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BQ2004: Ni-Cd charger questions

Kazuki Itoh
Genius 10145 points
Part Number: BQ2004

Hello team,

Could you please help me to answer customer questions below?

  1. The charging current is determined by the resistor RSNS between SNS pin and GND, correct?
  2. The allowed RSNS power is calculated from IREG^2 * RSNS. When fast-charge, IREG could be twice or 4 times larger, so will it be (IREG * (2 or 4)) * RSNS?
  3. The charge current value set by RSNS corresponds to "C" value which is described in DS Table 1, correct?
  4. When the NiCd battery is charged by below specification, could you please let me know the procedure to design RSNS, TM1 and TM2?
    - Battery capacity: 5500mAh
    - Fast charging time: - 1.0h (Max) / 5000mA (Max)
    - Normal charging time: 16.0h / 500mA
    - Note: as a system, it is needed to be charged in 4h

Also, could you please let me know about the EVM manual?

  1. Do R1 (510k) and C6 (1uF) from LPF for BAT pin? If so, could you please elaborate on the formula Fc=Hz?
  2. Do R2 (300k) and C7 (0.1uF) form LPF for TS pin? If so, could you please elaborate on the formula Fc=Hz?
  3. Why R13 (2.2k) is needed in this design?
  4. The numbers in note1 after recommended DC operating conditions are different from DV2004L1 board schematic. Could you please let me know the correct numbers?
  5. Could you please let me know which is the operation mode, switch mode configuration or external regulation in DV2004L1 Board schematic?

Regards,

Itoh   

  • 0
    TI__Mastermind 24075 points

    Hi,

    1.   Yes
    2. Is this for power dissipation calculation? You can use the nominal regulated current for I^2*R calculation as DC current is measured by RSNS.
    3. No. C is referring to the timer as shown in column 4 of table 1. C corresponds to 90 minutes and the other rates are based off of that. The charge current is set solely through RSNS

    I will have to check our internal documentation for the other questions. This is a very old part so we don't have many resources available for deep dive into operation. I will respond by end of day tomorrow with what I am able to find.