DESIGN GUIDELINES
6.3.3. SDRAM
The STPC provides all the signals for SDRAM
control. Up to 128 MBytes of main memory are
supported. All Banks must be 64 bits wide. Up to 4
memory banks are available when using 16Mbit
devices. Only up to 2 banks can be connected
when using 64Mbit and 128Mbit components due
to the reallocation of CS2# and CS3# signals. This
is described in Table 6-4 and Table 6-5.
Graphics memory resides at the beginning of
Bank 0. Host memory begins at the top of graphics
memory and extends to the top of populated
SDRAM. Bank 0 must always be populated.
Figure 6-4, Figure 6-5 and Figure 6-6 show some
typical implementations.
The purpose of the serial resistors is to reduce
signal oscillation and EMI by filtering line
reflections. The capacitance in Figure 6-4 has a
filtering effect too, while it is used for propagation
delay compensation in the 2 other figures.
Figure 6-4. One Memory Bank with 4 Chips (16-bit)
MCLKI
Length(MCLKI) = Length(MCLKy) with y = {A,B,C,D}
MCLKO
10pF
CS0#
MA[12:0]
BA[1:0]
RAS0#
CAS0#
WE#
DQM[7:0]
MD[63:0]
Reference Knot
MCLKD
MCLKC
MCLKB
MCLKA
DQM[7:6]
MD[63:48]
DQM[5:4]
MD[47:32]
DQM[3:2]
MD[31:16]
DQM[1:0]
MD[15:0]
62/87
Release 1.3 - January 29, 2002
This is preliminary information on a new product now in development or undergoing evaluation. Details are subject to change without notice.