PIC17C42AT-33I/PQ - 33MHz 8-Bit PIC MCU, 4KB OTP, MQFP-44
MPN: PIC17C42AT-33I/PQ ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $18.5 | $18.50 |
| 10 | $16.2 | $162.00 |
| 100 | $14.05 | $1,405.00 |
| 500 | $12.3 | $6,150.00 |
| 1,000 | $10.85 | $10,850.00 |
PIC17C42AT-33I/PQ Overview
Background Knowledge: A microcontroller (MCU) is a single-chip computer containing a CPU core, program memory, data RAM, and peripherals. The PIC17C series is part of Microchip's 8-bit PIC (Peripheral Interface Controller) RISC architecture family, sitting between the PIC16 mid-range family and the PIC18 enhanced family in performance. RISC (Reduced Instruction Set Computer) architectures use a small, fixed-length instruction set executed in single cycles (with limited exceptions). OTPs are programmed once and cannot be erased, unlike UV-EPROM (windowed) parts, making them suited to volume production where code is finalized. EPROM-based MCUs historically preceded Flash-based ones in the PIC lineup.
Key features include a Harvard architecture with separate program and data buses, an 8-level hardware stack, a 4-cycle hardware multiplier (8 x 8 -> 16-bit result in one instruction cycle), 192 bytes of general-purpose RAM, 33 I/O pins, and a wide operating voltage range of 4.5V to 6.0V. The instruction set is highly orthogonal, with most instructions able to use any register as both source and destination, and direct/indirect addressing modes plus a 16-bit program counter.
On-chip peripherals include a Capture/Compare/PWM (CCP) module, two 8-bit timer/counters with programmable prescalers, an asynchronous serial port (USART), and a watchdog timer with its own on-chip RC oscillator for maximum reliability. The MCU also has a power-on reset, brown-out detect, and various interrupt sources with two priority levels.
Typical applications include industrial control systems, automotive body electronics, motor control (stepper and DC), smart sensor interfaces, embedded instrumentation, and legacy embedded products designed in the mid-1990s. Its 33 MHz throughput and 16-bit-wide program word made it the highest-performance 8-bit PIC of its era. The OTP version is ideal for production runs where field firmware updates are not required.
When designing with this part, note that OTP memory cannot be erased after programming, so code must be fully validated before production programming. The 44-pin Metric MQFP (PQ) footprint differs from the 40-pin PDIP (P) package used on the same family, so board layouts are not interchangeable. Programming requires a PIC17C-compatible device programmer supporting high-voltage (typically 13V) Vpp programming mode.
This page synthesizes distributor stock, drop-in alternatives from the same PIC17C family, and practical design notes - context not available from the manufacturer datasheet alone.
Drop-in alternatives for PIC17C42AT-33I/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-33I/PQ (same form factor and footprint) — differing in Package, Mounting Type, Program Memory Type, Operating Temperature Range, Instruction Cycle.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC17C42AT-33E/PQ
✅ Drop-In✓ In Stock
$10.6 / Unit
View Datasheet →PIC17C42A-33I/PQ
✅ Drop-In✓ In Stock
$11.4 / Unit
View Datasheet →PIC17C42A-33I/P
✅ Drop-In✓ In Stock
$6.2 / Unit
View Datasheet →PIC17C42A-33/PT
✅ Drop-In✓ In Stock
$9.65 / Unit
View Datasheet →PIC17C42A-25E/P
✅ Drop-In✓ In Stock
$5.6 / Unit
View Datasheet →PIC17C42AT-33I/PQ Maximum Ratings & Electrical Characteristics
