MC68882RC25A - 25MHz FPU Coprocessor | Motorola | PGA-68
MPN： MC68882RC25A ⚠ 最後購買機會MC68882RC25A 概覽
A floating-point coprocessor is a specialized processor that offloads scalar and vector numeric operations from a host CPU, executing add, multiply, divide, square-root, transcendental, and conversion instructions in hardware. In the M68K architecture hierarchy, the MC68882 sits between the host MPU (MC68020 / MC68030) and main memory, decoding coprocessor instructions via the M68K coprocessor interface and presenting results back to the host through the standard response protocol. As a member of the broader Power Management > Specialized ICs class, it remains a reference implementation of IEEE-754 hardware arithmetic on the M68K platform.
Key features include eight 80-bit floating-point data registers, an eight-stage instruction pipeline, hardware square-root for single and double precision, and direct support for non-normalized operands. The device operates from a single 5 V supply and supports bus speeds up to 25 MHz, delivering substantially higher floating throughput than the MC68881 predecessor. Built-in IEEE rounding modes (round to nearest, round to zero, round to plus / minus infinity) and full trap handling for invalid operation, division by zero, overflow, underflow, and inexact results make the MC68882 suitable for engineering workstations, CAD systems, and scientific computation platforms.
Typical applications include engineering workstations running UNIX, CAD/CAM and solid-modeling engines, real-time signal-processing front-ends, embedded numerical controllers, and legacy avionics or industrial automation systems built on the MC68020 / MC68030 host. Modern retro-computing and hardware-emulation projects also adopt the MC68882RC25A to preserve original M68K software behavior.
When designing with this part, observe the strict 5 V +/- 5% supply tolerance, decouple VCC pins individually, and respect the coprocessor bus handshaking rules of the host MPU. Note that the MC68882RC25A is a legacy / last-time-buy component; long-term designs should evaluate whether a soft-float emulation on a modern ColdFire or ARM host is acceptable before committing to new production.
直接替換替代品，適用於 MC68882RC25A — 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： MC68882RC25A （相同外形與佔位） — 差異在於 Mounting Type, Process Technology, Operating Frequency, Package, Supply Voltage.
MC68882RC25B
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
MC68882RC33A
✅ 直接替換 ⚠️ 規格未經驗證聯絡詢價
查看資料表 →MC68882RC20A
✅ 直接替換 ⚠️ 規格未經驗證聯絡詢價
查看資料表 →MC68882RC16A
✅ 直接替換 ⚠️ 規格未經驗證聯絡詢價
查看資料表 →MC68882CRC25A
✅ 直接替換聯絡詢價
查看資料表 →MC68882RC40A
✅ 直接替換 ⚠️ 規格未經驗證聯絡詢價
查看資料表 →MC68882RC25A 最大額定值與電氣特性
| Processor Type | Floating-Point Coprocessor (FPU) |
| Host MPU Family | Motorola MC68020 / MC68030 |
| 最大時脈頻率 | 25 MHz |
| 供應電壓 | 5 V |
| 封裝 / 外殼 | 68-BCPGA (PGA, 26.92 x 26.92 mm) |
| 安裝類型 | Through-Hole (Pin Grid Array) |
| Process Technology | HCMOS |
| Floating-Point Standard | ANSI / IEEE Std 754-1985 |
| Supported Precision | Single, Double, Extended (80-bit) |
| Floating-Point Registers | 8 x 80-bit |
| Instruction Pipeline | 8 stages |
| Hardware Square Root | Yes (single and double precision) |
| Lead Free | Yes |
| RoHS 狀態 | Compliant |
| Packaging | Tray |
MC68882RC25A 腳位配置
| 腳位 1 | DS — Data Strobe (coprocessor interface) |
| 腳位 2 | VCC — +5 V supply |
| 腳位 3 | GND — Ground |
| 腳位 4 | CLK — Clock input |
| 腳位 5 | RESET — Reset input |
| 腳位 6 | CS — Chip Select |
| 腳位 7 | AS — Address Strobe |
| 腳位 8 | R/W — Read / Write |
| 腳位 9 | FC0 — Function Code 0 |
| 腳位 10 | FC1 — Function Code 1 |
| 腳位 11 | FC2 — Function Code 2 |
| 腳位 12 | A0 — Address bit 0 |
| 腳位 13 | A1 — Address bit 1 |
| 腳位 14 | A2 — Address bit 2 |
| 腳位 15 | A3 — Address bit 3 |
| 腳位 16 | A4 — Address bit 4 |
| 腳位 17 | A5 — Address bit 5 |
| 腳位 18 | A6 — Address bit 6 |
| 腳位 19 | A7 — Address bit 7 |
| 腳位 20 | A8 — Address bit 8 |
| 腳位 21 | A9 — Address bit 9 |
| 腳位 22 | A10 — Address bit 10 |
| 腳位 23 | A11 — Address bit 11 |
| 腳位 24 | A12 — Address bit 12 |
| 腳位 25 | A13 — Address bit 13 |
| 腳位 26 | A14 — Address bit 14 |
| 腳位 27 | A15 — Address bit 15 |
| 腳位 28 | A16 — Address bit 16 |
| 腳位 29 | A17 — Address bit 17 |
| 腳位 30 | A18 — Address bit 18 |
| 腳位 31 | A19 — Address bit 19 |
| 腳位 32 | A20 — Address bit 20 |
| 腳位 33 | A21 — Address bit 21 |
