Part Number: TCA9803
I have one question about TCA9803 may need your help.
Customer's application is like below. Master is NXP LS1046A CPU, Slave is EEPROM.
In testing, we found there is a 700~800mV/100ns voltage step in SDAB and SCLB falling edge as shown below. Is it caused by the device internal current source?
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In reply to Eric Schott48:
The step is not narrowd when i changed the end up resister to 200 ohms ,but after I have replaced the TCA9803 with a PCA9617 ,there is not step on the falling edge.The waveform is below.
In reply to user4179467:
1.PORTB has no pull-up resistor
2.We tried the TCA9800/TCA9801 two devices again. In contrast to the waveform, the steps seem to be caused by different current source sizes of PORTB.The edge of TCA9800/TCA9801 is monotonous
3.However, the SCL&SDA rising edge of the TCA9800 device still has a small step, which helps me see why.
In reply to Bobby Nguyen:
I am sure the master has not an internal pull up resistor.I remove the pull-up resistor of SCL/SDA to make the pin float, then send the data, and the signal is detected to be unchanged, and remains low.
Hello user4179467 , I believe we have taken this discussion offline via Email and have sent back a message asking about the test set up and have not yet heard back. (this was a few weeks ago) Thanks, -Bobby
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