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TPS65138: Set the negative voltage up&down

Hideki Hayashi1
Expert 6000 points
Part Number: TPS65138

Hi experts,

A customer plans to use TPS65138 for biasing OLED. Regarding the CTRL pin, is it able to set the voltage up again after the end of adjustment? Or should it be pull-down again to disable and then send a desired number of pulse (rising edge)? 

After CTRL pin is toggled to adjust voltage and keeping to be pullup, does the customer simply toggle the CTRL again to set the next voltage?

On other hands, Is it able not to output -4.9V? For example, the rising edge counting is done before the default voltage output, or there is any way to change the default output voltage. Customer want more bigger >-4.5V.

Best regards,

Hideki

  • +1
    TI__Mastermind 18550 points

    Hello Hideki,

    Yes, customer can change (set) the negative voltage again any time after power up. In normal operation, CTRL should be held high to enable the device and only during changing the negative voltage should CTRL pin see rising edges per the timing diagram in figure 9 in the datasheet.

    After CTRL pin is used to adjust the voltage, it should be held high to keep the device enabled. Customer can apply rising edges to CTRL pin again to set the next voltage.

    The device will initially output -4.9V default voltage and after tinit time of 400us, customer can set new voltage using CTRL pin.

    I hope this answers your questions.

    Kind Regards,

    Liaqat

  • 0 in reply to Liaqat Khan
    TI__Expert 6000 points

    Hi Liaqat,

    It is understood that the CTRL pin usage and the sequence. It is unfortunate that TPS65138 must output -4.9V before a new voltage set by CTRL pin.

    Regards,

    Hideki