Since there are 8 three-phase motors in my project, it creates a serious cost in total. Unfortunately, the high costs of not using something like TMCS1101 for isolated current session. 'Why not using isolated current sensing?' But since the sinus time is very long (15.35mS), I want to detect on the high side so that it is not damaged in case of any short circuit. 'Why high side sensing? Isn't there a return path in the low side?' I am sharing the full version of the design I planned below. Since I do not have a diagram describing my entire project, I had only drawn and shared the relevant part before. Tell us your timing requirements in values with units. Why high side sensing? Isn't there a return path in the low side?

It rather relates to the high ohmic resistor. Your power calculation: does not apply for the comparator since it never sees a high voltage difference wrt the supply pins. Most probably with respect to the negative supply pin. with respect to what? The datasheet should tell. just means it can drive at least (worst case) a load with 6mA. then a high ohmic path in combination with stray capacitance will create some delay. Consider to galvanically isolate (according safety regulations) the MCU circuit from the high voltage circuit. So if all voltages at the comparator are within it's supply rails everything is fine.ģ00V. It may work.Ī comparator has no dedicated GND pin, thus indeed it does never know that 300V exist. The schematic without bjt does not work at all, thus let's focus on the one with bjt. Thinking that I can benefit from the zener diode, I also thought of using a 270V zener diode in series with the 1M5 resistor in Scheme1, but I gave up because I could not find it in a small size.

If it is not applicable, if it can be made usable with minor changes, I would be happy if you could help. The LM339 datasheet says 'Output voltage max.36v' but in my application it produces a voltage of around 281v.Īlthough there is a lower value (36v x 20mA=720mW = 281v x 0.3mA=85mW) in terms of power, unfortunately I am not educated enough to decide whether this usage will cause problems.

Because it says in the datasheet that the output current should be Min.6mA, but while researching, I found many example schematics designed with 500uA (5v/10k). I'm also undecided whether the absence of this resistor would be a downside for the LM339. I am aware that the output of the LM339 in schematic 2 is not a pull-up resistor. However, since I use a lot of this process in my project, I'm thinking of using the Scheme2 style in order to both take up less space on the card and not have extra delays. I think I should use Scheme1 to reduce the comparator's output to the level of the mictocontroller. I am trying to detect High side current control with LM339.

Voltage comparator lm339 proteus