Analog Devices Inc./Maxim Integrated DS80C320-QNL+T&R

Overview

DS80C320-QNL+T&R from Maxim Integrated is a high-speed, 80C32-compatible 8-bit microcontroller with 4-clock-per-machine-cycle architecture, 33MHz max crystal frequency, -40°C to +85°C industrial temperature range, and 44-pin PLCC package. It delivers ~2.5× average instruction speedup over standard 8051 while retaining full pin and instruction set compatibility - used in industrial control panels requiring deterministic real-time I/O and dual-serial communication.

For engineers reviewing the DS80C320-QNL+T&R datasheet, DS80C320-QNL+T&R pinout, DS80C320-QNL+T&R application, or DS80C320-QNL+T&R equivalent, key selection considerations include its dual hardware serial ports (UART0/UART1), programmable MOVX memory access stretch (2–9 cycles), dual data pointer (DPTR0/DPTR1), power-fail reset/interrupt, and watchdog timer - all operating within 4.25V–5.5V supply at extended temperature.

Technical Context

The DS80C320-QNL+T&R implements a redesigned 8051 core eliminating dummy clock cycles, executing most instructions in 4 oscillator clocks versus 12 in legacy 80C32. Its timer subsystem defaults to 12-clock mode on reset for backward timing compatibility but supports 4-clock operation via CKCON register bits for higher-resolution timing.

It integrates two independent full-duplex UARTs (UART0 on P3.0/P3.1; UART1 on P1.2/P1.3), seven external interrupt sources (INT2–INT5 added beyond standard INT0/INT1), and configurable off-chip data memory access timing via stretch value (CKCON.2–0) - enabling direct interfacing with both fast SRAM and slow peripherals like LCD controllers without glue logic.

Key Specifications

Pinout & Package

DS80C320-QNL+T&R is housed in a 44-pin Plastic Leaded Chip Carrier (PLCC) package with J-lead geometry, designed for socketed or surface-mount industrial PCBs requiring thermal and mechanical robustness across temperature cycling.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8051-compatible microcontroller applications.

Compared with DS80C320-QNL+T&R, DS80C320-QCL+ offers identical functionality at lower temperature grade and cost, while DS80C323-QND+ trades speed for wider voltage tolerance - neither is pin- or code-compatible drop-in replacements without validation of timing margins and power constraints.

Availability

DS80C320-QNL+T&R is available at Aetrix Electronics and suitable for industrial automation, smart metering, and factory gateway applications requiring stable component supply, long-term lifecycle support, and guaranteed extended-temperature performance.

Supply support for DS80C320-QNL+T&R includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and high-reliability microcontrollers for industrial, medical, and communications infrastructure.

The DS80C320-QNL+T&R belongs to Maxim's high-speed 8051-compatible microcontroller family, engineered to upgrade legacy 5V control systems with deterministic real-time performance, dual serial interfaces, and industrial-grade robustness - without requiring software rewrite or PCB redesign.

FAQ

What is the maximum crystal frequency supported by DS80C320-QNL+T&R?

The DS80C320-QNL+T&R supports a maximum crystal frequency of 33MHz, enabling an effective instruction execution rate of approximately 82.5MHz due to its 4-clock-per-machine-cycle architecture. This specification is validated across the full -40°C to +85°C operating temperature range and is explicitly listed in the Maxim ordering information table for the QNL variant.

Does DS80C320-QNL+T&R require external pull-up resistors on Port 0?

Yes, DS80C320-QNL+T&R requires external pull-up resistors on Port 0 (P0.0–P0.7) because it lacks internal port latches and functions as a true open-drain multiplexed address/data bus. The datasheet states Port 0 has "no true port latch" and cannot be written directly by software - external 4.7kΩ pull-ups are standard practice for reliable ALE-synchronized address latching and data read/write operations.

How does the dual data pointer (DPTR0/DPTR1) improve performance in DS80C320-QNL+T&R?

The dual data pointer in DS80C320-QNL+T&R reduces 64-byte RAM-to-RAM block moves from 1869 to 1097 machine cycles - a 41% reduction - by eliminating software address save/restore overhead. DPTR0 (SFR 82h/83h) and DPTR1 (84h/85h) are selected via DPS bit (86h), enabling single-instruction pointer switching during memory transfers - a measurable advantage confirmed in Maxim's application example code.

Is DS80C320-QNL+T&R pin-compatible with standard 80C32 microcontrollers?

Yes, DS80C320-QNL+T&R is fully pin-compatible with the standard 80C32 in the 44-pin PLCC package, including identical pin functions for P0–P3, RST, XTAL1/XTAL2, PSEN, ALE, EA, VCC, and GND. The datasheet explicitly states "pin compatible with all three packages of the standard 80C32" and confirms matching timer/counters, serial port, and I/O port placement - enabling drop-in replacement in existing designs.

What is the function of the EA pin on DS80C320-QNL+T&R, and how must it be connected?

The EA (External Access) pin on DS80C320-QNL+T&R must be hard-wired LOW to disable internal ROM and enable external program memory access - a mandatory configuration since the DS80C320 contains no on-chip ROM. The datasheet specifies "EA must be connected to ground for proper operation", and leaving it floating or HIGH will prevent program execution from external Flash or EPROM.