PIC17C42A-25/PQ - 25MHz 8-bit OTP MCU, 4KB, 44-MQFP | Microchip
MPN: PIC17C42A-25/PQ ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $13.03 | $13.03 |
| 10 | $11.85 | $118.50 |
| 100 | $10.2 | $1,020.00 |
| 500 | $8.95 | $4,475.00 |
| 1,000 | $7.8 | $7,800.00 |
PIC17C42A-25/PQ Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory, working RAM, and peripheral interfaces into one IC. The PIC17C family sits above the PIC16C/PIC12C in Microchip's 8-bit hierarchy and is upward-compatible with PIC16C5X, PIC12CXXX, and PIC16CXX devices. PIC17C42A extends the original PIC17C42 with architectural enhancements, providing 58 single-word instructions and a powerful RISC core aimed at high-throughput embedded control.
Key specifications include a 25 MHz maximum operating frequency, 8-bit data width with 16-bit instruction word, 4KB OTP program memory, 232 bytes data RAM, 33 I/O pins, and commercial operating temperature grade. The device uses a Harvard architecture with separate code and data buses, plus dedicated peripherals including timers, capture/compare/PWM modules, USART, and an 8-channel 10-bit (typical) A/D converter — making it suitable for mixed analog/digital control tasks.
Architecturally, PIC17C42A employs an enhanced 8-bit RISC pipeline with 16-bit instruction words and an 8-level deep hardware stack for fast context switching. The OTP program memory allows factory or production-line programming of a fixed code image, which is typical for cost-optimized mass production where firmware is stable. Brown-out reset, watchdog timer, power-on reset, and interrupt controller are integrated for robust embedded operation.
Typical applications include industrial control panels, motor control, instrumentation, HVAC controllers, security and alarm systems, and embedded sensor interfaces. The wide peripheral set also suits small-form factor human-machine interface (HMI) boards. The -25 speed grade supports time-critical control loops requiring deterministic 121 ns instruction execution.
When designing with this OTP device, remember that program memory is one-time programmable — firmware bugs cannot be patched in the field. Use a flash-based equivalent such as PIC18F4220 for prototypes, then port final code to the OTP PIC17C42A-25/PQ for production. Ensure in-circuit emulation or socket programming for development to avoid scrapping parts.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not found in the standalone manufacturer datasheet, helping engineers make a faster sourcing decision for legacy and maintenance designs.
Drop-in alternatives for PIC17C42A-25/PQ — 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-25/PQ (same form factor and footprint) — differing in Package, Mounting Type, Core Architecture, Data Bus Width, Program Memory Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC17C42A-16/PQ
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C42A-25I/PQ
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C43-25/PQ
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17CR42A-25/PQ
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C42A-25E/PQ
✅ Drop-In✓ In Stock
$9.86 / Unit
View Datasheet →PIC17C42A-25/PQ Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC RISC |
| Family | PIC17C |
| Maximum Clock Frequency | 25 MHz |
| Instruction Execution Time | 121 ns (8.25 MIPS) |
| Program Memory Type | OTP (One-Time Programmable) EPROM |
| Program Memory Size | 4 KB (2K x 16) |
