Hi,
I'm using a Sipex SP3232 chip in a 5V circuit.
I discovered that as long as the sp3232 is powered, even when it's not actually connected to a serial line or being used actively, it creates a periodic disturbance in my supply voltage.
The waveform is at a frequency of 130 kHz, and consists of a distinct bump that is 13mV in amplitude. It almost looks like a 25% duty cycle PWM signal, to help you visualize. This behavior seems to correspond to one of the internal operations of the 232 chip, as it cycles through 4 internal processes.
The problem with this disturbance, is that it is causing troublesome noise for some instrumentation amplifiers sharing the same power source.
Anyway, it isn't obvious to me how to filter this sort of thing, since it's not sinusoid in nature. I already have numerous bypass capacitors of the common values used all over in my circuit (0.1, 0.01, 0.22 uF, etc.)
Has anyone here ever had to address this issue before? Any thoughts on filtering, etc?
thanks,
Eric
I'm using a Sipex SP3232 chip in a 5V circuit.
I discovered that as long as the sp3232 is powered, even when it's not actually connected to a serial line or being used actively, it creates a periodic disturbance in my supply voltage.
The waveform is at a frequency of 130 kHz, and consists of a distinct bump that is 13mV in amplitude. It almost looks like a 25% duty cycle PWM signal, to help you visualize. This behavior seems to correspond to one of the internal operations of the 232 chip, as it cycles through 4 internal processes.
The problem with this disturbance, is that it is causing troublesome noise for some instrumentation amplifiers sharing the same power source.
Anyway, it isn't obvious to me how to filter this sort of thing, since it's not sinusoid in nature. I already have numerous bypass capacitors of the common values used all over in my circuit (0.1, 0.01, 0.22 uF, etc.)
Has anyone here ever had to address this issue before? Any thoughts on filtering, etc?
thanks,
Eric