MC68LC302AF20VCT - 20MHz M68K Comm Processor | NXP | 100-LQFP
MPN： MC68LC302AF20VCT ✗ 停產MC68LC302AF20VCT 概覽
An integrated multiprotocol processor is a system-on-chip that combines a general-purpose CPU core with dedicated communications hardware for handling serial protocols such as HDLC, UART, and bisync. By collapsing the CPU, DMA engine, serial channels, and memory controller onto one die, an IMP reduces board area, simplifies PCB routing, and shortens firmware debug cycles for embedded network nodes. The MC68LC302 sits in the M683xx product family within NXP's legacy M68000 lineage, and is positioned between the original MC68302 (full-featured) and lower-end members of the LC (low-cost) family.
Key features include a 20 MHz clock speed, three independent full-duplex serial communications controllers supporting HDLC/SDLC, UART, and transparent modes, an on-chip DMA controller with two channels, a DRAM refresh controller, and parallel I/O. The device operates from a 5 V supply and is offered in a 100-pin LQFP (14x14 mm) surface-mount package. Compared to the MC68302, the LC version removes certain advanced features to reduce cost while retaining the same M68000 instruction set for software compatibility.
The architecture is built around the industry-standard MC68000 core executing 16-bit instructions with a 24-bit address space, paired with a RISC communications processor that offloads bit-level protocol work. This dual-engine approach allows the CPU to run higher-layer networking stacks while the CPM handles real-time serial framing, error detection, and DMA-driven buffer management. The result is deterministic throughput on multiple serial links without taxing the main CPU.
Typical applications include ISDN terminal adapters, industrial routers and bridges, frame-relay access devices, low-end protocol converters, and legacy serial multiplexing equipment. The LC variant is especially common in cost-sensitive designs that need M68K software reuse but do not require the full MC68302 feature set.
When designing with this part, ensure that signal-integrity constraints for the 20 MHz bus are met, use proper ground-plane partitioning between the analog serial section and the digital core, and confirm DRAM timing parameters against the chosen memory. Designers migrating from the MC68302 should verify register-level differences in the LC variant before reusing firmware.
This page synthesizes distributor availability, drop-in alternatives, and design notes not found in the manufacturer datasheet alone, giving procurement and engineering teams a single source for sourcing decisions.
直接替換替代品，適用於 MC68LC302AF20VCT — 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： MC68LC302AF20VCT （相同外形與佔位） — 差異在於 Manufacturer, Part Status.
MC68LC302AF20CT
✅ 直接替換聯絡詢價
查看資料表 →MC68LC302PU20VCT
✅ 直接替換📋 參考替代品（不在目錄中）
MC68302AF20CT
✅ 直接替換📋 參考替代品（不在目錄中）
MC68LC302AF16VCT
✅ 直接替換 ⚠️ 規格未經驗證聯絡詢價
查看資料表 →MC68LC302AF25VCT
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
MC68LC302AF20VCT 最大額定值與電氣特性
| Manufacturer | NXP Semiconductors (formerly Freescale, Motorola) |
| Product Type | Integrated Multiprotocol Processor (IMP) |
| Core Processor | M68000 |
| Number of Cores | 1 |
| Core Width | 8/16-Bit |
