I am using the ADG719 switch. I have two inputs with a frequency of 125kHz. I am switching between the two using a logic signal of 250kHz. But when I look at the output of the switch I just see a pulse of one of the signals then about a gap of 12ms then a pulse again. Its as though the switch is only letting through one of the signals every so often. Anyone have any idea why this would be?
Thanks for your query. To look at your issue in more detail, can you provide scope plots of what you are seeing? And possibly a snapshot of your schematic including the ADG719?
Hi David. Here is the schematic.
Here is one of the inputs
This is the output. If I zoom out then I get a pulse about every 12ms, as though its only letting a channel through at that rate.
This is the select signal
I have just tried simulating the part in ADsim and it doesn't seem to work in that. If anything its worse as I just get a thin pulse out. So it seems as though I am driving the select too fast. But where does it state in the datasheet how fast it can be driven? I see parameters for the select switching on/off. But nothing that gives information about the switching frequency (unless I have overlooked it).
Anyone from ADI have any idea what the problem is?
Could you send me your ADsimPE file?