PIC17C42AT-33/PQ - 8-Bit 33MHz OTP MCU 4KB | Microchip
MPN: PIC17C42AT-33/PQ ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $12.5 | $12.50 |
| 10 | $11.25 | $112.50 |
| 100 | $9.85 | $985.00 |
| 500 | $8.4 | $4,200.00 |
| 1,000 | $7.1 | $7,100.00 |
PIC17C42AT-33/PQ Overview
What is an OTP microcontroller? An OTP (One-Time Programmable) microcontroller contains EPROM-based program memory that can be written once using an EPROM programmer, then behaves like a mask-ROM device for the remainder of its operating life. OTP parts bridge prototyping and low-to-medium volume production by avoiding the high NRE charges of mask-ROM while still providing the same long-term retention as ROM. Within the broader hierarchy, a microcontroller is a single-chip computer containing a CPU core, program memory, data memory, and peripherals; the PIC17C family specifically targets high-performance 8-bit applications that exceed the throughput of the PIC16C family.
Key features of the PIC17C42AT-33/PQ include an 8-bit data path, 33 MHz maximum clock, 4 KB (2K x 16) OTP program memory, 232 bytes of RAM, a 16-level hardware stack, and a RISC architecture with single-cycle instruction execution. The 44-MQFP surface-mount package supports hand-soldering rework and standard SMT lines, and the commercial temperature grade makes the part suitable for cost-sensitive industrial control and embedded designs.
The PIC17C architecture uses a Harvard bus with separate program and data paths, providing deterministic single-instruction-cycle execution at 33 MHz (121 ns per instruction). With 33 I/O pins, multiple timers, a USART, and capture/compare/PWM peripherals, the PIC17C42A was the highest-throughput 8-bit PIC at the time of introduction. Its OTP memory enables rapid design iteration, while its CMOS process yields low operating current for line-powered and battery-tolerant designs.
Typical applications include industrial control, motor control, automotive body electronics, security and alarm systems, and embedded data acquisition where the deterministic interrupt response and 33 MHz throughput exceed PIC16C capability. The 44-MQFP package provides sufficient I/O for keypad scanning, LCD drive, and serial communication.
When designing with the PIC17C42AT-33/PQ, note that the OTP memory cannot be erased or rewritten once programmed - prototype code on a windowed CERDIP part (PIC17C42A-33/PQ is the MQFP OTP variant), then commit production code. Operating voltage range and absolute maximum ratings should be confirmed against the latest Microchip datasheet prior to board bring-up.
This page synthesizes distributor pricing, drop-in same-package alternatives from the PIC17C family, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for PIC17C42AT-33/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 PIC17C42AT-33/PQ (same form factor and footprint) — differing in Program Memory Type, Core Architecture, Package, RAM Size, Family.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC17C42A-33/PQ
✅ Drop-In✓ In Stock
$6.45 / Unit
View Datasheet →PIC17C42AT-25/PQ
✅ Drop-In✓ In Stock
$8.65 / Unit
View Datasheet →PIC17C42A-33I/PQ
✅ Drop-In✓ In Stock
$11.4 / Unit
View Datasheet →PIC17C42A-25/PT
✅ Drop-In✓ In Stock
$5.55 / Unit
View Datasheet →PIC17C42AT-25/PT
✅ Drop-In✓ In Stock
$10.5 / Unit
View Datasheet →PIC17C42AT-33/PQ Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC17C RISC |
| Family | PIC 17C |
| Maximum Clock Frequency | 33 MHz |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 4 KB (2K x 16) |
| Data RAM | 232 bytes |
| Data EEPROM | Not present |
| Instruction Word Width | 16-bit |
| Package | 44-MQFP (10 x 10 mm) |
| Mounting Type | Surface Mount |
| Pin Count | 44 |
| Operating Temperature Grade | Commercial |
| Peripherals | Timers, USART, Capture/Compare/PWM (per datasheet) |
PIC17C42AT-33/PQ Pin Configuration
| Pin 1 | OSC1/CLKIN — Oscillator crystal input or external clock input |
| Pin 2 | OSC2/CLKOUT — Oscillator crystal output or clock output |
| Pin 3 | MCLR — Master clear reset input (active low) |
| Pin 4 | RA0 — Port A digital I/O bit 0 |
| Pin 5 | RA1 — Port A digital I/O bit 1 |
