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TXB0108: Power calculation

Deep Sharma
Prodigy 50 points
Part Number: TXB0108
Other Parts Discussed in Thread: SN74AVC16T245,

1) which current parameter to be used for power calculation of this component (or any comonent) in circuit.
2) current rating at various voltage levels (page 6 of datasheet)
3) contineous current through Vcca, Vccb or GND, and how it is diffrent from same specification mentioned in SN74AVC16T245. (page 5 of datasheet)

  • 0
    TI__Guru 56100 points
    Hi Deep,

    Icc refers to the static current with no load at the output.
    TXB0108 device is designed to be a weak driver and hence the IOH IOL is limited to 20uA.
    The abs max values are the values beyond which the device is susceptible to damage and malfunction. They are never to be followed as a design parameter value.
  • 0 in reply to ShreyasRao
    TI__Guru 56100 points
    Deep,

    Also, please refer to the app note for power calculation of CMOS devices. www.ti.com/.../scaa035b.pdf
    The static power is calculated with Vcc*Icc.
    The dynamic power depends on the frequency of operation, load capacitance, power dissipation capacitance and the number of bits simultaneously switching .
  • 0 in reply to ShreyasRao
    Prodigy 50 points
    Dear Shreyas,
    pls help me by explaining " continuous current through Vcca, Vccb or GND, and how it is diffrent from same specification mentioned in SN74AVC16T245 which is continuous current through each Vcca, Vccb and GND,(page 5 of datasheet)
  • 0 in reply to Deep Sharma
    TI__Guru* 96591 points
    Hi Deep,
    TXB0108 is a low-drive buffer, however it has high-drive one-shot circuits (see the functional diagram in the datasheet).

    The link I posted in one of your other threads applies to this part as well, but it's a bit more complex since this device has multiple output drive strengths and a fairly complex internal structure. I would recommend looking at the TXB's structure to understand how it works (series output resistors with one-shots that bypass them for a short time).

    Can I ask why you are calculating power consumption for this device? Is your system constrained by power consumption? Or are you worried about thermal issues?