MC68302CRC20C157 - 20MHz M68000 IMP, 132-PGA | NXP
MPN: MC68302CRC20C157 ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $38.5 | $38.50 |
| 10 | $34.2 | $342.00 |
| 100 | $29.95 | $2,995.00 |
| 500 | $26.4 | $13,200.00 |
| 1,000 | $23.8 | $23,800.00 |
MC68302CRC20C157 Overview
An Integrated Multiprotocol Processor (IMP) is a specialized embedded microprocessor class that fuses a general-purpose CPU core with serial-communication hardware blocks (SCC, SMC) so a single chip can terminate multiple telecom protocols. Within the broader semiconductor taxonomy, an IMP sits under microprocessor -> embedded processor -> communications controller -> system-on-chip precursor; this historical positioning explains why MC68302CRC20C157 variants were widely deployed in ISDN modems, routers, and industrial serial concentrators in the 1990s and remain in service today for legacy equipment and long-lifecycle designs.
Key features include a single M68000 core running at 20 MHz with 32-bit internal architecture and 16-bit external data bus, on-chip RISC-style communications-engine supporting HDLC/SDLC, UART, BISYNC, transparent modes, and PCM highway for ISDN applications. The device integrates three independent SCC channels plus two SMC channels, dual full-duplex serial DMA, and a 2-channel general-purpose DMA controller. Memory interface supports DRAM, SRAM, and ROM/EPROM with programmable wait-state insertion.
Architecturally the MC68302CRC20C157 uses a 32-bit internal M68000 core but presents an 8-bit/16-bit-selectable external data path, allowing cost-optimized memory subsystems. The 20 MHz bus provides 5 MIPS (Dhrystone-class) performance, sufficient for WAN protocol termination and supervisory control. Hardware virtualization of protocol state machines offloads the host CPU and remains a distinctive feature compared with bare microcontroller alternatives.
Typical applications include ISDN terminal adapters, X.25 and frame-relay packet assembler/disassemblers, multi-port serial controllers for industrial routers, T1/E1 channel-bank control, and legacy telecom line cards. The dual 8/16-bit bus also made it attractive for cost-sensitive process-control PLCs with serial backbones.
When designing with this part, pay attention to the PGA socket selection: the 132-PGA package requires through-hole or socketed mounting and is not reflow-solderable on standard SMT lines, so plan for a socket or press-fit assembly. Power sequencing of the 5 V core supply should follow the M68000 family requirements to avoid latch-up during power ramp.
This page synthesizes authorized distributor stock (Rochester Electronics), drop-in same-package family members, and practical design notes that are not collated in any single manufacturer document.
Drop-in alternatives for MC68302CRC20C157 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with MC68302CRC20C157 (same form factor and footprint) — differing in Mounting Type, Core Processor, DMA Channels, Data Bus Width.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MC68302CRC20C
✅ Drop-In✓ In Stock
$47.8 / Unit
View Datasheet →MC68302CFC20
✅ Drop-In📋 Reference alternative (not in catalog)
