Hello
I’m using this converter with a Pulse PA3855.003NL and see a 500mV ripple at 12V 0.9A.
My output capacitor is 10uF(ceramic) // 200uF (eletr.) and a dumping CR.
Current limit is set with R= 51K
Hello massimo.romano,
What is your specific question?
Hello i observed a 450-500mV ripple on the output, but later i saw the graph on the evaluation board PDF.
Seems it is a normal condition, bad luck I hadn’t noticed it before…
Also the circuit generate a quite big ringing, but i think i can deal with that with an LC filter and dumping.
I think there is nothing i can do to decrease the ripple (ripple frequency depends on load current–>MP6004 switching freq. 10-200Khz). Am i correct?
We can begin by comparing your circuit to the MP6004 Flyback EVB.
Our evaluation design should perform with ~200mV of peak-peak ripple for Vin = 48V, Vout = 12V @ 1A, per the datasheet. This measurement was taken at Fsw = 125KHz.
Second, your worst case output ripple can be estimated with Equation (21) from the datasheet (Pg. 19) below. Since the MP6004 is a primary side converter, the variables in this equation are your best tools for improving output ripple. You could conceivably increase your output capacitance or chose a transformer with bigger Ns/smaller Np.
Lastly, you can also use Equation (15) on Pg. 18 to allow a higher max Fsw, which in turn can also help reduce the output ripple. Though you mentioned you’re already planning to work up to 200KHz (generally the max frequency for designing with the MP6004), this is something else to keep in mind.
