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pc817
I encounter PWM on/off and phase shift on/off.....
Now, I fixed R6, it is a phase shift on/off
Added after 1 minutes:
is it better if I add a C parallel to C1 and R5?
tl431 feedback
here's my design, I got some problems.....
My topology is full bridge phase shift
Vin=48-96V, N1/N2=5:26, Vo=200V,
When I boost my input to about 36V, the feebback path starts work. But the circuit become odd. The Vo can keep 200V but this is a on off control, which means phase...
loop compensation tl431
How to determine R6? why 2.5K
My analysis:
For Min, If min = 1.5V/4.3K=0.35mA, for min CTR20%, Ic=0.07mA
For Max, If max= (30-2.5-1.5)/4.3k=6mA, CTR about 1.1, Ic= 6.6mA
Is it right for min and max Ic?
feedback tl431
1)why R6 is about 2.5K, how to determind?
2)What do you mean replace D1? use R3(two R3 in circuit)?or take it out(it seems become my very original design, it does not work)?
3)if I keep using the approach (by Z-diode), what is the good value for R5,c1,R3?
4)if i just replace R6...
how to increase the phase margin with tl431
1)first i would like to ask how to determind operate V of TL431???depend on Id mentioned above i.e Id=1mA, then Vtl431=20v????
2)here's my design,pls check....
R1=2.5K,R2=197.5K (such that Id=1mA)
R3+R4>200/10mA=20K
R3=(30-Vf-Vmin of TL431)/2/3mA...
phase margin compensation using tl431
is it better if I design IF=2mA???
This is a voltage control...will it become worse in no-load operation or light load?
how pc817 works with tl431
thanks for VVV and FvM very very much. I used 4N25 for my coupler, but acutally I don't know it is good or not and the design from the CTR curve....
Initially, I design IF=3mA and Ic=2.5mA then using 1K for phototransistor so that the VEAP operates at Vref/2.....
I...
tl431 pc817
seems little compliated for me...
I decided R4=(200-30)/3mA=56.7K,R1=2.5K,R2=197.5K,c1=0.1u,VD1=30V, is this ok????
how to determine R3 and R in series C1?
Added after 5 minutes:
and , how to achieve the maximum LED current (+ some margin).
improved tl431
I used 4N25 for opt coupler
how's the rating of other component such as Z-diode
Added after 8 minutes:
also, is 4N25 good? if not, any suggestion?
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