Part Number: SN74LVC1G3157
Using for video signal switching.
When the analog switch is switched from pin 3 to 1, a voltage of 3.3+Video appears at pin 3, and because of this voltage, Vout cannot switch back to pin 3.
We find a surge voltage(because of Integrated inductance) at Vcc when the switching happened. And the datasheet of SN74LVC1G3157 recommends waiting until VCC has ramped to a level in Recommended Operating Conditions before applying any signals, so we suspect that if this surge voltage of Vcc cause the problem.
So will the unstable of Vcc causes the switching failure? If not, then is there any other probability may cause the problem?
Sincerely thanks for your help!
You are correct that this device doesn't have powered off protection like the TS5A12301E and Vcc must be within the recommended operating conditions before signals are placed on the I/O path.
A typical symptom of signals on the I/O path before Vcc is high leakage into the device I/O pins to ground or Vcc through the ESD protection once it is above the forward bias voltage ~0.5V.
I would like to understand a little bit more about "switching failure" means.
Do you have a scope capture of the pin 1, pin 3, pin 5, and pin 6 during both cases?
Do you suspect the device is damaged? Does replacing the device with a new IC allow normal switching?
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In reply to Adam Torma:
In reply to Yazhu Liu:
I'm not familiar with the CVBS video signal. Would you please provide the voltage range and bandwidth of the signal you are attempting to support? This will help make sure the switch will support your signal.
Adam, Sorry for answering so late, I've got serious personal things to deal with and forgot to check E2E. Really sorry again. The voltage range of the signal is between -1V to 1V, and its bandwidth is 6MHz. Our customer would like us to find pin-to-pin device for them so that they won't have to change the design. But as far as we know, there do not seem to have pin-to-pin device which can support their requirements. I've already update your solution TS5A22362 to them, and haven't got their feedback yet.I'm the FAE Intern of Suzhou branch, TI China. Really thank you for the help. Thanks again. Yazhu
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