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TL331: Sink Current

Part Number: TL331
Other Parts Discussed in Thread: LM339

Dear Team,

May I have the sink current rating of this device?



  • Hi Kuan,

    "absolute maximum ratings" of datasheet say: <= 20mA is allowed to be sinked.

    Section 7.5 of datasheet says: <=4mA is allowed to be sinked for guaranteeing TTL compatibility.

    Section 7.5 also says: If the output low voltage during sinking is allowed to rise up to 1.5V (no longer TTL compatibility, but still CMOS compatibility), what current is allowed to be sinked then? Answer: The datasheet guarantess a sink current of at least 6mA @25°C.

    And figure 3 of datasheet, finally, shows the typical output low voltage versus (sinked) output current at different temperatures.


  • HI Kevin,

    Kai summed it up - but the key is the FIgure3 graph that shows the expected output low voltage vs. sinking current.

    After 10mA, you start to get into the current limiting zone. We recommend keeping it under 8mA.

    Also see the LM339 family application note, section 3:

     Application Design Guidelines for LM339, LM393, TL331 Family Comparators (Rev. A)