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BUF16821: Re-power on time

Part Number: BUF16821

Hi Team,

Does BUF16821 have the spec of re-power on time? or any spec that acceptable initial voltage.

I mean if I plug on/off the power supply quickly, does IC fail start up?

Regards,

Roy

  • Hi Roy,

    I have notified our expert regarding this topic. Please expect a response by 5/25/20. 

    Thanks,

    Costin

  • Hi Costin,

     Thank you for your help. Could you help notice the expert today again. Customer schedule is urgent. 

    Regards,

    Roy

  • Hi Roy,

    BUF1681 will not "failed" the power on/off, the output response will follow the control power on sequence.

    BUF16821 has two  internal power-up threshold:

    1)  2V threshold, up tp this threshold the output voltage is same as Vs, above 2V output voltage is Vs/2

    2) 5V threshold- at Vs=5V, the device automatically updates the non-volatile stored values into the DAC output. After Vs reaches 5V for ~1mS

    output will be be Vs/2 until the automatic read finish this update. This timing is a critical in the system if Vs ramp is fast and output non-volatile store value is different from Vs/2. 

    For example: Vout set Vs/3, Vs=12V and Vs ramp up time = 1mS.( datasheet fig23 with a faster Vs)

    a) up to 2V Vout=Vs

    b) 2V<Vs<5V, output = Vs/3

    c) Vs>5V, output = Vs/2 for 1mS. Since Vs ramp is 1mS, output will get to 6V before switching to the programed output voltage =4V. This may look like a device malfunction due to fast Vs ramp up.

    Another potential issue during Vs On/Off is the risk to damage the internal ESD diode. If the output capacitance is large,for short time  Vout  > Vs+diode vollage..In this condition the internal ESD protection diode will turn on, a series  resistor at the output is needed to protect The ESD diode.

    Regards,

    Costin