PIC17C42A-25E/L - 8-Bit 25MHz OTP MCU 4KB PLCC | Microchip
MPN: PIC17C42A-25E/L ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $13.97 | $13.97 |
| 10 | $12.45 | $124.50 |
| 100 | $10.85 | $1,085.00 |
| 500 | $9.6 | $4,800.00 |
| 1,000 | $8.5 | $8,500.00 |
PIC17C42A-25E/L Overview
An 8-bit microcontroller is a small, self-contained computing element built around an 8-bit data bus and Harvard architecture. The PIC17C42A family sits between baseline PIC16C5X and enhanced PIC16CXX devices in the Microchip PIC hierarchy: PIC16C5X (12-bit instructions, OTP/ROM) -> PIC17C42A (16-bit instructions, OTP, 8.25 MIPS) -> PIC18F (16-bit instructions, Flash, >10 MIPS). It uses a RISC core with only 58 single-word instructions, yet offers significantly more horsepower than earlier PIC16 devices, making it suitable for applications that need real-time response without moving to the PIC18 platform.
Key features include a 25 MHz external clock, an 8-level hardware stack, multiple interrupt sources, two 8-bit timer/counters, a 16-bit timer/counter, a synchronous serial port (SSP) supporting SPI/I2C master modes, an 8-bit parallel slave port, and a USART. The device is built on a low-power CMOS process and operates from 4.5 V to 5.5 V. Compared with later PIC18F devices, PIC17C42A offers a wider supply tolerance and a robust 8-bit ALU optimized for byte-oriented control.
Typical applications include industrial control logic, motor control, automotive body electronics, point-of-sale terminals, security panels, and embedded instrumentation. Per Microchip, the recommended migration path is PIC18F4220 - new designs should generally not start on PIC17C42A.
When designing with PIC17C42A-25E/L, note that it is OTP, not Flash - firmware cannot be re-programmed in-circuit. Use the 'E' windowed (UV-erasable) or emulator variants for prototyping. The 44-PLCC footprint is common with PIC17C43/44 devices, allowing pin-compatible upgrades within the family.
Drop-in alternatives for PIC17C42A-25E/L — 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 PIC17C42A-25E/L (same form factor and footprint) — differing in Operating Temperature Range, Oscillator Type, Package, Program Memory Size, Program Memory Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC17C42A-25I/L
✅ Drop-In✓ In Stock
$7.2 / Unit
View Datasheet →PIC17C43-25E/L
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$9.78 / Unit
View Datasheet →PIC17C44-25E/L
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC17C42A-25E/P
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$5.6 / Unit
View Datasheet →PIC17C42A-25E/L Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC |
| Instruction Set Width | 16-bit (58 single-word instructions) |
| Maximum Clock Frequency | 25 MHz |
| Performance | 8.25 MIPS (121 ns instruction cycle) |
| Program Memory Size | 4 KB (2K x 16), OTP EPROM |
| RAM Size | 232 x 8 bytes (454 bytes user RAM) |
| Number of I/O Pins | 33 |
| Package | 44-PLCC (J-Lead), 16.59 x 16.59 mm |
| Mounting Type | Surface Mount |
| Oscillator Type | External |
| Supply Voltage (Vcc) | 4.5 V to 5.5 V |
| Operating Temperature Range | -40 C to +85 C (E suffix = industrial) |
| Program Memory Type | OTP EPROM (one-time programmable) |
| Hardware Stack | 8 levels |
| Peripherals | SSP (SPI/I2C), USART, 8-bit Parallel Slave Port, 2x 8-bit + 1x 16-bit Timer |
| RoHS Status | Non-compliant (SnPb finish, PLCC windowed ceramic variant exempt) |
| Legacy Replacement Recommendation | PIC18F4220 |
PIC17C42A-25E/L Pin Configuration
| Pin 1 | RA0/INT — PORTA bit 0 / external interrupt input |
| Pin 2 | RA1 — PORTA bit 1 |
| Pin 3 | RA2 — PORTA bit 2 |
| Pin 4 | RA3 — PORTA bit 3 |
| Pin 5 | RA4/RTCC — PORTA bit 4 / RTCC I/O |
