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White Electronic Designs Corporation (602) 437-1520 www.whiteedc.com
White Electronic Designs
WEDPN4M64V-XBX
January 2005
Rev. 8
White Electronic Designs Corp. reserves the right to change products or specications without notice.
GENERAL DESCRIPTION
The 32MByte (256Mb) SDRAM is a high-speed CMOS,
dynamic random-access ,memory using 4 chips containing
67,108,864 bits. Each chip is internally congured as a
quad-bank DRAM with a synchronous interface. Each of the
chip’s 16,777,216-bit banks is organized as 4,096 rows by
256 columns by 16 bits.
Read and write accesses to the SDRAM are burst oriented;
accesses start at a selected location and continue for
a programmed number of locations in a programmed
sequence. Accesses begin with the registration of an ACTIVE
command, which is then followed by a READ or WRITE
command. The address bits registered coincident with the
ACTIVE command are used to select the bank and row to
be accessed (BA0, BA1 select the bank; A0-11 select the
row). The address bits registered coincident with the READ
or WRITE command are used to select the starting column
location for the burst access.
The SDRAM provides for programmable READ or WRITE
burst lengths of 1, 2, 4 or 8 locations, or the full page, with
a burst terminate option. An AUTO PRECHARGE function
may be enabled to provide a self-timed row precharge that
is initiated at the end of the burst sequence.
The 256Mb SDRAM uses an internal pipelined architecture to
achieve high-speed operation. This architecture is compatible
with the 2n rule of prefetch architectures, but it also allows
the column address to be changed on every clock cycle to
achieve a high-speed, fully random access. Precharging one
bank while accessing one of the other three banks will hide
the precharge cycles and provide seamless, high-speed,
random-access operation.
The 256Mb SDRAM is designed to operate in 3.3V, low-
power memory systems. An auto refresh mode is provided,
along with a power-saving, power-down mode.
4Mx64 Synchronous DRAM
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Discrete Approach
S
A
V
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Area
4 x 265mm2 = 1061mm2
441mm2
58%
ACTUAL SIZE
22.3
11.9
54
TSOP
54
TSOP
54
TSOP
54
TSOP
WEDPN4M64V-XBX
FEATURES
High Frequency = 100, 125, 133MHz
Package:
219 Plastic Ball Grid Array (PBGA), 21 x 21mm
Single 3.3V ±0.3V power supply
Fully Synchronous; all signals registered on positive
edge of system clock cycle
Internal pipelined operation; column address can be
changed every clock cycle
Internal banks for hiding row access/precharge
Programmable Burst length 1,2,4,8 or full page
4096 refresh cycles
Commercial, Industrial and Military Temperature
Ranges
Organized as 4M x 64
User Congurable as 2x4Mx32 or 4x4Mx16
Weight: WEDPN4M64V-XBX - 2 grams typical
BENEFITS
58% SPACE SAVINGS
Reduced part count
Reduced trace lengths for lower parasitic
capacitance
Laminate interposer for optimum TCE match
Suitable for hi-reliability applications
Upgradeable to 8M x 64 (contact factory for
availability)
*This product is subject to change without notice.