R1EX25032ASA00I Datasheet, PDF (18/22 Pages) Renesas Technology Corp – Serial Peripheral Interface Electrically Erasable and Programmable Read Only Memory

R1EX25032Axx00I/R1EX25064Axx00I
Hold Condition
The hold (HOLD) signal is used to pause any serial communications with the device without resetting the clocking
sequence.
During the hold condition, the serial data output (Q) is high impedance, and serial data input (D) and serial clock (C)
are don’t care.
To enter the hold condition, the device must be selected, with chip select (S) low.
Normally, the device is kept selected, for the whole duration of the hold condition. Deselecting the device while it is in
the hold condition, has the effect of resetting the state of the device, and this mechanism can be used if it is required to
reset any processes that had been in progress.
The hold condition starts when the hold (HOLD) signal is driven low at the same time as serial clock (C) already being
low (as shown in the following figure).
The hold condition ends when the hold (HOLD) signal is driven high at the same time as serial clock (C) already being
low.
The following figure also shows what happens if the rising and falling edges are not timed to coincide with serial clock
(C) being low.
Hold Condition Activation
HOLD status
HOLD status
C
HOLD
Notes
Data Protection at V_CC On/Off
When V_CC is turned on or off, noise on S inputs generated by external circuits (CPU, etc) may act as a trigger and turn
the EEPROM to unintentional program mode. To prevent this unintentional programming, this EEPROM have a power
on reset function. Be careful of the notices described below in order for the power on reset function to operate
correctly.
• S should be fixed to V_CC during V_CC on/off. Low to high or high to low transition during V_CC on/off may
cause the trigger for the unintentional programming.
• V_CC should be turned on/off after the EEPROM is placed in a standby state.
• V_CC should be turned on from the ground level (V_SS) in order for the EEPROM not to enter the unintentional
programming mode.
• V_CC turn on speed should be slower than 10 µs/V.
• When WRSR or WRITE instruction is executed before V_CC turns off, V_CC should be turned off after waiting
write cycle time (t_W).
REJ03C0362-0001. Rev.0.01 Feb.21.2008
page 18 of 20