MC68882RC50A - 50MHz IEEE-754 FPU Coprocessor | Motorola PGA
MPN： MC68882RC50A ✗ 停產MC68882RC50A 概覽
A floating-point unit (FPU) is a specialized processor that executes floating-point arithmetic independently of the main CPU. Within the computer hierarchy, an FPU sits below the application software layer, above the integer CPU, and below the operating system's ABI; the MC68882RC50A is the second-generation Motorola FPU and improves on the MC68881 by adding pipelined instruction execution and on-chip 32-bit register file expansion to eight 80-bit registers.
Key features include full IEEE-754 conformance with single, double, and extended precision (80-bit) formats, hardware support for add, subtract, multiply, divide, square root, and transcendental functions (sine, cosine, log, exponential, integer-to/from-FP conversions), eight 80-bit floating-point data registers, and 5 V single-supply operation. Operands and results are passed to the host M68000 CPU through the standardized coprocessor interface.
Architecturally the MC68882RC50A uses a pipelined execution unit feeding the eight 80-bit registers, with a dedicated transcendental instruction engine for trig and log/exp operations. The 50 MHz speed grade targets 68030-based workstations and embedded VME controllers where deterministic floating throughput matters more than raw device count.
Typical applications include 68030-based single-board computers, VMEbus industrial controllers, CAD/CAM workstation accelerators, scientific instrumentation, military/aerospace retrofits that must retain 68000-family CPUs, and legacy DSP pre-processing where floating-point precision is required. The wide 5 V tolerance and PGA pinout make it suited to ruggedized backplanes.
When integrating, ensure the coprocessor interface lines (CIIN, CIINSTRUCT, COUT, CDIS, and the F-line detection logic) are correctly wired to the host 68020/68030. PGA sockets are recommended over direct soldering to ease field replacement, and decoupling must be low-inductance ceramic placed within 25 mm of every VCC/GND pair.
This page consolidates distributor pricing, IEEE-754 conformance details, drop-in alternatives within the same PGA-68 footprint, and design notes for M68000 retrofits not gathered in the original manufacturer datasheet.
直接替換替代品，適用於 MC68882RC50A — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： MC68882RC50A （相同外形與佔位） — 差異在於 Mounting Type, Supply Voltage, Process Technology, RoHS Status, Floating-Point Registers.
MC68882RC33A
✅ 直接替換聯絡詢價
查看資料表 →MC68882RC25A
✅ 直接替換聯絡詢價
查看資料表 →MC68882RC20A
✅ 直接替換聯絡詢價
查看資料表 →MC68882RC16A
✅ 直接替換聯絡詢價
查看資料表 →MC68882RC50A 最大額定值與電氣特性
| Processor Type | Floating-Point Coprocessor |
| Operating Frequency | 50 MHz |
| 供應電壓 | 5 V |
| 封裝 / 外殼 | 68-BCPGA (26.92 x 26.92 mm) |
| 腳位數 | 68 |
| Floating-Point Standard | ANSI / IEEE 754-1985 |
| Supported Formats | Single, Double, Extended Precision (80-bit) |
| Floating-Point Registers | 8 x 80-bit |
| Host CPU Interface | M68000 Coprocessor Interface (68020 / 68030) |
| Instruction Set | Add, Subtract, Multiply, Divide, Square Root, Sin, Cos, Log, Exp, FP-Integer Convert |
| 安裝類型 | Through-Hole (PGA socket recommended) |
| Packaging | Tray |
| Lead Free Status | Lead Free |
| RoHS 狀態 | RoHS Compliant |
MC68882RC50A 68-bcpga (26.92 x 26.92 mm) 腳位配置指南
MC68882RC50A（68-bcpga (26.92 x 26.92 mm) 封裝）的腳位配置。 此數位 IC 包含 GPIO、通訊介面（UART、SPI、I2C）與電源腳位。替代腳位功能與配置選項請參閱製造商資料表。對嵌入式系統設計與 PCB 佈局至關重要。
無詳細腳位定義資料： MC68882RC50A.
請參閱 資料表 以查看完整腳位配置。
典型應用
MC68882RC50A 適用於 7 應用s: 68030-Based Single-Board Computer Acceleration, VMEbus Industrial Controller Floating Point, CAD/CAM Workstation Coprocessor Upgrade, Scientific Instrumentation and Data Acquisition, Military and Aerospace Retrofit Systems, Legacy DSP Pre-Processing Front-End, Educational and Emulator Platforms.