| Maximum Clock Speed | 20 MHz |
| Co-Processor / DSP | Communications; RISC CPM |
| Series | M683xx |
| 封裝 | 100-LQFP (14x14 mm) |
| 安裝類型 | Surface Mount |
| RAM Controllers | DRAM |
| 工作電源電壓 | 5 V |
| Serial Communications | 3 SCC channels (HDLC/SDLC, UART, transparent) |
| DMA Channels | 2 |
MC68LC302AF20VCT 腳位配置
| 腳位 1 | A0 — Address bus bit 0 (or strapping option) |
| 腳位 2 | A1 — Address bus bit 1 |
| 腳位 3 | A2 — Address bus bit 2 |
| 腳位 4 | A3 — Address bus bit 3 |
| 腳位 5 | A4 — Address bus bit 4 |
| 腳位 6 | VCC — +5V power supply |
| 腳位 7 | A5 — Address bus bit 5 |
| 腳位 8 | A6 — Address bus bit 6 |
| 腳位 9 | A7 — Address bus bit 7 |
| 腳位 10 | A8 — Address bus bit 8 |
| 腳位 11 | A9 — Address bus bit 9 |
| 腳位 12 | A10 — Address bus bit 10 |
| 腳位 13 | A11 — Address bus bit 11 |
| 腳位 14 | A12 — Address bus bit 12 |
| 腳位 15 | A13 — Address bus bit 13 |
| 腳位 16 | A14 — Address bus bit 14 |
| 腳位 17 | A15 — Address bus bit 15 |
| 腳位 18 | GND — Ground |
| 腳位 19 | A16 — Address bus bit 16 |
| 腳位 20 | A17 — Address bus bit 17 |
| 腳位 21 | A18 — Address bus bit 18 |
| 腳位 22 | A19 — Address bus bit 19 |
| 腳位 23 | A20 — Address bus bit 20 |
| 腳位 24 | A21 — Address bus bit 21 |
| 腳位 25 | A22 — Address bus bit 22 |
| 腳位 26 | A23 — Address bus bit 23 |
| 腳位 27 | D0 — Data bus bit 0 |
| 腳位 28 | D1 — Data bus bit 1 |
| 腳位 29 | D2 — Data bus bit 2 |
| 腳位 30 | D3 — Data bus bit 3 |
| 腳位 31 | VCC — +5V power supply |
| 腳位 32 | D4 — Data bus bit 4 |
| 腳位 33 | D5 — Data bus bit 5 |
| 腳位 34 | D6 — Data bus bit 6 |
| 腳位 35 | D7 — Data bus bit 7 |
| 腳位 36 | D8 — Data bus bit 8 |
| 腳位 37 | D9 — Data bus bit 9 |
| 腳位 38 | D10 — Data bus bit 10 |
| 腳位 39 | D11 — Data bus bit 11 |
| 腳位 40 | D12 — Data bus bit 12 |
| 腳位 41 | D13 — Data bus bit 13 |
| 腳位 42 | D14 — Data bus bit 14 |
| 腳位 43 | D15 — Data bus bit 15 |
| 腳位 44 | GND — Ground |
| 腳位 45 | BR — Bus Request |
| 腳位 46 | BG — Bus Grant |
| 腳位 47 | BGACK — Bus Grant Acknowledge |
| 腳位 48 | RESET — Reset (active low) |
| 腳位 49 | HALT — Halt (active low) |
| 腳位 50 | CLK — System clock input |
| 腳位 51 | VCC — +5V power supply |
| 腳位 52 | TCLK — Timer clock |
| 腳位 53 | TIN1 — Timer input 1 |
| 腳位 54 | TOUT1 — Timer output 1 |
| 腳位 55 | TIN2 — Timer input 2 |
| 腳位 56 | TOUT2 — Timer output 2 |
| 腳位 57 | IRQ1 — Interrupt request 1 |
| 腳位 58 | IRQ2 — Interrupt request 2 |
| 腳位 59 | IRQ3 — Interrupt request 3 |
| 腳位 60 | IRQ4 — Interrupt request 4 |
| 腳位 61 | IRQ5 — Interrupt request 5 |
| 腳位 62 | IRQ6 — Interrupt request 6 |
| 腳位 63 | GND — Ground |
| 腳位 64 | CS0 — Chip select 0 |
| 腳位 65 | CS1 — Chip select 1 |
| 腳位 66 | CS2 — Chip select 2 |
| 腳位 67 | CS3 — Chip select 3 |
| 腳位 68 | RAS0 — DRAM row address strobe 0 |
| 腳位 69 | RAS1 — DRAM row address strobe 1 |
| 腳位 70 | CAS0 — DRAM column address strobe 0 |
| 腳位 71 | CAS1 — DRAM column address strobe 1 |
| 腳位 72 | VCC — +5V power supply |
| 腳位 73 | WE — Write enable |
| 腳位 74 | OE — Output enable |
| 腳位 75 | TA — Transfer acknowledge |
| 腳位 76 | R/W — Read/Write |
| 腳位 77 | DS — Data strobe |
| 腳位 78 | AS — Address strobe |
| 腳位 79 | GND — Ground |
| 腳位 80 | PA0 — Parallel I/O port A bit 0 |
| 腳位 81 | PA1 — Parallel I/O port A bit 1 |
| 腳位 82 | PA2 — Parallel I/O port A bit 2 |
