ADV476KN70

Digital To Analog Converters Overview

The ADV476KN70 is an obsolete CMOS monolithic RAM-DAC designed for VGA and Personal System/2 color graphics. It integrates a 256x18-bit color palette RAM, a pixel mask register, and three 6-bit video DACs on a single chip. The device supports pipelined operation at clock rates of 35 MHz, 50 MHz, or 66 MHz, enabling simultaneous display of up to 256 colors from a 262,144-color palette. It features RS-343A/RS-170 compatible analog outputs without external buffering and includes an asynchronous MPU interface for independent access to internal registers. Packaged in a 28-pin DIP (N-28), it operates on a +5 V supply with low power dissipation.

Digital To Analog Converters Feature Summary

• Integrated 256x18 Color Palette RAM and Triple 6-Bit Video DACs
• Pipelined Operation Supporting 35 MHz, 50 MHz, and 66 MHz Clock Rates
• Asynchronous MPU Interface for Independent Register Access
• Pixel Read Mask Register for On-Chip Pixel Processing

Digital To Analog Converters Applications

• High Resolution Color Graphics Systems
• CAE/CAD/CAM Applications
• Image Processing Equipment
• Desktop Publishing Hardware

Digital To Analog Converters Procurement Notes

This component is officially classified as Obsolete by Analog Devices Inc. Verification of availability requires checking distributor archives for remaining stock or secondary market sources. No new production units are manufactured. Designers should confirm the specific speed grade suffix (e.g., KN35, KN50, KN66) matches system timing requirements when sourcing legacy inventory.

Digital To Analog Converters Selection Notes

Select the appropriate speed variant based on the system clock: ADV476KN35 (35 MHz), ADV476KN50 (50 MHz), or ADV476KN66 (66 MHz). The 'KN' prefix indicates the 28-pin plastic DIP package. Ensure the design accommodates the required IREF current (typically 8.88 mA for RS-343A levels) and provides adequate decoupling for the +5 V supply to maintain signal integrity at high clock frequencies.

Digital To Analog Converters Part Context

The ADV476 series serves as a pin-compatible and software-compatible replacement for INMOS 171/176 devices. It is part of the ADV47x family of video RAM-DACs, sharing functional similarities with the ADV478 and ADV471. The device was engineered to provide complete analog output functionality on a single monolithic chip, reducing board space and component count for VGA-era graphics controllers.

Digital To Analog Converters Replacement Considerations

Publicly confirmed direct substitute part numbers are not available in the provided documentation due to the obsolete status. Designers should evaluate modern FPGA-based solutions or newer generation RAM-DACs from Analog Devices or other manufacturers that support VGA timings with updated packaging and process technologies.