I am trying to do a power analysis of an IC. It is an I2C isolator. Now, there are 2 I2C buses (hence bidirectional). I want to analyse the effects of its working on the temperature. The ambient temp is 25Degrees celcius.
Now, I am connecting it between an MCU and a temp sensor (for eg).
The current rating is as shown below -
Now, this IC is being run at 3.3V Vcc.The Iol1 and Iol2 are the current that is supplied from the source .
MCU <---> I2C1 <----> Isolator <----> I2C2 <----> Sensor.
So, the current sourced by the Iol1/2 as 3.5mAmps is nothing but the current sourced/sunk by the MCU/sensor. Now, suppose the data is coming via the SDA line from the MCU. Then probably the MCU sends a very low current. The I2C ASIC then sends a max of 3.5mAmps to the sensor, right ?
Now, the logic high is 3.3, which implies Power = 3.3*0.0035 =11mW. This is for the data lines. Likewise for clock. So merely doubling it would give me the power consumption of the said IC.
But, then a small current is needed for the IC to work. Provide power to the logic inside. How much is that ? Is it not the quiscent current ? That info is not given.
Now, I want to calculate the temperature aspect. Now, Vout =3.3 and I = 3.5mAmps.
Power = 11mW per pin (SDA). Power total = 22mW (power and clock).
Theta-ja = 117C/W.
Temperature = 0.022*117 = 2.577 Degrees C.
The temp of the IC = 25(ambient) + 2.5 = approx 27.5 Degrees Celcius.
Is my analysis accurate ?