Question:
We have 1.6Kohms resistor on I2C Bus. I wanted to know about the maximum rated current for SCL and SDA internal FETs. What is the worst case current? There is no specific information on this in datasheet.
In our design, pullup are connected with 4V supply. Hence, I can estimate current flowing through internal FETs as 4V / 1.6Kohms = 2.5mA (Will flow through the SDA/SCL internal FETs when it is driving logic low on I2C Bus)
Can I consider the minimum pullup resistor of Kohms. If so, can I assume internal FETs will guarantee 4V / 1Kohm = 4mA of current maximum through it? Or will I need to use a 3.3V supply with 1Kohm pullup resistors? Therefore, maximum current through internal FETs can be maximum up to 3.3V / 1Kohms = 3.3mA ?
Answer:
3mA to 4mA is well within rated limits. The SCL and SDA internal FETs in the MAX20094 can handle up to 30mA.