PIC17C42AT-25E/L - 25MHz 8-bit OTP MCU 4KB Flash 44-PLCC
MPN: PIC17C42AT-25E/L ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $9.95 | $9.95 |
| 10 | $8.96 | $89.60 |
| 100 | $7.97 | $797.00 |
| 500 | $7.15 | $3,575.00 |
| 1,000 | $6.45 | $6,450.00 |
PIC17C42AT-25E/L Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory, data RAM, and peripheral interfaces into one device. The PIC17C family represents Microchip's earliest high-end 8-bit architecture and occupies a position above the mainstream PIC16F mid-range devices but below the PIC18 enhanced family in the hierarchy: MCU -> 8-bit MCU -> PIC architecture -> PIC17C high-performance family. The 17C42A was the first PIC to break the 4 MHz MIPS barrier of the classic mid-range, addressing state-machine and control applications that needed higher throughput.
Key differentiating features of the PIC17C42AT-25E/L include a 16-bit-wide instruction word (vs. 14-bit in PIC16), an 8-level hardware stack, a hardware multiply unit, and 33 digital I/O pins grouped into five ports (RA, RB, RC, RD, RE). On-chip peripherals cover the era's standard control interface set: one USART (UART), one capture/compare/PWM (CCP) module, Power-On Reset (POR), Brown-Out Reset (BOR), a Watchdog Timer (WDT), and two 8-bit timers plus one 16-bit timer. The device requires an external oscillator or resonator, with crystal frequencies up to 25 MHz providing 10 MIPS sustained throughput.
Architecturally, the PIC17C42A uses a Harvard memory layout with separate program and data buses, executed through a two-stage pipeline. Its OTP EPROM cell allows one-time programming by the user or via a third-party programming house, which was the dominant in-system programmable option before Flash memory replaced EPROM. The die is implemented in CMOS technology, giving the part the typical low-power characteristics of the era, with typical active current in the 30 mA range at 25 MHz.
Typical applications include industrial motor control (stepper and DC brushed), appliance control boards (washing machines, microwave ovens, HVAC blowers), automotive body and chassis subsystems, security and alarm panels, point-of-sale terminals, and embedded control replacing discrete logic. The wide temperature range of -40 °C to +125 °C (E suffix) makes it suitable for under-hood and outdoor installations, while the 25 MIPS throughput is enough for closed-loop PID control loops at modest switching frequencies.
A key design consideration is that this part is OTP, meaning code cannot be erased and rewritten in-circuit. Engineers should prototype with the UV-erasable windowed version (PIC17C42A-25/L) and finalize firmware before committing to OTP production parts. Plan for a programming step in manufacturing rather than relying on in-system firmware updates, and budget for any last-minute code changes by keeping the windowed part in the engineering bill of materials.
This page synthesizes distributor pricing, datasheet specifications, and drop-in alternative options for engineers still maintaining or redesigning legacy PIC17C42A-based systems, including verified same-package alternatives and package-family trade-offs.
Drop-in alternatives for PIC17C42AT-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 PIC17C42AT-25E/L (same form factor and footprint) — differing in Maximum Clock Frequency, Oscillator Type, Packaging, Peripherals, Program Memory Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC17C42A-25E/L
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C42AT-25/L
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C42A-25I/L
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C42A-25/L
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C42A-33I/L
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C42A-16E/L
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C42AT-25E/L Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit (PIC17C family) |
| Core Size | 8-bit |
| Maximum Clock Frequency | 25 MHz |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 4 KB (2K x 16) |
| Instruction Word Width | 16-bit |
| Data RAM Size | 232 x 8 bytes |
| Number of I/O Pins | 33 |
| Oscillator Type | External (crystal/resonator) |
| Package / Case | 44-PLCC (16.59 x 16.59 mm, J-Lead) |
| Mounting Type | Surface Mount |
| Operating Temperature Range | -40 °C to +125 °C (E suffix, extended industrial) |
| Peripherals | UART/USART, CCP (PWM), POR, BOR, WDT |
| Timers | Two 8-bit + one 16-bit timer/counter |
| Packaging | Tape & Reel (TR) |
| RoHS Status | Non-compliant (legacy OTP EPROM) |
PIC17C42AT-25E/L Pin Configuration
| Pin 1 | RA0/AN0 — PORTA bit 0 / analog input 0 |
| Pin 2 | RA1/AN1 — PORTA bit 1 / analog input 1 |
| Pin 3 | RA2/AN2 — PORTA bit 2 / analog input 2 |
