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SN75DP139: Output problem for Vcc: 0V condition

Satoshi
Guru 19645 points
Part Number: SN75DP139

When SN75DP139's Vcc: 0V condition, TMDS data pin（OUT_D1～OUT_D4） supply voltage, is it no problem?

Is there possible to damage by the wraparound voltage?

Best regards,

Satoshi

  • 0
    Guru 317260 points

    The absolute maximum ratings forbid a voltage higher than Vcc + 0.3 V for the OUT_Dx pins.

    With a higher voltage, current will flow through the ESD protection diodes to Vcc, which can power up the chip, and might burn out those diodes.

  • 0 in reply to Clemens Ladisch
    Guru 19645 points
    Clemens-san

    Thank you for reply;

    Is there reference structure for countermeasure the wraparound voltage?
    About application, customer will use PC and Display cable(power) always ON for the real use case.

    If unrealistic, are the other countermeasure below, correct?
    ①At first, PC power ON, after that monitor power ON.
    ②At first, PC power ON, after that connect DVI cable.
    ③Use the monitor for prevent wraparound voltage.

    Best regards,
    Satoshi
  • 0 in reply to Satoshi
    Guru 317260 points

    The "Typical Application" in the datasheet shows that connection the OUT_Dx pins to a cable is possible. And figure 22 appears to imply that there are no ESD protection diodes to Vcc, but Zener diodes (which would work regardless of the actual level of Vcc).

    An absolute maximum rating of at least 4 V would make more sense, and other devices like, e.g., SN75‍DP126, TMDS‍261B, or TDP‍158 do not have Vcc-dependent maximum voltages.
    So I suspect that this entry in the absolute maximum ratings table is not correct.

  • 0 in reply to Clemens Ladisch
    Guru 19645 points
    Clemens-san

    I got additional information from customer.
    Normal or abnormal operation are depend on display.
    Is there display condition? or, is there no recommend display in the use case of SN75DP139?
    If there similar cases, please let me know.

    Reference case is below,
    ・RTD234WLM(Mitsubishi)⇒Normal operation
    ・IPCD076A(Toshiba)⇒One output (Red color) is voltage drop and display found a little dark.
    ・LCD-AD222EB(I/O data)⇒Voltage waveform is square wave, but display found normal.

    Best regards,
    Satoshi
  • 0 in reply to Satoshi
    Guru 317260 points

    The SN75DP139 should work with any DVI/HDMI display.

    The video data is transmitted digitally. If there were any problem with the transmissions, some random pixels would be garbled, or the display would not be able to detect the source at all. If one color is off, or if the display is too dark, then this points to a problem with the pixel processing in the display itself.

  • 0 in reply to Clemens Ladisch
    Guru 19645 points
    Clemens-san

    Sorry for reply delay,

    Two update;
    ①the use case of some the other monitor, display was not work.
    ②A few years model was not occur these problem, but this year model are occur in many times.

    About SN75DP139, is there any revision change?
    (Especially, the point of wraparound voltage)

    Best regards,
    Satoshi