DP8422AV-20

Controllers Overview

The DP8422AV-20 is a microCMOS programmable dynamic RAM controller and driver designed for 256k, 1M, and 4M DRAMs. It provides a single-chip interface between DRAM and 8-, 16-, or 32-bit systems. The device features dual access ports (Port A and Port B) with on-chip arbitration to simplify dual-accessing scenarios. It generates all required access control signal timing, including an on-chip refresh request clock for automatic array refresh. High capacitance drivers support RAS, CAS, WE, and DRAM address lines. The controller supports byte writing, memory interleaving, and address pipelining.

Controllers Feature Summary

• Dual access ports with on-chip arbitration for simplified multi-CPU memory access
• On-chip high precision delay line ensuring critical DRAM timing parameters
• Programmable RAS and CAS configuration supporting byte writing without external logic
• Integrated refresh request clock and arbitration logic for automatic DRAM maintenance

Controllers Applications

• Interface between dynamic RAM and 8-bit system buses
• Interface between dynamic RAM and 16-bit system buses
• Interface between dynamic RAM and 32-bit system buses
• Dual-port memory systems requiring concurrent CPU access

Controllers Procurement Notes

Verify the component status as obsolete in current catalogs. Confirm package compatibility with legacy designs using the specified pinout. Ensure programming methods align with existing system reset and initialization sequences. Check for availability of equivalent replacement controllers if new production is planned.

Controllers Selection Notes

Select this controller for applications requiring dual-port access to DRAM arrays up to 64 Mbytes. It is suitable for systems needing programmable wait states and flexible refresh modes. Consider its microCMOS process for low power requirements. Evaluate the need for specific RAS/CAS configurations and byte enable features during design.

Controllers Part Context

The DP8422A is part of the DP8420A/21A/22A family of microCMOS programmable DRAM controllers. While the DP8420A and DP8421A offer single access ports, the DP8422A uniquely provides two access ports (A and B). This family supports various DRAM capacities and interfaces with major microprocessors through programmable signals.

Controllers Replacement Considerations

Public confirmed substitute part numbers are not available in the provided documentation.