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TLV710: Need clarification

Ramkumar R
Prodigy 30 points
Part Number: TLV710
Other Parts Discussed in Thread: PCA9306

Tool/software:

I saw the TLV7103318DSET part in the PROC141E4_RP schematic.in that I have on doubt.

This IC has two enable pin's and the EN2 is high so OUT2 comes by default (VLDO_CSI_1V8) and the 1.8V is going to all ICs connected with it.

As per my understanding, if we need 3.3V, I should toggle the EN1 Pin input to high using the DIP switch and remove the R1241 resistor. Could you confirm whether this is correct?

Note:

We need the 3.3V operation for I2C and GPIO's so that I ask above clarification. 

  • 0
    TI__Expert 4660 points

    Hi Ramkumar,

    Device: TLV7103318DSET

    From the schematic, EN2 is always connected to 5.0V supply, and thus OUT2 will be 1.8V when supply is provided.

    When you toggle the EN1>= 0.9V, the OUT1 will rise to 3.3V.

    From schematic, you will need to remove either R1240 or R1241 (to prevent two different voltages being tied together), and you will need to use an output cap separately for each output (recommendation given in page 18 of the datasheet).

    Regards,

    Bobby

  • 0 in reply to Bobby
    Prodigy 30 points

    Hi Bobby,

    Thanks for your clarification.

    I need another clarification. Both Output voltages of the above LDO are connected to the level shifters (See below image). I understood at a time we can anyone voltage from LDO due to the design. Connect any one volage to level shifter.

    By default, the OUT2 is enabled from the LDO due to that 1.8V is connected to the level shifters (PCA9306DCTR, SN74AVC4T245PW and TXS0108ERGYR). Now 3.3V to 1.8V level translation happens on level translator.  

    As per my understanding.3.3V comes If we enable the OUT1 of the LDO and we should also remove the R1241 resistor. In this condition, 3.3V goes to the above-level shifters (PCA9306DCTR, SN74AVC4T245PW, and TXS0108ERGYR). 

    May I know whether the level translation working if we give the 3.3V to output sides? because by default 3.3V is connected to the input side and now we changed to 3.3V in the output side from 1.8V.

    Thanks,

    Ramkumar R

  • 0 in reply to Ramkumar R
    TI__Expert 4660 points

    Hi Ramkumar,

    The image you attached is small resolution, and I cannot make out connections or parts from it. Could you please attach a larger better resolution picture of the level shifter circuit?

  • 0 in reply to Bobby
    Prodigy 30 points

    PROC141E4(001)_SCH.pdf

    Hi bobby,

    Please see page 37

    Thanks,

    Ramkumar R

  • 0 in reply to Ramkumar R
    TI__Expert 4660 points

    Hi Ramkumar,

    Ramkumar R said:
    I understood at a time we can anyone voltage from LDO due to the design. Connect any one volage to level shifter.

    This is not correct. TLV7103318 has two regulators working independently, with OUT1 giving 3.3V when EN1 is given and OUT2 giving 1.8V when EN2 is given (provided ample Vin is supplied) at the same time.

    But we have noticed customers using this part like you said, and the reasoning is could be likely be explained in this thread

    https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1176624/tlv710-priority-of-en

    So even though switching of voltage MIGHT happen, the LDO itself is not designed to switch the outputs.

    Regarding the working of Level Shifters, I am not super familiar with its working, and if you let me know, I can connect you to experts for those parts.

    Regards,

    Bobby

  • 0 in reply to Bobby
    Prodigy 30 points

    Hi Booby,

    Thans for your info.

    May I know whether the level translation working if we give the 3.3V to output sides? because by default 3.3V is connected to the input side and now we planned to connect the 3.3V at output side.

    PROC141E4(001)_SCH.pdf

    The level shifter circuit are there in the page no 37 in the attached datasheet.

    Thanks,

    Ramkumar.R

  • 0 in reply to Ramkumar R
    TI__Expert 4660 points

    Hi Ramkumar,

    I am going to assign this thread to another team that can better assist you regarding level shifters and part PCA9306DCTR.

    Regards,

    Bobby

  • 0 in reply to Ramkumar R
    TI__Guru 51526 points

    Hi Ramkumar,

    If I understand correctly, Vref1 and Vref 2 will both have 3.3 V. Unfortunately, device will not be biased correctly as PCA9306's 9.2.1 data sheet clarifies Vref2 requires at least Vref1 +0.6 V. Note that this is a Vref requirement. However, output pins can be pulled to another 3.3 V voltage while Vref2 can be at least Vref1 +0.6 V.

    You may also see 8.1.5 of the data sheet as an exception where there would be no concerns to have 3.3 V on both sides. No concerns for the other level-shifters, thanks.

    Best Regards,

    Michael.