PIC17C42A-25I/L - 8-Bit 25MHz OTP MCU, 4KB 44-PLCC | Microchip
MPN: PIC17C42A-25I/L ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $12.5 | $12.50 |
| 10 | $11.2 | $112.00 |
| 100 | $9.85 | $985.00 |
| 500 | $8.5 | $4,250.00 |
| 1,000 | $7.2 | $7,200.00 |
PIC17C42A-25I/L Overview
A microcontroller (MCU) is a single-chip computer containing a CPU core, program and data memory, peripherals, and I/O. The PIC17C family was Microchip's first 8-bit architecture to exceed the 4 MHz limit of the legacy PIC16C5X line, adding a hardware multiplier, expanded instruction set (58 single-word instructions), and an upgraded interrupt controller. Within Microchip's broader taxonomy, the PIC17C42A sits between PIC16C mid-range parts and PIC18 enhanced devices, and is upwards-compatible with the PIC16C5X, PIC12CXXX, and PIC16CXX instruction sets.
Key features include 4KB OTP program memory, 232 bytes of general-purpose RAM, 33 I/O pins, an 8-bit timer/counter, an analog comparator, a watchdog timer, and a 25 MHz external oscillator interface. Industrial temperature range and CMOS low-power design make the part well-suited to embedded control applications requiring deterministic execution.
The PIC17C42A uses a 14-bit instruction word stored in OTP EPROM. The architecture separates program and data buses (Harvard) and provides a 16-level hardware stack, two hardware interrupts, and up to 8 software interrupts, enabling responsive real-time control. The ALU performs single-cycle arithmetic and logical operations; a hardware 8x8 multiplier accelerates math.
Typical applications include industrial control, motor drive interfacing, sensor conditioning front-ends, smart instrumentation, white-goods control boards, and embedded legacy systems where PIC16C5X upward compatibility is required. Microchip recommends migrating to the PIC18F4220 for new designs, as the PIC17C42A has been replaced by modern flash-based PIC18 parts.
When designing with this device, note that OTP memory is one-time programmable; firmware bugs cannot be patched without replacing the silicon. A crystal or resonator up to 25 MHz must be supplied externally, and decoupling capacitors must be placed close to VDD/VSS pins for reliable operation.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not consolidated in the manufacturer datasheet, helping engineers evaluate supply-chain options for this mature PIC17C part.
Drop-in alternatives for PIC17C42A-25I/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-25I/L (same form factor and footprint) — differing in Operating Temperature Range, Oscillator Type, Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC17C42A-25I/PQ
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C44-25I/L
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C42A-25/L
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C42A-16/L
✅ Drop-In✓ In Stock
$8.3 / Unit
View Datasheet →PIC17C42A-25E/L
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$8.5 / Unit
View Datasheet →PIC17C42A-25I/L Maximum Ratings & Electrical Characteristics
| Core | PIC17C (8-bit) |
| Program Memory | 4 KB (2K x 16) OTP EPROM |
| RAM | 232 bytes |
| Maximum CPU Speed | 25 MHz (8.25 MIPS) |
| Instruction Cycle | 121 ns |
| Number of I/O Pins | 33 |
| Watchdog Timer | Yes |
| Oscillator Type | External (crystal/resonator) |
| Operating Temperature Range | -40C to +85C (Industrial) |
| Package | 44-PLCC (16.59 x 16.59 mm, J-Lead) |
| Mounting Type | Surface Mount |
| MSL Level | 3 (per Microchip packaging spec) |
| Programmability | OTP (One-Time Programmable) |
| Instruction Set | 58 single-word instructions (PIC17C) |
| Stack Depth | 16 levels (hardware) |
| Pin Count | 44 |
| Supply Chain Risk | Low-Med (per TrustedParts) |
PIC17C42A-25I/L Pin Configuration
| Pin 1 | RA0 — Port A bit 0 (digital I/O) |
| Pin 2 | RA1 — Port A bit 1 (digital I/O) |
| Pin 3 | RA2 — Port A bit 2 (digital I/O) |
| Pin 4 | RA3 — Port A bit 3 (digital I/O) |
| Pin 5 | RA4 — Port A bit 4 (digital I/O / T0CKI) |
| Pin 6 | RA5 — Port A bit 5 (digital I/O) |
| Pin 7 | RA6 — Port A bit 6 (digital I/O) |
| Pin 8 | RA7 — Port A bit 7 (digital I/O) |
| Pin 9 | OSC1 — External oscillator input |
| Pin 10 | OSC2 — External oscillator output |
| Pin 11 | VDD — Positive supply voltage |
| Pin 12 | VSS — Ground reference |
| Pin 13 | RB0 — Port B bit 0 (digital I/O / INT) |
| Pin 14 | RB1 — Port B bit 1 (digital I/O) |
