I have an ultra low power application where the minimum VDD of my temperature sensor (ADT7420) is 2.7V, while I need to run my MCU at 2.4V. The circuit is powered from either a 3V coin cell or USB 5V [debug mode]. I have space for a single 2.4V regulator on board.
The temperature sensor interface is I2C and it also has an interrupt output that is connected to the MCU. Sensor supply min and max is 2.7V and 5.5V.
My question is:
SDA/SCL and the interrupt pins on the sensor are configured as open drain. Therefore, would I be OK if I used pull up resistors to 2.4V and connected the signals directly to the MCU? i.e., because the signals to be interfaced are open drain, I do not really need level shifters OR even current limiting resistors b/w the sensor and the MCU.