PIC17C42AT-16I/L - 8-Bit 16MHz OTP MCU, 4KB EPROM | Microchip | 44-PLCC
MPN: PIC17C42AT-16I/L ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $18.5 | $18.50 |
| 10 | $16.2 | $162.00 |
| 100 | $14.1 | $1,410.00 |
| 500 | $12.45 | $6,225.00 |
| 1,000 | $10.95 | $10,950.00 |
PIC17C42AT-16I/L Overview
An MCU (microcontroller unit) is a single-chip computer that integrates a CPU core, program memory, working RAM, and configurable peripheral blocks such as timers, I/O ports, and communication interfaces. Within the broader taxonomy, the PIC17C42AT-16I/L sits as: MCU -> microcontroller -> embedded controller -> semiconductor. PIC17C devices specifically targeted the high-end 8-bit segment where complex control loops and faster interrupt latency were required versus the entry-level PIC16C family.
Key features include 232 bytes of general-purpose RAM, 33 digital I/O pins, an external oscillator interface, an industrial operating temperature range of -40 °C to +85 °C, and supply voltage support of 4.5 V to 6.0 V. The OTP EPROM program memory eliminates the need for separate programming hardware and enables fast prototype-to-production transitions, while the 16 MHz clock input supports 121 ns minimum instruction cycles for deterministic real-time response.
Technically, the PIC17C42A uses a RISC-style Harvard architecture with separate program and data buses, allowing simultaneous instruction fetch and operand access. Its 33 I/O pins are organized into ports that can be individually configured as digital inputs or outputs, and the device includes built-in EPROM programming support, brown-out reset, and a programmable counter array for capture/compare/PWM.
Typical applications include industrial control systems, automotive electronics sub-modules, medical instrumentation, and consumer appliances. The compact 44-PLCC (J-lead) footprint is ideal for through-hole or socketed designs where field serviceability matters. The PIC17C42A is now considered a mature legacy device, suitable for maintenance of installed equipment rather than new high-volume designs.
When designing with this part, ensure the EPROM programming window (on windowed variants) is covered with opaque label after programming to prevent UV-induced data loss, and verify the industrial temperature grade supports the target deployment environment. For new designs, evaluate the PIC18F family as a more modern drop-in successor with flash memory and lower power.
This page synthesizes distributor availability, parametric comparisons, and engineering design notes not found in the manufacturer datasheet alone, supporting both new procurement decisions and legacy maintenance of installed PIC17C42A systems.
Drop-in alternatives for PIC17C42AT-16I/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-16I/L (same form factor and footprint) — differing in Core Architecture, Operating Temperature Range, Mounting Type, RoHS Status, Program Memory Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC17C42AT-16I/PT
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C42A-16I/L
✅ Drop-In✓ In Stock
$9.95 / Unit
View Datasheet →PIC17C42A-16/P
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$7.45 / Unit
View Datasheet →PIC17C42A-16E/P
✅ Drop-In✓ In Stock
$5.85 / Unit
View Datasheet →PIC17C42A-25/PT
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$5.55 / Unit
View Datasheet →PIC17C42A-33I/P
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$6.2 / Unit
View Datasheet →PIC17C42AT-16I/L Maximum Ratings & Electrical Characteristics
| Product Family | PIC 17C |
| Core Architecture | 8-bit RISC Harvard |
| Core Size | 8-bit |
| Max Clock Frequency | 16 MHz |
| Instruction Cycle | 121 ns (single cycle) |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 4 KB (2K x 16) |
| RAM Size | 232 x 8 bytes |
| Number of I/O Pins | 33 |
| Supply Voltage Range | 4.5 V to 6.0 V |
| Operating Temperature Range | -40 °C to +85 °C (Industrial) |
| Package Type | 44-PLCC (J-Lead, 16.59 x 16.59 mm) |
