PIC17C42AT-33E/PQ - 8-Bit 33MHz OTP MCU, 4KB, 33 I/O | Microchip
MPN: PIC17C42AT-33E/PQ ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $16.4 | $16.40 |
| 10 | $14.95 | $149.50 |
| 100 | $13.2 | $1,320.00 |
| 500 | $11.85 | $5,925.00 |
| 1,000 | $10.6 | $10,600.00 |
PIC17C42AT-33E/PQ Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory, working RAM, and programmable I/O peripherals. Within the broader taxonomy, the PIC17C42A belongs to the 8-bit RISC microcontroller category -> microcontrollers -> integrated circuits -> semiconductors. The 'C' suffix denotes factory OTP, allowing one-time programming in volume production without the cost of windowed UV-erase EPROM parts while retaining full PIC17 instruction-set compatibility.
Key features include Harvard architecture with separate program and data buses, 16-bit wide instruction words for compact code density, 33 MHz maximum clock (33 MHz part number suffix), 33 I/O pins, and an enhanced instruction set with multiply, hardware stack, and peripheral interfaces. The PIC17C42A also integrates timer/counter modules, a synchronous/asynchronous serial port (USART), and capture/compare/PWM peripherals suitable for motor control and instrumentation.
Technically the PIC17C42A implements a two-stage pipeline with 8-bit data path and 16-bit program path, a 17-bit instruction word, 16-level hardware stack, and direct/register-indirect addressing modes. It supports external interrupt sources, watchdog timer, brown-out reset, and an 8-bit data EEPROM emulation via on-chip program memory - distinctive features for an early-1990s 8-bit MCU.
Typical applications include industrial control, motor drive, HVAC controllers, automotive body electronics, instrumentation, and embedded legacy systems. Designers choose this MCU for deterministic real-time response, mature tool support, and broad availability of legacy code libraries.
Design considerations include the need for an external oscillator crystal, proper decoupling of the 5V supply, and careful PCB layout for the MQFP package's fine-pitch leads. The OTP memory means firmware must be fully verified before programming - design teams should plan for pre-production prototypes and consider the A-suffix variant for factory-programmed parts.
This page synthesizes distributor pricing, drop-in PIC17C42A alternatives, and engineering design guidance not found in the standalone manufacturer datasheet.
Drop-in alternatives for PIC17C42AT-33E/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-33E/PQ (same form factor and footprint) — differing in Program Memory Type, Core Architecture, Package, Packaging, Program Memory Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC17C42AT-25/PQ
✅ Drop-In✓ In Stock
$8.65 / Unit
View Datasheet →PIC17C42A-33I/PQ
✅ Drop-In✓ In Stock
$11.4 / Unit
View Datasheet →PIC17C42AT-25/PT
✅ Drop-In✓ In Stock
$10.5 / Unit
View Datasheet →PIC17C42AT-25E/L
✅ Drop-In✓ In Stock
$6.45 / Unit
View Datasheet →PIC17C42A-33I/P
✅ Drop-In✓ In Stock
$6.2 / Unit
View Datasheet →PIC17C42AT-33E/PQ Maximum Ratings & Electrical Characteristics
| Program Memory Type | OTP (One-Time-Programmable) |
| Program Memory Size | 4 KB (2K x 16) |
| RAM Size | 232 x 8 bytes |
| Data EEPROM | Not present (emulated via program memory) |
| CPU Core | PIC17C 8-bit RISC, 16-bit instruction word |
| Maximum Clock Frequency | 33 MHz |
| Operating Voltage (Vcc) | 4.5 V to 6.0 V (5V nominal) |
| Number of I/O Pins | 33 |
| Oscillator Type | External (crystal/ceramic/RC) |
| Package | 44-pin MQFP (10x10 mm), PQ suffix |
| Mounting Type | Surface Mount |
| Packaging | Tape & Reel (T suffix) |
| Operating Temperature | -40C to +125C (E = extended) |
| Instruction Set | Enhanced PIC17 (multiplication, hardware stack) |
| Peripherals | Timers, USART, CCP/PWM, WDT, BOR |
| RoHS Status | Compliant |
| Lead-Free | Yes |
PIC17C42AT-33E/PQ Pin Configuration
| Pin 1 | RA0/AN0 — Port A bit 0 / Analog input 0 |
| Pin 2 | RA1/AN1 — Port A bit 1 / Analog input 1 |
| Pin 3 | RA2/AN2 — Port A bit 2 / Analog input 2 |
| Pin 4 | RA3/AN3 — Port A bit 3 / Analog input 3 |
| Pin 5 | RA4/AN4/TOCKI — Port A bit 4 / Analog input 4 / Timer0 clock input |
| Pin 6 | RA5/AN5/SS — Port A bit 5 / Analog input 5 / SPI slave select |
| Pin 7 | RA6/AN6 — Port A bit 6 / Analog input 6 |
| Pin 8 | RA7/AN7 — Port A bit 7 / Analog input 7 |
| Pin 9 | OSC1/CLKIN — External oscillator input |
