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Plasma TV Service Manual
05/01/2006
12.29.
SDRAM 4M x 16 (MT48LC4M16A2TG-75)
12.29.1. General Description
The Micron ® 64Mb SDRAM is a high-speed CMOS, dynamic random-access memory containing
67,108,864 bits. It is internally configured as a quad-bank DRAM with a synchronous interface (all
signals are registered on the positive edge of the clock signal, CLK). Each of the x4’s 16,777,216-bit
banks is organized as 4,096 rows by 1,024 columns by 4 bits. Each of the x8’s 16,777,216-bit banks is
organized as 4,096 rows by 512 columns by 8 bits. Each of the x16’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-A11 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 64Mb 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 64Mb SDRAM is designed to operate in 3.3V memory systems. An auto refresh mode is provided,
along with a power-saving, power-down mode. All inputs and outputs are LVTTL-compatible.
SDRAMs offer substantial advances in DRAM operating performance, including the ability to
synchronously burst data at a high data rate with automatic column-address generation, the ability to
interleave between internal banks in order to hide precharge time and the capability to randomly
change column addresses on each clock cycle during a burst access.
Summary of Contents for 17MB11
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