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Uln2803

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Jpsinghbrar

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how to use ULN2803 as an inverver. i mean which supply be given to pin-10(common).
i first connectd it to ground nothing happnd.then i connected it to 12V with input either 2V or 0V but output was approx. 1.2uV for each input. I only get the inveter operation from this IC if i connect pin-10 to approx. 1200000000V (in Proteus software) which is not achievable in practice. Pls tell me the possible solution to get the inverter action from ULN2803. I will b very thankful to u..
 
Pin 9 goes to ground.
Pin 10 can be not connected.
The output only pulls down to ground. It can not pull up!!! Use a resistor to 12 volts to pull the output high.
Look at figure 8 in TI's data sheet. You need a load or resistor to 12 volts.
 
Sorry dear couldnot understand fig 8 and ur post. whether pin10 is to be connecte do 12V through resisitor or something else.pls explain if u can..
 
Ya i got ur point @ronisimpson. i connected each output to 12 through reisitor and getting inverter action but only when the high input is above 2.5V but i have to use it with 8051 where input to it(output from ports) is apprix 1.5... pls help what to do..
 
i have to use it with 8051 where input to it(output from ports) is apprix 1.5
What is the supply voltage of your 8051? If it's in the specified 4-6V range then 1.5V from the I/O pins seems unduly low.
 
Ya i got ur point @ronisimpson. i connected each output to 12 through reisitor and getting inverter action but only when the high input is above 2.5V but i have to use it with 8051 where input to it(output from ports) is apprix 1.5... pls help what to do..

2.5V.....that is how it works.
Depending on which port you use on the 8051, the 8051 does not pull up well. You may need to add a pull up resistor to the out puts of the 8051. (VCC to pin 1k resistor)
 
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