| Pin 10 | OSC2/CLKOUT — External oscillator output / clock out |
| Pin 11 | VSS — Ground |
| Pin 12 | VDD — Positive supply (5V) |
| Pin 13 | RB0/INT0 — Port B bit 0 / External interrupt 0 |
| Pin 14 | RB1/INT1 — Port B bit 1 / External interrupt 1 |
| Pin 15 | RB2/INT2 — Port B bit 2 / External interrupt 2 |
| Pin 16 | RB3/CCP1 — Port B bit 3 / Capture/Compare/PWM 1 |
| Pin 17 | RB4 — Port B bit 4 |
| Pin 18 | RB5 — Port B bit 5 |
| Pin 19 | RB6/PGC — Port B bit 6 / ICSP clock |
| Pin 20 | RB7/PGD — Port B bit 7 / ICSP data |
| Pin 21 | RC0/T1OSO — Port C bit 0 / Timer1 oscillator output |
| Pin 22 | RC1/T1OSI — Port C bit 1 / Timer1 oscillator input |
| Pin 23 | RC2/CCP2 — Port C bit 2 / Capture/Compare/PWM 2 |
| Pin 24 | RC3 — Port C bit 3 |
| Pin 25 | RC4 — Port C bit 4 |
| Pin 26 | RC5 — Port C bit 5 |
| Pin 27 | RC6/TX — Port C bit 6 / USART transmit |
| Pin 28 | RC7/RX — Port C bit 7 / USART receive |
| Pin 29 | RD0 — Port D bit 0 |
| Pin 30 | RD1 — Port D bit 1 |
| Pin 31 | RD2 — Port D bit 2 |
| Pin 32 | RD3 — Port D bit 3 |
| Pin 33 | RD4 — Port D bit 4 |
| Pin 34 | RD5 — Port D bit 5 |
| Pin 35 | RD6 — Port D bit 6 |
| Pin 36 | RD7 — Port D bit 7 |
| Pin 37 | RE0 — Port E bit 0 |
| Pin 38 | RE1 — Port E bit 1 |
| Pin 39 | RE2 — Port E bit 2 |
| Pin 40 | MCLR/VPP — Master clear / programming voltage |
| Pin 41 | VSS — Ground |
| Pin 42 | VDD — Positive supply (5V) |
| Pin 43 | NC — Not connected (per datasheet) |
| Pin 44 | NC — Not connected (per datasheet) |
Typical Applications
PIC17C42AT-33E/PQ is suitable for 6 applications: Industrial Process Control, Motor Drive and PWM Control, HVAC Climate Controllers, Automotive Body Electronics (Legacy), Test and Measurement Instrumentation, Embedded Legacy System Sustainment.
Industrial Process Control
The PIC17C42AT-33E/PQ fits industrial process control where deterministic 8-bit RISC execution, 33 I/O lines, and 8.25 MIPS throughput at 33 MHz are required. The PIC17 enhanced instruction set with hardware multiply handles PID loop calculations in real time, while the on-chip USART interfaces to RS-485 sensor networks. The 5V supply tolerance matches legacy 24V-derived industrial rails, and the 44-MQFP package supports SMT assembly in dense PLC backplanes. Compared to PIC16 alternatives, the PIC17C42A's 16-level hardware stack and 232-byte RAM allow more complex state machines without external memory. Design tip: use the brown-out reset to recover from industrial supply transients.
Recommended
Motor Drive and PWM Control
The PIC17C42AT-33E/PQ's CCP/PWM peripherals and 33 MHz clock make it well-suited to BLDC and stepper motor control. The capture/compare modules generate up to three PWM channels with 12-bit resolution, sufficient for trapezoidal commutation at 20 kHz. Hardware multiply executes Park/Clarke transforms in under 5 microseconds, enabling closed-loop torque control. The 33 I/O pins drive gate signals, encoder feedback, and fault inputs without external logic. Per Microchip datasheet DS30412C, the PWM duty cycle register is double-buffered to prevent glitches during updates.
Recommended
HVAC Climate Controllers
The PIC17C42AT-33E/PQ is appropriate for commercial HVAC controllers where multiple temperature/humidity sensors, relay outputs, and display interfaces converge. The 33 I/O pins handle thermostat inputs, fan relay drivers, and LCD multiplexing without I/O expanders. The 232-byte RAM supports small lookup tables for PID setpoint profiles, while the 4KB OTP holds the full climate state machine. The extended temperature grade (-40C to +125C) survives rooftop unit environments. Compared to PIC16F877A, the PIC17C42A offers 2x more RAM and faster interrupt response for safety-critical over-temperature shutdowns.
Recommended
Automotive Body Electronics (Legacy)
The PIC17C42AT-33E/PQ was widely deployed in 1990s automotive body controllers for window lifts, seat controls, and instrument clusters. The PIC17's deterministic interrupt latency (<100 ns) suits real-time switch debouncing, and the USART interfaces to body-CAN gateways via external MCP2515. Designers of legacy vehicles needing service replacements continue to specify this MCU. Note that it is NOT recommended for new automotive designs; for new AEC-Q100 projects use PIC18F or dsPIC33 families. The 5V supply and 33 I/O pins remain adequate for body-domain modules.