| Data RAM | 232 bytes |
| I/O Pins | 33 |
| Data Bus Width | 8-bit |
| Instruction Word Width | 16-bit |
| Instruction Set Size | 58 single-word instructions |
| Package | 44-MQFP (10x10 mm) |
| Mounting Type | Surface Mount (Gull-Wing) |
| Operating Temperature Grade | Commercial |
| A/D Converter | 8-channel (per datasheet family) |
| RoHS Status | Compliant (per DigiKey listing) |
PIC17C42A-25/PQ Pin Configuration
| Pin 1 | MCLR/VPP — Master Clear (reset) input / Programming voltage |
| Pin 2 | OSC1/CLKIN — Oscillator crystal input / External clock input |
| Pin 3 | OSC2/CLKOUT — Oscillator crystal output / Clock output |
| Pin 4 | RA0/AN0 — PORTA bit 0 / Analog input 0 |
| Pin 5 | RA1/AN1 — PORTA bit 1 / Analog input 1 |
| Pin 6 | RA2/AN2 — PORTA bit 2 / Analog input 2 |
| Pin 7 | RA3/AN3/VREF — PORTA bit 3 / Analog input 3 / A/D reference |
| Pin 8 | RA4/AN4/T0CKI — PORTA bit 4 / Analog input 4 / Timer0 clock |
| Pin 9 | RA5/AN5 — PORTA bit 5 / Analog input 5 |
| Pin 10 | RA6/AN6 — PORTA bit 6 / Analog input 6 |
| Pin 11 | RA7/AN7 — PORTA bit 7 / Analog input 7 |
| Pin 12 | VDD — Positive supply voltage |
| Pin 13 | VSS — Ground |
| Pin 14 | RB0/INT — PORTB bit 0 / External interrupt |
| Pin 15 | RB1 — PORTB bit 1 |
| Pin 16 | RB2 — PORTB bit 2 |
| Pin 17 | RB3 — PORTB bit 3 |
| Pin 18 | RB4 — PORTB bit 4 |
| Pin 19 | RB5 — PORTB bit 5 |
| Pin 20 | RB6 — PORTB bit 6 |
| Pin 21 | RB7 — PORTB bit 7 |
| Pin 22 | RC0 — PORTC bit 0 |
| Pin 23 | RC1 — PORTC bit 1 |
| Pin 24 | RC2 — PORTC bit 2 |
| Pin 25 | RC3 — PORTC bit 3 |
| Pin 26 | RC4 — PORTC bit 4 |
| Pin 27 | RC5 — PORTC bit 5 |
| Pin 28 | RC6/TX/CK — PORTC bit 6 / USART TX / Clock |
| Pin 29 | RC7/RX/DT — PORTC bit 7 / USART RX / Data |
| Pin 30 | RD0 — PORTD bit 0 |
| Pin 31 | RD1 — PORTD bit 1 |
| Pin 32 | RD2 — PORTD bit 2 |
| Pin 33 | RD3 — PORTD bit 3 |
| Pin 34 | RD4 — PORTD bit 4 |
| Pin 35 | RD5 — PORTD bit 5 |
| Pin 36 | RD6 — PORTD bit 6 |
| Pin 37 | RD7 — PORTD bit 7 |
| Pin 38 | RE0/CCP1 — PORTE bit 0 / Capture Compare PWM 1 |
| Pin 39 | RE1/CCP2 — PORTE bit 1 / Capture Compare PWM 2 |
| Pin 40 | RE2 — PORTE bit 2 |
| Pin 41 | VDD — Positive supply voltage |
| Pin 42 | VSS — Ground |
| Pin 43 | NC — Not connected (per datasheet) |
| Pin 44 | NC — Not connected (per datasheet) |
Typical Applications
PIC17C42A-25/PQ is suitable for 6 applications: Industrial Control Panels, Motor Control and PWM Drives, HVAC and Building Automation Controllers, Security and Alarm Systems, Embedded Instrumentation and Data Acquisition, Appliance and White-Goods Control.
Industrial Control Panels
The PIC17C42A-25/PQ fits industrial control panel applications because its 25 MHz / 8.25 MIPS throughput (121 ns instruction execution) handles real-time control loops in PLC-style front-ends and HMI boards. The 33 digital I/O pins drive multiplexed key matrices, LED status indicators, relay banks, and 7-segment displays without external bus expanders, while the integrated 8-channel A/D converter reads analog sensor inputs such as temperature, pressure, and current sense. The 4KB OTP program memory holds substantial ladder-logic-equivalent or state-table code for panel firmware, and the 232 bytes RAM supports runtime flag reentry. Placed near optoisolated I/O drivers on the panel main board, the MCU provides deterministic scan times. Unlike flash MCUs, OTP requires factory programming, which is acceptable for high-volume production runs where firmware is stable.
