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LM2904B-Q1: Input diodes - Absolute maximum current?

Daniel Stancu
Prodigy 10 points
Part Number: LM2904B-Q1
Other Parts Discussed in Thread: TS321

Tool/software:

What is the current limit of the input (to V-) diode? Voltage is specified in datasheet, but not current. 

  • 0
    Guru 317550 points

    Section 9.3.3 says:

    If either input more than 0.3 V below V– then input current should be limited to 1 mA and the output phase is undefined.

  • 0 in reply to Clemens Ladisch
    Prodigy 10 points

    Is this an absolute maximum rating? If so, why isn't it in chapter 7. Specifications.  The word "should" doesn't covey legal responsibility, rather a recommendation. 

  • 0 in reply to Daniel Stancu
    TI__Mastermind 25118 points

    Daniel,

    This device does not have ESD diodes (see Figure 9.2).  Some older general purpose devices fall into this category.  If you look at the abs max table (table 7.1), you will see that the absolute maximum input ratings are not based on the power supply as most devices are, but is based on an absolute voltage ( -32<differential <+32V, and  -0.3V< Vin < +40).  Note that the negative limit is a diode limit, but this is not an ESD diode but a substrate diode.  Exceeding these voltages will damage the device.  You could look at TS321 for more details on current as this has a similar input structure.  The voltage ratings are based on breakdown voltages and not turning on ESD structures.

    Best regards, Art