PIC17LC42A-08/PQ - 8-bit CMOS MCU, 4KB OTP, 33 I/O | Microchip
MPN: PIC17LC42A-08/PQ ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.95 | $8.95 |
| 10 | $7.85 | $78.50 |
| 100 | $6.5 | $650.00 |
| 500 | $5.2 | $2,600.00 |
| 1,000 | $4.1 | $4,100.00 |
PIC17LC42A-08/PQ Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, memory, and peripherals on one die. The PIC17C/PIC17LC family sits at the upper end of Microchip's 8-bit line, sharing the RISC instruction-set philosophy of the smaller PIC16 family but with a wider 16-bit instruction word, a 16-bit data path, and hardware multiply support. The "LC" suffix indicates a low-voltage CMOS variant suitable for battery-powered or 3.3 V designs. Within the broader taxonomy, the PIC17LC42A is a microcontroller -> 8-bit MCU -> RISC MCU -> EPROM/OTP MCU -> power-aware (LC) family member.
Key features of the PIC17LC42A-08/PQ include 4 KB OTP program memory, 232 bytes of data RAM, 33 general-purpose I/O pins, an 8-bit timer/counter, a USART, and the PIC17-series 16-bit instruction architecture with only 58 single-word instructions to learn. The "/PQ" suffix designates a 44-pin Metric Quad Flat Pack (MQFP) with gull-wing leads and a square footprint. The "-08" speed grade indicates an 8 MHz oscillator rating within the LC low-voltage family.
Architecturally, the device uses a Harvard memory layout (separate program and data buses), enabling simultaneous instruction fetch and operand access. The single-cycle instruction pipeline (two-cycle for branches and table operations) simplifies deterministic real-time control loops. The 8-bit ALU, combined with the 16-bit instruction word, supports bit-oriented, byte-oriented, and literal operations natively.
Typical applications include industrial control panels, instrumentation front-ends, motor-control signal conditioning, low-cost remote sensor terminals, and legacy embedded-system upgrades where PIC16-series parts lack sufficient I/O or memory. The wide I/O count and OTP memory make it well suited for moderate-volume production.
When designing with this part, note that OTP memory allows only a single programming cycle, so code must be verified before final programming. Designers should budget decoupling on VDD/VSS pins, follow Microchip's MQFP PCB layout recommendations for leaded gull-wing packages, and ensure oscillator rise/fall times meet the 33 MHz spec.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for PIC17LC42A-08/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 PIC17LC42A-08/PQ (same form factor and footprint) — differing in Package, Program Memory Size, Program Memory Type, Maximum Clock Frequency, Core Architecture.
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No drop-in alternatives available for this product.
Request AlternativesPIC17LC42A-08/PQ Maximum Ratings & Electrical Characteristics
| Product Type | 8-bit Microcontroller (MCU) |
| Family | PIC17LC |
| Program Memory Type | OTP (EPROM) |
| Program Memory Size | 4 KB |
| RAM Size | 232 bytes |
| I/O Pins | 33 |
| Instruction Set | 58 single-word instructions |
| Instruction Word Width | 16 bits |
| Data Path Width | 8 bits |
| Maximum Clock Input | 33 MHz |
| Instruction Cycle | 121 ns (single-cycle) |
| Two-Cycle Operations | Program branches, table reads/writes |
| Speed Grade | -08 |
| Technology | CMOS |
| Package | 44-pin MQFP (PQ), gull-wing |
| Mounting Type | Surface Mount |
| Temperature Grade | Commercial |
| Terminal Form | GULL WING |
| Package Code | QFP |
| Package Shape | SQUARE |
PIC17LC42A-08/PQ Pin Configuration
| Pin 1 | MCLR — Master Clear (Reset) input |
| Pin 2 | RA0 — PORTA bit 0 / analog input |
| Pin 3 | RA1 — PORTA bit 1 / analog input |
| Pin 4 | RA2 — PORTA bit 2 / analog input |
| Pin 5 | RA3 — PORTA bit 3 / analog input |
| Pin 6 | RA4 — PORTA bit 4 / analog input |
| Pin 7 | RA5 — PORTA bit 5 / analog input |
| Pin 8 | RA6 — PORTA bit 6 / analog input |
| Pin 9 | RA7 — PORTA bit 7 / analog input |
| Pin 10 | OSC1/CLKIN — Oscillator crystal input / external clock |
| Pin 11 | OSC2/CLKOUT — Oscillator crystal output / clock output |
| Pin 12 | VSS — Ground reference |
| Pin 13 | VDD — Positive supply voltage |
| Pin 14 | RB0 — 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 / programming clock |
| Pin 21 | RB7 — PORTB bit 7 / programming data |
| 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 — PORTC bit 6 / TX |
| Pin 29 | RC7 — PORTC bit 7 / RX |
| 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 | VSS — Ground reference |
| Pin 42 | VDD — Positive supply voltage |
| Pin 43 | NC — Not connected |
| Pin 44 | NC — Not connected |
Typical Applications
PIC17LC42A-08/PQ is suitable for 6 applications: Industrial Control Panels, Instrumentation Front-Ends, Motor Control Signal Conditioning, Low-Cost Remote Sensor Terminals, Legacy Embedded System Upgrades, Consumer Appliance Control Boards.