Recommended
Motor Control and PWM Drives
PIC17C42A-25/PQ's integrated Capture/Compare/PWM (CCP) peripherals and 25 MHz throughput make it well-suited for small motor control boards such as DC, stepper, and BLDC drivers. The 121 ns instruction cycle supports high-resolution PWM generation at switching frequencies above 20 kHz — above the audible band — for quiet operation, while the 33 I/O drive Hall sensors, encoder feedback, gate-driver enable signals, and current-sense comparator outputs. The 8-channel 10-bit A/D converter samples motor phase currents for closed-loop torque control, and the integrated USART handles command interfaces to a host controller or DSP. With 4KB OTP and 232 bytes RAM, the MCU holds a full trapezoidal or sinusoidal commutation table plus speed PI loop. Best deployed on a 4-layer PCB with proper gate-driver ground separation; OTP programming locks firmware at factory, so field updates require MCU swap.
Recommended
HVAC and Building Automation Controllers
HVAC zone controllers and building-automation nodes benefit from PIC17C42A-25/PQ's 25 MHz core, 33 I/O, and integrated A/D converter. The MCU reads thermistor or RTD temperature inputs, humidity sensors, and pressure transducers via the 8-channel A/D while driving triac outputs for fans, dampers, and solenoid valves through its GPIO ports. The USART interfaces to a Modbus or BACnet transceiver, allowing the MCU to operate as a sub-node on a building automation bus. The 232-byte RAM comfortably holds scheduler state and PID loop variables, and the 4KB OTP supports full HVAC control firmware. The 44-MQFP package fits compact PCBAs inside thermostat backplates and rooftop unit controllers. Unlike flash parts, OTP enforces firmware version control, ideal for OEM high-volume HVAC production.
Recommended
Security and Alarm Systems
PIC17C42A-25/PQ is a strong fit for security alarm panels and PIR sensor nodes, where its 25 MHz core scans multiple zones and the integrated A/D reads battery voltage and analog sensor inputs. The 33 I/O pins connect to reed-switch zones, PIR detectors, keypad matrices, sirens, and relay outputs without external bus expanders, and the USART links to a central monitoring transceiver. The 4KB OTP holds substantial event-log and zone-configuration firmware, and 232 bytes RAM supports running event queues. Brown-out reset and watchdog timer maintain robust unattended operation across power events. Production-programmed OTP prevents firmware tampering in the field — a security advantage. Suitable for 16-zone wired panels in commercial installations.
Recommended
Embedded Instrumentation and Data Acquisition
Portable test and measurement instruments benefit from PIC17C42A-25/PQ's 25 MHz instruction throughput, 8-channel A/D converter, and 33 I/O pins. The MCU samples analog signals at deterministic intervals, drives LCD segment displays or character displays through GPIO, and manages keypad input via polled or interrupt-driven scans. The USART connects to a host PC or remote data logger for streaming acquired data. With 4KB OTP and 232 bytes RAM, the MCU handles basic DSP tasks such as running averages or peak detection directly on-chip. The 44-MQFP 10x10 mm package suits compact handheld instrument boards. OTP programming locks calibration constants, which is desirable for certifiable test equipment where firmware must remain tamper-free in production.
Recommended
Appliance and White-Goods Control
Major appliance controllers — washing machines, dishwashers, ovens, and induction cooktops — historically use PIC17C42A-25/PQ for its 25 MHz throughput, 33 I/O, and integrated A/D converter. The MCU drives triac-based load controls (motors, heaters, valves), reads temperature sensors via A/D, scans keypad or touch inputs, and drives display indicators. The 4KB OTP holds full appliance state machines including safety interlocks and fault diagnostics. The 232-byte RAM comfortably handles running mode state and timing variables, while the integrated watchdog timer and brown-out reset provide the robustness required for unattended appliance operation. Cost-optimized OTP suits the very high unit volumes of consumer appliances.
