CY14MB064Q1B Datasheet, PDF (8/28 Pages) Cypress Semiconductor – 64-Kbit (8 K × 8) SPI nvSRAM

CY14MB064Q1B/CY14MB064Q2B
PRELIMINARY _{CY14ME064Q1B/CY14ME064Q2B}
SPI Operating Features
Power-Up
Power-up is defined as the condition when the power supply is
turned on and V_CC crosses V_switch voltage.
As described earlier, at power-up nvSRAM performs a Power-Up
RECALL operation for t_FA duration during which, all memory
accesses are disabled.
The following are the device status after power-up.
■ Selected (Active power mode) if CS pin is LOW
■ Deselected (Standby power mode) if CS pin is HIGH
■ Not in the Hold condition
■ Status Register state:
❐ Write Enable (WEN) bit is reset to ‘0’.
❐ WPEN, BP1, BP0 unchanged from previous STORE
operation.
The WPEN, BP1, and BP0 bits of the Status Register are
non-volatile bits and remain unchanged from the previous
STORE operation.
Power-Down
At power-down (continuous decay of V_CC), when V_CC drops from
the normal operating voltage and below the V_SWITCH threshold
voltage, the device stops responding to any instruction sent to it.
If a write cycle is in progress and the last data bit D0 has been
received when the power goes down, it is allowed t_DELAY time to
complete the write. After this, all memory accesses are inhibited
and a conditional AutoStore operation is performed (AutoStore is
not performed if no writes have happened since the last RECALL
cycle). This feature prevents inadvertent writes to nvSRAM from
happening during power-down.
However, to completely avoid the possibility of inadvertent writes
during power-down, ensure that the device is deselected and is
in standby power mode, and the CS follows the voltage applied
on V_CC.
Active Power and Standby Power Modes
When CS is LOW, the device is selected and is in the active
power mode. The device consumes I_CC current, as specified in
DC Electrical Characteristics on page 18. When CS is HIGH, the
device is deselected and the device goes into the standby power
mode after t_SB time if a STORE or RECALL cycle is not in
progress. If a STORE/RECALL cycle is in progress, the device
goes into the standby power mode after the STORE or RECALL
cycle is completed. In the standby power mode, the current
drawn by the device drops to I_SB.
Document Number: 001-70382 Rev. *E
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