PIC17C42AT-25/PT - 25MHz 8-Bit CMOS EPROM MCU | Microchip
MPN: PIC17C42AT-25/PT ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $18.5 | $18.50 |
| 10 | $16.2 | $162.00 |
| 100 | $13.85 | $1,385.00 |
| 500 | $11.95 | $5,975.00 |
| 1,000 | $10.5 | $10,500.00 |
PIC17C42AT-25/PT Overview
A microcontroller (MCU) integrates a CPU core, non-volatile program memory, working RAM, and configurable I/O peripherals onto a single silicon die. Within the broader PIC taxonomy, the PIC17 sits above PIC16 (mid-range, 14-bit instruction word) and below PIC18 (enhanced 8-bit, 16-bit instruction word with extended instruction set). Architecturally the PIC17 family is closer to PIC18 than to PIC16, and it bridges the gap between traditional 8-bit controllers and the higher pin-count, register-rich designs later standardized in PIC24/dsPIC devices.
Key features of the PIC17C42AT-25/PT include 58 single-word instructions, 33 MHz maximum clock input, 121 ns instruction cycle (except for program branches and table reads/writes which are two-cycle), 232 bytes of general-purpose RAM, 33 I/O pins, and two 8-bit timers plus one 16-bit timer/counter with capture/compare/PWM capability. The on-chip peripherals include a USART, hardware multiply, 16-level hardware stack, watchdog timer, and power-on reset. The 25 in the part number designates the 25 MHz speed grade, the A denotes the second silicon revision, T indicates OTP (One-Time Programmable) EPROM windowless package, and PT refers to the 44-pin TQFP surface-mount form factor.
Typical applications include industrial control, motor drive interfaces, instrumentation, security and alarm panels, automotive body electronics, smart sensors, and embedded control nodes requiring deterministic 8-bit performance in a moderate pin-count footprint. The PIC17C42A also served as a popular migration target for designers transitioning from PIC16 to PIC18 systems.
Designers should note that PIC17C parts are now mature legacy devices; verify current Microchip lifecycle status before committing to new designs. For new designs consider PIC18F or PIC24/dsPIC families which offer modern peripherals, Flash memory, and lower cost while remaining migration-friendly. Always use Microchip's MPLAB XC8 toolchain and an EPROM programmer rated for the 44-pin TQFP package.
This page consolidates distributor pricing, drop-in compatible Microchip alternatives, and practical design considerations for legacy industrial designs. Engineers searching for a 25 MHz 8-bit EPROM MCU in TQFP-44 will find verified pricing as of 2026-09-25, parametric comparison with same-package PIC17C42A variants, and recommendations for selecting between the PIC17 family and its modern PIC18 successors.
Drop-in alternatives for PIC17C42AT-25/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 PIC17C42AT-25/PT (same form factor and footprint) — differing in Package, Program Memory Type, Core Architecture, Program Memory Size, RAM Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC17C42A-25/PT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$5.55 / Unit
View Datasheet →PIC17C42A-33/PT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$9.65 / Unit
View Datasheet →PIC17C42A-33I/PT
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC17C42A-16E/PT
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC17C42A-25E/PT
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC17C42AT-25E/PT
✅ Drop-In✓ In Stock
$3.25 / Unit
View Datasheet →PIC17C42AT-25/PT Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC (PIC17) |
| Family | PIC® 17C |
| Program Memory Type | EPROM (OTP) |
| Program Memory Size | 2 KB (1 K x 16) |
| RAM Size | 232 bytes |
| Maximum Clock Frequency | 25 MHz |
| Instruction Cycle | 121 ns (single-cycle) |
| Instruction Set Size | 58 instructions |
| Operating Supply Voltage | 5 V |
| I/O Pins | 33 |
| Timers | 2 x 8-bit, 1 x 16-bit |
| Communication Interface | USART |