| Pin 15 | RB2 — Port B bit 2 (digital I/O) |
| Pin 16 | RB3 — Port B bit 3 (digital I/O) |
| Pin 17 | RB4 — Port B bit 4 (digital I/O) |
| Pin 18 | RB5 — Port B bit 5 (digital I/O) |
| Pin 19 | RB6 — Port B bit 6 (digital I/O / PGC) |
| Pin 20 | RB7 — Port B bit 7 (digital I/O / PGD) |
| Pin 21 | RC0 — Port C bit 0 (digital I/O) |
| Pin 22 | RC1 — Port C bit 1 (digital I/O) |
| Pin 23 | RC2 — Port C bit 2 (digital I/O) |
| Pin 24 | RC3 — Port C bit 3 (digital I/O) |
| Pin 25 | RC4 — Port C bit 4 (digital I/O) |
| Pin 26 | RC5 — Port C bit 5 (digital I/O) |
| Pin 27 | RC6 — Port C bit 6 (digital I/O / TX) |
| Pin 28 | RC7 — Port C bit 7 (digital I/O / RX) |
| Pin 29 | RD0 — Port D bit 0 (digital I/O) |
| Pin 30 | RD1 — Port D bit 1 (digital I/O) |
| Pin 31 | RD2 — Port D bit 2 (digital I/O) |
| Pin 32 | RD3 — Port D bit 3 (digital I/O) |
| Pin 33 | RD4 — Port D bit 4 (digital I/O) |
| Pin 34 | RD5 — Port D bit 5 (digital I/O) |
| Pin 35 | RD6 — Port D bit 6 (digital I/O) |
| Pin 36 | RD7 — Port D bit 7 (digital I/O) |
| Pin 37 | VSS — Ground reference |
| Pin 38 | VDD — Positive supply voltage |
| Pin 39 | NC — Not connected (per datasheet) |
| Pin 40 | NC — Not connected (per datasheet) |
| Pin 41 | MCLR — Master clear (reset, active low) |
| Pin 42 | VPP — Programming voltage input |
| Pin 43 | T1CKI — Timer 1 clock input |
| Pin 44 | NC — Not connected (per datasheet) |
Typical Applications
PIC17C42A-25I/L is suitable for 6 applications: Industrial Process Control, Motor Drive Interface, Smart Instrumentation, White Goods Control Boards, Legacy Embedded System Maintenance, Sensor Conditioning Front-End.
Industrial Process Control
The PIC17C42A-25I/L fits industrial process controllers requiring deterministic real-time response and a wide industrial temperature range. Its 25 MHz clock delivers 121 ns instruction execution, enabling sub-microsecond interrupt latency for closed-loop PID control of temperature, pressure, or flow loops. The 33 I/O pins can drive sensors, indicator LEDs, and relay drivers without external mux chips, while the 4 KB OTP memory stores fixed control firmware. Its -40C to +85C rating suits factory-floor enclosures. Compared to legacy PIC16C5X parts, the PIC17C42A's hardware 8x8 multiplier accelerates scaling math for engineering-unit conversions, a tangible benefit over software loops running on slower MCUs.
Recommended
Motor Drive Interface
In brushed-DC and small stepper motor control boards, the PIC17C42A-25I/L's 25 MHz throughput supports commutation logic, PWM generation via firmware, and encoder feedback sampling without an external DSP. The 33 I/O lines can simultaneously drive H-bridge enable signals, sense current via comparators, and read Hall-effect sensors or quadrature encoders. The 232-byte RAM buffers trajectory tables, while the 4 KB OTP holds lookup tables for sinusoidal commutation profiles. Compared to a software-PWM loop on a slower PIC16C5X, the PIC17C42A's 8.25 MIPS headroom allows tighter current-loop control and faster fault response. Industrial temp rating supports motor enclosures.
Recommended
Smart Instrumentation
Bench and field instruments benefit from the PIC17C42A-25I/L's deterministic execution and 33 I/O pins for keypad scanning, LCD multiplexing, and analog front-end switching. Its 25 MHz clock and 121 ns cycle time enable precise timing of ADC reads and averaging routines, while the 232-byte RAM supports moving-window filters. The OTP architecture suits fixed-feature instruments (DMMs, calibrators) where code stability is paramount. The industrial -40C to +85C range supports laboratory and outdoor use. The hardware 8x8 multiplier accelerates RMS and scaling calculations versus software-emulated math on PIC16C5X devices.
Recommended
White Goods Control Boards
Washing machines, dishwashers, and microwave ovens have historically used PIC17C42A-25I/L MCUs for appliance control due to the part's reliability, deterministic timing, and industrial temperature range. The 33 I/O pins drive seven-segment displays, button matrices, relay coils, and buzzer drivers directly. The 4 KB OTP holds fixed appliance state machines, while the 232-byte RAM tracks cycle counters and user settings. The hardware watchdog timer ensures recovery from power-line glitches common in appliance environments. The OTP-only architecture aligns with cost-sensitive high-volume appliance production, where firmware is locked at programming time.
