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ISO7741-Q1: Digital ISolator for SPI interface ISO7741-Q1

Part Number: ISO7741-Q1
Other Parts Discussed in Thread: ISO7741

Dear Sir/Madam,

   In our custom card we are using ISO7741-Q1 digital isolator for SPI interface signals to other card. One side(Vcc1) we are powering up using 3.3v and other side(Vcc2) we are giving 5v supply. 

My Question is will it do level translation of the signals along with isolation ? Else will we get same level of signals only at Vcc2(Slave) side ?

Thank YOU


  • Hi Saranraj,

    Welcome to TI E2E Forum!

    ISO7741 has two dice inside device and each of them are independently powered. Since each die is independently powered, their supply voltages can be independent of each other and each die will operate with respect to its local power supply voltage.

    This means that VCC1 can be 3.3V while VCC2 can be at 5V, the input/output logic levels on VCC1 side will be as per 3.3V while the input/output logic levels at VCC2 side will be as per 5V. The outcome is identical to level translation.

    I hope this clarifies your question, thanks.

    Koteshwar Rao

  • Dear Rao,

      I got your point Then Can i use this device for my application ?

     will signal levels  be same in output side as in input side ? or signal level will be based on powering up die voltage on respective section even though input section voltage  of isolator is different from output section ?

     Thank You

  • Hi Saranraj,

    The signal levels on the output side will be same as the output side power supply and do not depend on input side power supply. If this is what you desire then yes, you can use this device for your application.

    This is similar to a level translator where there will SideA with VCCA power supply and SideB with VCCB. SideA signals will follow VCCA while SideB signals will follow VCCB.

    Let me know if you have any further doubts, thanks.

    Koteshwar Rao