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LSF0204: Enquiry: Power Consumption

David Tandri
Expert 1355 points
Part Number: LSF0204

Hi,

I am using LSF0204 for SPI communication lines. I am connecting Vref_B to 3.3V power source which is always supplying 3.3V to Vref_B without any control to turn it off.

Then I tie the EN pin toghether with Vref_A pin (1.8V), the EN pin will be HIGH and allow data transfer via the shifter whenever Vref_A pin receives input voltage. Am I right?

I know that when EN is LOW, level shifter will be in High-impedance state.

In my case, my concern is:

1. During High-impedance state, Vref_A willl be 0V and EN is LOW since they are tied. Therefore, does the level shifter still consume power due to the 3.3V power supply on Vref_B?

2. If the shifter still consumes power, how much power is being consumed due to Vref_B 3.3V supply voltage?

Please advise.

Thanks.

  • 0
    TI__Guru 62280 points

    Hi David,

    Yes, once the VrefA is active ( and hence the EN), the data transfer and voltage translation happens in LSF0204.

    When the EN and VrefA is low, the IOs will be in HiZ. The A/ B ports can still have signals with low leakage of 1uA.

    There will be minimal leakage from 3.3V VrefB as it passes through the internal 200kohm resistor. however, the datasheet doesnt spec any limits or numbers for the same.