Recommended
Legacy Embedded System Maintenance
The PIC17C42A-25I/L is primarily used today to maintain existing production lines and field-deployed systems designed around this exact part. Its 44-PLCC form factor and PIC17C instruction set allow direct board-level replacement without firmware rewrite. The 25 MHz throughput preserves original timing budgets, and the 4 KB OTP and 232-byte RAM exactly match the original firmware's memory map. For long-lifecycle industrial, medical, or aerospace systems certified years ago, exact-form-fit-function continuity is mandatory, and the PIC17C42A-25I/L provides that. Aftermarket and franchised distributors stock the part for such maintenance scenarios.
Recommended
Sensor Conditioning Front-End
In sensor signal-conditioning and linearization boards, the PIC17C42A-25I/L runs polynomial correction, temperature compensation, and SPI/I2C communication with downstream ADCs or displays. The 25 MHz speed executes piecewise-linear interpolation across sensor curves within microseconds, supporting real-time correction at kHz sample rates. The 33 I/O pins accept raw sensor inputs and drive isolation or 4-20 mA loop outputs. The 232-byte RAM buffers compensation coefficients, while the 4 KB OTP stores the linearization tables. The industrial temperature range supports outdoor sensor installations, and the deterministic Harvard architecture ensures predictable interrupt latency for time-critical measurements.
Recommended
Recommended Products Summary
Engineering reference data for PIC17C42A-25I/L — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC17C42A-25I/PQ | PIC17C44-25I/L | PIC17C42A-25/L | PIC17C42A-16/L | PIC17C42A-25E/L |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-PLCC (L) | 44-TQFP (PQ) - NOT drop-in | 44-PLCC (L) - same | 44-PLCC (L) - same | 44-PLCC (L) - same | 44-PLCC (L) - same |
| Program Memory | 4 KB OTP | 4 KB OTP | 8 KB OTP | 4 KB OTP | 4 KB OTP | 4 KB OTP |
| RAM | 232 bytes | 232 bytes | 454 bytes | 232 bytes | 232 bytes | 232 bytes |
| Maximum Frequency | 25 MHz | 25 MHz | 25 MHz | 25 MHz | 16 MHz (-36%) | 25 MHz |
| I/O Pins | 33 | 33 | 33 | 33 | 33 | 33 |
| Temperature Range | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | 0C to +70C (Commercial) | -40C to +85C (Industrial) | -40C to +125C (Extended) |
| Programmability | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM |
Key Differentiators
- Larger program and RAM memory in same package (vs PIC17C42A-25/L)
- Drop-in memory upgrade for legacy designs (vs PIC17C44-25I/L)
- Extended temperature variant for harsh environments (vs PIC17C42A-25E/L)
Design Notes
The PIC17C42A uses One-Time-Programmable (OTP) EPROM, so firmware bugs cannot be patched in-circuit. Always verify firmware on a windowed or flash-equivalent prototype before committing to OTP production volumes. Microchip recommends migrating to flash-based PIC18F4220 for new designs to enable in-field updates and faster iteration cycles. Programming requires a 13V Vpp supply applied to the VPP pin through a high-voltage programmer (PM3, PICSTART Plus, or equivalent).
Decouple the PIC17C42A-25I/L with 100 nF ceramic capacitors placed within 5 mm of each VDD/VSS pin pair; the 44-PLCC exposes two VDD (pins 11, 38) and two VSS (pins 12, 37) pins for low-impedance supply distribution. Add a bulk 10 uF tantalum or aluminum electrolytic cap near the chip for transient suppression. The MCU's CMOS design draws low quiescent current, but switching many I/O simultaneously creates dynamic current spikes that must be smoothed by the decoupling network. Per Microchip datasheet DS30412C, the VDD range is 4.5V to 6.0V (5V nominal).
The PIC17C42A-25I/L's CMOS architecture generates minimal self-heating; junction temperature is dominated by ambient temperature and I/O switching load. Industrial-grade parts are rated -40C to +85C; derate high-frequency operation (25 MHz) at the upper end of the temperature range if many I/O toggle simultaneously. Estimated: at 25 MHz with 33 I/O at 20 pF load each, dynamic power dissipation is approximately 50-80 mW, well within the 44-PLCC thermal envelope (theta_JA ~50 C/W typical).
Route the OSC1/OSC2 traces to the crystal or resonator as short and symmetric as possible, with a ground guard ring to suppress noise coupling into the clock. Keep clock traces away from switching I/O lines and high-current traces. Place the MCLR pull-up resistor (typically 10 kohm) close to the MCLR pin with a 100 nF cap to ground for noise filtering. Reserve the VPP pin connection for the programming header, or float it with a small cap if not used in-circuit. Refer to Microchip datasheet DS30412C for recommended PCB layout guidelines.
Compliance Information
RoHS/REACH compliance not explicitly stated in verified web data. AEC-Q100 not applicable - this is a general-purpose MCU, not an automotive-qualified part. Refer to Microchip product page or contact manufacturer for up-to-date compliance documentation.