Industrial Control Panels
The PIC17LC42A-08/PQ fits industrial control panels thanks to its 33 digital I/O pins and 4 KB OTP program memory. In a typical control panel application, the MCU scans 16-24 discrete inputs from pushbuttons and limit switches, drives relay outputs via optocouplers, and runs a 121 ns deterministic state machine for safety interlocks. The Harvard architecture ensures predictable interrupt latency for time-critical control loops. The CMOS LC variant suits battery-backed or low-power 3.3 V panel designs where energy efficiency matters. Industrial control panels benefit from the 58 single-word instruction set, which simplifies code review and certification, while the 232 byte RAM accommodates local variables for debounce, sequencing, and PID loops.
Recommended
Instrumentation Front-Ends
Front-ends of bench instruments such as multimeters, signal generators, and laboratory data loggers can use the PIC17LC42A-08/PQ to manage display driving, keypad scanning, and serial communication. The 33 MHz clock input and 121 ns instruction cycle handle real-time serial protocols (USART) without jitter. The 232 byte RAM supports small FIFO buffers and command parsing for an RS-232 or RS-485 interface. For battery-powered instrumentation, the LC low-voltage CMOS variant extends operating time. The 4 KB OTP is sufficient for menu logic, calibration routines, and measurement sequencing. Engineers appreciate the 16-bit instruction word for compact bit-manipulation code when driving multiplexed LCD or LED displays.
Recommended
Motor Control Signal Conditioning
Signal conditioning boards for stepper motors, DC motor drivers, and small BLDC fans can use the PIC17LC42A-08/PQ to generate PWM timing, monitor current sense amplifiers, and orchestrate commutation sequences. The 121 ns instruction cycle supports PWM frequencies above 20 kHz (above audible range) with fine duty-cycle resolution. The 33 I/O pins accommodate multiple phase outputs, Hall sensor inputs, fault lines, and a USART for host communication. The PIC17 instruction set includes bit-oriented operations that simplify the state-machine logic for commutation tables. The OTP memory ensures code security in distributed motor-control modules. Low-voltage operation (LC variant) enables direct 3.3 V interface with modern gate drivers.
Recommended
Low-Cost Remote Sensor Terminals
Remote sensor terminals for environmental monitoring, agricultural telemetry, and HVAC zone controllers can leverage the PIC17LC42A-08/PQ. The MCU reads analog or digital sensors, packages data, and transmits via USART to a radio module or wired bus. The 232 byte RAM accommodates protocol frame buffers, while 4 KB OTP stores application logic and calibration tables. The LC low-voltage CMOS operation suits battery or solar-powered deployments. The 33 I/O lines interface multiple sensor channels and status LEDs without external I/O expanders. The deterministic single-cycle execution ensures predictable timing for synchronous serial protocols (SPI, I2C) used by environmental sensors.
Recommended
Legacy Embedded System Upgrades
The PIC17LC42A-08/PQ enables drop-in upgrades for legacy systems originally designed around the PIC17 family, preserving PCB layout and toolchain investments. Sites where the PIC17C42A-25/PQ or PIC17C43-16I/PQ was deployed can migrate to the LC variant for lower power consumption while retaining the same instruction set and development environment. The 44-pin MQFP package matches the original footprint, and the PIC17 instruction set ensures code compiled for the older part runs on the newer LC silicon with minimal changes. This is valuable for industrial equipment manufacturers maintaining long-term support contracts on installed bases.
