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SN74CB3T3245: Not clear what are the currents relate to for the Ron spec

Ohad Fundoianu
Intellectual 540 points
Part Number: SN74CB3T3245
Other Parts Discussed in Thread: TXB0108

Hi,

In the Datasheet of the "SN74CB3T3245 8-Bit FET Bus Switch 2.5-V and 3.3-V Low-Voltage With 5-V-Tolerant Level Shifter"

it was not clear if each of these currents values in this table relate to a single channel or to all 8 channels together.

  • 0
    TI__Mastermind 45575 points

    Ohad,

    I can't see what table you are referencing but the max continuous current you can place through each channel of the device is 128 mA.

    Thank you,

    Adam

  • 0 in reply to Adam Torma
    Intellectual 540 points

    I don't know why it wasn't shown on the post, I meant to that table :

  • 0 in reply to Ohad Fundoianu
    TI__Mastermind 45575 points

    Ohad,

    The values you are referencing are the test conditions that were used to measure the on-state resistance.  These measurements are taken one channel at a time so the current value is per channel.  The on-state resistance is measured by forcing a known current through the device and measuring the voltage on the input and output.  The Ron is calculated using Ron = (Vi-Vo)/Io.

    The current stated in test condition is not the max current the device can handle.  The max current the device can handle is 128mA as stated above.

    Thank you,

    Adam 

  • 0 in reply to Adam Torma
    Intellectual 540 points

    So I do not understand, if these values are only related to the Test conditions, 

    What is the current rating consumed by this level shifter when all 8 channels are working and supply voltage is 2.5v ? 

    Ohad

  • 0 in reply to Ohad Fundoianu
    TI__Mastermind 45575 points

    Ohad,

    The current consumption for these devices is specified by Icc.  If all the inputs voltages are at Vcc or GND the current consumption is max 40 uA.  Each input voltage that is in between Vcc or GND will increase the device current consumption.   

    For example if you have Vcc = 2.5V and you inputs were at 2.5 V the current consumption will be max 40 uA.  If all 8 of your inputs are 1.9 V with Vcc = 2.5 V your current consumption will be max an additional 300uA x 8 inputs at 1.9 V. 

    If you want a better performing device you can look at our portfolio of level shifters like the TXB0108.

    Thank you,

    Adam