Toshiba 4560 Service Manual page 316

18.11.6 EEPROM circuit
This circuit is the EEPROM and peripheral circuit. It is used for storing data of each of the ADFs.
This EEPROM is memory for storing adjustment values (e.g. reflective sensor sensitivity data or set
position data on the copy glass) and counter values (e.g. number of discharged sheets). Data manipula-
tion with the CPU is carried out on the 3-lead serial interface. Once data is stored to EEPROM, it is held
in memory and does not disappear even if the power is turned OFF.
IC7 pin 1 is the chip select terminal, and is H-level during data manipulation.
IC7 pin 2 is the serial clock terminal. Serial data is transmitted synchronized with the clock input to this
terminal.
IC7 pin 3 is the serial data input terminal, and pin 4 is the serial data output terminal.
D6, R60 and C31 comprise the circuit for holding the power of IC7 until writing ends even if something
causes the power voltage to drop during writing of data.
4560/4570 RADF 18 - 58 Nov. 1997 © TOSHIBA