| Pin 6 | RA2 — Port A digital I/O bit 2 |
| Pin 7 | RA3 — Port A digital I/O bit 3 |
| Pin 8 | RA4 — Port A digital I/O bit 4 |
| Pin 9 | RA5 — Port A digital I/O bit 5 |
| Pin 10 | VSS — Ground reference |
| Pin 11 | VDD — Positive supply voltage |
| Pin 12 | RB0/INT — Port B bit 0 / external interrupt input |
| Pin 13 | RB1 — Port B digital I/O bit 1 |
| Pin 14 | RB2 — Port B digital I/O bit 2 |
| Pin 15 | RB3 — Port B digital I/O bit 3 |
| Pin 16 | RB4 — Port B digital I/O bit 4 |
| Pin 17 | RB5 — Port B digital I/O bit 5 |
| Pin 18 | RB6 — Port B digital I/O bit 6 |
| Pin 19 | RB7 — Port B digital I/O bit 7 |
| Pin 20 | RC0 — Port C digital I/O bit 0 |
| Pin 21 | RC1 — Port C digital I/O bit 1 |
| Pin 22 | RC2 — Port C digital I/O bit 2 |
| Pin 23 | RC3 — Port C digital I/O bit 3 |
| Pin 24 | RC4 — Port C digital I/O bit 4 |
| Pin 25 | RC5 — Port C digital I/O bit 5 |
| Pin 26 | RC6 — Port C digital I/O bit 6 |
| Pin 27 | RC7 — Port C digital I/O bit 7 |
| Pin 28 | VSS — Ground reference |
| Pin 29 | VDD — Positive supply voltage |
| Pin 30 | RD0 — Port D digital I/O bit 0 |
| Pin 31 | RD1 — Port D digital I/O bit 1 |
| Pin 32 | RD2 — Port D digital I/O bit 2 |
| Pin 33 | RD3 — Port D digital I/O bit 3 |
| Pin 34 | RD4 — Port D digital I/O bit 4 |
| Pin 35 | RD5 — Port D digital I/O bit 5 |
| Pin 36 | RD6 — Port D digital I/O bit 6 |
| Pin 37 | RD7 — Port D digital I/O bit 7 |
| Pin 38 | RE0 — Port E digital I/O bit 0 |
| Pin 39 | RE1 — Port E digital I/O bit 1 |
| Pin 40 | RE2 — Port E digital I/O bit 2 |
| Pin 41 | TOCKI — Timer0 clock input or Port E bit 3 |
| Pin 42 | NC — Not connected (per datasheet) |
| Pin 43 | NC — Not connected (per datasheet) |
| Pin 44 | TEST — Test mode pin (factory use, tie to VDD) |
Typical Applications
PIC17C42AT-33/PQ is suitable for 6 applications: Industrial Motor Control, Security and Alarm Panels, HVAC and Building Control, Automotive Body Electronics, Point-of-Sale Terminals, Uninterruptible Power Supply Controllers.
Industrial Motor Control
The PIC17C42AT-33/PQ fits industrial motor control because its 33 MHz throughput delivers a 121 ns instruction cycle, supporting real-time PID loops for brushed DC and stepper motor commutation. The 4 KB OTP program memory holds state-machine firmware and lookup tables for trapezoidal acceleration profiles, while the 232-byte RAM retains runtime setpoints. Its 44-MQFP package offers enough I/O for quadrature encoder input, PWM output, and RS-485 comms to a host PLC. The Harvard bus and 16-level hardware stack guarantee deterministic interrupt latency for current-loop control. Designers should add external flyback diodes and opto-isolation since the 5 V CMOS port pins cannot directly drive inductive loads.
Recommended
Security and Alarm Panels
The PIC17C42AT-33/PQ is well suited to security panel controllers because its 8-bit RISC core runs scan loops across multiple zones faster than PIC16C alternatives, while the 4 KB OTP stores zone-config tables and dialer strings. The 232-byte RAM buffers event logs and tamper counters between power-line events. The 44-MQFP package exposes enough I/O for keypad matrix scanning, piezo buzzer drive, and PSTN/GSM dialer handshake. The OTP memory ensures the firmware cannot be electronically reverse-engineered, which is desirable for anti-tamper designs. Engineers typically add a battery-backed RTC and a watchdog supervisor external to the MCU since the PIC17C42A has no internal EEPROM.
Recommended
HVAC and Building Control
The PIC17C42AT-33/PQ drives HVAC controllers where the 33 MHz core handles concurrent temperature-sensor polling, proportional valve actuation, and display refresh without round-robin jitter. Its 4 KB OTP program memory holds the multi-mode thermostat state machine, while 232-byte RAM tracks setpoint history. The 44-MQFP package offers pins for NTC thermistor input bridges, triac-fired compressor drivers, and I2C/SPI expansion to a wireless module. The commercial temperature grade is adequate for indoor enclosure use. For rooftop units, migrate to the industrial-grade PIC17C42A-33I/PQ so the MCU operates from -40 C to +85 C. External MOV protection on the triac outputs is essential.