| Pin 6 | RA5 — PORTA bit 5 |
| Pin 7 | RA6 — PORTA bit 6 |
| Pin 8 | RA7 — PORTA bit 7 |
| Pin 9 | RB0 — PORTB bit 0 |
| Pin 10 | RB1 — PORTB bit 1 |
| Pin 11 | RB2 — PORTB bit 2 |
| Pin 12 | RB3 — PORTB bit 3 |
| Pin 13 | OSC1 — Oscillator input (external clock) |
| Pin 14 | OSC2 — Oscillator output (crystal) |
| Pin 15 | RC0 — PORTC bit 0 |
| Pin 16 | RC1 — PORTC bit 1 |
| Pin 17 | RC2 — PORTC bit 2 |
| Pin 18 | RC3 — PORTC bit 3 |
| Pin 19 | RC4 — PORTC bit 4 |
| Pin 20 | RC5 — PORTC bit 5 |
| Pin 21 | RC6 — PORTC bit 6 |
| Pin 22 | RC7 — PORTC bit 7 |
| Pin 23 | RD0 — PORTD bit 0 / PSP |
| Pin 24 | RD1 — PORTD bit 1 / PSP |
| Pin 25 | RD2 — PORTD bit 2 / PSP |
| Pin 26 | RD3 — PORTD bit 3 / PSP |
| Pin 27 | RD4 — PORTD bit 4 / PSP |
| Pin 28 | RD5 — PORTD bit 5 / PSP |
| Pin 29 | RD6 — PORTD bit 6 / PSP |
| Pin 30 | RD7 — PORTD bit 7 / PSP |
| Pin 31 | RE0 — PORTE bit 0 |
| Pin 32 | RE1 — PORTE bit 1 |
| Pin 33 | VSS — Ground |
| Pin 34 | VDD — Positive supply (4.5-5.5 V) |
| Pin 35 | RE2 — PORTE bit 2 |
| Pin 36 | RE3 — PORTE bit 3 |
| Pin 37 | RF0 — PORTF bit 0 |
| Pin 38 | RF1 — PORTF bit 1 |
| Pin 39 | RF2 — PORTF bit 2 |
| Pin 40 | RF3 — PORTF bit 3 |
| Pin 41 | RF4 — PORTF bit 4 |
| Pin 42 | RF5 — PORTF bit 5 |
| Pin 43 | RB7/PGM — PORTB bit 7 / low-voltage programming |
| Pin 44 | RB6/PGC — PORTB bit 6 / ICSP clock |
Typical Applications
PIC17C42A-25E/L is suitable for 6 applications: Industrial Control Logic, Motor Control (BLDC/Stepper), Point-of-Sale Terminals, Security and Alarm Panels, Automotive Body Electronics, Embedded Instrumentation.
Industrial Control Logic
The PIC17C42A-25E/L is well suited to industrial control logic where deterministic real-time response is required. Its 25 MHz core delivers 8.25 MIPS (121 ns instruction cycle), giving the headroom to scan I/O and execute PID-style control loops within tight millisecond budgets. The 33 digital I/O pins interface directly to 5 V industrial sensors, relays, and triac drivers, while the on-chip USART links to RS-485 transceivers for fieldbus-style wiring. OTP memory locks firmware against field tampering, which is desirable in factory-automation equipment. The 4.5-5.5 V supply tolerance tolerates loosely regulated 5 V industrial rails. Note that new designs should migrate to PIC18F4220 for Flash in-field reprogrammability.
Recommended
Motor Control (BLDC/Stepper)
The PIC17C42A-25E/L can drive small BLDC and stepper motors via PWM generated in firmware or with external driver ICs. The 16-bit timer/counter provides the time base for closed-loop commutation, and the two 8-bit timers handle PWM channels. At 25 MHz / 8.25 MIPS the device sustains commutation update rates above 20 kHz, suitable for sub-100 W motors. Per Microchip datasheet DS30412C, the parallel slave port allows a host MCU to stream motion profiles into the PIC17C42A acting as a co-processor. The OTP memory is well suited to fixed motor-control firmware where the program is finalized at production.
Recommended
Point-of-Sale Terminals
The PIC17C42A-25E/L has been used historically in point-of-sale terminals where its OTP memory, 5 V I/O, and integrated USART support both magnetic-stripe readers and serial peripherals. The 232 x 8 RAM is sufficient to buffer transaction strings, and 4 KB OTP holds the fixed terminal application. The synchronous serial port (SSP) drives a small SPI display or keyboard scanner, while the parallel slave port connects to the host POS processor for command and response. Its 8.25 MIPS performance handles keystroke debounce and packet framing without DMA. Modern POS designs use Flash-based MCUs, so PIC17C42A is now seen mainly in legacy equipment sustaining existing fleets.
