Keantoken's CFP cap multiplier

[RCruz]

Thank you Andrew

 

[sianturi]

Direct replacement for discontinued transistors

Hello Keantoken,

2SA1930/2SC5171 have been discontinued. Mouser doesn't stock them anymore

OTOH, the discontinuation notice from Toshiba states that the replacement for these are TTA004B/TTC004B, respectively. Can we use this?

 

[keantoken]

I think those will work. Please report your results.

 

[sianturi]

I think those will work. Please report your results.

Ok thx. I'll report the result.

 

[merlin el mago]

Kean how can mod the HV version to have 90mA?

TIA
Felipe

 

[keantoken]

Try this.

 

[merlin el mago]

Thank You Kean.

 

[keantoken]

If you use a film capacitor for C1 you can increase R2 to 100k.

 

[merlin el mago]

OK thank you again.

 

[alexkosha]

What does it means if my led blinking short time (about 1/2 sec) after turn on, and then it is blinking second time and slowly (about 2 sec) is going off?

 

[keantoken]

Interesting, the first thing I would do is check whether the input or output voltage is fluctuating by a large amount after turn-on. Also a basic health check makes sense just to see if it's still doing it's job.

 

[alexkosha]

No V fluctuations at input and output. V drop is 2.1v on 30V 100mA. I’m trying to measure it as I used to measure C Multiplier where I got 100mV at its input and 5mV in its output, but here is different.... My input and output is same low ripple. It is about 20mV with high frequency noise still added. Is it injecting back? Why I’m asking, just I know that my PSU is min 100mV ripple+noise.

 

[alexkosha]

No V fluctuations at input and output. V drop is 2.1v on 30V 100mA. I’m trying to measure it as I used to measure C Multiplier where I got 100mV at its input and 5mV in its output, but here is different.... My input and output is same low ripple. It is about 20mV with high frequency noise still added. Is it injecting back? Why I’m asking, just I know that my PSU is min 100mV ripple+noise.

Maybe I'm doing something wrong with measurement setup?
Yellow trace in IN and blue is OUT. Files names are indication condition.
How to see if it is working ok?

 

[keantoken]

So the input ripple should have been 100mV but is 12mV for some reason? There are some weird HF bursts on the waveform. The KM should be working better assuming the measurements are accurate.

 

[alexkosha]

Yes, the input should be100mV from my switch PSU and buck convertor-controller. HF is due to scope probes GND, a assume. Will replace both transistors and try again tonight. It is 30V/90mA test.

 

[keantoken]

I would look for the KM to be overloaded in this situation, since there is extra input ripple and the voltage drop seems more than it should be. The KM shouldn't have any influence over the input ripple, which is mainly determined by load current.

 

[alexkosha]

What max Load to set for my test? I can run up to 30V 6A with my Switch PSU and LoadPro DC load module.

 

[keantoken]

90mA is reasonable, I'm just suggesting your load current may be more than that for some reason.

 

[alexkosha]

No. I monitored it with external DVM. It was same 90mA on load screen and DVM via 1R resistor.

 

[keantoken]

What is the voltage across R1?