Control a KIS-3R33S or LM317 power supply module ?

Go To Last Post
13 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Is is possible to control a KIS-3R33S module with an ATtiny or ATmega ?

A used KIS-3R33S module can be bought on Ebay for about 50 cents each. They are high efficient DC-DC converters which can also be modified for output voltages higher than 5 volts.

To control my load, I don't want to use a PWM signal but I want a controlled DC voltage. The KIS-3R33S has a sense-input, somewhat like the adjust-pin of a LM317.

I could use a transistor with resistor for every voltage I want. The transistor simply pulls the resistor to the ground.
But if I need many voltages, I also need many outputs and many transistor.

I could send a PWM signal to a fet connected to the sense-input. But the KIS-3R33S is already a switching DC-DC converter. That might interfere.

Are there any examples ?
An example of a bench power supply with a LM317 controlled by an atmega would help a lot, but I can't find it.
Or do I really need a seperate DAC chip to get an analog signal?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

How about a digital pot controlled from the spi? You would add the control volts thru an R right to pin 5 it looks like.

Imagecraft compiler user

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

bobgardner wrote:
How about a digital pot controlled from the spi? You would add the control volts thru an R right to pin 5 it looks like.

Thanks, that might be the most simple solution. I didn't think of it, because I never used one.

They are about 3...5 dollars and with 100 or 256 steps.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

What's your project? (Just curious)

Imagecraft compiler user

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

You might be able to use the AVR port to connect to control line to ground. The AVR port pin acts as ground. Set the output to logic 0 and use the DDR for the port pin to switch between high-impedence input and 0 volts output. Check the data sheet for how much current each port pin can sink. Generally the more pins used on a port, the less each pin can sink.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

@bobgardner
(1) I like the KIS-3R33S modules. It would prevent a smoking hot universal adapter. So an ATmega8 with a 16x2 LCD display and a KIS-3R33S module could make a nice multivoltage power supply.
(2) I bought a back massage thing with vibrating 12V motors. But it is very annoying. If I could program the motors and turn them off now and then, it might be good for my back. I have already a mosfet RFP12N10L (logic level power mosfet) connected to an ATtiny13 for on/off or PWM. But the KIS-3R33S modules can also be used as a power switch. I doubt however if those motors are really 12V since they spark inside at 12V, so a programmable DC voltage between 5 en 10V might be better.

@Simonetta
That's a nice idea. The output as a open collector. As long as the signal is below 5V ofcourse.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Found one: http://www.electronics-lab.com/p...
It is a well documented project, with transistors and resistors to select different voltages.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Just about any type of "adjustable" voltage regulator, that is one where a voltage divider on the output provides feedback to a sense input, can be easily controlled by a filtered pwm signal injected into the sense terminal in addition to the signal already provided by the feedback divider.

Tom Pappano
Tulsa, Oklahoma

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

tpappano wrote:
... a filtered pwm signal injected into the sense terminal in addition to the signal already provided by the feedback divider.

A filtered PWM to the sense terminal.
That sounds a bit tricky. Is there a schematic as example or something ?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:

A used KIS-3R33S module can be bought on Ebay for about 50 cents each.

Quote:

digital pot

Quote:

They are about 3...5 dollars

So you are going to add some $$$ of circuitry to utilize used DC-DC converters? Hmmm...

Microchip DAC family MCP48xx/49xx is less than $2 in qty. 1. Dual channel models less than $1/channel.

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

theusch wrote:
So you are going to add some $$$ of circuitry to utilize used DC-DC converters? Hmmm...

Microchip DAC family MCP48xx/49xx is less than $2 in qty. 1. Dual channel models less than $1/channel.

Thanks.
I just happen to like those KIS-3R33S modules. The low price adds just extra fun.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Place a RC filter on a PWM output.
Connect the filter output to an opamp input for buffering and if needed, gain.
Connect a resistor from the opamp output to the voltage regulator feedback pin, in addition to the existing feedback resistor network.
Careful calculation of these three resistors will give you pretty much full control of the regulator output voltage. The calculation part is an exercise for the student.

Tom Pappano
Tulsa, Oklahoma

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

tpappano wrote:
... RC filter ... opamp ... feedback pin ... addition to the existing feedback ...

Thanks!
I didn't know it was possible.
There are many variables and interaction between software and hardware, but the hardware is easy to make.