| 腳位 83 | PA3 — Parallel I/O port A bit 3 |
| 腳位 84 | PA4 — Parallel I/O port A bit 4 |
| 腳位 85 | PA5 — Parallel I/O port A bit 5 |
| 腳位 86 | PA6 — Parallel I/O port A bit 6 |
| 腳位 87 | PA7 — Parallel I/O port A bit 7 |
| 腳位 88 | PB0 — Parallel I/O port B bit 0 |
| 腳位 89 | PB1 — Parallel I/O port B bit 1 |
| 腳位 90 | PB2 — Parallel I/O port B bit 2 |
| 腳位 91 | PB3 — Parallel I/O port B bit 3 |
| 腳位 92 | PB4 — Parallel I/O port B bit 4 |
| 腳位 93 | PB5 — Parallel I/O port B bit 5 |
| 腳位 94 | PB6 — Parallel I/O port B bit 6 |
| 腳位 95 | PB7 — Parallel I/O port B bit 7 |
| 腳位 96 | TXD1 — SCC1 transmit data |
| 腳位 97 | RXD1 — SCC1 receive data |
| 腳位 98 | TXD2 — SCC2 transmit data |
| 腳位 99 | RXD2 — SCC2 receive data |
| 腳位 100 | TXD3/RXD3 — SCC3 transmit/receive data |
典型應用
MC68LC302AF20VCT 適用於 6 應用s: ISDN Terminal Adapter / NT1, Industrial Router / Bridge, Frame-Relay Access Device (FRAD), Legacy Serial Multiplexer / Concentrator, X.25 Packet Assembler / Disassembler (PAD), POS Terminal / ATM Communications Controller.
ISDN Terminal Adapter / NT1
The MC68LC302AF20VCT is well-suited for ISDN terminal adapters because its RISC CPM handles HDLC framing on the ISDN D-channel autonomously, freeing the M68000 core to run higher-layer protocols. At 20 MHz the core delivers sufficient MIPS for V.120 rate adaptation and PPP multiplexing while the on-chip DMA moves data between serial channels and DRAM buffers without CPU intervention. Three independent SCCs enable simultaneous handling of D-channel, B1/B2 channels, and an external UART for terminal-side command-line interface.
推薦
Industrial Router / Bridge
For industrial routers and bridges, the MC68LC302AF20VCT offers deterministic multi-protocol serial handling without an external coprocessor. Its three SCCs can terminate HDLC WAN links, RS-232/RS-485 console ports, and a packet-over-sonet channel concurrently, while the M68000 core runs an IP forwarding stack in roughly 1 MIPS throughput per MHz. The integrated DRAM controller eliminates external memory glue logic, simplifying PCB layout in ruggedized industrial enclosures where board area and component count matter for reliability.
推薦
Frame-Relay Access Device (FRAD)
Frame-relay access devices benefit from the MC68LC302AF20VCT's hardware HDLC/SDLC support, which is the native protocol for frame-relay LAPF framing. At 20 MHz the device can sustain multiple T1/E1 frame-relay channels with the RISC CPM offloading CRC16 and zero-bit-insertion tasks, while the CPU runs the frame-relay PVC management and SNMP agent. The DRAM interface supports burst-mode page accesses typical of FRAD buffer pools, and the chip's low power dissipation suits customer-premises equipment.
推薦
Legacy Serial Multiplexer / Concentrator
The MC68LC302AF20VCT excels at legacy serial concentration tasks where multiple async UARTs are aggregated onto a higher-speed synchronous link. Each SCC can be configured as a UART (16C750-compatible mode) and the RISC CPM handles DMA-driven buffer fills independent of the main core. This makes the LC302 ideal for industrial telemetry, point-of-sale terminal multiplexers, and SCADA remote-terminal units that must aggregate dozens of slow serial channels without consuming CPU cycles per character.
