Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Microcontroller with battery backup

Status
Not open for further replies.
B

bikashh

Full Member level 5
Full Member level 5
Joined
Nov 28, 2009
Messages
264
Helped
3
Reputation
6
Reaction score
3
Trophy points
1,298
Location
india
Activity points
3,132
i am trying to design a battery back for my microcontroller circuit.I am sensing the mains using optocoupler. when the mains is On the controller pin is low and vice-versa. But on testing the circuit the microcontroller pin does not go low when the mains in ON. it comes down to 2.6V from 3.3V. Do i need to change any of the component value. Please Reply.

Thanks in advance
 

Attachments

  • backup circuit2.doc
    34 KB · Views: 142

Your Circuit have error like +5Volts Connected to GND of microcontroller, GND connected to VCC of microcontroller. and you have shown some other GND Symbol for Optocoupler Emmiter.
Check the Optocoupler Emitter Is Connected to GND of Microcontroller and the PIN is configured as INPUT PORT.
Which Optocoupler you are using?

P.Ashok Kumar
 

Thanks for the reply, yes there was a little bit mistake in drawing. I am using 4N35 optocoupler. Auxilary supply is nothing but a battery backup. please check the corrected diagram
 

Attachments

  • backup circuit2.doc
    34 KB · Views: 136

Circuit is ok.
Is it opto isolator is necessary simple circuit like
+5V---resistor(low value)----PIN-----PIN----resistor(high value)---GND can also detect Mains Fail

P.Ashok Kumar
 
thanks for the reply but i didn't get your circuit. i want to use the optocoupler just to isolate my microcontroller pin. Thanks again




you mean to say i should use a voltage divider.
 

from where is the logic pin of the Microcontroller getting +5V? Is it from Mains? I think that logic pin should be pulled up to Vcc. Basicaly the pin should work when either of the two supplies are present.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top