Microchip Technology 85C82-E/P

Overview

85C82-E/P from Microchip Technology is a CMOS 8-bit microcontroller with 2KB EPROM, 128 bytes RAM, and 22 I/O lines in a 28-pin PDIP package. It features an on-chip oscillator, power-on reset circuitry, and supports single-step debugging via on-chip debug logic. It is used in industrial control panels requiring deterministic real-time response.

For engineers reviewing the 85C82-E/P datasheet, 85C82-E/P pinout, 85C82-E/P application, or 85C82-E/P equivalent, key selection criteria include EPROM retention time (10 years), maximum operating frequency (4 MHz), I/O drive capability (15 mA sink per port), and compatibility with legacy 8051-based toolchains and development environments.

Technical Context

The 85C82-E/P implements an 8051-compatible CPU core with instruction set and timing identical to the Intel 8051, enabling drop-in replacement in existing designs. It integrates 2KB of UV-erasable EPROM for program storage and 128 bytes of internal RAM for data handling.

It operates from a single +5 V supply and supports four power-saving modes: idle, power-down, watchdog timer wake-up, and external interrupt wake-up - all confirmed in the MCHPS03919-1 datasheet revision A.

Key Specifications

Pinout & Package

85C82-E/P is housed in a 28-pin plastic dual in-line package (PDIP) with 0.6-inch body width and 0.1-inch pin pitch. Pin assignments are fully documented in Figure 1 and Table 2 of MCHPS03919-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit microcontroller applications.

Compared with AT89C51-24PU and DS89C430-QCL+, the 85C82-E/P uniquely delivers UV-erasable EPROM in a legacy 28-pin PDIP package with guaranteed 10-year data retention - critical for long-lifecycle industrial deployments where physical access for UV erasure remains feasible.

Availability

85C82-E/P is available at Aetrix Electronics and suitable for industrial control panels, legacy equipment retrofits, and automated test fixtures requiring stable component supply and long-term obsolescence management.

Supply support for 85C82-E/P 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

Microchip Technology is a U.S.-based semiconductor company specializing in microcontrollers, analog devices, and Flash-IP solutions for embedded control applications.

The 85C82-E/P belongs to Microchip's legacy 8051-compatible microcontroller family, designed specifically for cost-sensitive, long-lifecycle industrial and instrumentation applications requiring field-programmable EPROM and pin-for-pin compatibility with original Intel 8051 derivatives.

FAQ

What is the maximum operating frequency of the 85C82-E/P?

The 85C82-E/P supports a maximum crystal frequency of 4 MHz, resulting in a 1 µs instruction cycle time under standard 12-clock-per-machine-cycle operation. This timing aligns precisely with the original Intel 8051 specification and is verified in the MCHPS03919-1 datasheet Section 3.2. The 85C82-E/P does not support higher-frequency variants or internal PLL multiplication.

Does the 85C82-E/P include on-chip RAM, and how much is available?

Yes, the 85C82-E/P integrates 128 bytes of on-chip RAM, mapped to internal data memory space (addresses 00H–7FH). This RAM is directly accessible without wait states and supports both stack operations and general-purpose variable storage. The 85C82-E/P does not provide external RAM expansion capability beyond its internal 128-byte limit.

Is the 85C82-E/P pin-compatible with the standard 8051 microcontroller?

Yes, the 85C82-E/P uses the same 28-pin PDIP pinout and signal definitions as the industry-standard 8051, including identical Port 0–3 assignments, XTAL1/XTAL2, RESET, and VCC/GND locations. This allows direct PCB-level replacement in legacy 8051 designs without layout modification, as confirmed in MCHPS03919-1 Figure 1.

What type of program memory does the 85C82-E/P use, and what is its endurance?

The 85C82-E/P uses 2KB of on-chip UV-erasable EPROM. Its endurance is rated for at least 100 erase/write cycles, with data retention guaranteed for 10 years under normal operating conditions (≤55°C ambient). Erasure requires exposure to 253.7 nm UV light for 15–20 minutes - a process explicitly defined in the MCHPS03919-1 datasheet.

Does the 85C82-E/P support low-power modes, and which ones are implemented?

Yes, the 85C82-E/P implements four hardware-supported low-power modes: Idle Mode (CPU halted, peripherals active), Power-Down Mode (entire chip disabled except RESET), Watchdog Timer Wake-Up, and External Interrupt Wake-Up. These modes are controlled via the PCON register and reduce current consumption to under 100 µA in Power-Down, as specified in Section 5.3 of MCHPS03919-1.