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BQ24130: Super capacitor charger with power path function.

Nam, Dino
Expert 6445 points
Part Number: BQ24130
Other Parts Discussed in Thread: TPS2121

Tool/software:

Dear team, 

The customer want to find super capacitor charger with power path function. 

BQ24130 would be good solution but  it need external FET for power path. Below is customer requirement. 

- super cap charging current : 1 ~ 1.5A 

- power path function , If main power is down, super cap have to connect to system power. 

- competitor device : Littelfuse / LS0502SCD33 but charging current max value is 0.35A 

  => https://www.littelfuse.com/media?resourcetype=datasheets&itemid=47d7119d-a735-48a9-8e7d-63ec87e03a19&filename=littelfuse-protection-ic-ls0502scd33-datasheet 

- The customer prefer linear type charger or converter type charger, integrates power path FET. 

- Stand-Alone type 

Can the customer use BQ24130 to charge super capacitor? 

I can see below concept. How can we control Q3,Q4,Q6? Do we use external MCU to control these FETs? 

 

Is there any super cap charger solution having internal power path FET? 

Please review it and let me know your opinion. 

Thank you, 

  • +1
    TI__Guru**** 166996 points

    Hi Dino,

    Unfortunately, TI does not have a super cap charger with power path and internal FET.  BQ24130 is the closest switching converter fit.  The FETs in the schematic above were intended to be controlled by an MCU.  But, since those are PFETs, Q3 and Q4 with pull resistors could be auto turned on with a NFET pull down having gate tide to AVCC.  Also, Q6 could have gate tied to AVCC and auto turns on when AVCC goes away. That assumes that the PFETs Vgsth > applied input voltage.  Might need some RC delays to time the turn on/off appropriately.

    TI has the https://www.ti.com/lit/ds/symlink/bq25173.pdf 800mA linear charger but you would need to build a discrete power path circuit like above or maybe add a dual MUX like TPS2121 to implement power path.  

    Regards,

    Jeff