Winsu
Full Member level 3
Hi All,
I have designed a converter using the FL7701MX to step down the voltage from 230V AC to 12V. It is actually a LED driver and current is set at 500mA.
The driver works fine when the Neutral and the Live is connected, but when the earth cable is also connected it start to make a noise. The earth cable is connected to two Cy capacitor of 1nf ( live and neutral). It is also connected to a mounting hole to make connection between the mechanical earth and the electrical earth.
Between the mounting hole mentioned before and the the electrical earth connection there is a 0ohm resistor. The application keep making noise with and without that 0 ohm resistor.
The driver is placed on a metallic tray and the LED board is placed on a metallic tray as well. There is a cable from the driver to the LED board to make the connection. There are also ferrites at the output stage of the PCB driver for high frequency noise( this may not be very relevant for this problem).
I don't what is causing this issue. I think this is a bit weird, I don't actually know what could be causing this and what is worst I don't know what investigate further, because I have never faced a similar problem.
Could anyone point me the right direction?
Thanks all!
I have designed a converter using the FL7701MX to step down the voltage from 230V AC to 12V. It is actually a LED driver and current is set at 500mA.
The driver works fine when the Neutral and the Live is connected, but when the earth cable is also connected it start to make a noise. The earth cable is connected to two Cy capacitor of 1nf ( live and neutral). It is also connected to a mounting hole to make connection between the mechanical earth and the electrical earth.
Between the mounting hole mentioned before and the the electrical earth connection there is a 0ohm resistor. The application keep making noise with and without that 0 ohm resistor.
The driver is placed on a metallic tray and the LED board is placed on a metallic tray as well. There is a cable from the driver to the LED board to make the connection. There are also ferrites at the output stage of the PCB driver for high frequency noise( this may not be very relevant for this problem).
I don't what is causing this issue. I think this is a bit weird, I don't actually know what could be causing this and what is worst I don't know what investigate further, because I have never faced a similar problem.
Could anyone point me the right direction?
Thanks all!