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STPC4HEBI Datasheet(PDF) 66 Page - STMicroelectronics |
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STPC4HEBI Datasheet(HTML) 66 Page - STMicroelectronics |
66 / 93 page ![]() DESIGN GUIDELINES 66/93 Release 1.5 - January 29, 2002 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) CS0# BA[1:0] MA[12:0] WE# RAS0# DQM[7:0] MCLKI MCLKO DQM[7:6] Reference Knot CAS0# MD[63:48] DQM[5:4] MD[47:32] DQM[3:2] MD[31:16] DQM[1:0] MD[15:0] MD[63:0] MCLKA MCLKB MCLKC MCLKD 10pF Length(MCLKI) = Length(MCLKy) with y = {A,B,C,D} |