PIC18C601T-I/PT - 8-bit 25MHz ROM-less MCU, TQFP-64 | Microchip
MPN: PIC18C601T-I/PT ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.16 | $5.16 |
| 10 | $4.65 | $46.50 |
| 100 | $4.14 | $414.00 |
| 500 | $3.73 | $1,865.00 |
| 1,000 | $3.32 | $3,320.00 |
PIC18C601T-I/PT Overview
What is a ROM-less microcontroller? A ROM-less microcontroller is an MCU variant that ships without on-chip non-volatile program memory, exposing an external memory bus so the firmware can reside in external parallel EPROM, Flash, or SRAM. This category sits within the broader PIC18 family hierarchy (PIC18 ROM-less -> PIC18 -> PIC microcontrollers -> 8-bit MCU -> microcontroller -> embedded processor) and is preferred when the application code exceeds internal Flash budgets, when the firmware must be field-upgradable, or when emulation/development requires swapping memory devices.
Key features of the PIC18C601 include 1.5 KB (1536 bytes) of general-purpose RAM, 26 digital I/O pins, a hardware external memory bus capable of addressing up to 2 MB of external code space, and the standard PIC18 peripheral set (timers, USART, I2C/SPI, capture/compare/PWM, and 10-bit ADC channels). The part uses the enhanced PIC18 instruction set with 16-bit wide instructions and an 8-bit data path, achieving single-cycle execution for most instructions.
Architecturally, the PIC18C601 integrates a 16-bit program counter with a 21-bit external addressing capability, an 8-level hardware stack, and a priority interrupt controller. Because the device has no internal program memory, every fetch is routed through the external bus controller, which adds deterministic latency and simplifies in-circuit emulation by substituting the external memory device with a debugger.
Typical applications include industrial automation controllers, motor-drive front-end logic, large-state-machine instrumentation, and educational or development platforms where the external bus is leveraged for code visibility. It is also used in legacy 5 V-only designs where the original PIC18C601 has been qualified for production.
When designing with the PIC18C601, plan the external memory interface (address latch, bus timing, wait states) and verify the 5 V-only I/O constraints against your sensor and bus levels; the part has no on-chip Flash and cannot boot from internal memory.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, with citations to the verified Microchip datasheet.
Drop-in alternatives for PIC18C601T-I/PT — 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 PIC18C601T-I/PT (same form factor and footprint) — differing in Operating Temperature, Package, Program Memory Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC18C601-I/PT
✅ Drop-In✓ In Stock
$6.08 / Unit
View Datasheet →PIC18C601T-I/PT Maximum Ratings & Electrical Characteristics
| Core | PIC18 8-bit RISC |
| Program Memory Type | ROM-less (external memory bus) |
| Maximum Clock Frequency | 25 MHz |
| Supply Voltage (Vdd) | 5 V |
| RAM Size | 1.5 KB (1536 bytes) |
| Number of I/O Pins | 26 |
| External Memory Bus | Yes, 21-bit address (up to 2 MB external code) |
| ADC | 10-bit (per PIC18C601 family) |
| Package | TQFP-64 (PT), 10 mm x 10 mm x 1.0 mm, MS-026 |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (Industrial) |
| Peripherals | Timers, USART, I2C, SPI, CCP, ADC |
| Data Bus Width | 8-bit |
| Instruction Set | Enhanced PIC18 (16-bit instructions, 8-bit data) |
PIC18C601T-I/PT tqfp-64 (pt), 10 mm x 10 mm x 1.0 mm, ms-026 Pin Configuration Guide
Pin configuration for PIC18C601T-I/PT (tqfp-64 (pt), 10 mm x 10 mm x 1.0 mm, ms-026 package). This digital IC includes GPIO, communication interfaces (UART, SPI, I2C), and power pins. Refer to the manufacturer datasheet for alternate pin functions and configuration options. Essential for embedded system design and PCB layout.
No detailed pinout data available for PIC18C601T-I/PT.
Refer to the datasheet for full pin configuration.
Typical Applications
PIC18C601T-I/PT is suitable for 6 applications: Industrial Automation Controller, Motor Drive Front-End Logic, Test and Measurement Instrumentation, Embedded Development Platform / Emulation Target, Large State-Machine Controllers, Educational and Legacy 5 V Embedded Designs.
Industrial Automation Controller
The PIC18C601T-I/PT fits industrial automation controllers thanks to its 25 MHz PIC18 core, 26 I/O lines, and external memory bus capable of addressing up to 2 MB of program memory. The 5 V-only I/O matches legacy 5 V industrial sensors and actuator drivers without level shifters, while the -40C to +85C industrial temperature rating suits factory-floor enclosures. In a typical PLC or distributed-I/O module, the part drives opto-isolated outputs, reads digital inputs via interrupts, and uses the external memory bus to hold large state-machine tables in parallel EPROM. Its single-cycle PIC18 instruction set keeps deterministic loop timing for motor and solenoid control loops.
Recommended
Motor Drive Front-End Logic
The PIC18C601T-I/PT serves as the front-end logic controller in stepper and BLDC motor-drive stages where deterministic interrupt latency is more important than Flash memory. The PIC18 core's 8-level hardware stack and 25 MHz instruction rate let the firmware execute a 4-axis step sequencer in well under 10 us, while the external memory bus holds large motion-profile tables in EPROM. The 26 digital I/Os map directly to step/direction/enable pairs, current-sense comparators, and Hall-effect encoder inputs. The 5 V CMOS I/O interfaces cleanly to standard opto-coupler and gate-driver inputs common in motor power stages.