| Package | TQFP-44 (PT), 10x10 mm |
| Mounting Type | Surface Mount |
| Operating Temperature | 0C to +70C (commercial) |
| Watchdog Timer | Yes |
| Hardware Multiply | Yes |
| Hardware Stack | 16 levels |
PIC17C42AT-25/PT Pin Configuration
| Pin 1 | RA0/AN0 — Port A bit 0 / analog input |
| Pin 2 | RA1/AN1 — Port A bit 1 / analog input |
| Pin 3 | RA2/AN2 — Port A bit 2 / analog input |
| Pin 4 | RA3/AN3 — Port A bit 3 / analog input |
| Pin 5 | RA4 — Port A bit 4 |
| Pin 6 | RA5 — Port A bit 5 |
| Pin 7 | RA6 — Port A bit 6 |
| Pin 8 | RA7 — Port A bit 7 |
| Pin 9 | RB0/INT — Port B bit 0 / external interrupt |
| Pin 10 | RB1 — Port B bit 1 |
| Pin 11 | RB2 — Port B bit 2 |
| Pin 12 | RB3 — Port B bit 3 |
| Pin 13 | RB4 — Port B bit 4 |
| Pin 14 | RB5 — Port B bit 5 |
| Pin 15 | RB6/PGC — Port B bit 6 / ICSP clock |
| Pin 16 | RB7/PGD — Port B bit 7 / ICSP data |
| Pin 17 | VDD — Positive supply voltage (5V) |
| Pin 18 | VSS — Ground reference |
| Pin 19 | RC0 — Port C bit 0 |
| Pin 20 | RC1 — Port C bit 1 |
| Pin 21 | RC2 — Port C bit 2 |
| Pin 22 | RC3 — Port C bit 3 |
| Pin 23 | RC4 — Port C bit 4 |
| Pin 24 | RC5 — Port C bit 5 |
| Pin 25 | RC6/TX — Port C bit 6 / USART transmit |
| Pin 26 | RC7/RX — Port C bit 7 / USART receive |
| Pin 27 | RD0 — Port D bit 0 |
| Pin 28 | RD1 — Port D bit 1 |
| Pin 29 | RD2 — Port D bit 2 |
| Pin 30 | RD3 — Port D bit 3 |
| Pin 31 | RD4 — Port D bit 4 |
| Pin 32 | RD5 — Port D bit 5 |
| Pin 33 | RD6 — Port D bit 6 |
| Pin 34 | RD7 — Port D bit 7 |
| Pin 35 | RE0 — Port E bit 0 |
| Pin 36 | RE1 — Port E bit 1 |
| Pin 37 | RE2 — Port E bit 2 |
| Pin 38 | VDD — Positive supply voltage (5V) |
| Pin 39 | OSC1/CLKIN — Crystal oscillator input / external clock |
| Pin 40 | OSC2/CLKOUT — Crystal oscillator output |
| Pin 41 | MCLR — Master clear reset (active low) |
| Pin 42 | VSS — Ground reference |
| Pin 43 | T0CKI — Timer 0 external clock input |
| Pin 44 | NC — Not connected (per datasheet) |
Typical Applications
PIC17C42AT-25/PT is suitable for 6 applications: Industrial Control Systems, Motor Drive and PWM Control, Instrumentation and Data Acquisition, Security and Alarm Panels, Smart Sensor and HVAC Nodes, Automotive Body Electronics.
Industrial Control Systems
The PIC17C42AT-25/PT fits legacy industrial control applications requiring deterministic 8-bit performance with 33 I/O pins for sensor and actuator interfacing. The 25 MHz clock delivers 121 ns instruction cycle suitable for real-time control loops under 100 microseconds, and the hardware multiply enables efficient PID computation without software emulated math libraries. The 5V supply tolerance provides noise immunity in factory floor environments, and the 44-pin TQFP package suits compact PLC I/O modules and HMI front-end boards. Designers should pair this MCU with optoisolated digital I/O and provide proper 5V LDO regulation from the 24V industrial bus. The 58 single-word instructions simplify assembly-level firmware maintenance for long-life industrial deployments where field-proven code is preferred over rewriting in modern C.
Recommended
Motor Drive and PWM Control
The PIC17C42AT-25/PT is well matched to small DC and stepper motor drive interfaces via its 16-bit timer/counter with capture and compare/PWM capability. The hardware PWM module generates precise duty cycles at the 25 MHz system clock without CPU overhead, freeing the core for position feedback, encoder quadrature decoding, and current sensing. The 33 I/O pins accommodate direction, brake, fault, enable, and H-bridge signals for a complete 4-quadrant DC drive or two-axis stepper controller. At 5V supply the MCU interfaces directly to TTL-level gate drivers such as the IR2104; for higher voltage MOSFETs an external level shifter or gate driver IC is recommended. Designers should add dead-time generation in firmware to prevent shoot-through in H-bridge configurations.
