Variable Output voltage by changing feedback resistor for TOP271
1. We need to design a 65W laptop adapter with different output depending on feedback resistor by keeping rest of circuit same. Output voltage requried are: 15.27V , 19 , 19.8V, 20V or 20.67V .
2. We selected this IC: https://www.mouser.com/datasheet/2/328/topjx_family_datasheet-11851.pdf
3. On its page 15, a reference design for 19V/65W is given.
4. What we are planning is to keep R18 as 13K fixed & connect a parallel resistor across(call it Rp) it to change the output voltage & keep rest of circuit as it is.. There are few cases for it:
a) R18 = 13K & Rp=open, then output voltage will be 15.38V
b) R18 = 13K & Rp=51.1K, then output voltage will be 18.98V
c) R18 = 13K & Rp=41.2K, then output voltage will be 19.84V
d) R18 = 13K & Rp=40.2K, then output voltage will be 19.95V
e) R18 = 13K & Rp=34.8K, then output voltage will be 20.66V
5. Will this work? We want to keep circuit common and change output voltage as required?
6. If this dont work, then can you please suggest correct method to do it.