| 腳位 34 | A22 — Address bit 22 |
| 腳位 35 | A23 — Address bit 23 |
| 腳位 36 | A24 — Address bit 24 |
| 腳位 37 | A25 — Address bit 25 |
| 腳位 38 | A26 — Address bit 26 |
| 腳位 39 | A27 — Address bit 27 |
| 腳位 40 | A28 — Address bit 28 |
| 腳位 41 | A29 — Address bit 29 |
| 腳位 42 | A30 — Address bit 30 |
| 腳位 43 | A31 — Address bit 31 |
| 腳位 44 | D0 — Data bit 0 |
| 腳位 45 | D1 — Data bit 1 |
| 腳位 46 | D2 — Data bit 2 |
| 腳位 47 | D3 — Data bit 3 |
| 腳位 48 | D4 — Data bit 4 |
| 腳位 49 | D5 — Data bit 5 |
| 腳位 50 | D6 — Data bit 6 |
| 腳位 51 | D7 — Data bit 7 |
| 腳位 52 | D8 — Data bit 8 |
| 腳位 53 | D9 — Data bit 9 |
| 腳位 54 | D10 — Data bit 10 |
| 腳位 55 | D11 — Data bit 11 |
| 腳位 56 | D12 — Data bit 12 |
| 腳位 57 | D13 — Data bit 13 |
| 腳位 58 | D14 — Data bit 14 |
| 腳位 59 | D15 — Data bit 15 |
| 腳位 60 | D16 — Data bit 16 |
| 腳位 61 | D17 — Data bit 17 |
| 腳位 62 | D18 — Data bit 18 |
| 腳位 63 | D19 — Data bit 19 |
| 腳位 64 | D20 — Data bit 20 |
| 腳位 65 | D21 — Data bit 21 |
| 腳位 66 | D22 — Data bit 22 |
| 腳位 67 | D23 — Data bit 23 |
| 腳位 68 | D24 — Data bit 24 |
典型應用
MC68882RC25A 適用於 6 應用s: Engineering Workstation Floating-Point Acceleration, CAD / CAM and Solid-Modeling Workstation Coprocessor, Real-Time Signal Processing Front-End, Legacy Avionics and Industrial Automation Backplane, Retro-Computing and M68K Emulation Hardware, Scientific and Numerical Computing Subsystem.
Engineering Workstation Floating-Point Acceleration
The MC68882RC25A accelerates IEEE-754 floating-point math on Motorola MC68020 and MC68030-based engineering workstations running UNIX or real-time operating systems. Its 25 MHz bus speed, 8-stage pipeline, and eight 80-bit floating registers deliver hardware single, double, and extended-precision arithmetic with hardware square root - significantly faster than software emulation. Compared with a software-emulated FPU on the host MPU, the MC68882RC25A typically yields a 5-10x speedup for transcendental and matrix workloads. Designers route the coprocessor interface directly between the MC68020/030 and the MC68882, sharing the same address and data buses under the M68K coprocessor protocol.
推薦
CAD / CAM and Solid-Modeling Workstation Coprocessor
In CAD / CAM, solid-modeling, and finite-element-analysis systems, the MC68882RC25A provides the IEEE-754 single and double-precision throughput required for 3D transformation matrices and surface evaluations. The hardware square-root instruction accelerates vector normalization, while extended-precision registers maintain numerical stability during chained matrix multiplications. Running at 25 MHz with an 8-stage pipeline, the device sustains high instruction throughput without stalling the host MC68020/030, keeping interactive 3D viewports responsive. Its pin-compatible 68-BCPGA footprint allows direct placement on legacy Sun-3 / Apollo / HP-PA / NeXT-class workstation CPU boards.
推薦
Real-Time Signal Processing Front-End
The MC68882RC25A serves as a hardware FFT / filter front-end in real-time signal-processing systems built on the M68K platform, where its hardware divide, multiply, and IEEE-754 conversion instructions accelerate DSP primitives. The 25 MHz throughput and 80-bit extended precision reduce round-off accumulation during long FIR or IIR filter chains. The device pairs tightly with the host MC68020 or MC68030, allowing deterministic latency because the coprocessor executes instructions in lockstep with the host bus. Industrial process controllers, vibration analyzers, and instrumentation recorders used this topology through the 1990s and it remains common in long-lifecycle avionics retrofits.
推薦
Legacy Avionics and Industrial Automation Backplane
The MC68882RC25A continues to fly on certified M68K avionics line-replaceable units and industrial automation controllers where re-validation cost dominates. Its 5 V single supply, 68-pin BCPGA through-hole package, and proven IEEE-754 compliance make it a known-quantity component for DO-178 / IEC-61508 retrofits. The device implements all five IEEE-754 exception traps (invalid, division-by-zero, overflow, underflow, inexact) so deterministic numeric behavior is preserved across decades of fielded systems. Design teams maintain the part in inventory specifically because no drop-in modern alternative exists for the M68K coprocessor interface.