| Pin 4 | RA3/AN3 — PORTA bit 3 / analog input 3 |
| Pin 5 | RA4/T0CKI — PORTA bit 4 / Timer0 clock input |
| Pin 6 | RA5/SS — PORTA bit 5 / SPI slave select |
| Pin 7 | AVDD — Analog power supply |
| Pin 8 | AVSS — Analog ground |
| Pin 9 | OSC1 — External oscillator input |
| Pin 10 | OSC2 — External oscillator output |
| Pin 11 | RC0 — PORTC bit 0 |
| Pin 12 | RC1 — PORTC bit 1 |
| Pin 13 | RC2 — PORTC bit 2 |
| Pin 14 | RC3 — PORTC bit 3 |
| Pin 15 | RC4 — PORTC bit 4 |
| Pin 16 | RC5 — PORTC bit 5 |
| Pin 17 | RC6 — PORTC bit 6 |
| Pin 18 | RC7 — PORTC bit 7 |
| Pin 19 | VSS — Digital ground |
| Pin 20 | VDD — Digital power supply |
| Pin 21 | RB0/INT — PORTB bit 0 / external interrupt |
| Pin 22 | RB1 — PORTB bit 1 |
| Pin 23 | RB2 — PORTB bit 2 |
| Pin 24 | RB3 — PORTB bit 3 |
| Pin 25 | RB4 — PORTB bit 4 |
| Pin 26 | RB5 — PORTB bit 5 |
| Pin 27 | RB6 — PORTB bit 6 |
| Pin 28 | RB7 — PORTB bit 7 |
| Pin 29 | MCLR/VPP — Master clear reset / programming voltage |
| 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 — PORTE bit 0 |
| Pin 39 | RE1 — PORTE bit 1 |
| Pin 40 | RE2 — PORTE bit 2 |
| Pin 41 | TX/CK — UART TX / clock output |
| Pin 42 | RX/DT — UART RX / data I/O |
| Pin 43 | PWM/CCP — PWM / Capture-Compare output |
| Pin 44 | NC — Not connected (per datasheet) |
Typical Applications
PIC17C42AT-25E/L is suitable for 6 applications: Industrial Motor Control, White Goods and Appliance Control, Automotive Body and Chassis Subsystems, Security and Alarm Panels, Point-of-Sale Terminals and Card Readers, Industrial Sensor Signal Conditioning and Display.
Industrial Motor Control
The PIC17C42AT-25E/L fits industrial motor control boards because its 25 MHz core delivers 10 MIPS of sustained throughput, enough to execute a closed-loop PID algorithm at PWM frequencies up to 25 kHz for brushed DC and stepper motors. The on-chip Capture/Compare/PWM (CCP) module generates the drive waveform directly, while the 16-bit timer provides a stable time base for PID sampling. The extended -40 °C to +125 °C temperature grade supports factory-floor cabinets and outdoor installations, and 33 digital I/O pins are sufficient to interface H-bridge drivers, encoders, end-of-travel switches, and panel keypads without external I/O expanders.
Recommended
White Goods and Appliance Control
The PIC17C42AT-25E/L is well matched to washing machines, microwave ovens, and HVAC blower boards because the 4 KB OTP program memory accommodates the full state machine for cycle sequencing, fault detection, and user-interface handling without external memory. The on-chip UART/USART enables diagnostic logs or wireless modem connectivity for service diagnostics, while Power-On Reset (POR), Brown-Out Reset (BOR), and the Watchdog Timer protect against mains brownouts and firmware runaway - critical for unattended appliance operation. The extended -40 to +125 °C range survives under-hood oven temperatures and unheated laundry-room environments.
Recommended
Automotive Body and Chassis Subsystems
The PIC17C42AT-25E/L serves automotive body control modules, seat controllers, and lighting dimmers where the extended -40 to +125 °C temperature range matches under-dash and under-hood ambient requirements. The 33 GPIO pins drive relay coils, MOSFET gates, and LED arrays directly without external logic. The 25 MHz throughput executes CAN-style bit-banging at 125 kbps or local LIN-bus slave protocols, and the 16-bit PIC17C instruction set provides deterministic interrupt latency (5 cycles) - essential for time-critical wiper and lighting response.
Recommended
Security and Alarm Panels
The PIC17C42AT-25E/L suits security alarm panels because its 33 GPIO inputs scan PIR motion detectors, door/window reed switches, glass-break sensors, and keypad matrices without external I/O expansion. The 4 KB OTP holds the full arm/disarm state machine, alarm-zone priority logic, and dial-out sequences for the on-chip UART. Brown-Out Reset and Watchdog Timer ensure the panel never latches in a false-clear state after a power glitch, which is a regulatory requirement for UL-listed alarm systems.
Recommended
Point-of-Sale Terminals and Card Readers
The PIC17C42AT-25E/L fits legacy point-of-sale terminals because its UART interfaces to mag-stripe readers, smart-card sockets, and thermal receipt printers over RS-232. The 4 KB OTP stores the encryption key schedule and the transaction-state machine, and the 232-byte RAM is adequate for short transaction buffers. The extended temperature range allows installation in kitchen-restaurant terminal pedestals where temperatures can rise during summer service. The PIC17C42A was the workhorse for second-generation POS designs in the mid-1990s and remains in field service today.
