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MSP430F147 current consumption

ZeroD
Expert 1470 points
Other Parts Discussed in Thread: MSP430F147

Hi,

In the datasheet of MSP430F147 says that:

Ultralow-Power Consumption:
− Active Mode: 280μA at 1 MHz, 2.2V
My question is:
If the MSP430 is 1h in active mode that means the power consumption is 280μAh?
And I have a battery of 1000mAh using the formula from page
I get that the MSP430 should work for 2500h.
Is that correct?
Regards David.
  • 0
    Guru 227245 points

    David V said:
    Is that correct?

    No. Because the creator of this current calculator apparently failed to perform simple math for checking his code.

    Enter 10mAh capacity and 1mA load, you won't get 10hrs but 7 instead. At first, I suspected some clever consideration of self-discharge for long discharge times, or capacity vs. load (load rating) compensation, but no. The result is always off by a factor of 0.7, no matter if you discharge the battery in 1 hour or 1000 hrs, with high or low current.

    So with 1Ah battery and 280µA current consumption of the MSP, the battery should last for 3571hrs = 149 days (minus self-discharge)

    But this means the MSP is not doing anything. Not using RS232, not doing A/D conversion, not driving any digital circuity or sensing buttons. These 280µA are the plain CPU/memory consumptions. Including the specified clock source for the CPU.

    Note, that battery capacity is rated for a certain load. So a battery that has a capacitance of 1Ah for a load of 1A will be able to provide, say, 1.2Ah if the load is 100mA only. But due to self-discharge, the effective capacity will drop to 0.9Ah when the load is only 1mA.

    Usually, the manufacturer picks the condition that gives the highest effective capacity. Looks better in the datasheet.

  • 0 in reply to Jens-Michael Gross
    Expert 1470 points

    Hi Jens,

    Thanks for the answer.

    Ok when I say MY uC will use UART then the consumption will go up. Is there a way to predict the consumption or I have to connect an AMP meter to determine the consumption?

    Regards.

  • 0 in reply to ZeroD
    Guru 227245 points

    David V said:
    Is there a way to predict the consumption

    No. because it depends on external impedance, baudrate, parasitic capacitance, Duty cycle,  whatever.

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