• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 49 subscribers
  • Views 1652 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM393: LM393 output sink current

Terry Wu2
Expert 2110 points
Part Number: LM393

Hello Sirs,

We have a sink current not enough issue for LM393 output low .

There's proportion that LM393 can't sink current up to 10mA .Will cause output voltage not low enough .

Below is test circuit . Would you pls give advice if this test method ok or not ?

BTW. Current limit setting is by power supply .

Many thanks !

  • 0
    Guru 140200 points

    Hi Terry,

    as you can clearly see from the datasheet, the LM393 is not designed to properly sink a low-level output current of more than 4mA:

    Kai

  • 0
    TI__Mastermind 49966 points
    Hello Terry,

    Yes. You sink a current and measure the voltage between the output and GND.

    Please see Figure 3, Output Saturation Voltage graph, in the LM393 datasheet. This gives the expected "low" output voltage over load current, and over temperature - so it has already been done for you!

    The "X" value is your load current (2/5/6.5/10mA), and the "Y" value is the resulting output low voltage.

    So at 2mA, at 25°C, the resulting output voltage is about 90mV. 10mA will be about 230mV.

    After 10mA, you start to get into current limiting (typically 12-16mA) I recommend you stay below 5mA to keep away from the current limit and minimize power dissipation. You will need an external MOSFET or transistor to sink higher currents.
  • 0 in reply to Paul Grohe
    Expert 2110 points
    Hello Paul,
    Got it and many thanks your support !