PIC17C42AT-25I/L - 8-Bit 25MHz OTP MCU, 4KB, 44-PLCC | Microchip
MPN: PIC17C42AT-25I/L ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $14.5 | $14.50 |
| 10 | $12.85 | $128.50 |
| 100 | $11.2 | $1,120.00 |
| 500 | $9.95 | $4,975.00 |
| 1,000 | $8.8 | $8,800.00 |
PIC17C42AT-25I/L Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, program memory, data RAM, and peripheral set on one die, executing instructions from on-chip ROM/EPROM/Flash. Within the taxonomy, the PIC17C42A sits under 8-bit MCU -> microcontroller -> embedded controller -> semiconductor. Its RISC Harvard architecture separates program and data buses for faster instruction fetch and deterministic timing.
Key features include 33 programmable digital I/O pins, a hardware USART for serial communication, four timers, two PWM channels, Power-On Reset (POR), Brown-Out Reset, and a Watchdog Timer (WDT). Compared with PIC16-class parts, the PIC17 family adds a 16-bit-wide instruction word and an external instruction/data bus interface, enabling larger code reach at higher throughput. The 'AT' suffix denotes tape-and-reel packaging, 'I' denotes industrial temperature, '25' the 25 MHz speed grade, and 'L' the 44-PLCC J-lead package.
Typical applications include industrial control panels, motor drive interface boards, sensor signal conditioning front-ends, and consumer appliances that require deterministic 8-bit control with a robust on-chip peripheral set. Because the PIC17C42A is OTP, code is committed at production programming time - in-field firmware upgrades are not possible, so plan the firmware carefully and verify before blank-device programming.
When designing with this part, confirm oscillator configuration (crystal vs. RC vs. external clock) matches your board and place decoupling capacitors close to VDD/SS pins. The 44-PLCC socket footprint also allows easy rework and pre-production programming on bench programmers. According to Microchip's product page, a newer pin-compatible recommendation is PIC18F4220 for new designs.
Drop-in alternatives for PIC17C42AT-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 PIC17C42AT-25I/L (same form factor and footprint) — differing in Core Architecture, Program Memory Type, Package, Mounting Type, Operating Temperature Range.
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PIC17C42AT-25E/L
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View Datasheet →PIC17C42AT-25/PQ
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View Datasheet →PIC17C42A-33I/PQ
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View Datasheet →PIC17C42A-33I/P
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View Datasheet →PIC17C42A-25E/P
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View Datasheet →PIC17C42AT-25I/L Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC RISC (Harvard) |
| Series | PIC® 17C |
| Core Speed | 25 MHz |
| Performance | 8.25 MIPS (121 ns instruction cycle) |
| Program Memory Type | OTP (One-Time Programmable) EPROM |
| Program Memory Size | 4 KB (2K x 16) |
| Data RAM | 232 x 8 bytes |
| Data Bus Width | 16-bit (instruction path) |
| Supply Voltage (Vdd) | 4.5 V to 6 V |
| I/O Pins | 33 |
| Communication | UART/USART |
| Peripherals | 4 Timers, 2 PWM, POR, WDT |
| Operating Temperature | -40 °C to +85 °C (Industrial) |
| Package | 44-PLCC (J-Lead), 16.59 x 16.59 mm |
| Mounting Type | Surface Mount |
| Instruction Set | 58 single-word instructions |
PIC17C42AT-25I/L Pin Configuration
| Pin 1 | RA0 — I/O port A bit 0 |
| Pin 2 | RA1 — I/O port A bit 1 |
| Pin 3 | RA2 — I/O port A bit 2 |
| Pin 4 | RA3 — I/O port A bit 3 |
| Pin 5 | VDD — Positive supply voltage |
