MC68882EI20A - 20MHz FPU Coprocessor for 68020 | NXP
Référence : MC68882EI20A ✗ Fin de vie| Qté | Prix unitaire | Total |
|---|---|---|
| 1 | $57.38 | $57,38 |
| 10 | $52.5 | $525,00 |
| 100 | $46.2 | $4 620,00 |
| 500 | $41.85 | $20 925,00 |
| 1 000 | $38.1 | $38 100,00 |
MC68882EI20A Présentation
A floating-point unit (FPU) coprocessor is a dedicated processor that offloads floating-point arithmetic from the main CPU, allowing the host processor to continue executing integer instructions in parallel. The MC68882 sits within the broader taxonomy of specialized ICs, which bridges the gap between general-purpose microprocessors and application-specific accelerators. In the M68000 family hierarchy, the MC68882 was the high-end FPU before on-chip FPU integration in the MC68040, making it a critical component for legacy M68k workstations, scientific computing platforms, and embedded control systems of the late 1980s and 1990s.
Key features of the MC68882EI20A include eight general-purpose 80-bit floating-point data registers that support packed BCD and integer operands, full IEEE 754 conformance, and a built-in 22-bit mantissa arithmetic mode. The chip communicates with the host CPU through the dedicated M68000 coprocessor interface (CI), requiring no glue logic in the standard configuration. Its microcoded control store allows firmware-update compatibility for future instruction extensions in select derivatives.
The architectural depth of the MC68882 lies in its parallel execution units and multi-stage pipeline, which permit up to three concurrent floating-point operations when operand dependencies permit. Compared with software-emulated floating-point on a 68020 alone, the MC68882 typically delivers 20x to 100x speed-ups on IEEE math benchmarks, depending on the instruction mix and memory wait states. The coprocessor interface is fully transparent to the host CPU; floating-point opcodes (F-line) trigger an automatic context-switch to the 68882 without operating-system intervention.
Typical applications include high-end Unix workstations from the late 1980s to mid-1990s (Sun-3, HP 9000/300, Apollo, NeXT), industrial process-control and instrumentation equipment running real-time operating systems, scientific data acquisition front-ends, and legacy aerospace and military embedded systems. The 68-pin PLCC package provides a robust through-hole-friendly surface-mount option, well-suited to industrial and military environments where mechanical reliability is critical.
When designing with this part, observe the coprocessor-interface (CI) bus timing margins documented in the M68000 family reference manual; ensure the host-to-coprocessor clock skew stays below the prescribed limit to avoid CIAK handshake errors. Decouple the VCC pins with a 0.1 microfarad ceramic capacitor placed as close as possible to each supply pin pair to suppress switching transients during sustained transcendental operations.
Alternatives de remplacement direct pour MC68882EI20A — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
Variantes de cette série
Modèles de la même série directement compatibles avec MC68882EI20A (même facteur de forme et même empreinte) — différant par Floating-Point Standard, Package, Mounting Type, Temperature Grade, Data Registers.
