The TRF2443 contains an integrated EEPROM that can easily be read from an external read-back pin (pin RDBKSPI, pin 64). The embedded EEPROM contains information measured and stored at RF final test that allows the user to optimize performance of the TRF2443. In order to ensure the integrity of the EEPROM contents, it is important that the user adhere to the correct power supply sequence. The pin VCCREF (pin 15) must be powered to 3.3 V at the same time or before pin VCCSPI (pin 75). If VCCSPI is powered before VCCREF, the contents of the EEPROM registers will be erased. For this reason, it is recommended that the user read the EEPROM contents once and store this data in memory outside of the TRF2443 for future use. The EEPROM SPI block (address < 00 >) has three 32-bit registers (Reg0, 1, 2). Register 1 and Register 2 contain the actual bit information stored in the EEPROM registers. These registers are READ ONLY. Register 0 is used to invoke a read-back operation of the information stored in the EEPROM registers 1 and 2 by specifying which register to read back. This register is a WRITE ONLY register.