W968D6DA Datasheet, PDF (19/75 Pages) Winbond – Low-power features

W968D6DA
256Mb Async./Page,Syn./Burst CellularRAM
8.4 Registers
Two user-accessible configuration registers define the device operation. The bus configuration register (BCR)
defines how the CellularRAM interacts with the system memory bus and is nearly identical to its counterpart on burst
mode flash devices. The refresh configuration register (RCR) is used to control how refresh is performed on the
DRAM array. These registers are automatically loaded with default settings during power-up, and can be updated
any time the devices are operating in a standby state.
A DIDR provides information on the device manufacturer, CellularRAM generation, and the specific device
configuration. The DIDR is read-only.
8.4.1 Access Using CRE
The registers can be accessed using either a synchronous or an asynchronous operation when the control register
enable (CRE) input is HIGH. When CRE is LOW, a READ or WRITE operation will access the memory array. The
configuration register values are written via addresses A[max:0]. In an asynchronous WRITE, the values are latched
into the configuration register on the rising edge of ADV#, CE#, or WE#, whichever occurs first; LB# and UB# are
―don’t care.‖ The BCR is accessed when A[19:18] are 10b; the RCR is accessed when A[19:18] are 00b. The DIDR
is read when A[19:18] are 01b. For reads, address inputs other than A[19:18] are ―don’t care,‖ and register bits 15:0
are output on DQ[15:0]. Immediately after performing a configuration register READ or WRITE operation, reading the
memory array is highly recommended.
8.4.1.1 Configuration Register WRITE, Asynchronous Mode Followed by READ ARRAY Operation
A [ max : 0 ]
( except A [ 19 : 18 ] )
A [ 19 : 18 ] ¹
OPCODE
tAVS
Select Control Register
tAVH
Address
Address
CRE
ADV #
CE #
OE #
WE #
LB # / UB #
DQ [ 15:0 ]
tAVS
tAVH
tC RES
tVP
Initiate Control Register Access
tCW
tCPH
tWP
Write Address Bus Value
to Control Register
Note : 1. A[19:18]=00b to load RCR, and 10b to load BCR.
Data Valid
Don‟t Care
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Publication Release Date : June 27, 2013
Revision : A01-003