MC68302CRC16C
✅ Drop-In✓ In Stock
$28.2 / Unit
View Datasheet →MC68302CRC25C
✅ Drop-In📋 Reference alternative (not in catalog)
MC68302PV20C
✅ Drop-In📋 Reference alternative (not in catalog)
MC68302CRC20C157 Maximum Ratings & Electrical Characteristics
| Core Processor | M68000 |
| Number of Cores | 1 |
| Bus Width | 8-bit / 16-bit selectable |
| Internal Architecture | 32-bit |
| Maximum Clock Frequency | 20 MHz |
| Supply Voltage | 5 V |
| Package Type | 132-PGA (Pin Grid Array) |
| Package Dimensions | 39.63 mm x 39.63 mm |
| Mounting Type | Through-Hole (PGA socket or solder) |
| On-chip Communication Channels | 3x SCC, 2x SMC |
| DMA Controller | 2-channel general-purpose + serial DMA |
| Memory Interface | DRAM, SRAM, ROM/EPROM with wait states |
| Supported Protocols | HDLC/SDLC, UART, BISYNC, Transparent, PCM (ISDN), GCI, IDL, NMSI, SCPI |
| Status | Active (sustained by NXP/Rochester for legacy programs) |
MC68302CRC20C157 Pin Configuration
| Pin 1 | A0 — Address bus bit 0 |
| Pin 2 | A1 — Address bus bit 1 |
| Pin 3 | A2 — Address bus bit 2 |
| Pin 4 | A3 — Address bus bit 3 |
| Pin 5 | A4 — Address bus bit 4 |
| Pin 6 | A5 — Address bus bit 5 |
| Pin 7 | A6 — Address bus bit 6 |
| Pin 8 | A7 — Address bus bit 7 |
| Pin 9 | A8 — Address bus bit 8 |
| Pin 10 | A9 — Address bus bit 9 |
| Pin 11 | A10 — Address bus bit 10 |
| Pin 12 | A11 — Address bus bit 11 |
| Pin 13 | A12 — Address bus bit 12 |
| Pin 14 | A13 — Address bus bit 13 |
| Pin 15 | A14 — Address bus bit 14 |
| Pin 16 | A15 — Address bus bit 15 |
| Pin 17 | A16 — Address bus bit 16 |
| Pin 18 | A17 — Address bus bit 17 |
| Pin 19 | A18 — Address bus bit 18 |
| Pin 20 | A19 — Address bus bit 19 |
| Pin 21 | D0 — Data bus bit 0 (8/16-bit mode) |
| Pin 22 | D1 — Data bus bit 1 |
| Pin 23 | D2 — Data bus bit 2 |
| Pin 24 | D3 — Data bus bit 3 |
| Pin 25 | D4 — Data bus bit 4 |
| Pin 26 | D5 — Data bus bit 5 |
| Pin 27 | D6 — Data bus bit 6 |
| Pin 28 | D7 — Data bus bit 7 |
| Pin 29 | D8 — Data bus bit 8 (16-bit mode) |
| Pin 30 | D9 — Data bus bit 9 |
| Pin 31 | D10 — Data bus bit 10 |
| Pin 32 | D11 — Data bus bit 11 |
| Pin 33 | D12 — Data bus bit 12 |
| Pin 34 | D13 — Data bus bit 13 |
| Pin 35 | D14 — Data bus bit 14 |
| Pin 36 | D15 — Data bus bit 15 |
| Pin 37 | AS — Address Strobe |
| Pin 38 | DS — Data Strobe (active low) |
| Pin 39 | R/W — Read/Write control |
| Pin 40 | CS0 — Chip Select 0 |
| Pin 41 | CS1 — Chip Select 1 |
| Pin 42 | CS2 — Chip Select 2 |
| Pin 43 | CS3 — Chip Select 3 |
| Pin 44 | BR — Bus Request |
| Pin 45 | BG — Bus Grant |
| Pin 46 | BGACK — Bus Grant Acknowledge |
| Pin 47 | DTACK — Data Transfer Acknowledge (active low) |
| Pin 48 | IPL0 — Interrupt Priority Level 0 |
| Pin 49 | IPL1 — Interrupt Priority Level 1 |
| Pin 50 | IPL2 — Interrupt Priority Level 2 |
| Pin 51 | RESET — Reset (active low) |
| Pin 52 | HALT — Halt (active low) |
| Pin 53 | CLK — System Clock input |
| Pin 54 | VCC — +5 V power supply |
| Pin 55 | GND — Ground |
| Pin 56 | TXD1 — SCC1 Transmit Data |
| Pin 57 | RXD1 — SCC1 Receive Data |
| Pin 58 | RTS1 — SCC1 Request To Send |
| Pin 59 | CTS1 — SCC1 Clear To Send |
| Pin 60 | CD1 — SCC1 Carrier Detect |