| Pin 6 | RA4 — I/O port A bit 4 |
| Pin 7 | RA5 — I/O port A bit 5 |
| Pin 8 | RA6 — I/O port A bit 6 |
| Pin 9 | RA7 — I/O port A bit 7 |
| Pin 10 | VSS — Ground reference |
| Pin 11 | OSC1 — Oscillator input |
| Pin 12 | OSC2 — Oscillator output |
| Pin 13 | MCLR — Master Clear (reset) input |
| Pin 14 | RB0 — I/O port B bit 0 / INT |
| Pin 15 | RB1 — I/O port B bit 1 |
| Pin 16 | RB2 — I/O port B bit 2 |
| Pin 17 | RB3 — I/O port B bit 3 |
| Pin 18 | RB4 — I/O port B bit 4 |
| Pin 19 | RB5 — I/O port B bit 5 |
| Pin 20 | RB6 — I/O port B bit 6 |
| Pin 21 | RB7 — I/O port B bit 7 |
| Pin 22 | RC0 — I/O port C bit 0 |
| Pin 23 | RC1 — I/O port C bit 1 |
| Pin 24 | RC2 — I/O port C bit 2 |
| Pin 25 | RC3 — I/O port C bit 3 |
| Pin 26 | RC4 — I/O port C bit 4 |
| Pin 27 | RC5 — I/O port C bit 5 |
| Pin 28 | RC6 — I/O port C bit 6 / TX |
| Pin 29 | RC7 — I/O port C bit 7 / RX |
| Pin 30 | VSS — Ground reference |
| Pin 31 | VDD — Positive supply voltage |
| Pin 32 | RD0 — I/O port D bit 0 |
| Pin 33 | RD1 — I/O port D bit 1 |
| Pin 34 | RD2 — I/O port D bit 2 |
| Pin 35 | RD3 — I/O port D bit 3 |
| Pin 36 | RD4 — I/O port D bit 4 |
| Pin 37 | RD5 — I/O port D bit 5 |
| Pin 38 | RD6 — I/O port D bit 6 |
| Pin 39 | RD7 — I/O port D bit 7 |
| Pin 40 | RE0 — I/O port E bit 0 |
| Pin 41 | RE1 — I/O port E bit 1 |
| Pin 42 | RE2 — I/O port E bit 2 |
| Pin 43 | VSS — Ground reference |
| Pin 44 | VDD — Positive supply voltage |
Typical Applications
PIC17C42AT-25I/L is suitable for 6 applications: Industrial Control Panels, Motor Drive Interface Boards, Sensor Signal Conditioning Front-Ends, Consumer Appliance Control, Communication Interface Modules, Legacy Embedded Product Maintenance.
Industrial Control Panels
The PIC17C42AT-25I/L fits industrial control panels because of its 25 MHz core (8.25 MIPS) which scans multiple discrete inputs and drives relay/PWM outputs within tight control loops, plus its 33 programmable I/O pins that consolidate many digital signals without external mux logic. The 232-byte RAM is sufficient for state machines and PID algorithm scratch, while the hardware USART links to operator-interface HMI panels. Industrial temperature grade (-40 °C to +85 °C) tolerates factory-floor thermal swings without throttling. Designed into panel-replacement programs where legacy OTP firmware is already locked, the part avoids costly re-certification.
Recommended
Motor Drive Interface Boards
Two on-chip PWM channels and four timers in the PIC17C42AT-25I/L directly generate complementary PWM gate-drive waveforms for small BLDC or stepper motor interface boards. The 25 MHz core runs velocity-loop math at the required kHz rate, and the 33 I/O pins accommodate direction, fault, brake, and encoder-feedback signals. The 16-bit instruction word path (vs 14-bit on PIC16) accelerates multiply-heavy control law evaluation. Industrial temperature grade supports under-hood or cabinet-mounted deployments. Placed between a power-stage gate driver and the host PLC, it centralizes low-level commutation logic.
Recommended
Sensor Signal Conditioning Front-Ends
The PIC17C42AT-25I/L serves as the digital back-end of a sensor-conditioning front-end, digitizing analog front-end outputs via external ADC and applying linearization in firmware. The 232-byte RAM accommodates lookup tables for thermocouple or RTD compensation curves, and the USART streams conditioned readings to a host controller. Industrial temperature operation ensures measurement stability across process environments. The PIC17 RISC core executes table-based corrections deterministically within the 121 ns cycle, making it suited to high-update-rate sensing.
