DPA forward design with TRANSFORMER in the feedback path
hello sir..
iam currently involved in the design of forward converter (5v/2A)with dpa switch.BUT i was asked to perform the design with transformer in the feedback path.but all ur designs are based on opto in the feedback path.is it that the converter will not work with transformer in the feedback portion.
kindly suggest some reference designs for forward converter using TRANSFORMER in the feedbak portion.please do help me
please help me with the design ....
Comments
Hi,
can we use DPAswitch in buck converter mode?
Yes you can. See attached schematic idea. The catch is that the output voltage has to be more than 6.8 V for this to work.
Hi,
Pls find attached circuit where i connected DPA424 in buck mode. am not getting regulation for 12V, as i increase the input voltage output voltage also increases beyond +12V. At 20V am getting output of around +18V.Pls give me suggestion.
Not able to attach the schematic. i ll write the values
Device : DPA424P
Zener : 6.2V
Freewheeling & feedback diode : UF4007
Inductor : 2.2uH
Output filter capacitor : 220uF
Rest of the values are same as the suggested schematic
Please go through the schematic & provide the solution
What is the formula to calculate the inductor value?
Try a 1 mH inductor.
(For CCM operation) The inductor formula can be derived from the standard expression V = L * di/dt
V = Output voltage
di = allowable ripple current
dt = off time
For DCM operation approximate the minimum value of inductance from the expression - PO = 0.5 * L * IP^2 * F
IP = Peak primary current (0.8 * Current limit of DPASwitch)
F = Switching frequency
Please check your feedback circuit for values of components used. The regulating zener should be equal to the difference between outpout voltage and the control pin voltage (about 6.2 V)
sending you a PM
With DPASwitch the only way I can suggest is to use bias winding feedback... but the regulation you will get using this approach is not particularly good.