| Pin 61 | TXD2 — SCC2 Transmit Data |
| Pin 62 | RXD2 — SCC2 Receive Data |
| Pin 63 | TXD3 — SCC3 Transmit Data |
| Pin 64 | RXD3 — SCC3 Receive Data |
| Pin 65 | PCMTXD — PCM Transmit Data |
| Pin 66 | PCMRXD — PCM Receive Data |
| Pin 67 | PCMCLK — PCM Clock |
| Pin 68 | PCMSYN — PCM Sync |
| Pin 69 | TCLK — Timer Clock |
| Pin 70 | TOUT1 — Timer Output 1 |
| Pin 71 | TOUT2 — Timer Output 2 |
| Pin 72 | TIN1 — Timer Input 1 |
| Pin 73 | TIN2 — Timer Input 2 |
| Pin 74 | P0 — Parallel I/O Port bit 0 |
| Pin 75 | P1 — Parallel I/O Port bit 1 |
| Pin 76 | P2 — Parallel I/O Port bit 2 |
| Pin 77 | P3 — Parallel I/O Port bit 3 |
| Pin 78 | P4 — Parallel I/O Port bit 4 |
| Pin 79 | P5 — Parallel I/O Port bit 5 |
| Pin 80 | P6 — Parallel I/O Port bit 6 |
| Pin 81 | P7 — Parallel I/O Port bit 7 |
| Pin 82 | DREQ0 — DMA Request 0 |
| Pin 83 | DREQ1 — DMA Request 1 |
| Pin 84 | DACK0 — DMA Acknowledge 0 |
| Pin 85 | DACK1 — DMA Acknowledge 1 |
| Pin 86 | DON0 — DMA Done 0 |
| Pin 87 | DON1 — DMA Done 1 |
| Pin 88 | RAS0 — DRAM Row Address Strobe 0 |
| Pin 89 | RAS1 — DRAM Row Address Strobe 1 |
| Pin 90 | CAS0 — DRAM Column Address Strobe 0 |
| Pin 91 | CAS1 — DRAM Column Address Strobe 1 |
| Pin 92 | WE — DRAM Write Enable |
| Pin 93 | OE — Output Enable |
| Pin 94 | AVEC — Autovector (active low) |
| Pin 95 | FC0 — Function Code 0 |
| Pin 96 | FC1 — Function Code 1 |
| Pin 97 | FC2 — Function Code 2 |
| Pin 98 | SIZE — Bus Size (0=8-bit, 1=16-bit) |
| Pin 99 | DSACK0 — Data Size Acknowledge 0 |
| Pin 100 | DSACK1 — Data Size Acknowledge 1 |
| Pin 101 | BERR — Bus Error (active low) |
| Pin 102 | VCC — +5 V power supply |
| Pin 103 | GND — Ground |
| Pin 104 | A20 — Address bus bit 20 |
| Pin 105 | A21 — Address bus bit 21 |
| Pin 106 | A22 — Address bus bit 22 |
| Pin 107 | A23 — Address bus bit 23 |
| Pin 108 | TXD_SMC1 — SMC1 Transmit Data |
| Pin 109 | RXD_SMC1 — SMC1 Receive Data |
| Pin 110 | TXD_SMC2 — SMC2 Transmit Data |
| Pin 111 | RXD_SMC2 — SMC2 Receive Data |
| Pin 112 | RTS_SMC1 — SMC1 Request To Send |
| Pin 113 | CTS_SMC1 — SMC1 Clear To Send |
| Pin 114 | VCC — +5 V power supply |
| Pin 115 | GND — Ground |
| Pin 116 | P8 — Parallel I/O Port bit 8 |
| Pin 117 | P9 — Parallel I/O Port bit 9 |
| Pin 118 | P10 — Parallel I/O Port bit 10 |
| Pin 119 | P11 — Parallel I/O Port bit 11 |
| Pin 120 | P12 — Parallel I/O Port bit 12 |
| Pin 121 | P13 — Parallel I/O Port bit 13 |
| Pin 122 | P14 — Parallel I/O Port bit 14 |
| Pin 123 | P15 — Parallel I/O Port bit 15 |
| Pin 124 | IRQ1 — External Interrupt 1 |
| Pin 125 | IRQ2 — External Interrupt 2 |
| Pin 126 | IRQ3 — External Interrupt 3 |
| Pin 127 | IRQ4 — External Interrupt 4 |
| Pin 128 | IRQ5 — External Interrupt 5 |
| Pin 129 | IRQ6 — External Interrupt 6 |
| Pin 130 | IRQ7 — External Interrupt 7 |
| Pin 131 | VCC — +5 V power supply |
| Pin 132 | GND — Ground |
Typical Applications
MC68302CRC20C157 is suitable for 6 applications: ISDN Terminal Adapter, X.25 / Frame-Relay Packet Assembler-Disassembler (PAD), Multi-Port Industrial Serial Concentrator, T1/E1 Channel-Bank Control Processor, Legacy Telecom Line Card, Serial Protocol Bridge / Gateway.
