Electronics > Projects, Designs, and Technical Stuff
Disable or trick pulse-skipping/skip-cycle/eco-mode
mikerj:
--- Quote from: T3sl4co1l on May 27, 2019, 12:47:49 am ---Keep FB above Vskip (0.8V).
Since FB has an internal pullup, a series resistor between the optotransistor (assuming the application circuit) and FB will do this.
The R_UP doesn't seem to be rated, so YMMV.
Tim
--- End quote ---
But this will cause loss of regulation, unless performed indirectly by adding load. Additionally the OP want's to avoid the drop in frequency prior to pulse skipping, so FB voltage would have to be limited somewhat higher than 0.8v, as much as 1.9v to avoid any change in switching frequency.
Miyuki:
If it is not a consumer product and thus dont need to pass green/eco requirement
Just use simple old UC38xx or similar driver with steady regulation in all range
I dont see any reason to use modern eco controller in situations where it cause instability and other problems when you dont need that low standby power consumption
And that NCP1239 dont look like have any fancy resonant mode to offer benefits in efficiency at full load so it have no benefits for your use
T3sl4co1l:
--- Quote from: mikerj on May 27, 2019, 01:57:36 pm ---But this will cause loss of regulation, unless performed indirectly by adding load. Additionally the OP want's to avoid the drop in frequency prior to pulse skipping, so FB voltage would have to be limited somewhat higher than 0.8v, as much as 1.9v to avoid any change in switching frequency.
--- End quote ---
They asked, that's what the block diagram says. ¯\_(ツ)_/¯
If that solution requires a bleeder resistor, then change the transformer ratio. Or, check that the transformer's leakage is what it needs to be (which, if light-load regulation is the problem, more leakage might actually be helpful?).
--- Quote from: Miyuki on May 27, 2019, 04:17:30 pm ---If it is not a consumer product and thus dont need to pass green/eco requirement
...
--- End quote ---
All this ^^^ :)
Tim
b_force:
--- Quote from: Miyuki on May 27, 2019, 04:17:30 pm ---I dont see any reason to use modern eco controller in situations where it cause instability and other problems when you dont need that low standby power consumption
And that NCP1239 dont look like have any fancy resonant mode to offer benefits in efficiency at full load so it have no benefits for your use
--- End quote ---
To be very honest, I am investigating if I can take an off the shelf PSU.
The reason is that nowadays they are cheap as chips and perform pretty reasonable.
As far as I know, these ECO modes are only to make the people at the government happy that idle power isn't than a certain value.
In our case not a huge problem since the device is being powered of by a hard switch.
But like I said, the biggest problem it has that it goes down to much lower frequencies, which is causing all kings of noise problems.
--- Quote from: T3sl4co1l on May 27, 2019, 12:47:49 am ---Keep FB above Vskip (0.8V).
Since FB has an internal pullup, a series resistor between the optotransistor (assuming the application circuit) and FB will do this.
The R_UP doesn't seem to be rated, so YMMV.
Tim
--- End quote ---
The issue is that I need the voltage regulation, or at least that it's not going through the roof.
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