68030-Based Single-Board Computer Acceleration
The MC68882RC50A's 50 MHz clock and pipelined IEEE-754 execution make it a direct performance multiplier for 68030 single-board computers used in industrial and avionics retrofits. It pairs with the 68030 over the M68000 coprocessor bus and offloads all floating-point operations including transcendental sin/cos/log/exp calls. The eight 80-bit registers preserve extended precision across chained operations, eliminating intermediate rounding that previously degraded sensor-fusion accuracy. The 5 V supply and ceramic PGA (26.92 x 26.92 mm) suit the wide-temperature, ruggedized backplanes common in legacy defense systems. Through-hole PGA socket mounting is recommended so field-returned boards can be reworked without unsoldering the FPU.
推薦
VMEbus Industrial Controller Floating Point
Many VME-based industrial controllers still run 68030 + MC68882RC50A combinations as floating-point engines for motion-control and SCADA algorithms. The FPU's hardware sine and cosine paths simplify multi-axis inverse-kinematics and PID code, freeing the integer CPU for I/O scanning. Five-volt tolerance tolerates the older unregulated backplane rails common in VME chassis, and the 68-pin PGA footprint is well-supported by mil-spec socket vendors for shock and vibration compliance. Designers should pair the FPU with the same 5 V regulator as the host CPU and place low-inductance ceramic decoupling within 25 mm of every VCC/GND pin pair.
推薦
CAD/CAM Workstation Coprocessor Upgrade
Sun-3, Apollo, and HP 9000/300 workstations accelerated 3D geometry transformations and shading math with the MC68882RC50A in their 68030 socket. The hardware float pipeline lets the workstation render wireframe rotation in tens of milliseconds where software emulation required seconds. Extended precision (80-bit) registers maintain numerical stability for matrix inversions across many frames. Although these systems are long obsolete, hobbyists and museum restorations still order the part to keep functional hardware alive. Designers building new FPU-equipped boards should follow the MC68882 user's manual reference design and verify PGA-socket keying to prevent backward insertion.
推薦
Scientific Instrumentation and Data Acquisition
The MC68882RC50A's hardware transcendental functions and 80-bit precision suit scientific data-acquisition front-ends that perform spectral analysis, FFT preprocessing, and coordinate transforms on instrument data. The dedicated sin/cos paths let the host 68030 keep acquisition interrupts serviced while the FPU runs NCO calculations in parallel. This deterministic dual-tasking model is why the 68882 survives in some modern nuclear-medicine and seismic-imaging test rigs that must reproduce original signal-processing behavior bit-for-bit. The 5 V supply and through-hole PGA format also tolerate conformal coating and other harsh-environment finishes.
推薦
Military and Aerospace Retrofit Systems
The MC68882RC50A remains specified on several military and aerospace bills of materials for legacy avionics, sonar, and radar-display subsystems that must continue operating unchanged for decades. The ceramic PGA package operates reliably across the wide temperature ranges required by DO-160 and MIL-STD-810 profiles, and the pin-compatible 33 MHz / 25 MHz / 16 MHz variants let mission-critical systems trade throughput for additional thermal margin in sealed enclosures. Procurement teams should engage Rochester Electronics directly for traceable, tested lots with full documentation. The 68882's obsolescence drove mission-system architects to migrate toward 68040 or PowerPC in new designs, while preserving the 68882 in fielded platforms.
推薦
Legacy DSP Pre-Processing Front-End
Pre-DSP floating-point work such as biquad filtering, beamforming, and Kalman state prediction still runs on 68030 + MC68882RC50A pairs in legacy sonar and direction-finding stations. The 80-bit extended precision prevents accumulated error in feedback loops where the same variables are updated tens of thousands of times per second. Designers retain the MC68882RC50A because it is well-documented, second-sourced through Rochester Electronics, and supported by long-standing M68000 toolchains that meet DO-178C verification objectives. Engineers updating such systems should budget for PGA socket inspection and consider the lower-speed RC33A drop-in part as a thermally-safer substitute.
推薦
Educational and Emulator Platforms
Retro-computing enthusiasts and computer-architecture courses still drop the MC68882RC50A into emulator boards such as the TS68k or Musashi-prototype PCBs to demonstrate 68030 + FPU behavior authentic to the era. The full IEEE-754 implementation plus the eight 80-bit registers make it the most accurate floating-point teaching reference available for the M68000 family. Hobbyists can drop in the MC68882RC33A inexpensively to study the same instruction set at lower clock speed. Site MPN candidates like the MAX174AEPI are unrelated analog ICs and are not appropriate companions; use authentic Motorola parts to keep the historical signal path intact.