ISDN Terminal Adapter
The MC68302CRC20C157's on-chip PCM highway and SCC channels map directly to ISDN basic-rate interface (BRI) U and S/T transceivers, removing the need for an external protocol framer. At 20 MHz the M68000 core sustains Layer 2 (D-channel LAPD) and Layer 3 (X.25/Q.931) call control concurrently with serial data flow. Placed between the line-interface transformer/codec and the host CPU, the part terminates the D-channel and presents a clean serial or parallel host interface, cutting BOM count by one or two ASICs. The 5 V supply matches legacy telecom card rails; 132-PGA socket mounting simplifies field service for installed base units. Trade-off: at 20 MHz there is no spare headroom for software-defined crypto or high-layer encapsulation, so newer designs use the higher-speed 25 MHz M68302 variants.
Recommended
X.25 / Frame-Relay Packet Assembler-Disassembler (PAD)
The MC68302CRC20C157's three SCCs each independently run HDLC/SDLC framing, which is exactly the bit-level requirement for X.25 LAPB and frame-relay LAPF links. The DMA controller pumps frames between the SCC FIFOs and host memory without CPU intervention, letting the 20 MHz core handle Layer 3 packet routing. Two SMC channels can drive console RS-232 plus a modem-control channel. Compared with a bare microcontroller, the integrated DMA and CRC engine save 30-50% of firmware complexity in legacy X.25 stacks. Drop the part into a 132-PGA socket on a backplane card, pair with a T1/E1 line interface unit, and the design is complete for a multi-port PAD.
Recommended
Multi-Port Industrial Serial Concentrator
Industrial routers and PLC concentrators need many async serial channels for SCADA RTUs; the MC68302CRC20C157's three SCCs plus two SMCs deliver five hardware-framed serial ports per device, enough for a small sub-station concentrator. The 5 V supply, -40 C to +85 C industrial temperature grade, and PGA socket form factor (field-replaceable) suit sub-station cabinets where downtime cost dominates. The M68000 core runs at 20 MHz, sustaining Modbus, DNP3, or IEC 60870-5 polling loops across five channels. Pair with external RS-485 transceivers and an Ethernet uplink ASIC for a complete industrial gateway. The 132-PGA footprint is larger than modern QFP alternatives, so PCB area grows.
Recommended
T1/E1 Channel-Bank Control Processor
In a T1/E1 channel bank, the MC68302CRC20C157 acts as the control processor that manages timeslot allocation and per-channel signaling across the backplane. Its PCM highway interface glues directly to the T1/E1 framer ASIC, and the SCC channels can carry out-of-band RS-232 maintenance links. The 20 MHz M68000 core is sufficient for timeslot-swap logic and SNMP/management stack on small banks. Power is straightforward 5 V, no special sequencing beyond the M68000 family standard. The 132-PGA package fits legacy channel-bank backplane card form factors that already define a PGA socket footprint.
Recommended
Legacy Telecom Line Card
The MC68302CRC20C157 ships in a 132-PGA package that is socket-compatible with installed telecom line-card bases, making it ideal for sparing and repair of legacy central-office equipment. The integrated SCC and SMC channels provide the per-line signaling and codec control needed for analog/POTS line cards. At 20 MHz the part handles ring-trip detection cadence, hook-switch polling, and PCM timeslot steering. The 5 V supply matches the -48 V telecom bus standard after DC-DC conversion. Most importantly, Rochester Electronics sustains the part for exactly this kind of installed-base repair scenario, so procurement is reliable.
Recommended
Serial Protocol Bridge / Gateway
The MC68302CRC20C157 can serve as a transparent protocol bridge between async UARTs and HDLC/SDLC links, translating framing in hardware rather than software. This is useful for industrial gateways that need to convert Modbus RTU (UART) into Modbus TCP over HDLC-derived serial links, or for legacy serial concentrators facing SDLC-based SCADA masters. The 20 MHz core handles routing tables, the SCC channels run the HDLC framing, and an external MAC connects upstream Ethernet. The 132-PGA footprint is bulkier than modern QFP MCU options but acceptable for fixed-form-factor gateway chassis.
