• State Resolved
  • Replies 8 replies
  • Answers 1 answer
  • Subscribers 33 subscribers
  • Views 82 views
  • Users 0 members are here
Support feedback
Options
Options
Related

TXU0104: TXU0104 IQ check under OE pull low

Will Wang47
Expert 8520 points

Part Number: TXU0104
Other Parts Discussed in Thread: TXB0604, SN74AXC4T774

Hi team,

Customer is evaluating TXU0104 in their wearable application. 

They find there is the power consumption data under normal condition. 

They also care alot about the chip disable(OE pulled power) status power consumption. Could you help check if we get this data? image.png

Besides that, customer work voltage is 1.2V -> 1.8V translation. All 4 signal are pull-pull, they would like  the lowest power consumption, does TXU0104 the most suitable?

They also get a 48MHz 4 line SPI signal, I recommend them the TXB0604. To support this high speed and lower power consumption, do we get any other suitable recommendation?

Regards,

Will

 

  • 0
    TI__Mastermind 39420 points

    Hello Will,

    When disabled, the part will go into a partial power down current. Below are the current measurements for Ioz (I/O current when disabled) and Ioff (Supply current during partial power down).

     

    For lower supply voltages, I would recommend looking into SN74AVC or SN74AXC (AXC devices can support down to 0.8V) especially when using high frequencies like 48MHz. TXU won't be able to support 48MHz at those supply ranges.

    My recommendation would be SN74AXC4T774

    Regards,

    Josh

  • 0 in reply to Joshua Salinas
    TI__Expert 8520 points

    Hi Josh,

    Thanks for your feedback.

    One more question regarding SN74AXC4T774, in the datasheet, I don't find the max frequency data supported by this chip. Do you get data?

    Regards,

    Will

  • 0 in reply to Joshua Salinas
    TI__Expert 8520 points

    Hi Josh,

    Customer care about the current consumption of VCCA and VCCB. I think Ioff / Ioz is the current goes into the A port or B port, rather than the VCCA, VCCB current. Could you help check this?

    Another question is when OE is pulled low, the chip is hiz mode; when one of VCCA / VCCB is 0V, another normal powered. it will also be in hiz mode, right?

    If that's the case, if we could talk the ICCA current with VCCA=5.5V, VCCB = 0V equal as ICCA current as OE pulled down. Do you get any comment for this?

    Regards,

    Will

  • 0 in reply to Will Wang47
    TI__Mastermind 39420 points

    Hello Will,

    Max Data Rate

    We don't have max data rate in AXC. We can estimate max data rate by using the following formula: 1/tpd

    If we take customer's supply range 1.2V -> 1.8V, we get a prop delay of 12ns. Using the formula above, we get ~83Mbps or ~41MHz.

    Current Consumption

    1. I misspoke here. The customer is right: Ioff and Ioz specify leakage current at the I/O pins (A or B ports), not the current drawn from the VCCA or VCCB supply rails. The supply current consumption is separately specified as ICCA and ICCB in the datasheet's electrical characteristics table.

    2. I think you meant to say when OE is pulled high? Pulling OE low enables outputs, and pulling OE high places all I/Os into Hi-Z

    When either VCCA or VCCB drops below 100 mV (i.e., properly grounded to 0V), the VCC isolation feature forces all I/Os into high-impedance state. This is functionally similar to pulling OE high — both result in Hi-Z on the I/O pins. One important note, Ioff only applies when VCCA/VCCB is truly at 0V (GND), not when left floating or disconnected.

    3. I think you meant to say 3.3V instead of 5.5V? AXC can support up to 3.6V.

    No ICC value is specified for the OE high condition but it's expected to be very low. The datasheet only characterizes output leakage in this state. 

    Regards,

    Josh

    .

  • 0 in reply to Joshua Salinas
    TI__Expert 8520 points

    Hi Josh,

    Sorry for the misleading. I mean TXU0104, so the OE pulled low disable the part and put all output into Hi-Z mode. 

    Since the TXU0104 also get the VCC isolation feature, and when one supply is GND, then it will also force all I/Os into Hi-Z mode. This is same to OE pulled low behavior. So could we talk the following spec as OE = GND, ICCA and ICCB spec?

    Regards,

    Will

  • +1 in reply to Will Wang47
    TI__Mastermind 39420 points

    Hello Will,

    You are correct in stating that when one supply is grounded it will force all I/Os into Hi-Z. 

    However, the overall current consumption will be lower when one supply is grounded. Let's say VCCB is tied to ground. All the internal circuitry referenced to VCCB will also be 0V or turned off. This includes input and output buffers and other types of logic.

    When OE is pulled low, yes I/Os are forced into Hi-Z but VCCA and VCCB stay powered on. In this scenario, all internal circuitry referenced to VCCB will be active and some current will be drawn from VCCB. However, I don't expect the current consumption on VCCB to drastically increase 

    Regards,

    Josh

  • 0 in reply to Joshua Salinas
    TI__Expert 8520 points

    Hi Josh,

    Thanks for your feedback, clear about the different mode power consumption.

    Regards,

    Will

  • 0 in reply to Will Wang47
    TI__Mastermind 39420 points

    Hello Will,

    No problem!

    Regards,

    Josh