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LM2904: About power up sequence

Tsukui Yusuke
Guru 21930 points
Part Number: LM2904

Hi,

Customer wants to control LM2904 ON/OFF.

When not supplying power to the Vs pin,
Is it okay to input a signal to IN±?

If that is not recommended,
Could you give me advice on the recommended ON/OFF method?

Regards,
Yusuke

  • 0
    Guru 140200 points

    Hi Tsukui,

    a schematic would be helpful :-)

    Kai

  • 0 in reply to kai klaas69
    Guru 21930 points

    Hi kai,

    Thank you for your response.
    Customer did not report me a schematic.
    I think there is no possibility that the LM2904 will be damaged from the information on the absolute maximum ratings.
    However, I am worried about a startup failure or a malfunction.
    Is there a risk of malfunction if power is applied to V± with a signal input to the IN± pins?
    From the block diagram of a data sheet, the internal protection diodes could not be confirmed.

    Could you give me your advice?

    Regards,
    Yusuke

  • 0
    TI__Guru*** 139956 points

    Yusuke-san,

    Inputs can be positive voltage (relative to GND pin 4) without any input pin current flow even with VCC (pin 8) at 0V. The output pin can pass current internally to VCC. Input voltage (or output voltage) must not be negative (relative to GND pin 4).

  • 0 in reply to Tsukui Yusuke
    Guru 140200 points

    Hi Yusuke,

    wants the customer to turn-off the LM2904 to save supply current or to turn-off the signal (make it 0V). In the latter case a resistor and a clamping transistor at the input of LM2904 could do the trick.

    Kai