Part Number: LM5022 Other Parts Discussed in Thread: PMP20745 , At the beginning of input appearing, how to calculate the voltage on U1 pin 1? Thiis partly schematic was copied from one of your reference circuit, PMP20745.
Hello Maor,
R106 sets the charging current for the primary-side bias supply. R121 sets the UVLO. Increasing R121 will allow it to start at a lower input voltage.
Vuvlo = (Vin * R121/(R121+R4+R5+R6)) - VBE_Q101.
However, this design will exceed the…
Hello Maor,
PMP7760 operated in DCM at lower load current and higher input voltage..
It operates in CCM at higher load current and lower input voltage.
You will exceed the maximum duty cycle operation at 12V input with this design. In this case…
Hi Bernard,
Thank you for showing options with various designs.
I looked at all three designs and based on efficiency data and complexity of design I think PMP20745 is best suitable option. Now I seek your help to design circuit for our requirement…
Hi Anand,
Yes you need to protect VIN pin by adding an linear circuit (small but high voltage NPN and a ~12V Zener), like in the following ref design.
http://www.ti.com/tool/PMP20745
Thanks,
Youhao
Hi Vishwanath,
The UCC28740 can also work. I checked and I do not see a reference design that supports your input/output requirements exactly. The closest I found is PMP20745 which is based on the LM5022.
One thing to watch is to make sure that…
Other Parts Discussed in Thread: PMP20745 , PMP9334 Dears:
There is a demand as follows:
1. DC-DC input is 18v~380v, output is 12V or 5V
2. Iout is 1.5A or 2A above.
I found the solution from reference design.
And from the PMP20745 datasheet…
Hi Massoud,
1. I have not evaluated the output capacitor ESR for stability. Since this regulates on the auxiliary winding voltage, increasing the value of C108 from 4.7uF to 10uF will improve stability.
2. I do not see mention on the schematic to…
Hello Jean,
A search through our Reference Designs indicates that the LM5022 is used quite often for such a wide-range type of application. Although this part is originally targeted for boost and SEPIC applications, it is also widely used for isolated…
