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200uA current consumption normal for TXS0108E?

TI Lady
Genius 4025 points
Other Parts Discussed in Thread: TXS0108E

I have a customer using the TxS0108E switch.   The datasheet claims much less current draw.  Can you please help me understand what we should be seeing?

It is being used to do a level translation from 2.2V to 1.8V. Highest transition is 16kHz and all lines but one are unidirectional. The TI part that is being used now draws about 200uA and they want to get down to 20uA and fit in a 15x7mm area. Let me know what you think.

Thanks 

  • 0
    Genius 4025 points

    Can you also provide the dynamic operating power for it as well?

    Thanks

  • 0 in reply to TI Lady
    TI__Expert 4705 points

    Hi, Amy,

     

    First, this current is measured when OE is in the enable status, right?

    If so, For TXS0108E, Yes, it will has a little large quiescent current when the input is in the “Low” state since it has the internal pull up resistor to Vcc.

     

    For their 200uA current (if confirm no circuit use this 2.2V), if they measure the I/O ports, they may see 3 or 4 I/O lines will be in the “Low” state, the reason is, for each channel, if it is in “Low”state, there will be a 40K Ohms pull up to 2.2V, so the total current will be 4(channel) *(2.2*/40K)=220uA.

     

    So, If the customer wants to get the Low quiescent, they need to put OE to Low which will disable the pull up resistor and decrease the current draw for TXS0108E.

     

    If not, and this 200uA comes when OE is in the Disable status, then we need to get clear below information.

    1. For the 200uA draw 2.2V, only our switch uses it, can customer confirm it? Did they share all the schematic to us? When they measured this 200uA current, no boards or cable connected to J1 and J4?

    2. For the source of J1 and J4 for A1-A8 signals, is there any additional pull up or pull down resistors? Or inside the connector J1 and J4, any pull down resistor or resistor connected to 2.2V (NEUTRON_PWR) 

    For the dynamic power data for an Analog Devices part that comes in at around 1.55uA on the A-side bus at 500kHz, it is a so low dynamic power data. If it does exit, this part will not be the translator, maybe it is just one channel inverter.  

    For the dynamic operating power of the TXS0108, here is the link which shows how to calculate it, any unclear, please let me know.

    http://e2e.ti.com/support/interface/etc_interface/f/391/p/182923/659716.aspx#659716