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TXB0104: Current consumption of PDM MIC with TXB0104

Stuart Nguyen
Prodigy 100 points
Part Number: TXB0104
Other Parts Discussed in Thread: SN74AXC2T245

Dear TI, 

Here's my system:

We have PDM mic powered 2.8V and MCU operate in 3.3V, Therefore we use a TXB0104 shifter level.

When measuring current consumption of MIC in 2.8V rail is higher than no using TXB0104. Offset current is about 200 - 300uA. 

However this doesn't affect to performance of MIC, PDM Data return is well.

PDM Clock is 2.8MHz.

We measure by Keysight Technologies N6705C DC Power Analyze. 

Btw, I found it's datasheet also mention drive current strength. Do this reason cause higher current ?

Do you have any recommend this case?

Best regard,

Thank You.

Stuart Nguyen

  • 0
    Guru 317370 points

    The TXB is an auto-bidirectional translator; the input and output buffers on both sides are always active. When switching, the mic must overcome the output impedance of the TXB, which is likely to cause the power consumption you have seen.

    For unidirectional signals, a direction-controlled translator like the SN74AXC2T245 would be a better idea.