Recommended
Test and Measurement Instrumentation
The PIC18C601T-I/PT is well suited to legacy test and measurement instruments where the external memory bus holds large calibration lookup tables and waveform descriptors. The 25 MHz core, 10-bit ADC, and CCP modules generate PWM stimulus signals and capture sensor responses with predictable timing. The ROM-less architecture allows the engineer to swap firmware via an external EPROM socket during development, accelerating instrument calibration cycles. The 5 V I/O level integrates directly with legacy analog front-ends built around 5 V op-amps and CMOS analog switches.
Recommended
Embedded Development Platform / Emulation Target
The PIC18C601T-I/PT functions as an excellent target MCU for in-circuit emulation because the ROM-less architecture exposes every instruction fetch on the external memory bus. An emulator probe can substitute an external SRAM containing the firmware image, providing real-time debugging without on-chip Flash limitations. The 25 MHz clock rate allows debugging of time-critical sections of code, and the 64-pin TQFP package is breadboard-friendly with standard 0.5 mm-pitch adapters. This application pattern was widely used in PIC18C-era educational and prototyping tools.
Recommended
Large State-Machine Controllers
The PIC18C601T-I/PT's external memory bus can address up to 2 MB of program space, which is ideal for implementing large state machines with thousands of states and transitions that would never fit in on-chip Flash. In vending-machine controllers, access-control panels, and industrial sequencers, the firmware is held in EPROM and the 1.5 KB of internal RAM provides the working variables. The hardware 8-level stack keeps nested-state call overhead minimal, while the PIC18 instruction set provides bit-manipulation primitives useful for compact state encoding.
Recommended
Educational and Legacy 5 V Embedded Designs
The PIC18C601T-I/PT is a teaching-friendly MCU because its 5 V-only I/O, simple external memory bus, and 64-pin TQFP footprint all map cleanly onto introductory 8-bit microcontroller courses. Students can program external EPROMs with simple C or assembly tools and observe fetch cycles on a logic analyzer. The part remains popular in legacy 5 V systems - medical monitors, factory-floor HMIs, and military/aerospace retrofits - where re-designing around a 3.3 V Flash MCU would invalidate decades of qualification testing. The 5 V-tolerant I/O and industrial temperature grade cover most of these application spaces.
Recommended
Recommended Products Summary
Engineering reference data for PIC18C601T-I/PT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC18C601-I/PT |
|---|---|---|
| Package | TQFP-64 (PT) 10x10mm | TQFP-64 (PT) 10x10mm - same |
| Brand | Microchip Technology | Microchip Technology |
| Core | PIC18 8-bit RISC | PIC18 8-bit RISC |
| Max Clock Frequency | 25 MHz | 25 MHz |
| RAM Size | 1.5 KB | 1.5 KB |
| Program Memory | ROM-less (external bus, up to 2 MB) | ROM-less (external bus, up to 2 MB) |
| Number of I/O Pins | 26 | 26 |
| Supply Voltage | 5 V | 5 V |
| Operating Temperature | -40C to +85C (Industrial) | -40C to +85C (Industrial) |
| Shipping Format | Tape & Reel | Tray |
Key Differentiators
- True pin-compatible drop-in available in alternative packaging (vs PIC18C601-I/PT)
- ROM-less architecture exposes full external memory bus (vs PIC18F452 (Flash-equipped PIC18))
- Industrial temperature grade and 5 V I/O for legacy compatibility (vs PIC18F67J11-I/PT (3.3 V Flash part))
Design Notes
The PIC18C601T-I/PT requires a regulated 5 V supply capable of delivering the core and I/O currents. Estimated: with all 26 I/O lines sourcing 20 mA, the Vdd pin can draw 520 mA from the regulator. Use a low-dropout regulator with at least 10% headroom and bulk decoupling of 100 uF electrolytic plus 0.1 uF ceramic close to each Vdd/Vss pair.
Because the part is ROM-less, the external memory bus (address latch, data bus, read/write strobes) must be routed with matched trace lengths and 22-33 ohm series damping resistors to suppress ringing. The address latch (typically a 74HC573) should be placed within 25 mm of the MCU; the EPROM or Flash memory should sit within 50 mm. Keep the external clock trace short and shield it with a ground guard trace.
Do not assume the PIC18C601T-I/PT can boot from internal memory - it cannot. A valid external memory device (EPROM, Flash, or SRAM with firmware) must be present at POR, otherwise the part will execute garbage or stall. Also note that the PIC18C601 is a one-time-programmable family; modern PIC18F Flash parts share the instruction set but require re-compilation of firmware with a Flash-aware toolchain (MPLAB XC8).
Estimated: at 25 MHz with all I/O toggling, the PIC18C601T-I/PT dissipates roughly 250 mW internally; the TQFP-64 package has a theta_JA around 50 C/W on a standard 4-layer JEDEC test board, giving a 12C junction rise above ambient. This is well within the 85C industrial limit, but in enclosed housings derate to 70C ambient to be safe.
Compliance Information
RoHS, REACH, lead-free, and halogen-free status for the PIC18C601T-I/PT are not explicitly stated in the verified web data and are marked [DATA_NEEDED]. PIC18C-era parts were generally not RoHS-compliant; engineers should verify the part marking before use in RoHS designs.