Recommended
Instrumentation and Data Acquisition
The PIC17C42AT-25/PT serves as a front-end controller in instrumentation equipment where its 25 MHz throughput supports oversampled ADC reading, digital filtering, and serial upload. The USART peripheral interfaces to RS-232/RS-485 transceivers for industrial instrumentation networks, while the 232-byte RAM accommodates ring buffers for incoming measurement streams. Although the PIC17C42A lacks an on-chip ADC, external 12- or 16-bit ADCs such as the MCP3201 can be read via SPI bit-banged or via the MSSP-compatible interface. The TQFP-44 package integrates well into compact benchtop instrument mainboards where 33 GPIO drive front-panel switches, LEDs, and LCD segments. Engineers should reserve one timer for ADC sampling pacing to maintain deterministic acquisition rate.
Recommended
Security and Alarm Panels
The PIC17C42AT-25/PT is suited to legacy security and alarm panel controllers due to its OTP EPROM memory (which prevents firmware reverse-engineering), 33 I/O pins for multi-zone sensor inputs, and hardware watchdog timer for fail-safe operation. The 25 MHz clock supports zone scanning loops at sub-millisecond rates for fast-response intrusion detection. The 16-level hardware stack enables efficient interrupt-driven event handling for keypad, siren, and dialer interfaces. With commercial 0C to +70C operating range, the part fits indoor panel installations; outdoor or vehicle applications should use the -40C to +85C industrial-grade PIC17C42A-33I/PT variant. Firmware stored in OTP prevents tampering once deployed, a critical property for certified security equipment.
Recommended
Smart Sensor and HVAC Nodes
The PIC17C42AT-25/PT serves as a smart sensor aggregator for HVAC and building automation nodes, where its 33 I/O pins connect to multiple temperature, humidity, and occupancy sensors, while the USART interfaces to BACnet, Modbus, or proprietary building automation networks. The 25 MHz throughput executes sensor linearization, averaging, and trend logging in firmware without offloading to a higher-tier processor. The 5V supply is compatible with industrial sensor transmitters that operate on 4-20 mA loops; a 100 mA onboard LDO is sufficient to power the MCU plus a few external transducers. For battery-backed nodes, the <10 uA sleep current enables duty-cycled operation waking every 5-10 seconds to read sensors and transmit.
Recommended
Automotive Body Electronics
The PIC17C42AT-25/PT has historical deployment in automotive body controllers, door modules, seat controllers, and lighting drivers where its 25 MHz RISC core, 33 I/O pins, and OTP firmware protection match the functional requirements of pre-CAN body networks. The hardware PWM drives LED current sinks and motor speed controls for power windows and seat adjusters, while the USART interfaces to older LIN or proprietary body bus transceivers. For new automotive designs AEC-Q100 qualified PIC18F or dsPIC families are mandatory; the PIC17C42A family is not AEC-Q100 qualified. For aftermarket automotive products and non-safety subsystems, the PIC17C42AT-25/PT remains a viable cost-effective controller with deterministic 8-bit behavior.
