I receive 120V DC from an inverter which, when it shuts down, starts to decrease until it reaches 0V. When it drops below 40V (Vref) I want an LED to light up.
I would like to realise the application using an LM393 comparator (I have this available) but I have some doubts:
1) On the datasheet of the LM393 I read that the maximum ratings of Input Differential Voltage and Input Common Mode Voltage Range are about 36V .. so I don't think it can directly give these voltages to the comparator. Am I wrong? Have I interpreted those parameters on the datasheet correctly?
If the answer is yes, what can I do? I need to reduce both Vin = 120V and Vref = 40V to something acceptable for the comparator input.
2) How do I create the Vref? Do I use a resistive divider on 120V? Or maybe a pair of Zener in series?
(P.S.: I only want to use Resistors, Capacitors, Diodes and the Comparator)
Thanks.
I would like to realise the application using an LM393 comparator (I have this available) but I have some doubts:
1) On the datasheet of the LM393 I read that the maximum ratings of Input Differential Voltage and Input Common Mode Voltage Range are about 36V .. so I don't think it can directly give these voltages to the comparator. Am I wrong? Have I interpreted those parameters on the datasheet correctly?
If the answer is yes, what can I do? I need to reduce both Vin = 120V and Vref = 40V to something acceptable for the comparator input.
2) How do I create the Vref? Do I use a resistive divider on 120V? Or maybe a pair of Zener in series?
(P.S.: I only want to use Resistors, Capacitors, Diodes and the Comparator)
Thanks.