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PGA460: Estimating power consumption PGA460

Eduardo Garcia68
Intellectual 385 points
Part Number: PGA460


Hi:

I'm evaluating the PGA460 for a battery operated product, and wanted to approximate the power consumption the device would require if it was, for example, reading for an object from 5cm-40cm away, with ten samples a second. 

What I did was: Assume a burst of 170us, a listening period of 2.5ms (time sound takes to go 40cm and back at room temperature), and sleep afterwards.

I got it would be in burst mode for 0.17ms * 10 SPS = 1.7ms,  @ 400mA

Listening for 2.5ms * 10SPS = 25ms @ 12mA

Sleep mode for the rest of the time (consuming 500uA).

Is this a fair assumption? Or am I missing something?

Thanks!

-Eduardo

  • 0
    TI__Mastermind 27950 points

    Hi Eduardo,

    The PGA460's Low Power Mode (LPM) takes 250ms to enter once the command (bit toggle) to go into LPM is given. This means you will have an additional 250ms of active current (12mA) to account for. If you are staggering each TOF measurement at 100ms intervals, then you'll never be able to enter LPM, and will constantly consume 12mA on average per second.

    You should considering load switching power after each measurement to completely disconnect power during the inactive times. Thus, the only difference to your numbers above would be "Load switch off for the rest of the time (consuming 0A)." I recommend the load switch approach over LPM anyway since in both cases you will need to rewrite to the threshold registers after each cycle of LPM or load switching. You should factor in the register read/write and command execution times also. Depending on your interface (UART or SPI) you can add ~10ms of communication overhead per measurement.

    The PGA460-Q1 EVM GUI includes a Power Budget Calculator tool to help with your calculations. You don't need the actual hardware to run this tool in the GUI.