I have to drive ac load through relay by micro controller. Problem is MCU reset as power dips when relay is on or off.
Relay contact is 220Vac/50Hz. My circuit is follow:
1. TO power the MCU I have +5V supply from SMPS of 2A(current is more than enough).
2. There is separate isolated 12V in circuit.
3. MCU pin drive opto, which Then turn on relay by 12V which turn on/off the laid.
4. problem is there is huge dip in supply which caused MCU reset. Although I have isolated 12V & 5V supply.
I have placed a diode in series of +5V also, no effect.
Huge parallel capacitors 1000uf/470uF/10uF/0.1uF very close to MCU supply but no effect.
There is free-wheeling diode on relay & relay card is separated from MCU board, jumper wires connect two boards.
5. One thing I have noticed that there is dip only when load is connected across relay, if load is disconnected then there is no dip in supply, relay turn on/off correctly.
If I connect load across it even a zero watt bulb even then dip happens
6. I dont understand that when +5V & +12V are isolated then why there is dip in +5V supply? There is huge spike across +5V supply.
7. I haven't tried snubber across the relay load contacts, since it is ready made relay board.
What could be the problem.
Relay contact is 220Vac/50Hz. My circuit is follow:
1. TO power the MCU I have +5V supply from SMPS of 2A(current is more than enough).
2. There is separate isolated 12V in circuit.
3. MCU pin drive opto, which Then turn on relay by 12V which turn on/off the laid.
4. problem is there is huge dip in supply which caused MCU reset. Although I have isolated 12V & 5V supply.
I have placed a diode in series of +5V also, no effect.
Huge parallel capacitors 1000uf/470uF/10uF/0.1uF very close to MCU supply but no effect.
There is free-wheeling diode on relay & relay card is separated from MCU board, jumper wires connect two boards.
5. One thing I have noticed that there is dip only when load is connected across relay, if load is disconnected then there is no dip in supply, relay turn on/off correctly.
If I connect load across it even a zero watt bulb even then dip happens
6. I dont understand that when +5V & +12V are isolated then why there is dip in +5V supply? There is huge spike across +5V supply.
7. I haven't tried snubber across the relay load contacts, since it is ready made relay board.
What could be the problem.