| Product Family | PIC17C (High-Performance 8-Bit) |
| Architecture | 8-bit RISC, Harvard (separate program/data buses) |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 4 KB (2K x 16 words) |
| Data RAM | 192 bytes |
| Maximum Clock Frequency | 33 MHz |
| Instruction Cycle | 121 ns (single cycle); 242 ns branches/table reads |
| Instruction Set Size | 58 instructions (16-bit wide program words) |
| Operating Voltage Range | 4.5 V to 6.0 V |
| Operating Temperature Range | -40 C to +85 C (industrial, 'I' suffix) |
| I/O Pins | 33 |
| Timers | Two 8-bit timer/counters with programmable prescaler |
| CCP Modules | 1 (Capture/Compare/PWM) |
| Serial Interface | 1x USART (asynchronous serial port) |
| Watchdog Timer | Yes (with dedicated on-chip RC oscillator) |
| Hardware Multiplier | 8 x 8 -> 16-bit, single instruction cycle |
| Hardware Stack | 8 levels |
| Package | 44-pin Metric MQFP (MQFP-44 / PQ) |
| Mounting Type | Surface Mount |
PIC17C42AT-33I/PQ Pin Configuration
| Pin 1 | RA0 — PORTA bit 0 (digital I/O, analog input) |
| Pin 2 | RA1 — PORTA bit 1 (digital I/O, analog input) |
| Pin 3 | RA2 — PORTA bit 2 (digital I/O, analog input) |
| Pin 4 | RA3 — PORTA bit 3 (digital I/O, analog input) |
| Pin 5 | RA4 — PORTA bit 4 (digital I/O) |
| Pin 6 | RA5 — PORTA bit 5 (digital I/O) |
| Pin 7 | OSC1 — Crystal oscillator input / external clock input |
| Pin 8 | OSC2 — Crystal oscillator output |
| Pin 9 | MCLR/Vpp — Master Clear (reset) input / Programming voltage input |
| Pin 10 | VSS — Ground reference |
| Pin 11 | VDD — Positive supply voltage (4.5V to 6.0V) |
| Pin 12 | VSS — Ground reference |
| Pin 13 | RB0 — PORTB bit 0 (digital I/O, external interrupt) |
| Pin 14 | RB1 — PORTB bit 1 (digital I/O) |
| Pin 15 | RB2 — PORTB bit 2 (digital I/O) |
| Pin 16 | RB3 — PORTB bit 3 (digital I/O) |
| Pin 17 | RB4 — PORTB bit 4 (digital I/O) |
| Pin 18 | RB5 — PORTB bit 5 (digital I/O) |
| Pin 19 | RB6 — PORTB bit 6 (digital I/O, ICD clock) |
| Pin 20 | RB7 — PORTB bit 7 (digital I/O, ICD data) |
| Pin 21 | RC0 — PORTC bit 0 (digital I/O, CCP1 output) |
| Pin 22 | RC1 — PORTC bit 1 (digital I/O, CCP2 input) |
| Pin 23 | RC2 — PORTC bit 2 (digital I/O) |
| Pin 24 | RC3 — PORTC bit 3 (digital I/O) |
| Pin 25 | RC4 — PORTC bit 4 (digital I/O) |
| Pin 26 | RC5 — PORTC bit 5 (digital I/O) |
| Pin 27 | RC6 — PORTC bit 6 (digital I/O, USART TX) |
| Pin 28 | RC7 — PORTC bit 7 (digital I/O, USART RX) |
| Pin 29 | RD0 — PORTD bit 0 (digital I/O) |
| Pin 30 | RD1 — PORTD bit 1 (digital I/O) |
| Pin 31 | RD2 — PORTD bit 2 (digital I/O) |
| Pin 32 | RD3 — PORTD bit 3 (digital I/O) |
| Pin 33 | RD4 — PORTD bit 4 (digital I/O) |
| Pin 34 | RD5 — PORTD bit 5 (digital I/O) |
| Pin 35 | RD6 — PORTD bit 6 (digital I/O) |
| Pin 36 | RD7 — PORTD bit 7 (digital I/O) |
| Pin 37 | RE0 — PORTE bit 0 (digital I/O, control) |
| Pin 38 | RE1 — PORTE bit 1 (digital I/O, control) |
| Pin 39 | RE2 — PORTE bit 2 (digital I/O, control) |
| Pin 40 | RE3 — PORTE bit 3 (digital I/O, control) |
| Pin 41 | RF0 — PORTF bit 0 (digital I/O) |
| Pin 42 | RF1 — PORTF bit 1 (digital I/O) |
| Pin 43 | RF2 — PORTF bit 2 (digital I/O) |
| Pin 44 | RF3 — PORTF bit 3 (digital I/O) |
Typical Applications
PIC17C42AT-33I/PQ is suitable for 6 applications: Industrial Control Systems, Automotive Body Electronics, Stepper and DC Motor Control, Smart Sensor Interface Hubs, Embedded Instrumentation and Test Equipment, Legacy Embedded Control Boards.