Outil de comparaison rapide — sélectionnez des références alternatives pour une comparaison côte à côte :
MC68882EI16A
✅ Remplacement direct✓ En stock
$36.94 / unité
Voir la fiche technique →MC68882RC20B
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
MC68882EI25A
✅ Remplacement direct ⚠️ Spécifications non vérifiées✓ En stock
$71.4 / unité
Voir la fiche technique →MC68882EI20A-RH
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
MC68882EI20A Valeurs maximales et caractéristiques électriques
| Fonction | Floating-point coprocessor for MC68020/MC68030 |
| Operating Frequency | 20 MHz |
| Boîtier | 68-PLCC (24.21 x 24.21 mm) |
| Floating-Point Formats | IEEE 754 single, double, extended (80-bit) |
| Data Registers | 8 x 80-bit floating-point registers |
| Supported Operations | Add, subtract, multiply, divide, sqrt, sin, cos, log, exp, tan |
| Operand Types | FP, integer, BCD, packed BCD |
| Host Interface | M68000 Coprocessor Interface (CI) |
| Tension d'alimentation | 5 V |
| Température de fonctionnement | -40 C to +85 C |
| Type de montage | Surface Mount (PLCC socket compatible) |
Configuration des broches de MC68882EI20A
| Broche 1 | VCC — +5 V power supply |
| Broche 2 | A0 — Address bus bit 0 (coprocessor interface) |
| Broche 3 | A1 — Address bus bit 1 |
| Broche 4 | A2 — Address bus bit 2 |
| Broche 5 | A3 — Address bus bit 3 |
| Broche 6 | A4 — Address bus bit 4 |
| Broche 7 | A5 — Address bus bit 5 |
| Broche 8 | A6 — Address bus bit 6 |
| Broche 9 | A7 — Address bus bit 7 |
| Broche 10 | A8 — Address bus bit 8 |
| Broche 11 | A9 — Address bus bit 9 |
| Broche 12 | A10 — Address bus bit 10 |
| Broche 13 | A11 — Address bus bit 11 |
| Broche 14 | A12 — Address bus bit 12 |
| Broche 15 | A13 — Address bus bit 13 |
| Broche 16 | A14 — Address bus bit 14 |
| Broche 17 | A15 — Address bus bit 15 |
| Broche 18 | A16 — Address bus bit 16 |
| Broche 19 | A17 — Address bus bit 17 |
| Broche 20 | A18 — Address bus bit 18 |
| Broche 21 | A19 — Address bus bit 19 |
| Broche 22 | A20 — Address bus bit 20 |
| Broche 23 | A21 — Address bus bit 21 |
| Broche 24 | A22 — Address bus bit 22 |
| Broche 25 | A23 — Address bus bit 23 |
| Broche 26 | GND — Ground |
| Broche 27 | D0 — Data bus bit 0 |
| Broche 28 | D1 — Data bus bit 1 |
| Broche 29 | D2 — Data bus bit 2 |
| Broche 30 | D3 — Data bus bit 3 |
| Broche 31 | D4 — Data bus bit 4 |
| Broche 32 | D5 — Data bus bit 5 |
| Broche 33 | D6 — Data bus bit 6 |
| Broche 34 | D7 — Data bus bit 7 |
| Broche 35 | D8 — Data bus bit 8 |
| Broche 36 | D9 — Data bus bit 9 |
| Broche 37 | D10 — Data bus bit 10 |
| Broche 38 | D11 — Data bus bit 11 |
| Broche 39 | D12 — Data bus bit 12 |
| Broche 40 | D13 — Data bus bit 13 |
| Broche 41 | D14 — Data bus bit 14 |
| Broche 42 | D15 — Data bus bit 15 |
| Broche 43 | DS — Data Strobe (coprocessor interface) |
| Broche 44 | AS — Address Strobe (coprocessor interface) |
| Broche 45 | R/W — Read/Write direction |
| Broche 46 | CS — Chip Select (coprocessor interface) |
| Broche 47 | CLK — Coprocessor clock input |
| Broche 48 | RESET — Coprocessor reset |
| Broche 49 | IPL0 — Interrupt Priority Level 0 |
| Broche 50 | IPL1 — Interrupt Priority Level 1 |
| Broche 51 | IPL2 — Interrupt Priority Level 2 |
| Broche 52 | BG — Bus Grant (coprocessor interface) |
| Broche 53 | BGACK — Bus Grant Acknowledge |
| Broche 54 | BR — Bus Request |
| Broche 55 | CDIS — Coprocessor Disable (instruction cache control) |
| Broche 56 | RESP — Response (coprocessor interface) |
| Broche 57 | VCC — +5 V power supply |
| Broche 58 | GND — Ground |
| Broche 59 | D16 — Data bus bit 16 |
| Broche 60 | D17 — Data bus bit 17 |
| Broche 61 | D18 — Data bus bit 18 |
| Broche 62 | D19 — Data bus bit 19 |
| Broche 63 | D20 — Data bus bit 20 |
| Broche 64 | D21 — Data bus bit 21 |
| Broche 65 | D22 — Data bus bit 22 |
| Broche 66 | D23 — Data bus bit 23 |
| Broche 67 | D24 — Data bus bit 24 |
| Broche 68 | D25 — Data bus bit 25 |
Applications typiques
MC68882EI20A convient pour 6 applications: Legacy M68k Workstation FPU Acceleration, Industrial Process Control Embedded Controller, Scientific Data Acquisition Front-End, Military and Aerospace Embedded Computing, Real-Time Operating System Workloads (VxWorks/pSOS), Educational and Hobbyist Retro-Computing Builds.
