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Adding suggested changes to fix the gating logic.
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juanmf
juanmf
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In LM393 datasheet it’s connected to GND on LOW, and disconnected of everything on HIGH. But on my tester I see on LOW: 100 Ohm when no load’s GND connected to Out pin. (No load at all). 850 Ohm when 12V led’d GND lead connected to LM393 out pin.

When I connect the GND of my (comparator-gated) PCB to the out pin nothing 12V fires up, only some 5V leds light up

Why? I expected zero Ohm on LOW. LM393 usage: enter image description here Big picture: enter image description here Fix (black): enter image description here Edit: @justme, I had to use the comparator as a gate driver, was forced to invert the inputs as the MOSFET was always on in the original setup. Driving the gate with 4V; 0.1mA Thanks for the help!

In LM393 datasheet it’s connected to GND on LOW, and disconnected of everything on HIGH. But on my tester I see on LOW: 100 Ohm when no load’s GND connected to Out pin. (No load at all). 850 Ohm when 12V led’d GND lead connected to LM393 out pin.

When I connect the GND of my (comparator-gated) PCB to the out pin nothing 12V fires up, only some 5V leds light up

Why? I expected zero Ohm on LOW. LM393 usage: enter image description here Big picture: enter image description here

In LM393 datasheet it’s connected to GND on LOW, and disconnected of everything on HIGH. But on my tester I see on LOW: 100 Ohm when no load’s GND connected to Out pin. (No load at all). 850 Ohm when 12V led’d GND lead connected to LM393 out pin.

When I connect the GND of my (comparator-gated) PCB to the out pin nothing 12V fires up, only some 5V leds light up

Why? I expected zero Ohm on LOW. LM393 usage: enter image description here Big picture: enter image description here Fix (black): enter image description here Edit: @justme, I had to use the comparator as a gate driver, was forced to invert the inputs as the MOSFET was always on in the original setup. Driving the gate with 4V; 0.1mA Thanks for the help!

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juanmf
juanmf
  • 135
  • 5

In LM393 datasheet it’s connected to GND on LOW, and disconnected of everything on HIGH. But on my tester I see on LOW: 100 Ohm when no load’s GND connected to Out pin. (No load at all). 850 Ohm when 12V led’d GND lead connected to LM393 out pin.

When I connect the GND of my (comparator-gated) PCB to the out pin nothing 12V fires up, only some 5V leds light up

Why? I expected zero Ohm on LOW.

  LM393 usage: enter image description here Big picture: enter image description here

In LM393 datasheet it’s connected to GND on LOW, and disconnected of everything on HIGH. But on my tester I see on LOW: 100 Ohm when no load’s GND connected to Out pin. (No load at all). 850 Ohm when 12V led’d GND lead connected to LM393 out pin.

When I connect the GND of my (comparator-gated) PCB to the out pin nothing 12V fires up, only some 5V leds light up

Why? I expected zero Ohm on LOW.

 enter image description here

In LM393 datasheet it’s connected to GND on LOW, and disconnected of everything on HIGH. But on my tester I see on LOW: 100 Ohm when no load’s GND connected to Out pin. (No load at all). 850 Ohm when 12V led’d GND lead connected to LM393 out pin.

When I connect the GND of my (comparator-gated) PCB to the out pin nothing 12V fires up, only some 5V leds light up

Why? I expected zero Ohm on LOW. LM393 usage: enter image description here Big picture: enter image description here

Source Link
juanmf
juanmf
  • 135
  • 5

LM393’s LOW shows high Ohm to GND

In LM393 datasheet it’s connected to GND on LOW, and disconnected of everything on HIGH. But on my tester I see on LOW: 100 Ohm when no load’s GND connected to Out pin. (No load at all). 850 Ohm when 12V led’d GND lead connected to LM393 out pin.

When I connect the GND of my (comparator-gated) PCB to the out pin nothing 12V fires up, only some 5V leds light up

Why? I expected zero Ohm on LOW.

enter image description here