| Mounting Type | Surface Mount |
| Oscillator Type | External |
| Instruction Set | 58 single-word instructions |
| RoHS Status | Non-compliant (legacy OTP device) |
PIC17C42AT-16I/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 / Timer0 clock) |
| 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 | RB0/INT — Port B bit 0 / External interrupt |
| Pin 10 | RB1 — Port B bit 1 (digital I/O) |
| Pin 11 | RB2 — Port B bit 2 (digital I/O) |
| Pin 12 | RB3 — Port B bit 3 (digital I/O) |
| Pin 13 | RB4 — Port B bit 4 (digital I/O) |
| Pin 14 | RB5 — Port B bit 5 (digital I/O) |
| Pin 15 | RB6 — Port B bit 6 (digital I/O / programming clock) |
| Pin 16 | RB7 — Port B bit 7 (digital I/O / programming data) |
| Pin 17 | VSS — Ground reference |
| Pin 18 | VDD — Positive supply (4.5 V to 6.0 V) |
| Pin 19 | OSC1 — Oscillator input / external clock |
| Pin 20 | OSC2 — Oscillator output (crystal mode) |
| 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 | RE0 — Port E bit 0 (digital I/O) |
| Pin 38 | RE1 — Port E bit 1 (digital I/O) |
| Pin 39 | RE2 — Port E bit 2 (digital I/O) |
| Pin 40 | MCLR/VPP — Master clear reset / Programming voltage |
| Pin 41 | VSS — Ground reference |
| Pin 42 | VDD — Positive supply (4.5 V to 6.0 V) |
| Pin 43 | NC — Not connected (per datasheet) |
| Pin 44 | NC — Not connected (per datasheet) |
Typical Applications
PIC17C42AT-16I/L is suitable for 6 applications: Industrial Control Systems, Automotive Electronics Sub-Modules, Medical Instrumentation, Consumer Appliance Control, Test and Measurement Equipment, Embedded Communication Controllers.
Industrial Control Systems
The PIC17C42AT-16I/L's 16 MHz core speed and 121 ns instruction cycle suit industrial control loops requiring deterministic real-time response. Its 33 I/O pins allow direct interface to sensors, relays, and motor drivers without external glue logic. The industrial temperature grade of -40 °C to +85 °C and 4.5-6.0 V supply range tolerate factory-floor electrical environments. The 4 KB OTP EPROM holds control firmware for PLC sub-modules, conveyor controllers, and HVAC actuators. The 232-byte RAM accommodates small state machines and PID loops.
Recommended
Automotive Electronics Sub-Modules
Although marked industrial temperature grade, the PIC17C42AT-16I/L has been historically deployed in non-safety automotive subsystems such as climate control panels, seat controllers, and infotainment peripherals. Its 16 MHz operation delivers sufficient throughput for CAN message handling via software bit-banging or external controllers. The OTP EPROM locks firmware against unauthorized field modification. The 33 I/O pins interface with switches, displays, and stepper motor drivers. Automotive tier-1 suppliers used this MCU extensively in 1990s vehicle platforms.
Recommended
Medical Instrumentation
The PIC17C42AT-16I/L is deployed in legacy medical devices such as infusion pumps, patient monitors, and laboratory analyzers where its deterministic 8-bit architecture and OTP firmware locking meet regulatory traceability requirements. The 16 MHz clock and 121 ns instruction cycle support real-time signal processing for sensor data acquisition. The 33 I/O pins interface with LCDs, keypads, and analog front-ends. The industrial temperature range and 4.5-6.0 V supply tolerance suit battery-backed or mains-isolated medical electronics.
Recommended
Consumer Appliance Control
The PIC17C42AT-16I/L powers control boards in washing machines, dishwashers, microwave ovens, and refrigerator user interfaces. Its 4 KB OTP EPROM stores appliance firmware with locked calibration constants. The 33 I/O pins drive LED indicators, seven-segment displays, membrane keypads, and triac-triggered loads. The 16 MHz throughput handles sensor multiplexing, motor PWM, and user-input debouncing. The PLCC package's socket compatibility enables service technicians to swap boards without re-soldering during warranty repairs.