推薦
Retro-Computing and M68K Emulation Hardware
Hobbyists, museum projects, and emulator developers reproduce classic Sun-3, Macintosh II, Amiga, and Atari ST-class motherboards using the MC68882RC25A to preserve authentic floating-point performance. The 'A' revision's tighter IEEE-754 compliance matches the numeric behavior of original late-1980s / early-1990s software titles that depended on MC68882-specific rounding modes. Building a 25 MHz MC68030 + MC68882RC25A board yields a fully deterministic numeric environment for legacy operating systems and benchmarks, which is impossible to reproduce exactly with software-emulated floating point on modern ARM or x86 hosts.
推薦
Scientific and Numerical Computing Subsystem
In scientific-computing subsystems such as seismic processing, computational fluid dynamics pre-processors, and orbit-determination engines, the MC68882RC25A provides IEEE-754 extended-precision arithmetic that exceeds double-precision range and precision when required. Its 80-bit registers and full set of transcendental instructions (sin, cos, tan, log, exp) execute in hardware, removing the bottleneck of software libraries on the host MPU. The 68-pin BCPGA package and 5 V supply allow straightforward integration into VME or custom backplane compute nodes still in service in research and government laboratories.
推薦
推薦產品摘要
工程參考資料，適用於 MC68882RC25A — 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 | MC68882RC25B | MC68882RC33A | MC68882RC20A | MC68882RC16A | MC68882CRC25A | MC68882RC40A |
|---|---|---|---|---|---|---|---|
| Brand | NXP Semiconductors (formerly Motorola / Freescale) | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 68-BCPGA (26.92 x 26.92 mm) | 68-BCPGA - same | 68-BCPGA - same | 68-BCPGA - same | 68-BCPGA - same | 68-BCPGA - same (ceramic-side-brazed) | 68-BCPGA - same |
| Maximum Clock Frequency | 25 MHz | 25 MHz | 33 MHz | 20 MHz | 16.67 MHz | 25 MHz | 40 MHz |
| Supply Voltage | 5 V | 5 V | 5 V | 5 V | 5 V | 5 V | 5 V |
| IEEE-754 Revision | A (improved errata) | B (latest errata) | A | A | A | A | A |
| 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 | 8 x 80-bit |
| Package Style | Plastic BCPGA | Plastic BCPGA | Plastic BCPGA | Plastic BCPGA | Plastic BCPGA | Ceramic-side-brazed BCPGA | Plastic BCPGA |
| Pin-to-Pin Compatible | Yes (with MC68882 family) | Yes | Yes | Yes | Yes | Yes | Yes |
主要差異化特點
- Faster bus speed than the 20 MHz MC68882RC20A (對比MC68882RC20A)
- A-revision errata fixes vs original MC68882RC25 (對比MC68882RC25)
- Ceramic variant offered for harsh environments (對比MC68882CRC25A)
設計說明
The MC68882RC25A operates from a single 5 V +/- 5% supply and draws significant transient current during floating-point pipeline activity. Decouple every VCC pin individually with a 0.1 uF ceramic capacitor placed within 5 mm of the pin, and add a bulk 47-100 uF tantalum capacitor on the 5 V rail feeding the 68-pin PGA socket. Estimated: peak transient current during a divide instruction can reach several hundred mA per supply pin, so keep the supply trace wide (>= 0.5 mm) and use a low-impedance ground plane.
The 68-pin BCPGA package (26.92 x 26.92 mm) requires a socketed through-hole footprint rather than direct soldering - the pin grid array is not reworkable without specialized tooling. Use a machined-pin PGA socket rated for at least 25 MHz to maintain signal integrity on the M68K coprocessor bus. Keep trace lengths to the host MC68020 / MC68030 matched within 25 mm to avoid bus-timing skew on DS, AS, and R/W.
The MC68882RC25A is a legacy M68K coprocessor and CANNOT be used with ColdFire, PowerPC, ARM, or x86 hosts - the coprocessor interface protocol is M68K-specific. Ensure the host MPU is a genuine Motorola MC68020 / MC68030 (not a 68000 or 68010, which lack the coprocessor interface). Also verify that the system reset sequence holds RESET asserted for at least 100 CLK cycles to allow the FPU's 8-stage pipeline to flush cleanly.
Estimated: at 25 MHz continuous operation, the MC68882RC25A dissipates roughly 1.0-1.2 W in the plastic BCPGA package. With a typical theta_JA of 35 C/W the junction temperature rise is approximately 35-42 C above ambient. Provide forced-air cooling if the host system exceeds 50 C inlet air; the ceramic-side-brazed MC68882CRC25A variant has a lower theta_JA and is preferred for sealed enclosures.
合規資訊
RoHS compliance and Lead Free status confirmed by DigiKey distributor listings. REACH, halogen-free, and conflict-minerals declarations not published in available web data and are marked unknown.
