5 I2C Interface
The I2C interface uses the SDA and SCL pins to indicate various I/O states to the ECC608-TNGHNT. This interface is designed to be compatible at the protocol level with the Microchip AT24C16 Serial EEPROM operating at 1 MHz.
Note: There are many differences between the two devices (for
example, the ECC608-TNGHNT and AT24C16 have different default
I2C addresses); therefore, designers must read the respective data sheets
carefully.
The SDA pin is normally pulled high with an external pull-up resistor because the ECC608-TNGHNT client includes only an open-drain driver on its output pin. The bus host may either be open-drain or totem pole. In the latter case, it must be tri-stated when the ECC608-TNGHNT is driving results on the bus. The SCL pin is an input and must be driven both high and low at all times by an external device or resistor.
Remember: The I2C
standard uses the terminology “Master” and “Slave”. The equivalent Microchip terminology
used in this document is “Host” and “Client”, respectively.