Industrial Control Systems
The PIC17C42AT-33I/PQ fits industrial control designs because of its 33 MHz instruction throughput, 16-bit-wide program word, and industrial -40C to +85C temperature range. The 8-bit PIC17C RISC core delivers deterministic 121 ns interrupt latency critical for closed-loop PID control. The on-chip CCP module, two 8-bit timers, and USART support PWM motor drive and serial sensor networks. The 4KB OTP program memory holds typical control logic; the 33 I/O pins connect directly to relays, sensors, and H-bridge drivers. Use it for conveyor controllers, machine-tool interfaces, and process-control PLCs where the proven PIC17C instruction set is required and 5V tolerant I/O simplifies interface to legacy 5V logic.
Recommended
Automotive Body Electronics
The PIC17C42AT-33I/PQ was widely designed into 1990s and early-2000s automotive body and chassis ECUs where its industrial temperature range, 5V operation, and high noise immunity were valued. The 33 MHz RISC core and 16-bit instruction word handled body-control algorithms (window lifters, seat controllers, climate control, lighting) with deterministic timing. The CCP module generates PWM for motor-drive and lamp-dimming outputs, while the USART interfaces to in-vehicle networks (LIN precursors, K-Line). Its OTP memory supports volume production runs where firmware is finalized. Note: for new automotive designs requiring AEC-Q100 qualification, modern PIC18F-K42 or dsPIC33EP families supersede the PIC17C. Use PIC17C42AT-33I/PQ only for legacy ECU repair and reproduction.
Recommended
Stepper and DC Motor Control
The PIC17C42AT-33I/PQ fits stepper and brushed DC motor control because of its CCP module with PWM generation, two 8-bit timers for commutation timing, and 33 I/O pins to drive H-bridge gate drivers directly. The 121 ns instruction cycle enables fine-grained PWM duty-cycle resolution at high switching frequencies. The 16-bit program word accommodates complex acceleration/deceleration profiles and microstepping lookup tables in 4KB OTP. The Harvard architecture and 8-level hardware stack handle nested ISRs for encoder feedback, current sensing, and over-current protection. Use it for printer paper-feed motors, valve actuators, HVAC damper control, and small CNC axis drivers where proven PIC17C firmware is required.
Recommended
Smart Sensor Interface Hubs
The PIC17C42AT-33I/PQ serves as a sensor-hub aggregator in industrial and embedded systems, taking inputs from analog and digital sensors via its 33 I/O pins and serial interfaces. The USART and CCP modules handle synchronous/asynchronous sensor protocols, while 192 bytes of RAM buffer small data bursts before forwarding to a host processor. The 33 MHz instruction rate and 16-bit program word provide headroom for sensor linearization, calibration, and digital filtering in firmware. The OTP memory holds calibration coefficients for production. The industrial -40C to +85C range supports factory-floor deployment. Use it in legacy sensor modules, environmental monitors, and instrumentation front-ends where the PIC17C toolchain and libraries are established.
Recommended
Embedded Instrumentation and Test Equipment
The PIC17C42AT-33I/PQ fits handheld test instruments and measurement front-ends because of its deterministic 121 ns interrupt response, USART for digital comms, and CCP for stimulus generation. The 33 MHz core processes measurement algorithms and UI handling in 4KB OTP, while 192 bytes of RAM hold display buffers and conversion results. The 33 I/O pins drive LCD segments, keypads, mode switches, and signal-conditioning relays. The 5V supply and industrial temperature range suit bench and field-instrument environments. Use it for legacy multimeters, calibrators, data loggers, and lab instruments where the PIC17C platform is locked by firmware dependencies and certifications.
Recommended
Legacy Embedded Control Boards
The PIC17C42AT-33I/PQ continues to serve as a repair-and-reproduction part for legacy embedded control boards originally designed in the mid-1990s, where its 33 MHz PIC17C RISC core, 44-pin Metric MQFP footprint, and OTP memory are mandated by the existing PCB and firmware. Replacement by modern parts would require PCB rework and revalidation. The PIC17C42A silicon revision provides identical instruction timing to its predecessors, ensuring firmware compatibility. Use this part for aerospace ground-support equipment, industrial line controllers, defense electronics, and medical-device control boards with locked PIC17C firmware and certifications.
