. 33u 16V IN 1 OU T 3 U2 L78L05/TO D6 BAT 54C Close to PSoC C 15 0.
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, batter y voltage and temperature must be measured accurately.
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.
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 .
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 In itialization state.
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 St.
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 Charg.
AN2309 November 25, 2007 Document No. 001- 17394 Rev. * B - 15 - The minimum cell-balance parameter consists of the voltage measure error value plus the internal impedance error value. The cell-balancing algorithm that is implemented here does not significantly lengthen the charge time.
AN2309 November 25, 2007 Document No. 001- 17394 Rev. * B - 16 - Two-Cell Battery Charger Par ameters All two-cell battery charger parameters are located in the header file globdefs.h in th e project folder. The header file globdefs.h contains the following parameters: Table 2.
AN2309 November 25, 2007 Document No. 001- 17394 Rev. * B - 17 - Cell-Balancing Paramet ers All cell-balanci ng parameters are located in the header file globdefs.h in the project folder. T he header file globdefs.h contains the following parameters: Table 3.
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 Con.
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.
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 com puter science in 2008 from Lviv Polytechnic National Universit y (Ukraine).
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 08/29/2007 Obtain spec.
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