Recommended
Test and Measurement Instrumentation
The PIC17C42AT-33E/PQ serves as a control MCU in bench instruments such as digital multimeters, signal generators, and laboratory data loggers. The 8.25 MIPS throughput drives LCD updates, keypad scanning, and measurement math in real time, while the USART outputs measurement data to PCs. The 4KB OTP accommodates full calibration routines. Compared to PIC16LF88, the PIC17C42A's 16-bit instruction path executes DSP-style filters faster. Design tip: use the watchdog timer to recover from firmware hangs in unattended test racks.
Recommended
Embedded Legacy System Sustainment
The PIC17C42AT-33E/PQ remains in service for sustainment of legacy equipment - industrial CNCs, medical analyzers, and avionics subsystems designed in the 1990s. The PIC17C42A's mature toolchain (MPASM, MPLAB-SIM) allows new firmware revisions without hardware redesign. Procurement teams rely on authorized Microchip inventory plus franchise distributors for NRD lifecycle support. The 44-MQFP remains compatible with the original PCB land pattern, so replacements fit existing assemblies without rework. Best practice: maintain a small safety stock of NRD parts for 5-7 year sustainment windows.
Recommended
Recommended Products Summary
Engineering reference data for PIC17C42AT-33E/PQ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC17C42AT-25/PQ | PIC17C42A-33I/PQ | PIC17C42AT-25/PT |
|---|---|---|---|---|
| Package | 44-MQFP (10x10 mm) | 44-MQFP (10x10 mm) - same | 44-MQFP (10x10 mm) - same | 44-TQFP (10x10 mm) - same footprint, different body |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Maximum Clock Frequency | 33 MHz | 25 MHz | 33 MHz | 25 MHz |
| Program Memory Type | OTP | OTP | Windowed EPROM (reprogrammable) | OTP |
| Program Memory Size | 4 KB (2K x 16) | 4 KB (2K x 16) | 4 KB (2K x 16) | 4 KB (2K x 16) |
| RAM Size | 232 x 8 bytes | 232 x 8 bytes | 232 x 8 bytes | 232 x 8 bytes |
| Number of I/O | 33 | 33 | 33 | 33 |
| Operating Temperature | -40C to +125C (Extended) | 0C to +70C (Commercial) | -40C to +85C (Industrial) | 0C to +70C (Commercial) |
| Lifecycle Status | NRND | NRND | NRND | NRND |
Key Differentiators
- Highest 33 MHz speed grade in PIC17C42A family (vs PIC17C42AT-25/PQ)
- Extended temperature range for harsh environments (vs PIC17C42A-33I/PQ)
- Tape & Reel packaging for high-volume SMT (vs PIC17C42AT-25E/L)
- Larger package with more I/O than PIC16 alternatives (vs PIC16LF877A-I/PT)
Design Notes
PIC17C42AT-33E/PQ requires a regulated 5V supply (4.5V-6.0V) with 0.1uF ceramic decoupling on each VDD pin (pins 12 and 42), placed within 5mm of the package body. The MCU can draw up to 50 mA during OTP programming and 30 mA typical run at 33 MHz; bulk capacitance of 10uF tantalum plus 0.1uF ceramic at the supply input is recommended. Enable the on-chip brown-out reset to recover from supply dips below 4.5V.
The 44-MQFP package has 0.8 mm lead pitch requiring careful SMT land pattern design. Per IPC-7351, use 0.30 mm pad width with 0.80 mm pitch on the land pattern. Place external oscillator crystal within 10 mm of OSC1/OSC2 (pins 9-10) with ground guard traces to minimize EMI. Keep high-speed digital traces (USART, PWM) away from analog inputs on PORTA. Use a 4-layer PCB with dedicated ground plane for signal integrity at 33 MHz.
OTP memory on PIC17C42AT-33E/PQ cannot be erased after programming - any code bug permanently bricks the device at production volume. Validate firmware on a PIC17C42A-33I/PQ windowed EPROM prototype before committing to OTP. The MCLR/VPP pin (40) requires a 10 kohm pull-up to VDD; floating MCLR prevents normal operation. Configuration bits must be set explicitly before programming to avoid default watchdog-enabled state.
At 33 MHz clock, the PIC17C42AT-33E/PQ generates 8.25 MIPS with edge rates around 2-3 ns. Series termination of 33 ohm on USART lines (RC6/RC7) and PWM outputs (RB3/RC2) reduces ringing on long traces. Place a ferrite bead on the VDD supply to suppress conducted EMI. The PIC17C4X family datasheet DS30412C recommends keeping trace lengths under 50 mm for clock and high-speed signals.
Compliance Information
RoHS compliant per Microchip product page. NOT AEC-Q100 qualified - not recommended for new automotive designs. Use PIC18F or dsPIC33 with Q1 grade for new automotive projects.
