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BQ24133: Components needed for Standalone Configuration

Deniel Go
Intellectual 395 points
Part Number: BQ24133


Tool/software:

Hello TI Engineers,

I want to change my current schematic (photo is attached below) of the BQ24133 charger circuit to a standalone configuration. I want to remove the power path circuits but still want to keep the reverse blocking FET (Q4a1) in order for the battery voltage in the VCHARGER node. I also do not need the input current limit to the charger. This means I will not be using the Rac (R29). I just want to confirm which components can I remove

1. I will be removing ACfet (Q4a2) since I only need Reverse Protection FET (Q4a1)

2. Since R29 will not be used, what is the connection for ACN and ACP? Is C29 and C30 still needed?

3. Since Input Current Limit will not be used, what is the connection for ACSET?

4. Since there is no power pathing and the 9V Input Power Adapter will just be connected to PVCC, do I only need a single bulk capacitor of value 4.7uF similar to Figure 10-5 in the BQ24133 datasheet?

5. According to the datasheet, for charging currents of 1A, we would need a 6.8uH inductor. If it is between 1A and 2A, what is the recommended value?  anything in between 3.3 and 6.8uH?

Thanks,

Deniel

  • 0
    TI__Guru**** 169156 points

    Hi Deniel,

    If input current limit is not used, short ACN to ACP and connect ACSET to VREF.  The capacitors on ACx are not needed.  The 4.7uF capacitor on PVCC is required.  For small signal stability, the output LC product 

    must be between 15kHz-25kHz.  For smaller sized inductor with lowest Rdson and highest efficiency use 3.3uH or 4.7uH.  For lowest inductor current ripple and therefore output voltage ripple as computed by equations below: 

    where D=Vout/Vin and fs=1.6MHz, use 6.8uH.

    Regards,

    Jeff