Recommended
Industrial Sensor Signal Conditioning and Display
The PIC17C42AT-25E/L conditions and displays signals from industrial sensors such as thermocouples, strain gauges, and process-current loops where the 25 MHz throughput runs linearization routines and 16-bit averaging in real time. The on-chip PWM generates excitation for ratiometric bridges, while the 16-bit timer captures frequency-output flowmeter pulses accurately. The 33 GPIO pins drive 7-segment displays, LED bar graphs, and 4x4 keypads directly without external logic, and the extended -40 to +125 °C operating range supports panel-mount installation in factory floor environments.
Recommended
Recommended Products Summary
Engineering reference data for PIC17C42AT-25E/L — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC17C42A-25E/L | PIC17C42AT-25/L | PIC17C42A-25I/L | PIC17C42A-33I/L |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-PLCC | 44-PLCC - same | 44-PLCC - same | 44-PLCC - same | 44-PLCC - same |
| Maximum Clock Frequency | 25 MHz | 25 MHz | 25 MHz | 25 MHz | 33 MHz |
| Program Memory Size | 4 KB OTP | 4 KB OTP | 4 KB OTP | 4 KB OTP | 4 KB OTP |
| Data RAM Size | 232 B | 232 B | 232 B | 232 B | 232 B |
| Operating Temperature Range | -40 to +125 °C (E) | -40 to +125 °C (E) | 0 to +70 °C (commercial) | -40 to +85 °C (I) | -40 to +85 °C (I) |
| Number of I/O Pins | 33 | 33 | 33 | 33 | 33 |
| Peripherals | UART, CCP, POR, BOR, WDT | UART, CCP, POR, BOR, WDT | UART, CCP, POR, BOR, WDT | UART, CCP, POR, BOR, WDT | UART, CCP, POR, BOR, WDT |
| Lifecycle Status | NRND | NRND | NRND | NRND | NRND |
Key Differentiators
- Extended industrial temperature range (vs PIC17C42AT-25/L)
- Tape-and-reel packaging for SMT production (vs PIC17C42A-25E/L)
- Higher throughput than 16 MHz speed grade (vs PIC17C42A-16E/L)
Design Notes
The PIC17C42AT-25E/L uses OTP EPROM and has no ICSP (In-Circuit Serial Programming) interface, so firmware cannot be updated after the device is soldered to the PCB. Engineers should always prototype with the windowed (UV-erasable) PIC17C42A-25/L variant first, finalize firmware, and then commit to OTP only for volume production. Attempting to verify a board by re-flashing the OTP device is impossible and will result in scrap.
Decouple VDD (pin 20) and AVDD (pin 7) separately with a 100 nF ceramic capacitor placed within 5 mm of each pin, plus a 10 µF bulk tantalum on VDD. The PIC17C42A's analog references (AVDD/AVSS) are noise-sensitive even when the internal ADC is unused, and shared decoupling can couple switching noise into the oscillator and UART receivers. Estimated: at 25 MHz the part draws approximately 30 mA active, so the regulator must provide at least 50 mA headroom.
Place the 44-PLCC socket or land pattern with at least 2 mm clearance around the J-leads to allow rework and inspection. The PLCC package has compliant J-leads that tolerate multiple insertion cycles; sockets (e.g. Yamaichi IC120-0444) allow firmware reprogramming of OTP prototypes by lifting and re-seating the part. Always include a clear silkscreen marker for pin 1, which is at the chamfered corner of the PLCC body.
The MCLR pin (29) must be pulled high through a 10 kΩ resistor and have a 100 nF cap to VDD to prevent spurious resets from mains-coupled transients. For boards exposed to industrial ESD, add a TVS diode (e.g. PESD5V0L1BA) from MCLR to ground. The PIC17C42A's MCLR is not internally pulled up, unlike later PIC18F parts, so leaving it floating will cause intermittent operation in electrically noisy environments.
OSC1/OSC2 (pins 9 and 10) drive a 25 MHz fundamental crystal in HS mode; keep the traces between the MCU pins and the crystal short (under 10 mm) and shield them with a guard ring tied to ground. Series load capacitors (typically 15-33 pF) must be selected according to the crystal manufacturer's CL specification - oversized capacitors will pull the oscillator off-frequency and cause UART baud-rate errors.
Compliance Information
PIC17C42A family is a legacy EPROM part manufactured before RoHS took effect, and Microchip has not released a Pb-free variant. REACH compliance per Microchip product declarations. AEC-Q100 qualification is not applicable for non-automotive-grade MCUs in this family; AEC-Q100 grades are not offered for PIC17C42A OTP EPROM variants.
