PCA9518: clock input

Hello,

Today is a holiday in the US, but we will try to get back to you tomorrow on this.

Max

Hey ACGUY,

Do you have a schematic of the PCA9518? I am particularly interested in the Vcc pin and if it has capacitors on it.

I believe the issue you are seeing is due to a POR (power on reset) not being properly implemented. We have seen in some of our older PCA devices which are sensitive to the ramp rates on Vcc. We typically recommend faster ramp rates on Vcc (below 10ms) in order for the device to reset properly.

Q1. How repeatable is this issue?

Q2. Is this issue seen at room temperature or does it occur during some type of temperature testing?

Q3. If you have capacitors on the Vcc pin, does removing them fix this issue?

Thanks,

-Bobby

Hi Bobby,

Thank you for your reply.

>> Do you have a schematic of the PCA9518?
-> Yes, I obtained it already. However, I don't get permission to upload it to E2E.

>> We typically recommend faster ramp rates on Vcc (below 10ms) in order for the device to reset properly.
-> Currently, Vcc ramp up time is about 6-msec. I think that it is no cause.


Q1. How repeatable is this issue?
A1. Yes, However, the occurrence frequency is low.

Q2. Is this issue seen at room temperature or does it occur during some type of temperature testing?
A2. Occur condition at near 0℃.

Q3. If you have capacitors on the Vcc pin, does removing them fix this issue?
A3. We didn't try it. We attached capacitors between EN to GND, I confirmed that this symptom will be resolved.

.
The number of occurrences is 2/1k. End product is semiconductor manufacturing equipment. Symptoms occurred while the final product was in operation.
I don't think that it is device issue. If there is accurate input, device operate correctly.

Short low clock time less than I2C spec will cause malfunction?
Or,
When during rise up the Vcc, if there is clock input to SCL0, is this device can't operating for normally?

Regards,
ACGUY