Recommended
Automotive Body Electronics
The PIC17C42AT-33/PQ was deployed in non-safety body modules such as seat controllers, mirror adjusters, and lighting timers where its 33 MHz MIPS rating handled multiple PWM channels at low latency. The OTP memory locks the body-control firmware against field tampering. The 44-MQFP package provides sufficient I/O for CAN-style transceivers and H-bridge driver enable lines, although CAN is implemented in firmware rather than hardware. For under-hood temperatures the industrial-grade PIC17C42A-33I/PQ must be used instead. Add TVS diodes on every connector pin to absorb load-dump transients common in 12 V automotive electrical systems.
Recommended
Point-of-Sale Terminals
The PIC17C42AT-33/PQ served as the I/O co-processor in legacy point-of-sale terminals, scanning mechanical keypad matrices, driving dot-matrix LCD character displays, and buffering serial receipt-printer traffic. Its 33 MHz throughput beats PIC16C alternatives in keypad-debounce loops, and the 4 KB OTP memory holds character-generator tables plus menu strings. The 44-MQFP package offers enough pins for a 4x5 keypad, RS-232 host link, and parallel LCD interface. The OTP memory prevents casual cloning of encrypted firmware. Engineers should route the MCU away from ESD-prone bezel connectors and add series resistors on every I/O line that contacts the user.
Recommended
Uninterruptible Power Supply Controllers
The PIC17C42AT-33/PQ is a strong fit for low-to-medium power UPS controllers because its deterministic single-cycle instruction execution guarantees a fixed interrupt response time when transferring mains to inverter mode. The 4 KB OTP memory holds sine-PWM lookup tables and battery-charger state machines, while 232-byte RAM retains run-time telemetry. The 44-MQFP package exposes enough I/O for current-sense amplifier inputs, H-bridge gate-drive outputs, and a battery-temperature thermistor input. For industrial UPS equipment in non-air-conditioned rooms, use the industrial-grade PIC17C42A-33I/PQ to extend the operating temperature envelope.
Recommended
Recommended Products Summary
Engineering reference data for PIC17C42AT-33/PQ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC17C42A-33/PQ | PIC17C42AT-25/PQ | PIC17C42A-33I/PQ | PIC17C42A-25/PT | PIC17C42AT-25/PT |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-MQFP (10x10) | 44-MQFP (10x10) - same | 44-MQFP (10x10) - same | 44-MQFP (10x10) - same | 44-MQFP (10x10) - same | 44-MQFP (10x10) - same |
| Maximum Clock Frequency | 33 MHz | 33 MHz | 25 MHz | 33 MHz | 25 MHz | 25 MHz |
| Program Memory | 4 KB OTP (2K x 16) | 4 KB OTP (2K x 16) | 4 KB OTP (2K x 16) | 4 KB OTP (2K x 16) | 4 KB OTP (2K x 16) | 4 KB OTP (2K x 16) |
| Data RAM | 232 bytes | 232 bytes | 232 bytes | 232 bytes | 232 bytes | 232 bytes |
| Temperature Grade | Commercial (0C to +70C) | Commercial | Commercial | Industrial (-40C to +85C) | Commercial | Commercial |
| Shipping Medium | Tape & Reel | Tray | Tape & Reel | Tray | Tray | Tape & Reel |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete |
Key Differentiators
- Tape-and-reel shipping medium for SMT production (vs PIC17C42A-33/PQ)
- 33 MHz highest-speed PIC17C42A bin (vs PIC17C42AT-25/PQ)
- One of the few PIC17C42A variants still in tape-and-reel distribution (vs PIC17C42A-25/PT)
Design Notes
The PIC17C42AT-33/PQ operates from a single 5 V supply; decouple VDD with a 0.1 uF ceramic capacitor placed within 5 mm of each VDD/VSS pin pair, plus a 10 uF bulk tantalum on the main VDD rail. The PIC17C family draws peak currents of 50-70 mA at 33 MHz, so verify regulator headroom and use a low-ESR bulk cap to suppress VDD droop during interrupt-driven peripherals. Estimated based on PIC17C42A datasheet DC characteristics; check the latest revision before production.
Because the part is OTP, a single programming error destroys the device - always program a windowed CERDIP PIC17C42A-33/P first to validate firmware before committing OTP production parts. Note also that the 'T' suffix is the tape-and-reel shipping medium, NOT a silicon revision; double-check the marking before assembly to avoid mixing tray and reel parts on the same line. Verified against Microchip ordering nomenclature.
Route the 33 MHz crystal traces to OSC1/OSC2 as short as possible (under 10 mm) and guard them with a ground pour on both sides of the PCB to minimize EMI coupling into adjacent ADC or comparator traces. Place decoupling caps directly at each port pin that drives an external load to limit ground bounce. Estimated layout guidance based on standard PIC17C reference designs from the Microchip PIC17C42A datasheet.
Compliance Information
RoHS / lead-free status not present in the verified web data; consult Microchip's material declaration for the specific lot date code. Not AEC-Q100 qualified; for automotive body modules use industrial-grade PIC17C42A-33I/PQ.
