you could try use a non volatile digital potentiometer (with sufficient voltage rating) instead of R2 in an LM317 circuit. But getting a low enough ohm value might be a challenge. So maybe a fixed resistor in parallel to reduce the ohms... ?
Hello,
I was thinking can i control the Voltage Regulators Like L200 or LM317 using pic microcontroller ? Can we use PWM Signal to control the reference voltage provide to the voltage regulator ? OR any other idea, Because i need to make one digital power supply which will increment and decrement voltage according to our need.
i need some guidance....Plz..
I tried the circuit given in the image attached...but not able to simulate properly in the protues.... do u have any PIC MCU Based circuit ? that would be helpful..[/QUOTE
on real hardware it is working fine, i made schamtic in isis for record only not for simulation purpose as i do not have picaxe license file
I tried the circuit given in the image attached...but not able to simulate properly in the protues.... do u have any PIC MCU Based circuit ? that would be helpful..[/QUOTE
on real hardware it is working fine, i made schamtic in isis for record only not for simulation purpose as i do not have picaxe license file
ok so you mean to say that i should connect pin 2 to the PIC PWM output pin ? right ?
ok so you mean to say that i should connect pin 2 to the PIC PWM output pin ? right ?
Looking at the schematic, Do you mean pin 2 of the regulator ? If so this is the input like it said 25V,
The feed from R10 is the feed back that reads into the ADC channel of the PIC and the pin on the pic axe that feeds the 1m resistor is where you connect the PWM pin from the PIC normally RC2. Say if you set the ouput to 5V then place a load on the output the voltage will drop so the feed back (R10) will give a voltage feed in then if the voltage drops below 5V you increase the PWM to maintain the 5V
my opinion this is not the best way to make a digital PSU. It is possible but for the current limit side you would need to add a 0.1R resistor in line on the 0V side of the output then use the voltage developed accrross the 0.1R resistor then use this to set the current limit in software say if you set it to 200ma anything over that you would cut off or reduce the PWM to the mosfet, Like I siad it's not the best way and not as easy as you think to make a PSU.
Looking at the schematic, Do you mean pin 2 of the regulator ? If so this is the input like it said 25V,
The feed from R10 is the feed back that reads into the ADC channel of the PIC and the pin on the pic axe that feeds the 1m resistor is where you connect the PWM pin from the PIC normally RC2. Say if you set the ouput to 5V then place a load on the output the voltage will drop so the feed back (R10) will give a voltage feed in then if the voltage drops below 5V you increase the PWM to maintain the 5V
my opinion this is not the best way to make a digital PSU. It is possible but for the current limit side you would need to add a 0.1R resistor in line on the 0V side of the output then use the voltage developed accrross the 0.1R resistor then use this to set the current limit in software say if you set it to 200ma anything over that you would cut off or reduce the PWM to the mosfet, Like I siad it's not the best way and not as easy as you think to make a PSU.
I mean to say Pin 2 of PICAXE. And i dont need to use feedback for now just need PWM signal to provide some voltage with no Load Resistance. I just need output settable on the output pin.... I just want to confirm that where should i apply PWM Signal. And as you said, Its 1M Resistor is your PWM Signal.
Thanks
hi i have uploaded a bunch of idea how to control LM317 with PWM input the best and good is from Atmel stk500 schematic
Fragrance
hi i have uploaded a bunch of idea how to control LM317 with PWM input the best and good is from Atmel stk500 schematic
Fragrance
The OP/output FET control loop can be suspected to expose instability by placing a low-pass and >1 gain in the OP feedback path without the required additional compensation means.Not sure what the ripple or load control would work like
Can you tell me the part no. of some generic digital non-volatile potentiometers for this purpose.you could try use a non volatile digital potentiometer (with sufficient voltage rating) instead of R2 in an LM317 circuit
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