Recommended
Recommended Products Summary
Engineering reference data for PIC17C42AT-25/PT — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC17C42A-25/PT | PIC17C42A-33/PT | PIC17C42A-33I/PT | PIC17C42A-16E/PT | PIC17C42A-25E/PT | PIC17C42AT-25E/PT |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | TQFP-44 (PT) | TQFP-44 (PT) - same | TQFP-44 (PT) - same | TQFP-44 (PT) - same | TQFP-44 (PT) - same | TQFP-44 (PT) - same | TQFP-44 (PT) - same |
| Maximum Clock Frequency | 25 MHz | 25 MHz | 33 MHz | 33 MHz | 16 MHz | 25 MHz | 25 MHz |
| Program Memory Type | OTP EPROM | EPROM | EPROM | EPROM | EPROM | EPROM | OTP EPROM |
| Program Memory Size | 2 KB (1 K x 16) | 2 KB | 2 KB | 2 KB | 2 KB | 2 KB | 2 KB |
| Operating Temperature | 0C to +70C (commercial) | 0C to +70C | 0C to +70C | -40C to +85C (industrial) | -40C to +125C (extended) | -40C to +125C (extended) | -40C to +125C (extended) |
| Instruction Cycle Time | 121 ns | 121 ns | 92 ns | 92 ns | 187 ns | 121 ns | 121 ns |
| Lifecycle Status | NRND | NRND | NRND | NRND | NRND | NRND | NRND |
Key Differentiators
- Highest clock speed in same-package PIC17 family (vs PIC17C42A-16E/PT)
- Commercial temperature grade with OTP EPROM protection (vs PIC17C42A-33I/PT)
- Pinout and footprint compatibility with PIC18F452-I/PT migration target (vs PIC17C42A-25E/PT)
Design Notes
PIC17C42AT-25/PT requires a regulated 5V supply (4.5V to 5.5V) with maximum active current of approximately 30 mA at 25 MHz with all peripherals enabled. Place a 100 nF ceramic decoupling capacitor within 1 cm of each VDD/VSS pin pair (the TQFP-44 has two VDD pins at positions 17 and 38, and two VSS pins at positions 18 and 42). Add a 10 uF bulk tantalum or ceramic capacitor at the supply entry point. Power-on reset (POR) requires VDD rise time under 100 ms; add an RC network on MCLR if the supply ramp is slow. For battery-backed applications, switch to PIC18F/dsPIC Flash parts to retain firmware state during brown-out events.
TQFP-44 (PT) package has 0.8 mm pin pitch on a 10x10 mm body, requiring surface-mount assembly with fine-pitch soldering capability. Per Microchip datasheet (DS30212B) PCB layout recommendations: route all 33 I/O signals on the top layer with the inner layer used as a continuous ground plane; keep oscillator traces (OSC1/OSC2) shorter than 5 mm and shield them with a ground guard trace; place the crystal within 5 mm of the MCU. Expose the thermal pad underneath the TQFP body to the ground plane via 4-6 thermal vias for improved heat dissipation at high ambient temperatures. Maintain 0.2 mm clearance between adjacent traces to prevent solder bridging during reflow.
Common pitfalls when designing with PIC17C42AT-25/PT: (1) reserving RB6 and RB7 for ICSP programming - they cannot be repurposed as outputs during programming without isolating them from the application circuit; (2) using OTP EPROM means firmware bugs cannot be corrected in-circuit - design with prototype windows (PIC17C42A-25/JW) and only commit to OTP after firmware is fully validated; (3) the PIC17 instruction set is NOT source-compatible with PIC16 or PIC18 - porting assembly code requires complete rewrite; (4) verify that downstream tooling (MPLAB IDE versions, compiler versions) still supports PIC17C parts, as newer MPLAB X IDE releases have deprecated PIC17 support in some XC8 builds.
Crystal oscillator layout for PIC17C42AT-25/PT: keep the crystal and its load capacitors within 5 mm of OSC1 (pin 39) and OSC2 (pin 40); use a grounded guard ring or shield trace around the crystal traces to prevent EMI coupling into adjacent I/O lines; place load capacitors (typically 15-33 pF depending on crystal specification) directly between each oscillator pin and ground. For highest frequency stability at 25 MHz, avoid routing any high-current switching signals (PWM outputs, relay drivers) within 5 mm of the oscillator traces. If the application requires a precise baud rate generator, select a crystal with 50 ppm or better initial accuracy and use the USART BRG register for fine tuning.
Signal integrity considerations for PIC17C42AT-25/PT: the 25 MHz system clock generates edge rates of approximately 2-3 ns on digital outputs, so route high-speed signals (USART TX at 115200+ baud, PWM outputs, timer toggle outputs) over an unbroken ground plane and keep trace lengths under 50 mm to avoid ringing. The 33 GPIO pins have 4 mA source/sink capability per pin (20 mA maximum per port), so for driving LEDs or relays directly use a buffer IC such as ULN2003 or TPIC6B595 rather than relying on the MCU pin alone. Add 100 ohm series termination resistors on outputs driving long cables (>100 mm) to dampen reflections. The USART RX input is TTL-level sensitive; for RS-232 use a MAX232 level translator, for RS-485 use a MAX485 or equivalent transceiver.
Compliance Information
RoHS compliant per Microchip product declaration; PT suffix denotes lead-free matte-tin TQFP package. AEC-Q100 not qualified - for automotive applications use PIC18F or dsPIC AEC-Q100 variants.