Recommended
Security and Alarm Panels
The PIC17C42A-25E/L is well matched to security panel applications: deterministic 8.25 MIPS performance guarantees scan loops run on schedule; OTP memory locks firmware to prevent field tampering; and 33 I/O easily accommodates 8-16 zone inputs plus keypad, siren, and dialer outputs. The integrated USART supports digital alarm communicators over the phone line via a modem chip. The parallel slave port enables a touchscreen or LCD module to share I/O with the panel CPU. PIC17C42A's wide 4.5-5.5 V supply tolerance works directly with lead-acid battery-backed 5 V rails common in fire and security panels. New security panels use Flash MCUs to enable remote firmware updates.
Recommended
Automotive Body Electronics
Automotive body controllers, HVAC panels, and instrument clusters historically employed PIC17C42A-25E/L at 25 MHz for deterministic control of relays, lamps, and displays. Its 5 V digital I/O is well matched to body-electronics drivers like the VNQ500 or BTS432E, while the on-chip timers and PWM channels drive stepper motors in instrument clusters. The 'I' temperature grade variant supports -40 C to +125 C ambient conditions. Note that modern automotive designs require AEC-Q100 qualification, which PIC17C42A does not carry; new automotive programs should use qualified Flash MCUs such as PIC18F4580-I/PT.
Recommended
Embedded Instrumentation
Embedded instrumentation such as bench-top meters, lab data loggers, and process controllers benefit from the PIC17C42A-25E/L's deterministic 8.25 MIPS core, USART, and parallel slave port. The USART connects to RS-232 instruments or RS-485 multi-drop networks; the parallel slave port interfaces to graphic LCD controllers or external data acquisition front-ends. 4 KB OTP comfortably stores fixed calibration tables and menu code, while 232 x 8 RAM buffers measurement strings. The wide 4.5-5.5 V supply tolerance works with unregulated instrumentation rails. Modern data loggers use Flash-based PIC18 or dsPIC parts, so PIC17C42A appears mainly in legacy instruments with stable firmware.
Recommended
Recommended Products Summary
Engineering reference data for PIC17C42A-25E/L — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC17C42A-25I/L | PIC17C43-25E/L | PIC17C44-25E/L | PIC17C42A-25E/P |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-PLCC (J-Lead) | 44-PLCC (J-Lead) - same | 44-PLCC (J-Lead) - same | 44-PLCC (J-Lead) - same | 40-PDIP (different package) |
| Program Memory | 4 KB OTP (2K x 16) | 4 KB OTP | 8 KB OTP | 16 KB OTP | 4 KB OTP |
| RAM | 232 x 8 | 232 x 8 | 454 x 8 | 454 x 8 | 232 x 8 |
| Clock Frequency | 25 MHz | 25 MHz | 25 MHz | 25 MHz | 25 MHz |
| Operating Temperature | -40 C to +85 C | -40 C to +125 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| Supply Voltage | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete |
Key Differentiators
- Drop-in PIC17 family member with extended industrial temperature grade (vs PIC17C42A-25I/L)
- Double the program memory in the same PLCC package (vs PIC17C43-25E/L)
- Quadruple program memory in same PLCC package (vs PIC17C44-25E/L)
Design Notes
PIC17C42A-25E/L is OTP - firmware cannot be re-programmed in-circuit. If there is any chance of firmware revision during development, use the JW windowed ceramic variant or a modern PIC18F4220 flash MCU instead. Programming requires a Microchip PIC17 programmer (e.g., PIC17C-PROG) targeting the LVP/PGC/PGM pins; the high-voltage parallel programming algorithm differs from PIC18.
Decouple VDD with a 0.1 uF ceramic capacitor placed within 1 cm of pin 34, plus a 10 uF bulk electrolytic or tantalum near the IC. The PIC17C42A datasheet recommends a 1k-ohm pull-up on MCLR with a 0.1 uF capacitor to VDD for proper power-on reset. Operating supply is 4.5 V to 5.5 V; under-voltage operation may cause program counter corruption in the 8-level hardware stack without raising an interrupt.
The 44-PLCC J-lead footprint has wider pads (about 0.045 in lead pitch) than QFP/QFN packages, so verify the PCB land pattern matches PLCC-44 rather than QFP-44 - they look similar but PLCC pads extend outward while QFP pads are inward-gullwing. Provide a generous copper pour under the PLCC socket for thermal spreading; the OTP die has moderate thermal resistance. Trace OSC1/OSC2 to a crystal/capacitor network within 1 cm; long oscillator traces pick up noise and cause instruction-cycle jitter.
Compliance Information
Microchip's OTP PLCC family uses SnPb lead finish and is generally not RoHS compliant; new designs should migrate to PIC18F4220 which is RoHS compliant. AEC-Q100 qualification not documented; choose PIC18F4580-I/PT for AEC-Q100 automotive programs.