推薦
X.25 Packet Assembler / Disassembler (PAD)
X.25 PAD equipment was a flagship application of the original MC68302 family and the MC68LC302AF20VCT inherits that pedigree. The RISC CPM's HDLC support provides ISO/IEC 3309-compliant framing for X.25 Level 2, while the M68000 core runs Level 3 packet assembly, call-setup, and LAPB state machines. The integrated DMA controller manages packet buffers efficiently, making the LC302 a strong fit for legacy X.25 networks in industrial, banking, and government installations still in service today.
推薦
POS Terminal / ATM Communications Controller
In point-of-sale terminals and ATM communications controllers, the MC68LC302AF20VCT manages dial-up modem links, encrypted PIN-pad interfaces, and back-office WAN connectivity from a single chip. The M68000 core runs the POS application logic while the CPM handles asynchronous serial for the dial modem and synchronous HDLC for the WAN link. At 20 MHz the part delivers the deterministic response times required for payment-processing protocols, and the integrated DRAM controller simplifies the bill-of-materials versus discrete designs.
推薦
推薦產品摘要
工程參考資料，適用於 MC68LC302AF20VCT — 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 | MC68LC302AF20CT | MC68LC302PU20VCT | MC68302AF20CT |
|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 100-LQFP (14x14) | 100-LQFP (14x14) - same | 100-LQFP (14x14) - same | 100-LQFP (14x14) - same |
| Core Processor | M68000 | M68000 | M68000 | M68000 |
| Clock Speed | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Core Width | 8/16-Bit | 8/16-Bit | 8/16-Bit | 8/16-Bit |
| Feature Set | Low-Cost (LC) | Low-Cost (LC) | Low-Cost (LC) | Full feature |
| SCC Channels | 3 | 3 | 3 | 3 |
| Packaging | Tray (VCT) | Tape & Reel (CT) | Tray, PQFP package | Tape & Reel (CT) |
主要差異化特點
- Lowest-cost variant of MC68302 in 100-LQFP footprint (對比MC68302AF20CT)
- Tray packaging (VCT) for low-volume and prototype builds (對比MC68LC302AF20CT)
- Same 100-LQFP AF footprint across LC and full feature families (對比MC68LC302PU20VCT)
設計說明
The MC68LC302AF20VCT operates from a single +5V supply and draws peak current during DRAM refresh bursts; bulk-decouple VCC pins (6, 31, 51, 72) with 10uF tantalum plus 0.1uF ceramic per pin to prevent bus-cycle voltage droops. Connect all VCC and GND pins (18, 44, 63, 79) directly to power planes; do not daisy-chain. Estimated local decoupling budget is 4 capacitors total on a 4-layer PCB, which is sufficient for 20 MHz operation.
Lay out the 100-LQFP package on a 4-layer PCB with continuous ground plane beneath the device. Keep the CLK trace (pin 50) short and matched-length with TCLK (pin 52) to avoid skew; use a clock-oscillator module with CMOS output drive. Route the parallel data bus D0-D15 (pins 27-43) as a matched-length group with series damping resistors if bus length exceeds 50 mm to control ringing on the 20 MHz bus.
Confirm whether your design requires the MC68LC302 (low-cost) or full MC68302 before sourcing, as register-level differences exist in the SCC, timer, and parallel I/O blocks. Pin-compatible in the same 100-LQFP package, the MC68302 adds features but the LC302 firmware is not always binary-compatible; consult the MC68LC302/D datasheet register appendix before reusing code. Always order factory-traceable parts from authorized distributors because counterfeit risk is elevated for legacy NXP/Motorola M68K parts.
The address bus A1-A23 (pins 1-5, 7-17, 19-26) and data bus D0-D15 (pins 27-30, 32-43) should be routed with controlled impedance of 50-70 ohms to ground. Place source-series termination resistors (22-33 ohm) on the address and data buses at the M68LC302 driver end if the load is concentrated. Failure to terminate results in significant overshoot on the 20 MHz bus that can corrupt reads from external peripherals.
合規資訊
Compliance status not explicitly stated in the verified distributor data. The MC68LC302AF20VCT is a legacy M68K part originally released in the 1990s; consult NXP's product compliance documentation directly for current RoHS/REACH status before use in new designs.