Recommended
Test and Measurement Equipment
The PIC17C42AT-16I/L's deterministic instruction cycle and Harvard architecture suit legacy bench instruments such as digital multimeters, signal generators, and oscilloscope front-end controllers. Its 16 MHz speed handles front-panel button scanning, rotary encoder decoding, and LCD refresh with minimal jitter. The OTP EPROM locks calibration data and instrument firmware. The 33 I/O pins interface with ADC/DAC chips, relays, and display drivers. The PLCC package's socketed mounting simplifies factory calibration and field service.
Recommended
Embedded Communication Controllers
The PIC17C42AT-16I/L acts as a low-cost communication co-processor in legacy embedded systems, handling UART, SPI, or I2C protocol conversion between legacy peripherals and modern microprocessors. Its 16 MHz clock supports 9600-115200 baud UART rates without hardware flow control. The 33 I/O pins interface with transceivers like RS-232, RS-485, or optoisolated networks. The OTP EPROM locks protocol stacks. Industrial temperature grade suits outdoor or factory installations.
Recommended
Recommended Products Summary
Engineering reference data for PIC17C42AT-16I/L — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC17C42AT-16I/PT | PIC17C42A-16I/L | PIC17C42A-16/P | PIC17C42A-25/PT |
|---|---|---|---|---|---|
| Package | 44-PLCC (L) | TQFP-44 (PT) | 44-PLCC (L) - same | PDIP-40 (P) | TQFP-44 (PT) |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Core Speed | 16 MHz | 16 MHz | 16 MHz | 16 MHz | 25 MHz |
| Program Memory | 4 KB OTP EPROM | 4 KB OTP EPROM | 4 KB OTP EPROM | 4 KB OTP EPROM | 4 KB OTP EPROM |
| RAM Size | 232 bytes | 232 bytes | 232 bytes | 232 bytes | 232 bytes |
| I/O Pins | 33 | 33 | 33 | 33 | 33 |
| Supply Voltage | 4.5 V to 6.0 V | 4.5 V to 6.0 V | 4.5 V to 6.0 V | 4.5 V to 6.0 V | 4.5 V to 6.0 V |
| Operating Temperature | -40 °C to +85 °C (Industrial) | -40 °C to +85 °C | -40 °C to +85 °C | 0 °C to +70 °C (Commercial) | 0 °C to +70 °C (Commercial) |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete |
Key Differentiators
- Identical silicon die across multiple packaging options (vs PIC17C42A-16/P (PDIP-40))
- Socket-compatible J-lead package for serviceability (vs PIC17C42AT-16I/PT (TQFP-44))
- Industrial temperature grade for harsh environments (vs PIC17C42A-25/PT (commercial temp))
Design Notes
The PIC17C42AT-16I/L uses One-Time Programmable EPROM. Once programmed, the firmware cannot be erased or modified. Always verify code with a windowed PIC17C42A-16JW (CERQUAD windowed package) during development before programming production units. Attempting to re-program the OTP version will not erase existing data and may damage the device if VPP over-voltage is applied incorrectly. Estimate: typical programming voltage is 13.0 V on the MCLR/VPP pin per Microchip programming specifications.
Place a 0.1 µF decoupling capacitor as close as possible to each VDD pin (pins 18 and 42 on the 44-PLCC) and a bulk 10 µF tantalum or electrolytic capacitor on the supply rail. Keep the OSC1/OSC2 traces short and symmetric to minimize EMI and clock jitter. The MCLR/VPP pin (pin 40) requires a 10 kΩ pull-up to VDD for normal operation; during programming, this pin receives 13 V from the programmer.
The PIC17C42AT-16I/L is not 5 V tolerant on I/O when operating at lower voltages - it requires 4.5 V to 6.0 V supply, and I/O levels follow VDD. When connecting to 3.3 V peripherals, use level shifters such as the TXB0108 or discrete MOSFET-based circuits. The RB6/RB7 pins double as ICSP programming lines; isolate these from external pull-ups exceeding 10 kΩ to prevent programming conflicts. Estimated: signal transition time is approximately 10 ns at 25 °C with 50 pF load.
Compliance Information
PIC17C42AT-16I/L is a legacy Microchip OTP device from the 1990s; original parts are non-RoHS (SnPb finish) and not AEC-Q100 qualified. For new automotive or RoHS-compliant designs, migrate to PIC18F family.
