R1EX25512ASA00I_15 Datasheet, PDF (18/22 Pages) Renesas Technology Corp – Serial Peripheral Interface 512K EEPROM (64-Kword × 8-bit)

R1EX25512ASA00I/R1EX25512ATA00I
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
C
HOLD
HOLD status
HOLD status
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 rate should be slower than 2 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).
• When setting the chip select signal (S) to the low level at power on, wait for 10 ms or longer after the supply
voltage 1.8V.
1.8V
(Vccmin)
Vcc
S
10ms min
R10DS0044EJ0100 Rev.1.00
Oct.04, 2010
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