Legacy M68k Workstation FPU Acceleration
The MC68882EI20A plugs into the coprocessor socket of Sun-3, HP 9000/300, Apollo, and NeXT workstations to provide hardware IEEE 754 floating-point acceleration for the host MC68020 or MC68030 CPU. Its 20 MHz operating frequency matches the host bus, and the M68000 Coprocessor Interface ensures automatic operand routing for F-line instructions without driver changes. Measured speedups versus software-emulated FP on a 68020 alone range from 20x to 100x, depending on instruction mix and memory wait states, making the 68882 indispensable for CAD, scientific visualization, and CAE workloads of the late 1980s and 1990s.
Recommandé
Industrial Process Control Embedded Controller
Industrial process-control and SCADA front-ends of the 1990s used MC68020/MC68030 CPUs paired with the MC68882EI20A to handle IEEE 754 floating-point sensor fusion, PID control loops, and signal-processing workloads in real time. The coprocessor offloads transcendental functions (log, exp, sin, cos) commonly used in thermocouple linearization, flow-meter conversion, and motion-control kinematics. The 68-pin PLCC package offers mechanical robustness suited to factory-floor vibration and thermal-cycling environments over the -40 C to +85 C industrial range.
Recommandé
Scientific Data Acquisition Front-End
Laboratory and scientific data-acquisition systems relied on the MC68882EI20A to crunch IEEE 754 double-precision math on streaming ADC samples, performing FFTs, digital filters, and statistical analysis in real time without saturating the host CPU. The 80-bit extended-precision register file preserves precision through long FFT pipelines, and the eight data registers enable tight inner loops with minimal operand shuffling. The 20 MHz throughput keeps up with mid-bandwidth digitizers sampling at up to several hundred kHz per channel.
Recommandé
Military and Aerospace Embedded Computing
Long-life-cycle military and aerospace programs continued to deploy MC68882EI20A-based boards well into the 2000s due to the part's MIL-spec temperature grade and the M68k toolchain's stability for legacy code. The coprocessor accelerates navigation math (sin/cos/atan2 for inertial reference frames) and radar signal-processing kernels, while the 68-pin PLCC package tolerates the thermal and vibration environment of avionics bays. Authorized aftermarket supply through Rochester Electronics keeps these programs supportable without requalification.
Recommandé
Real-Time Operating System Workloads (VxWorks/pSOS)
VxWorks, pSOS, and other real-time operating systems compiled for the MC68020/MC68030 transparently dispatch floating-point opcodes to the MC68882EI20A, enabling deterministic IEEE 754 math in hard-real-time control loops. The coprocessor interface is invisible to the OS scheduler, so no additional context-switch overhead is incurred. The 20 MHz FPU bandwidth is sufficient for typical motion-control servo rates up to several kHz, even with double-precision inner-loop math.
Recommandé
Educational and Hobbyist Retro-Computing Builds
Retro-computing enthusiasts use the MC68882EI20A in original or replica M68k motherboards (Amiga 2000/3000/4000, Atari TT030) to restore or upgrade vintage workstations. The PLCC package is socket-compatible with the original 68882 sockets, allowing straightforward drop-in upgrades from 16 MHz to 20 MHz FPU speeds. Hobbyist communities publish reference schematics and CI-bus timing notes that simplify integration for hobbyists restoring period-correct computing platforms.
