Other Parts Discussed in Thread: TCA9509, LSF0002, LSF0102, PCA9515A, TCA9803, TCA9517, TCA39306, TCA9517A, TCA9617B
Tool/software:
Hello Team,
I have to interface a 1.8V I2C master board (new board) with 2 existing 3.3V board (not in the same time) :
- one board with a FET based I2C transceiver.
- one board with a voltage offset I2C transceiver
Following the datasheet, the A side should be connected to the existing board because of the pullup resistors on the existing boards.
The master (1.8V) should connected to the B side.
The master is compliant with I2C standard:
VIL max <0.3VDD =0.3x1.8 = 0.54V
VIH min > 0.7VDD=0.7x1.8 = 1.26V
VOL < 0.2VDD@2mA = 0.36V@2mA
From the TCA980x datasheet, VIL, VOL are compatible with the master specifications. But there is is an issue with RILC (Low-level allowed pull-down resistance).
The maximum value should be 150ohms, whereas with my I2C compliant master, the RPD=Vol/Iol= 0.36/2mA=180ohm > RILC
I understand that this value is important for bus contention situations. but in which case "bus contention" can occur? Arbitration,?
Have you an idea to resolve my issue?
Best Regards.
Sylvain