DP8409AN National Semiconductor, DP8409AN Datasheet - Page 4

• Manufacturer Part Number: DP8409AN
• Description: IC CONTROLLER DYNAMIC RAM 48-DIP
• Manufacturer: National Semiconductor

Specifications of DP8409AN

• Controller Type: Dynamic RAM (DRAM) Controller, Drivers
• Voltage - Supply: 4.75 V ~ 5.25 V
• Current - Supply: 250mA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Through Hole
• Package / Case: 48-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Interface: -
• Other names: *DP8409AN

Conditions for All Modes
DP8409A DRIVING ANY 16k OR 64k DRAMs
The DP8409A can drive any 16k or 64k DRAMs All 16k
DRAMs are basically the same configuration including the
newer 5V-only version Hence in most applications differ-
ent manufacturers’ DRAMs are interchangeable (for the
same supply-rail chips) and the DP8409A can drive all 16k
DRAMs (see Figure 1a )
There are three basic configurations for the 5V-only 64k
DRAMs a 128-row by 512-column array with an on-RAM
refresh counter a 128-row by 512-column array with no on-
RAM refresh counter and a 256-row by 256-column array
FIGURE 1b DP8409A with 128 Row x 512 Column 64k DRAM
FIGURE 1c DP8409A with 256 x 256 Column 64k DRAM
DP8409A Interface between System and DRAM Banks
FIGURE 1a DP8409A with any 16k DRAMs
(Continued)
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with no on-RAM refresh counter The DP8409A can drive all
three configurations and at the same time allows them all to
be interchangeable (as shown in Figures 1b and 1c ) provid-
ing maximum flexibility in the choice of DRAMs Since the
9-bit on-chip refresh counter can be used as a 7-bit refresh
counter for the 128-row configuration or as an 8-bit refresh
counter for the 256-row configuration the on-RAM refresh
counter (if present) is never used As long as 128 rows are
refreshed every 2 ms (i e 256 rows in 4 ms) all DRAM types
are correctly refreshed
TL F 8409– 6
TL F 8409– 7
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