Recommended
Recommended Products Summary
Engineering reference data for PIC17C42A-25/PQ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC17C42A-16/PQ | PIC17C42A-25I/PQ | PIC17C43-25/PQ | PIC17CR42A-25/PQ | PIC17C42A-25E/PQ |
|---|---|---|---|---|---|---|
| Package | 44-MQFP (10x10) | 44-MQFP (10x10) - same | 44-MQFP (10x10) - same | 44-MQFP (10x10) - same | 44-MQFP (10x10) - same | 44-MQFP (10x10) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Maximum Clock Frequency | 25 MHz | 16 MHz | 25 MHz | 25 MHz | 25 MHz | 25 MHz |
| Instruction Throughput | 8.25 MIPS (121 ns) | 4 MIPS (250 ns) | 8.25 MIPS (121 ns) | 8.25 MIPS (121 ns) | 8.25 MIPS (121 ns) | 8.25 MIPS (121 ns) |
| Program Memory | 4 KB OTP | 4 KB OTP | 4 KB OTP | 8 KB OTP | 4 KB Mask ROM | 4 KB OTP |
| Data RAM | 232 bytes | 232 bytes | 232 bytes | 454 bytes | 232 bytes | 232 bytes |
| I/O Pins | 33 | 33 | 33 | 33 | 33 | 33 |
| Temperature Grade | Commercial (0C to +70C) | Commercial | Industrial (-40C to +85C) | Commercial | Commercial | Extended |
| Lifecycle Status | NRND | NRND | NRND | NRND | NRND | NRND |
Key Differentiators
- 25 MHz / 8.25 MIPS throughput in 44-MQFP for time-critical control loops (vs PIC17C42A-16/PQ)
- Industrial temperature grade option in same package for harsh environments (vs PIC17C42A-25/PQ (commercial))
- 8 KB OTP upgrade path in same 44-MQFP for firmware growth (vs PIC17C42A-25/PQ (4 KB))
- Mask-ROM variant available for highest-volume cost reduction (vs PIC17C42A-25/PQ (OTP))
Design Notes
PIC17C42A-25/PQ uses OTP (one-time programmable) EPROM, so firmware bugs cannot be erased or rewritten in the field. Always validate firmware on a flash-based equivalent (e.g., PIC18F4220, PIC16F877) or an in-circuit emulator before committing code to OTP parts. Production programming uses a high-voltage VPP on the MCLR/VPP pin — verify programmer compatibility with the PIC17C4X family before ordering a programming fixture.
At a typical 25 MHz clock and 5V VDD, the PIC17C42A core draws approximately 25 mA active and under 2 mA in sleep, dissipating ~125 mW active. The 44-MQFP package (theta_JA ~50 C/W typical) yields a 6 C junction temperature rise above ambient at active full load, so no heatsink is required for normal commercial-grade operation. Estimated: 5V x 25 mA = 125 mW x 50 C/W = 6.25 C rise. Above 70C ambient the junction enters the commercial limit, so consider the PIC17C42A-25I/PQ industrial variant for higher-temperature enclosures.
Place the 44-MQFP PIC17C42A on a 4-layer PCB with a continuous ground plane under the IC body to provide thermal spreading and EMI shielding. Route the 25 MHz oscillator traces (OSC1/OSC2) short and surrounded by ground pour to minimize radiated emissions; keep clock traces away from analog A/D inputs (RA0-RA7) to avoid coupling. Decouple VDD with a 100 nF ceramic capacitor placed within 5 mm of each VDD pin (pins 12 and 41), and add a bulk 10 uF tantalum at the PCB power entry. Leave the MCLR/VPP pin accessible for in-circuit programming during prototype bring-up.
The PIC17C42A-25/PQ integrates an 8-channel 10-bit A/D converter sharing PORTA pins (RA0-RA7). When using A/D, configure unused analog pins as digital outputs to prevent shoot-through, and add an external voltage-reference bypass capacitor on RA3/AN3/VREF when used as the A/D reference. Source impedance of analog signals should be below 2.5 kohm to avoid acquisition-time errors; add an op-amp buffer for higher-impedance sensors. Switch digital outputs to inputs during A/D conversion to minimize digital-coupling noise on the analog inputs.
For OTP production programming, leave test points on MCLR/VPP, VDD, VSS, and the oscillator pins to allow programming fixture access. The 44-MQFP 0.8 mm pitch requires solder-paste stencil apertures of 0.4 mm width with no-clean flux for reliable SMD assembly. Bake the MCUs per MSL guidelines before reflow if the floor-life has been exceeded; the OTP windowed package variant is more sensitive to moisture than plastic packages. Always order an extra 5-10% above BOM quantity to cover OTP programming yield losses.
Compliance Information
RoHS compliant per DigiKey listing. AEC-Q100 not applicable — PIC17C42A is not automotive qualified (not even as -25I/PQ). For automotive applications Microchip recommends PIC18F4520 or similar automotive-grade PIC18 family parts.