Recommended
Consumer Appliance Control Boards
Consumer appliances like washing machines, dishwashers, microwave ovens, and coffee machines use the PIC17LC42A-08/PQ as the central controller for user interface, sensor monitoring, and actuator driving. The 33 I/O lines drive displays, keypads, LEDs, relays, and buzzer/buzzer PWM. The 4 KB OTP stores the appliance state machine and timing logic. The 121 ns instruction cycle handles real-time tasks like triac zero-crossing detection for heater control. The LC variant's low-voltage operation enables simple 3.3 V regulator designs. The PIC17's 16-bit instruction word produces compact code that fits within the 4 KB OTP budget for complete appliance firmware.
Recommended
Recommended Products Summary
Engineering reference data for PIC17LC42A-08/PQ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC17C42A-25/PQ | PIC17C42AT-25/PQ | PIC17C42AT-33E/PQ | PIC17C43-16I/PQ | PIC17C43T-25I/PQ |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-pin MQFP (PQ) | 44-pin MQFP (PQ) - same | 44-pin MQFP (PQ) - same | 44-pin MQFP (PQ) - same | 44-pin MQFP (PQ) - same | 44-pin MQFP (PQ) - same |
| Program Memory | 4 KB OTP | 4 KB OTP | 4 KB OTP | 4 KB OTP | 8 KB OTP | 8 KB OTP |
| RAM Size | 232 bytes | 232 bytes | 232 bytes | 232 bytes | 454 bytes | 454 bytes |
| I/O Pins | 33 | 33 | 33 | 33 | 33 | 33 |
| Speed Grade | -08 | -25 (25 MHz) | -25 (25 MHz) | -33E (33 MHz, extended) | -16I (16 MHz, industrial) | -25I (25 MHz, industrial) |
| Voltage Range | LC low-voltage (3.0-5.5V typical) | Standard (4.5-5.5V) | Standard (4.5-5.5V) | Standard (4.5-5.5V) | Standard (4.5-5.5V) | Standard (4.5-5.5V) |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete |
Key Differentiators
- Low-voltage CMOS operation for battery-powered designs (vs PIC17C42A-25/PQ)
- Higher memory option available in same package (vs PIC17C43-16I/PQ)
- Modern active-lifecycle alternative for new designs (vs dsPIC33EP64GP504-E/MV)
Design Notes
The PIC17LC42A-08/PQ as an LC low-voltage variant typically operates from 3.0V to 5.5V. Place 100nF decoupling capacitors as close as possible to each VDD/VSS pin pair (pins 13, 42 for VDD and pins 12, 41 for VSS on the 44-pin MQFP). For battery-powered designs, use a low-dropout regulator and add a 10uF bulk capacitor near the MCU. The CMOS LC variant draws lower quiescent current than the standard PIC17C42A, which is critical for sleep-mode operation in remote sensor terminals.
The 44-pin MQFP (PQ) package has gull-wing leads on all four sides with a 0.8 mm pitch. Follow IPC-7351 land pattern recommendations for MQFP-44. Ensure the PCB footprint has adequate thermal relief pads under the leads and a center thermal pad if present. Keep oscillator traces short and routed over a continuous ground plane to minimize EMI. Place the MCLR pull-up resistor (typically 10k ohm) close to the MCLR pin (pin 1) to ensure a clean reset signal.
OTP (One-Time-Programmable) memory can be programmed only ONCE - the PIC17LC42A-08/PQ cannot be erased and reprogrammed. Verify code thoroughly in a windowed or flash equivalent (PIC17C42A-08/JW or PIC17F family if available) before programming production units. Also note that the -08 speed grade limits the oscillator input to 8 MHz; exceeding this causes timing violations. When migrating from PIC17C42A to PIC17LC42A, verify that peripheral timing is compatible with the lower voltage range.
Route the OSC1/OSC2 traces (pins 10/11) symmetrically and as short as possible to the crystal or ceramic resonator. Keep these traces away from high-current switching lines and digital I/O to avoid clock jitter. For USART lines (RC6/RC7), use series resistors or ferrite beads to limit EMI if the lines leave the PCB. The 44-pin MQFP has leads on all four sides - ensure the PCB silkscreen clearly marks pin 1 with a dot or bevel indicator to avoid assembly orientation errors.
Compliance Information
This is an obsolete part originally released before widespread RoHS adoption. Compliance status not stated in verified web data. For new designs requiring RoHS, choose a currently-produced dsPIC33EV family member. AEC-Q100 not applicable for this industrial/consumer-grade MCU.
