Other Parts Discussed in Thread: LM4040
Hello,
I am using a LM4050QAEM3-2.5/NOPB 2.5V voltage referenz in conjunction with an opamp (single supply 12V) as a current source for 1.1mA. See schematic attached.
This current is consumed by a resistor about 0.5 meters away. The sinal-lne to the resistor is placed in parallel to the 220V AC Power Supply mains lines for my device in the same cable.
I can not change this.
At EMI tests with injecting rf signal of 150kHz-80MHz Amplitude Modulation with tone 1kHz at 80% Modulation at 20V to my Mains Power Supply lines by a coupling device,
I find, that the referenz voltage of my LM4050 will rise and drop significantly from its nominal value of 2.5V (between 0V and supply voltage to the voltage Referenz)
at different rf signal resonant frequencies.
What I have done so far:
- I used a 2.2nF ceramic capacitor in parallel to the LM4050
- I used an inductor 680uH in the signal-line to the resistor
- I used a 2.2nF ceramic capacitor from current source signal line to ground
Question:
1. Is that behaviour of influencing the voltage referenc value by injected rf signals known?
2. What can i do to avoid this behaviour?
3. Is there an other voltage referenz which does not have such behaviour?
Any ideas?