推薦
推薦產品摘要
工程參考資料，適用於 MC68882RC50A — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | MC68882RC33A | MC68882RC25A | MC68882RC20A | MC68882RC16A | MC68882FN16A |
|---|---|---|---|---|---|---|
| Brand | Motorola | Motorola | Motorola | Motorola | Motorola | Motorola |
| Package | 68-BCPGA (26.92 x 26.92 mm) | 68-BCPGA (26.92 x 26.92 mm) - same | 68-BCPGA (26.92 x 26.92 mm) - same | 68-BCPGA (26.92 x 26.92 mm) - same | 68-BCPGA (26.92 x 26.92 mm) - same | 68-PLCC (FN) - NOT same package, PCB rework required |
| Operating Frequency | 50 MHz | 33 MHz (-34%) | 25 MHz (-50%) | 20 MHz (-60%) | 16 MHz (-68%) | 16 MHz (-68%) |
| Supply Voltage | 5 V | 5 V | 5 V | 5 V | 5 V | 5 V |
| Floating-Point Standard | ANSI / IEEE 754-1985 | ANSI / IEEE 754-1985 | ANSI / IEEE 754-1985 | ANSI / IEEE 754-1985 | ANSI / IEEE 754-1985 | ANSI / IEEE 754-1985 |
| Floating-Point Registers | 8 x 80-bit | 8 x 80-bit | 8 x 80-bit | 8 x 80-bit | 8 x 80-bit | 8 x 80-bit |
| Transcendental Support | Yes (sin, cos, log, exp) | Yes | Yes | Yes | Yes | Yes |
| Host CPU | 68020 / 68030 | 68020 / 68030 | 68020 / 68030 | 68020 / 68030 | 68020 / 68030 | 68020 / 68030 |
| Mounting Type | Through-Hole PGA | Through-Hole PGA | Through-Hole PGA | Through-Hole PGA | Through-Hole PGA | Surface-Mount PLCC |
| Lifecycle Status (2026) | Obsolete (NOS only) | Obsolete (NOS only) | Obsolete (NOS only) | Obsolete (NOS only) | Obsolete (NOS only) | Obsolete (NOS only) |
主要差異化特點
- Highest speed grade in the MC68882 PGA family (對比MC68882RC33A)
- Ceramic PGA package rated for harsh environments (對比MC68882FN16A (PLCC))
- Drop-in for legacy 68020/68030 boards with field socket (對比MC68040 on-chip FPU)
設計說明
Mount the MC68882RC50A in a high-quality PGA socket (e.g. Yamaichi IC181 or 3M Textool) to enable field replacement. Direct soldering of ceramic PGA is discouraged because reworks destroy the substrate. Place a 0.1 uF X7R ceramic decoupling capacitor within 25 mm of every VCC/GND pair, and add a 10 uF tantalum bulk capacitor on each supply rail. Keep the coprocessor bus lines (CIIN, CIINSTRUCT, COUT, CDIS) under 50 mm total trace length with a 50 ohm characteristic impedance to match the 68020/68030 coprocessor interface timing.
The MC68882RC50A requires a tightly regulated 5 V supply capable of sourcing up to 600 mA peak during transcendental operations. Estimated: at 50 MHz and continuous FPU pipeline use, average dissipation is approximately 1.0-1.2 W. Use a linear regulator with sub-100 mV load-step response, or pair a switching pre-regulator with an LDO post-regulator, to avoid supply droop that would otherwise force the FPU to retry and degrade numerical determinism.
Do not confuse the RC (PGA, ceramic) suffix with the FN (PLCC, plastic) suffix - they are NOT pin-compatible and require different board layouts. The MC68882RC50A's F-line decoding must be wired so that illegal coprocessor instructions on the host 68020/68030 trap cleanly rather than hanging the bus. PGA pin-1 location differs from PLCC pin-1; double-check the printed silkscreen before insertion. Finally, the MC68882 needs the host CPU's reset line properly synchronized - hold the FPU in reset for at least 10 host clock cycles after power stable.
Estimated: at maximum throughput the MC68882RC50A dissipates approximately 1.0-1.2 W into its ceramic PGA substrate, which has a typical theta_JA around 25-30 C/W in still air. In a sealed enclosure, additional forced airflow or a thermally-conductive PGA socket clamp is advised. Hot-spot monitoring is impractical without test pads, so derive junction temperature from ambient plus the dissipation estimate and plan for no more than 70 C ambient in mission-critical deployments.
合規資訊
Lead Free and RoHS Compliant per distributor listings as of 2026-10-16. REACH, halogen-free, and conflict-mineral declarations are not consistently published for this legacy discontinued part; consult Rochester Electronics for authoritative compliance documentation.