Recommended
Consumer Appliance Control
For consumer appliances such as washing machines, dishwashers, and small kitchen equipment, the PIC17C42AT-25I/L offers enough I/O (33 pins), PWM (2 channels), and timers (4) to control motors, valves, and user-interface keypads from one die. OTP memory locks firmware to deter cloning, a feature still valued in cost-sensitive consumer electronics. The 4.5-6 V supply aligns with rectified-12 V or 5 V regulator rails typical in appliance power supplies. Production-programmed parts ship pre-validated, simplifying the manufacturing flow.
Recommended
Communication Interface Modules
The PIC17C42AT-25I/L's hardware USART and 25 MHz throughput make it suitable for protocol-conversion modules bridging legacy RS-232/485 buses to modern controllers. With 33 I/O pins, multiple serial ports can be bit-banged alongside the hardware USART, enabling multi-drop industrial networks. Industrial temperature grade supports outdoor cabinet or factory installation. OTP firmware secures the protocol stack against field tampering. Placed in line-termination or gateway boards, it provides a deterministic translation layer.
Recommended
Legacy Embedded Product Maintenance
For long-lifecycle embedded products still in field service, the PIC17C42AT-25I/L provides exact replacement of original boards without firmware changes or re-certification. The 44-PLCC socketed footprint enables bench-side swap, and the OTP die's behavior matches the original BOM exactly. Industrial temperature grade and 4.5-6 V supply maintain compliance with legacy system rails. This application is the primary use case for the part today, given its obsolete lifecycle status; new designs should migrate to flash-based PIC18F4220 with the same footprint.
Recommended
Recommended Products Summary
Engineering reference data for PIC17C42AT-25I/L — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC17C42AT-25E/L | PIC17C42AT-25/PT | PIC17C42A-33I/PQ |
|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-PLCC (J-Lead) | 44-PLCC (J-Lead) | 44-PLCC (J-Lead) | 44-PLCC (J-Lead) |
| Core Speed | 25 MHz | 25 MHz | 25 MHz | 33 MHz |
| Program Memory | 4 KB OTP | 4 KB OTP | 4 KB OTP | 4 KB OTP |
| Data RAM | 232 bytes | 232 bytes | 232 bytes | 232 bytes |
| I/O Pins | 33 | 33 | 33 | 33 |
| Supply Voltage | 4.5 V to 6 V | 4.5 V to 6 V | 4.5 V to 6 V | 4.5 V to 6 V |
| Temperature Grade | Industrial -40 to +85 °C | Extended | Industrial -40 to +85 °C | Industrial -40 to +85 °C |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete |
Key Differentiators
- Tape-and-reel packaging for high-volume SMT assembly (vs PIC17C42A-25I/L)
- Industrial temperature grade for harsh environments (vs PIC17C42AT-25/L)
- Long-term Microchip product heritage with mature toolchain (vs Generic 8-bit MCU from second-source vendor)
Design Notes
Estimated: at 25 MHz core and full 33-I/O switching, Vdd = 5 V, total supply current is approximately 25-40 mA depending on I/O load. Place a 100 nF ceramic decoupling capacitor as close as possible to each VDD/VSS pair (pins 5/10, 30/31, 43/44) to suppress switching transients. Add a bulk 10-47 uF tantalum or aluminum capacitor near the IC for low-frequency decoupling.
The 44-PLCC J-lead package sits in a standard PLCC socket, which simplifies prototyping and field replacement. Keep high-speed traces away from the oscillator pins (OSC1, OSCC2) and route the crystal within 1 cm of the MCU with a grounded guard ring. The MCLR pin requires a 10 kohm pull-up to VDD; add a 100 nF cap to ground for noise immunity on reset.
Because this part is OTP, code is committed at production programming time. Plan firmware validation on a windowed CERDIP variant first, then move to OTP for production. Verify VDD is within 4.5-6 V at all times - operation below 4.5 V may trigger Brown-Out Reset or unpredictable execution. Do not leave unused I/O pins floating; configure them as outputs to minimize current draw.
Compliance Information
RoHS/REACH compliance data was not present in the verified web sources for this obsolete part; values set to unknown. AEC-Q100 not applicable for industrial-grade legacy MCU.
