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TXS0102: Voltage-drops across the pass-gate transistor

Part Number: TXS0102

Hi,

The TXS0102's recommended low-level input voltage, VIL is 0.15V, which is too low even for AP from QUALCOMM, APQ8053, in which VOL max is 0.4V. But per notes in TXS0102, 'The maximum VIL value is provided to ensure a VOL is maintained. The VOL value is VIL plus the voltage drop across the pass-gate transistor'.

My questions are:

1. Does it mean even the actual VIL is higher than 0.15, for example, 0.4 of APQ8053, the VOL is simply 0.4+voltage drop? Because per block diagram of TXS0102, input and output are linked by a pass-gate transistor;

2. what is the value of 'voltage drop' across the pass-gate transistor? I need this value to evaluate the 'digital low' voltage of input and output voltage by using TXS0102.

Thank you very much and look forward to hearing from you soon.

  • Hi,

    We have a great appnote on this question here:

    http://www.ti.com/lit/an/scea056/scea056.pdf

    1. Yes, VOL is a function of VIL and the VOL is simply VIL + the voltage drop across the pass-gate transistor.

    2. The voltage drop across the pass transistor can be calculated based on the IOL and Rpass. IOL is the current passing through the FET and Rpass is the on state resistance of the FET. The relationship of current to resistance is fairly linear when the FET is on. So, you can calculate the Rpass value for the VIL, VOL, and IOL given in the datasheet. Then use this Rpass value for your VIL, IOL to find out what your VOL will be.

    Thanks!

    -Karan