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Input current for TXB0104

Roy Nordstrom
Intellectual 320 points
Other Parts Discussed in Thread: DAC7562, MSP430F5529, TXB0104

Hi,  I am considering the TXB0104 as a level shifter between my MSP430F5529(at 3.3V)  and my DAC7562(at 5V).  This is a low power, battery operated application.

On the TXB0104, port A will always be an input(from the uC), and port B will alwya be an output(to the DAC).   

The data sheet states that my uC will need to be capable of driving + - 2mA minimum, on each output signal, to get correct operation.  The data sheet for the uC indicates that it can do this.

This is my question:  Is this a continuous 2ma load on each output pin of the uC ?  Or is this current only needed when changing directions ?

I would prefer that my uC not need to source or sink more than 50uA continuously, on each output pin.

Thank you for the help.

Roy Nordstrom

 

 

 

  • 0
    TI__Genius 9085 points

    Hi Roy,

    That 2mA is not continuous, and is only required during active switching. Page 10 has a graph illustrating the current sink/source requirements. The peak current happens during switching (HIGH to LOW or LOW to HIGH).  Once the internal buffers have been overpowered, the driver only sources/sinks minimal current. It doesn't relate to changing direction.

    You can use the CPD to calculate what typical power consumption will be while operational, though keep in mind, if your frequency is lower than the frequency specified, your current consumption will also be lower.

    http://www.ti.com/lit/an/scaa035b/scaa035b.pdf

     

  • 0 in reply to Hattie
    Intellectual 320 points

    Hi Hattie,

    Thank you for the information.  Given what you have told me, I am going to design it into my system.

    Roy