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TPS61221: Boost Converter or direct connection?

Part Number: TPS61221
Other Parts Discussed in Thread: TPS61291


I have a device with input voltage from 1.8 to 3.3 V and my question is: What is best battery non-recharable power supply for this device? 

Three options are available:

1) Use one AA battery 1.5 V with convertor (for example TPS61221 with output 3.3V)

2) Use two AA battery 1.5 + 1.5 V = 3V with convertor (for example TPS61221 with output 3.3V)

3) Use two AA battery 1.5 + 1.5 V = 3V directly

My question is, what is the best solution for maximum life time?

Why is good to use convertor when the output voltage is similar as input voltage? (for example two AA battery with converter). 

Than for your replies, Waldi

  • your question depends on the voltage requirement of your device, which voltage is best for device performance. what is load of the device? the pattern of the load; the solution size requirement of the produce. because more battery, more life time.

    the converter (buck or boost) can convert the voltage level with high efficiency, however maximum life time is system question.
  • Hello Jasper, 

    input voltage is from 1.8 to 5.5 V, but the ideal voltage is from 3.0 to 3.3 V. Load is a ARM with bluetooth transciever. 

    Current consumption is about 50 uA in sleep mode and 15 mA in transmitter mode. 


  • I would suggest two cell battery and TPS61221 to keep the VOUT at 3.3V.
    you can also have a look at TPS61291 to further reduce the current consumption in sleep mode. because TPS61291 has a ultra low Iq bypass mode