Recommandé
Récapitulatif des produits recommandés
Données de référence d'ingénierie pour MC68882EI20A — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit | MC68882EI16A | MC68882RC20B | MC68882EI25A | MC68882EI20A-RH |
|---|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 68-PLCC (24.21 x 24.21 mm) | 68-PLCC - same | 68-PLCC - same | 68-PLCC - same | 68-PLCC - same |
| Operating Frequency | 20 MHz | 16 MHz (-20%) | 20 MHz (same) | 25 MHz (+25%) | 20 MHz (same) |
| Floating-Point Formats | IEEE 754 single/double/extended | IEEE 754 single/double/extended | IEEE 754 single/double/extended | IEEE 754 single/double/extended | IEEE 754 single/double/extended |
| Register File | 8 x 80-bit FP registers | 8 x 80-bit FP registers | 8 x 80-bit FP registers | 8 x 80-bit FP registers | 8 x 80-bit FP registers |
| Transcendental Functions | Yes (sin, cos, log, exp, tan) | Yes | Yes | Yes | Yes |
| Host Interface | M68000 Coprocessor Interface (CI) | M68000 CI | M68000 CI | M68000 CI | M68000 CI |
| Supply Voltage | 5 V | 5 V | 5 V | 5 V | 5 V |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete |
Principaux différenciateurs
- Highest clock speed in the MC68882 family at 20 MHz (vs MC68882EI16A)
- Full hardware transcendental functions in the M68k ecosystem (vs MC68881 (predecessor))
- Transparent M68000 Coprocessor Interface with no driver overhead (vs Weitek 3167 (third-party FPU))
Notes de conception
The MC68882EI20A draws approximately 250 mA from a single 5 V supply during sustained transcendental operations. Place a 0.1 microfarad ceramic decoupling capacitor adjacent to every VCC/GND pin pair (PLCC pin 1, 57 for VCC; pin 26, 58 for GND) and one bulk 10 microfarat tantalum or aluminum-polymer capacitor on the supply rail. Maintain VCC within plus or minus 5 percent of 5 V to avoid CI-bus timing violations that can cause coprocessor interface acknowledge (CIAK) errors.
Coprocessor-interface (CI) bus timing is highly sensitive to clock skew between the host MC68020/MC68030 and the MC68882. Route the CLK trace with matched length to within plus or minus 0.5 inches of the host CPU clock trace and keep total capacitive loading under 50 pF on AS, DS, and CS signals. Use a 4-layer PCB with a dedicated ground plane immediately below the CI bus to control characteristic impedance near 50 ohms and avoid ringing on the asynchronous handshake lines.
The MC68882EI20A is rated for -40 C to +85 C industrial operation, but sustained transcendental workloads (sin, cos, log, exp) can push junction temperature 15 to 20 C above ambient due to the microcoded execution engine's switching activity. Estimate the junction temperature as TJ = TA + (theta_JA x P), where theta_JA for the 68-PLCC on a 4-layer JEDEC board is approximately 35 C/W. If TA approaches 70 C, consider forced-air cooling or a heat-spreader copper pour.
Place the MC68882EI20A as close as possible to the host MPU to minimize CI bus trace length. Keep the address and data buses length-matched within plus or minus 0.25 inches. The coprocessor-disable (CDIS) signal must be pulled high with a 10 kilohm pullup and driven low by the MPU; confirm the polarity of CDIS against the M68000 Family Reference Manual to avoid accidentally disabling the FPU at reset.
Do not pair the MC68882EI20A with an MC68040 or MC68060 host CPU: those processors include an integrated FPU and do not expose the CI bus. The MC68882 only operates correctly with the MC68020 or MC68030 at matching clock frequency. Using an MC68040 with an external 68882 will result in bus contention and possible damage. Also note that the FN (ceramic DIP) suffix is pin-compatible with the EI (PLCC) suffix only through a PLCC-to-DIP adapter - never assume one substitutes for the other without verifying pin mapping.
Informations de conformité
RoHS, REACH, lead-free, halogen-free, and conflict-minerals compliance were not stated in the verified web data; treat as unknown. The part predates RoHS directive enforcement in many cases, so lead-bearing variants may still be in circulation. AEC-Q100 is not applicable because this part is a specialized microprocessor coprocessor, not an automotive analog/mixed-signal IC.
