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DS3658: Using the quad peripheral driver as a level translator

Part Number: DS3658

I am considering using this part to provide voltage and current conditioning between a TTL buffer output and an isolated digital input on a PCI card

The output buffers used are CD4049 and CD4050 and do not have the current drive capability to drive the digital inputs on the PCI card

The PCI card is Acces I/O PCIe-IDO and can accept both DC and AC logic signals up to 30V

The PCI card inputs use a series 1.8K resister with a diode to rectify AC input and the combination is parralled with an opto-coupler led

Acces I/O application engineering states that the inputs require a minimum of 70ma to operate correctly

The buffers can only provide a maximum of 3ma output current - not enough to drive the PCI card inputs directly

My plan is to use the DS3648 with VCC / Enable of +5V and output voltage of +24V to translate the 5V / Low I buffer logic to 24V / High I logic for the PCI card inputs

Is the DS3648 the best choice for this application?

Also do you have a version of this IC that will allow VCC of +24? - I would like to use one power supply for this application

Thanks for any guidance you can give;

David Robinson

KAMAN Precision Products

  • Hi David,

    This device was made back in 1995, and we did not release a 24V version of it. However, do you think a device like the TPL7407LA would work here? The supply and outputs are rated for up to 32V abs max.

    Thanks,

    Alek Kaknevicius

  • I think we are leaning toward operating the outputs of the DS3658 at the same VCC voltage of +5V

    Just noticed the test set signal conditioning circuit containing the buffer outputs is powered by an isolated +5V supply ( no connection to earth)

    If we use an additional isolated +24V supply to power the DS3658 outputs, we have no way to guarantee the references will be at the same potential.

    It is probably better to try and make the entire signal conditioning circuit operate from a single isolated +5V supply

    Do you agree?