Recommended
Recommended Products Summary
Engineering reference data for MC68302CRC20C157 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MC68302CRC20C | MC68302CFC20 | MC68302CRC16C | MC68302CRC25C | MC68302PV20C |
|---|---|---|---|---|---|---|
| Package | 132-PGA (39.63x39.63 mm) | 132-PGA (39.63x39.63 mm) - same | 132-PGA (39.63x39.63 mm) - same | 132-PGA (39.63x39.63 mm) - same | 132-PGA (39.63x39.63 mm) - same | 132-PGA (39.63x39.63 mm) - same |
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Core Frequency | 20 MHz | 20 MHz | 20 MHz | 16 MHz (-20%) | 25 MHz (+25%) | 20 MHz |
| Core | M68000 | M68000 | M68000 | M68000 | M68000 | M68000 |
| Bus Width | 8/16-bit selectable | 8/16-bit selectable | 8/16-bit selectable | 8/16-bit selectable | 8/16-bit selectable | 8/16-bit selectable |
| SCC Channels | 3 | 3 | 3 | 3 | 3 | 3 |
| SMC Channels | 2 | 2 | 2 | 2 | 2 | 2 |
| Package Material | Ceramic PGA | Ceramic PGA | Ceramic PGA | Ceramic PGA | Ceramic PGA | Plastic PGA |
| Supply Voltage | 5 V | 5 V | 5 V | 5 V | 5 V | 5 V |
| Lifecycle | NRND (sustained for legacy) | NRND | NRND | NRND | NRND | NRND |
Key Differentiators
- Integrated hardware protocol engine offloads CPU (vs MC68302CRC16C)
- Higher-speed 25 MHz option for headroom (vs MC68302CRC25C)
- Ceramic PGA for industrial/extended reliability (vs MC68302PV20C)
- NXP (post-Freescale) sustained production (vs MC68302CRC20C (predecessor label))
Design Notes
The 132-PGA package is through-hole only and not reflow-solderable on standard SMT lines; plan for a PGA socket (e.g., machine-pin or low-insertion-force socket) or hand-soldered through-hole assembly to enable field replacement. The 39.63 mm x 39.63 mm body requires significant PCB real estate compared with QFP alternatives - verify mechanical clearance against neighboring tall components. PGA pin-grid assignments follow the M68000 family convention; consult the package outline drawing for the exact pin-1 orientation and pad layout. Estimated: at 20 MHz the 132-PGA decoupling is critical; place 100 nF ceramic bypass caps within 5 mm of every VCC/GND pin pair on the IC's footprint.
The MC68302CRC20C157 requires the M68000-family power-sequencing discipline: VCC must ramp monotonically to 5 V with RESET held low until the supply stabilizes for at least 100 ms, otherwise the M68000 core may latch up or fetch from an invalid program address. The 5 V rail should be sourced from a low-impedance regulator (LDO or 7805-class) with bulk decoupling of at least 22 uF and 100 nF ceramic near each VCC pin. Estimated: at 20 MHz with all SCCs active and DMA running, worst-case supply current is around 250 mA; budget 500 mA headroom for in-rush and transient loading.
The 8/16-bit external data bus must be length-matched within 10 mm across D0-D15 to avoid skew at 20 MHz; route address and data buses over a continuous ground plane to minimize crosstalk into the SCC transmit lines. Place the system clock trace short and guarded by ground pour to prevent the 20 MHz fundamental from coupling into adjacent analog sections. The SCC serial lines (TXD/RXD) should be routed as 50-ohm controlled-impedance pairs when driving external cables. Estimated: total bus-cycle time at 20 MHz is 50 ns, so peripheral logic must respond within four clock cycles (DTACK) or the system will insert wait states that halve throughput.
Do not confuse MC68302 variants: the MC68302CRC20C157 differs from the MC68EN302 (Ethernet variant), MC68360 (different family with QUICC engine), and MC68SEC000 (lower-end 8/16/32-bit core). Always verify the exact MPN string when ordering spares because family members are NOT cross-compatible in firmware. Common mistake is treating the on-chip RISC communications processor as software-configurable when in fact the SCC mode registers must be programmed in a specific order during initialization to avoid spurious FIFO flags. Also note that legacy 5 V parts may need re-validation for modern EMC/ESD compliance when dropped into new chassis.
Compliance Information
MC68302CRC20C157 is a legacy 5 V ceramic PGA part designed in the pre-RoHS era; the original silicon is not RoHS compliant per the M68302 family datasheet. Lead-free and RoHS-compliant variants exist within the M68302 family but the C157 suffix variant was not flagged RoHS in the Verified Web Data. The part is not AEC-Q100 qualified (it is a legacy telecom part, not an automotive MCU). Compliance values marked unknown - request a C of C from Rochester Electronics before any new procurement.
