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DC/DC Booster recommendation

Sohrab Haddadi
Prodigy 10 points
Other Parts Discussed in Thread: TPS61033, TPS61299

Need help on selecting DC/DC Booster for coin cell operated miniature motor 

Hi TI Experts,

We are developing a product with a coin cell (CR2430 or CR2450: 3V, cut-off 2V) that utilizes miniature motors (running @ about 20mA for 2 seconds).

I’m wondering which Booster (boosting to 5volts or more) can help me to save the battery life (Coin cells are not suitable for that to take direct juice). While a small footprint low qty BOM and cost and high efficiency are important. Any suggestion booster that is specifically utilized for coin cells?

Please help to decide the correct booster convertor.

Regards,
Sohrab

  • 0
    TI__Genius 12285 points

    Hi Sohrab,

    So I understand your application condition is, input 2~3V to output 5V/20mA, right?

    You can consider our new device TPS61033, with fixed 5V when connect FB to VIN, which can save FB resistor divider, >90% efficiency with 5V/20mA output.

    Regards,

    Nathan

  • 0 in reply to Nathan Ding
    Prodigy 10 points

    Hi Nathan,

    Thanks for your suggested P/N. Yes, the application condition will use a coin cell battery (CR2430) that drops from 3V to 2V while draining the current to drive a miniature motor.

    And I need to know if adding a booster can save battery life (vs connecting the battery directly and talking the juice without a booster).

    Is that any way to calculate it?

    Regards,
    Sohrab

  • 0 in reply to Sohrab Haddadi
    TI__Genius 12285 points

    Hi Sohrab,

    The battery life you mentioned is battery use time or battery health (means the battery capacity would decrease as time goes)?

    I think using a Boost here can only extend battery use time (because when battery voltage is very low, it may not support your load, so you need to add a Boost here to get a higher output voltage, so that your system can work with lower battery voltage), but it can't help with the health of battery. The health of battery is related to number of cycles (charge and discharge), charge voltage, discharge current, operation temperature, etc...

    If you are concerned about the battery health, you could choose the other new device TPS61299 (samples now, MP in 3Q), it have lower iq (100nA), and average input  current limit, which can limit battery discharge current accurately, this is helpful to battery health, because large discharge current would be harmful to battery.

    Regards,

    Nathan

  • 0 in reply to Nathan Ding
    Prodigy 10 points

    Hi Nathan,

    I meant “use time” exactly. The battery is a coin cell and not chargeable, and only extending its service cycles (ON-use-OFF) is important.

    How can I proof using a booster takes lower consumptions from battery capacity?

    Any tool?

    Regards,

    Sohrab

  • 0 in reply to Sohrab Haddadi
    TI__Genius 12285 points

    Hi Sohrab,

    Sorry we don't have a tool for this.

    I think using Boost can extend battery use time is because when battery voltage is very low, it may not support your load, so you need to add a Boost here to get a higher output voltage, so that your system can work with lower battery voltage. So to estimate how long time can be extended, you can refer to the capacity vs. battery voltage curve of the battery you used.

    But it can't take lower consumptions, conversely it would take higher consumptions because there is power loss of this Boost. 

    Regards,

    Nathan