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BQ24073: BQ24073

Paul Roche
Prodigy 80 points
Part Number: BQ24073

Ref the  BQ24073:

This device allows us to charge a battery between 0 and 50 however we need it to do 0 to 45.

What NTC to use to achieve this?


Thanks

  • 0
    TI__Guru* 75656 points
    Hello
    This would require a Beta NTC.
    Take a look at P/N ERT-JOER103J (Mouser P/N 667-ERT-JOER103J) 10k at 25 C with beta of 4250k package 0402 from Panasonic in stock at Mouser.

    The hot fault will trip less than 0.30V
    The cold fault will trip greater than 2.10V
  • 0 in reply to Bill Johns
    Prodigy 80 points
    Hi,
    The issue is they need Thu-Hole NTC. We cannot find Thru-Hole with this spec.
    They currently have an NTC in their design but this gives 0 to 50. Their battery cell is only meant to charge between 0 and 45.
    They are hoping that a resistor network or another through hole ntc could fixed this.
    10K 4480K would work perfect if this is in a through hole version. They cannot use 10K 4300K as this is what is currently in the system and is technically a safety fail.
    They have 1400 units which need to be reworked somehow so cannot change the IC on the current revision hence why they are exploring the option to have a different NTC through hole and/or a resistor network to achieve our 0 to 45 degree charging battery cell.

    Any thoughts on this? Resistor network?
    Thanks
    Paul
  • 0 in reply to Paul Roche
    TI__Guru* 75656 points
    Hello
    The bq24073 TS circuit will use a current source and widow comparators to set hot / cold trip points along with the external NTC ckt.
    Current source is 75uA out of TS, hot trip point is 300mV at TS pin and cold trip point is 2100mV at TX pin.
    The R value at TS for hot trip is 4.0k ohms and for cold is 28.0k ohms.

    You would need an NTC + external R that gives you 4.0k at 45C and 28.0k at 0C to meet your requirements.
    Using the circuit in data sheet figure 24 a higher Beta NTC will work, not sure what circuit the customer has on pcb.
  • 0 in reply to Bill Johns
    Prodigy 80 points

    Hi Bill,

    Can you recommend a Thru Hole version/equivalent to the P/N ERT-JOER103J (Mouser P/N 667-ERT-JOER103J) 10k at 25 C with beta of 4250k package 0402 from Panasonic?


    Thanks

    Paul.

  • 0 in reply to Paul Roche
    TI__Guru* 75656 points

    Hi Paul

    The customer will have additional requirements for the NTC to fit into the design, logistics system, price targets and others.  It would be best if the customer used the above recommendations for resistance hot / cold and contacted the NTC suppliers or manufactures.