Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

  • State TI Thinks Resolved
  • Replies 4 replies
  • Answers 2 answers
  • Subscribers 64 subscribers
  • Views 73 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

BQ25980: Could we use BQ25980 as a 10A output charge pump buck converter?

Andrew Su
Intellectual 1230 points
Part Number: BQ25980
Other Parts Discussed in Thread: BQ25790

Tool/software:

Dears,

one of my key customer is seeking for a high efficiency buck converter (Vin is 20~28V, Vout is half of the input voltage, iout max is 10A), the efficiency is expected to be higher than 98%, charge pump mode converter is preferred. i am wondering if BQ25980 might be the solution most close to the customer spec:

1. although BQ25980 is a flash charger IC, but it actually works like a 2:1 buck converter.

2. could we use resister divider to VBAT sense to set the output voltage to 10~14V?

3. could we disable the BUSOVP/BATOVP by masking the relevant set register bit?

4. in order to output 10A current, we may need to stack 2 pcs of BQ25980 in parallel 

5. The recommended max input voltage BQ25980 is 22V, but the Absolute Maximum BUS voltage is 28V, so could it stand with 28V stable input voltage?

would you please help to double check if there are any further risk of the application of 2 BQ25980 for this case?

thanks a lot!

  • 0
    TI__Intellectual 2200 points

    Hello Andrew,

    Andrew Su said:
    1. although BQ25980 is a flash charger IC, but it actually works like a 2:1 buck converter.

    The BQ25980 does not regulate charge current due to the nature of the switch cap topology. Rather, charge current is a function of input and output voltage.

    Andrew Su said:
    2. could we use resister divider to VBAT sense to set the output voltage to 10~14V?

    The absolute maximum specification for VOUT is 11V, so this output voltage range seems too high for BQ25980.

    Andrew Su said:
    3. could we disable the BUSOVP/BATOVP by masking the relevant set register bit?

    BATOVP can be disabled in the registers, but BUSOVP can only be configured up to a maximum of 22V.

    Andrew Su said:
    4. in order to output 10A current, we may need to stack 2 pcs of BQ25980 in parallel 

    Yes, 1x BQ25980 can charge up to 8A, but 2x BQ25980 can work in parallel to charge up to 12A.

    Andrew Su said:
    5. The recommended max input voltage BQ25980 is 22V, but the Absolute Maximum BUS voltage is 28V, so could it stand with 28V stable input voltage?

    It is not recommended to operate the BQ25980 at the absolute maximum VBUS voltage, as the device's performance cannot be guaranteed beyond this specification.

    Best regards,

    Alec Lehman

  • 0 in reply to Alec Lehman
    TI__Intellectual 1230 points

    Dear Alec，

    thank you very much for the kindly explanation.

    you referred that "BATOVP can be disabled in the registers, but BUSOVP can only be configured up to a maximum of 22V", but according to the datasheet, "1h = BUSOVP flag does not produce INT", BUSOVP might also be masked in the same way as BATOVP, am i right?

    "The absolute maximum specification for VOUT is 11V", this is really a big trouble as it is determined by the hardware design. i may need to discuss with the customer to reduce the VIN and VOUT.

    how about the transient response of BQ25980 to the VOUT load current jump? have we ever tested this?

    besides these points, do you have any further comments for the other risks for this application case?

    thanks a lot!

  • 0 in reply to Andrew Su
    TI__Intellectual 2200 points

    Hello Andrew,

    Andrew Su said:
    you referred that "BATOVP can be disabled in the registers, but BUSOVP can only be configured up to a maximum of 22V", but according to the datasheet, "1h = BUSOVP flag does not produce INT", BUSOVP might also be masked in the same way as BATOVP, am i right?

    The BUSOVP flag can be masked, which means that an interrupt signal will not be sent to the host on the /INT pin when BUSOVP is tripped, but the protection itself will not be disabled.

    Andrew Su said:
    "The absolute maximum specification for VOUT is 11V", this is really a big trouble as it is determined by the hardware design. i may need to discuss with the customer to reduce the VIN and VOUT.

    I agree, the VIN and VOUT requirements will need to be adjusted slightly to be within the BQ25980's recommended operating conditions.

    Andrew Su said:
    how about the transient response of BQ25980 to the VOUT load current jump? have we ever tested this?

    The BQ25980 is typically used with a main charger, such as BQ25790, that handles pre-charge and charge termination to achieve the highest overall charging efficiency. This means that the BQ25980 is often used to charge a battery and supply a system load through the main charger's BATFET, so it's expected that the converter will face system transients.

    Andrew Su said:
    besides these points, do you have any further comments for the other risks for this application case?

    This application of the BQ25980 seems possible, and a resistor divider on the output could work. The goal would be to get the output voltage to be half of the input voltage. It would be helpful if you could provide more details about the customer's system.

    Best regards,

    Alec Lehman

  • 0 in reply to Alec Lehman
    TI__Intellectual 1230 points

    dear Alec,

    BQ25980 may not be able to support this application due to the voltage limit.

    thanks a lot!