Recommended
Recommended Products Summary
Engineering reference data for PIC17C42AT-33I/PQ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC17C42AT-33E/PQ | PIC17C42A-33I/PQ | PIC17C42A-33I/P | PIC17C42A-33/PT | PIC17C42A-25E/P |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-pin Metric MQFP (PQ) | 44-pin Metric MQFP (PQ) - same | 44-pin Metric MQFP (PQ) - same | 40-pin PDIP (P) - NOT pin-compatible | 44-pin TQFP (PT) - different land pattern | 40-pin PDIP (P) - NOT pin-compatible |
| Program Memory | 4 KB OTP EPROM (2K x 16) | 4 KB OTP EPROM | 4 KB UV-EPROM (windowed) | 4 KB UV-EPROM | 4 KB UV-EPROM | 4 KB UV-EPROM |
| Max Clock Frequency | 33 MHz | 33 MHz | 33 MHz | 33 MHz | 33 MHz | 25 MHz (-24%) |
| Instruction Cycle | 121 ns | 121 ns | 121 ns | 121 ns | 121 ns | 160 ns |
| Operating Voltage | 4.5V to 6.0V | 4.5V to 6.0V | 4.5V to 6.0V | 4.5V to 6.0V | 4.5V to 6.0V | 4.5V to 6.0V |
| Temperature Range | -40C to +85C (industrial) | -40C to +125C (extended) | -40C to +85C | -40C to +85C | 0C to +70C (commercial) | -40C to +125C (extended) |
| Data RAM | 192 bytes | 192 bytes | 192 bytes | 192 bytes | 192 bytes | 192 bytes |
Key Differentiators
- 33 MHz instruction throughput with 16-bit program word (vs PIC17C42A-25E/P)
- OTP EPROM memory for production economics (vs PIC17C42A-33I/PQ (UV-EPROM))
- Industrial -40C to +85C temperature grade (vs PIC17C42A-33/PT (commercial 0C to +70C))
Design Notes
OTP memory cannot be erased after programming. Fully validate firmware on a windowed UV-EPROM variant (PIC17C42A-33I/PQ) before committing to OTP production programming. A single code error requires scrapping the entire programmed MCU. Plan for batch programming and consider buying pre-programmed parts from a Microchip-approved programming house to avoid in-house programming overhead.
The PIC17C42AT-33I/PQ operates only from 4.5V to 6.0V supply voltage (typical 5V +/-10%). It is NOT 3.3V tolerant and cannot be powered directly from a 3.3V rail. Decouple VDD with a 100nF ceramic capacitor close to each VDD pin pair (pins 11 and 32) plus a bulk tantalum or aluminum electrolytic (>=10uF) at the regulator output. Brown-out-reset configuration must be enabled in the configuration word to prevent undefined operation during VDD droop.
The 44-pin Metric MQFP (PQ) package has 0.8 mm pitch leads and requires careful PCB land pattern design with solder mask-defined pads for reliable reflow. Place a ground plane on the layer beneath the MCU to provide thermal mass and reduce EMI. Keep high-frequency signals (OSC, CCP PWM outputs) short and routed over a continuous ground reference. The MCLR/Vpp pin (pin 9) requires a 10k pull-up to VDD and a 100nF cap to ground for proper reset behavior.
Verify package mechanical drawing before laying out the PCB. The 44-pin Metric MQFP (PQ) has different body dimensions than the 40-pin PDIP (P) variant on the same PIC17C42A silicon. Land patterns are NOT interchangeable between /PQ and /P suffix parts. Use the JEDEC MO-022 package outline for the PQ variant. Add teardrops on VDD and VSS traces for mechanical reliability under thermal cycling.
Compliance Information
PIC17C42AT-33I/PQ is an obsolete Microchip part; modern RoHS/REACH compliance status for the PQ package is not confirmed in the verified web data. Original Microchip PIC17C-family datasheets predate widespread RoHS documentation. Not AEC-Q100 qualified - for new automotive designs use PIC18F-K42 or dsPIC33EP families.
