emc646sp16ak Emlsi Inc., emc646sp16ak Datasheet - Page 16

• Manufacturer Part Number: emc646sp16ak
• Description: 4mx16 Bit Cellularram
• Manufacturer: Emlsi Inc.

EMC646SP16AK
4Mx16 CellularRAM
Low-Power Operation
Standby Mode Operation
During standby, the device current consumption is reduced to the level necessary to perform the DRAM refresh operation. Standby
operation occurs when CE# is HIGH. The device will enter a reduced power state upon completion of a READ or WRITE operation, or
when the address and control inputs remain static for an extended period of time. This mode will continue until a change occurs to the
address or control inputs.
Temperature Compensated Refresh
Temperature compensated refresh (TCR) allows for adequate refresh at different temperatures. This CellularRAM device includes an
on-chip temperature sensor that automatically adjusts the refresh rate according to the operating temperature. The device continually
adjusts the refresh rate to match that temperature.
Partial Array Refresh
Partial array refresh (PAR) restricts refresh operation to a portion of the total memory array. This feature enables the device to reduce
standby current by refreshing only that part of the memory array required by the host system. The refresh options are full array, one-
half array, one-quarter array, one-eighth array, or none of the array. The mapping of these partitions can start at either the beginning or
the end of the address map. (See Table 7 on page 28) READ and WRITE operations to address ranges receiving refresh will not be
affected. Data stored in addresses not receiving refresh will become corrupted. When re-enabling additional portions of the array, the
new portions are available immediately upon writing to the RCR.
Deep Power-Down Operation
Deep power-down (DPD) operation disables all refresh-related activity. This mode is used if the system does not require the storage
provided by the CellularRAM device. Any stored data will become corrupted when DPD is enabled. When refresh activity has been re-
enabled, the CellularRAM device will require 150µs to perform an initialization procedure before normal operations can resume.
During this 150µs period, the current consumption will be higher than the specified standby levels, but considerably lower than the
active current specification. DPD can be enabled by writing to the RCR using CRE or the software access sequence; DPD starts when
CE# goes HIGH. DPD is disabled the next time CE# goes LOW and stays LOW for at least 10µs.
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