솔루션 찾기 기술 지원

LNK306 Problem

Posted by: xabingy on

I designed a +15VDC power following AN37. But I got a +3.5V output voltage.
BP pin voltage are 9.2V, and FB pin voltage are 3.6V.

Rfb = 16K
Rbias = 2.2K
Cbp = 0.1uF
Cfb = 0.33uF
Dfw = STTH1R06A
Dfb = 1N4007
Co = 100uF

Why?

I re-measured Vbp and Vfb against device source.
Results are:
Vbp = 5.8V
Vfb = 0.3V
Does it means that coil L is far less than 1.5mH?

댓글

Submitted by PI-Surak on 08/11/2010

Bp and FB voltages are not right -- they would need to be measured with respect to source of device but this cannot be done when device is switching since probe will introduce noise.

A schematic of your design would be helpful.

Submitted by xabingy on 08/11/2010

I re-measured Vbp and Vfb against device source.
Results are:
Vbp = 5.8V
Vfb = 0.3V
Does it means that coil L is far less than 1.5mH?