Line transient/load response circuit

[Chr1s]

hi all,

I need to build a line / load transient circuit test jig to testa DC DC converter. Can anyone help with a schematic that I could use to then build this type of jig onto some veroboard?

Any help would be much appreciated.


Thanks

 

[kellys_eye]

Check out the many projects on 'electronic loads' that abound the web these days. Feeding a squarewave to the MOSFET switching (load) device is all that's required.

A 555 timer configured as a monostable (for one-shot transients) or astable (for repeating transients) driving a low Rds(on) MOSFET will do what you want.

 

[Chr1s]

Check out the many projects on 'electronic loads' that abound the web these days. Feeding a squarewave to the MOSFET switching (load) device is all that's required.

A 555 timer configured as a monostable (for one-shot transients) or astable (for repeating transients) driving a low Rds(on) MOSFET will do what you want.

Thanks for this. However I unsure how I do this for a line transient as I need to step up the voltage on the input rapidly on the power supply which is feeding my circuit. Any ideas?

 

[kellys_eye]

For dedicated tests such as you describe it is usual practise to use a programmable power supply (GPIB enabled) but using a simple LM317 regulator and switching control resistors in/out of the program pin will achieve the effect.

Get the data sheet for the LM317 and see the application for setting the output voltage - it is often shown using a potentiometer on the 'set' pin but there's nothing stopping you using relays or transistors to switch fixed resistor values and thereby change the output voltage in increments you decide.

With some lateral thinking you could even make it adjustable (electronically switchable) in decimal or binary loaded increments and just 'ramp' through the values.

 

[Chr1s]

For dedicated tests such as you describe it is usual practise to use a programmable power supply (GPIB enabled) but using a simple LM317 regulator and switching control resistors in/out of the program pin will achieve the effect.

Get the data sheet for the LM317 and see the application for setting the output voltage - it is often shown using a potentiometer on the 'set' pin but there's nothing stopping you using relays or transistors to switch fixed resistor values and thereby change the output voltage in increments you decide.

With some lateral thinking you could even make it adjustable (electronically switchable) in decimal or binary loaded increments and just 'ramp' through the values.

Thank you for this information, however I don't have a programmable psu with gpib connection.

Can it be done with just a mosfet and some resistors? How would this circuit look?

 

[kellys_eye]

Apart from my GPIB comment, did you read the remainder of the post? It clearly states that you can use the LM317 to generate a supply voltage that can be 'stepped'...

I need to step up the voltage on the input rapidly on the power supply which is feeding my circuit.

....as you requested.

 

[Chr1s]

Apart from my GPIB comment, did you read the remainder of the post? It clearly states that you can use the LM317 to generate a supply voltage that can be 'stepped'...



....as you requested.

Yeah but i am pretty sure the lm317 will not allow the voltage to be stepped up rapidly. I need to switch between two voltage levels at say 1khz.

 

[kellys_eye]

Yeah but i am pretty sure the lm317 will not allow the voltage to be stepped up rapidly. I need to switch between two voltage levels at say 1khz.

Have you checked the data sheet?

Look at the line and load transient response times.