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MAX3243: ROUT output condition under Device is unpowered and signal is applied to RIN pins

Takashi Onawa
Genius 13200 points
Part Number: MAX3243

Hi Team,

Could you tell me ROUT output condition when MAX3243 is unpowered and signal is applied to RIN pins?
I would like to know if some voltage level is appeared to ROUT pins due to current leakage through RIN to ROUT or not.
Also How much leakage will be estimated on RIN to Vcc path under same condition?

Regards,

Takashi Onawa

  • 0
    TI__Guru 62920 points
    Hello Onawa-san,

    It is OK to have a signal at RIN when MAX3243 is unpowered. The input leakage current to receiver is primarily through the input resistance, which is nominally 5 kOhm from the pin to ground. The device will not become powered via RIN, so it will not be able to drive the ROUT outputs. These will remain high impedance until the VCC rail is active.

    Please let me know if this is not clear or if you have any further questions.

    Regards,
    Max
  • 0 in reply to Miguel Robertson
    TI__Genius 13200 points
    Hi Max-san,

    Thanks for your prompt response on this. I understood how MAX3243 works.

    Sorry, I have an additional question.
    When ROUT will be activated?
    I want to especially know how ROUT pins behaves when VCC is ramping up very slowly.

    Regards,
    Takashi Onawa
  • 0 in reply to Takashi Onawa
    TI__Guru 62920 points
    Onawa-san,

    Typically these devices will be fully disabled (outputs high-impedance) until the VCC level reaches a minimum threshold that is slightly below the minimum recommended operating voltage. I am not 100% sure whether the MAX3243 device was designed in this manner, though, and if so what the exact voltage threshold for turn-on might be. I have ordered some devices in order to do some testing so that we can better answer your question. It may take several days to receive the units and set up the test, though, and so we can get back to you next week. Please let me know if this is not OK.

    Thank you,
    Max
  • 0 in reply to Miguel Robertson
    TI__Genius 13200 points
    Hi Max-san,

    Thanks for your kindly support on this!
    It's OK, I'm waiting your update.

    Regards,
    Takashi Onawa
  • 0 in reply to Takashi Onawa
    TI__Mastermind 25705 points

    Onawa-san,

    As I checked in lab, Rout pin keeps close to ground during VCC ramp up. When VCC is high enough (around 0.5V), Rout voltage will become VCC (since Rin is pulled down by 5kOhm a resistor). The voltage during the transition is in this table.

    VCC Rout
    0V 0V
    0.4V 75mV
    0.45V 180mV
    0.46V 220mV
    0.47V 290mV
    0.48V 350mV
    0.49V 410mV
    0.5V 470mV
    0.51V 490mV
    0.52V 520mV

    Please let us know if you have more questions about MAX3243.

    Regards,

    Hao

  • 0 in reply to Hao L
    TI__Genius 13200 points
    Hi Hao-san,

    Thanks for your prompt lab work on this!
    Could you draw the experimental setup roughly for my well understanding?

    I understood the setup as below, is this correct?
    Vcc : Ramp up slowly
    ROUT : Open
    Rin : Open(Internal Pull down, should be logic low in default)

    Regards,
    Takashi Onawa
  • 0 in reply to Takashi Onawa
    TI__Mastermind 25705 points

    Onawa-san,

    You're right about the test procedure. Rin and Rout are both open. Since Rin has internal pull down, Rout would be high in normal operation. Please let me know if you have more questions.

    Regards,

    Hao

  • 0 in reply to Hao L
    TI__Genius 13200 points

    Hi Hao-san,

    Thanks. I understood.

    Sorry I have an additional request. I want to know current consumption at low Vcc condition.
    Could you check the leakage current from VCC under following condition(Please fill the blanks in the following table)?

    Vcc : 0V, 0.1V, 0.2V, 0.3V, 0.4V, 0.5V
    ROUT : Open
    Rin : Open and High

    [Table : Leakage from VCC pin]

    Vcc[V] Rin = Low Rin = High
    0
    0.1
    0.2
    0.3
    0.4
    0.5

    Regards,

    Takashi Onawa

  • 0 in reply to Takashi Onawa
    TI__Genius 13200 points
    Hi Hao-san,

    Could you take to data to close this issue?

    Regards,
    Takashi Onawa
  • 0 in reply to Takashi Onawa
    TI__Mastermind 25705 points

    Onawa-san,

    Sorry I was out of office last week. Here is the data. Please let me know if you have more questions.

    Vcc : 0V, 0.1V, 0.2V, 0.3V, 0.4V, 0.5V
    ROUT : Open
    Rin : Open and High

    Vcc(V) Icc (mA) Rin=Open Icc (mA) Rin=Vcc
    0 0 0
    0.1 0.0001 0.0171
    0.2 0.0001 0.0344
    0.3 0.0001 0.0517
    0.4 0.0001 0.0688
    0.5 0.0001 0.0863
    0.6 0.0008 0.1043

    Regards,

    Hao

  • 0 in reply to Hao L
    TI__Genius 13200 points

    Hi Hao-san,

    Thanks for taking the data. But, I want to know the leakage from Vcc under applying High or low level voltage at RIN pins.

    Could you take the data under following experimental setup again just in case?

    Regards,

    Takashi Onawa

  • 0 in reply to Takashi Onawa
    TI__Mastermind 25705 points

    Onawa-san,

    Sure. Here is the data with separated RIN.

    Vcc(V) Icc (mA) Rin=0V Icc (mA) Rin=5V
    0 0 0
    0.1 0.0001 0.0001
    0.2 0.0001 0.0001
    0.3 0.0001 0.0001
    0.4 0.0001 0.0001
    0.5 0.0001 0.0001

    Please let me know if you have any more questions.

    Regards,

    Hao

  • 0 in reply to Hao L
    TI__Genius 13200 points
    Hi Hao-san,

    It's perfect! Thanks for your prompt work on this.

    Regards,
    Takashi Onawa