PIC17C42A-33I/PQ - 33MHz 8-bit OTP MCU 4KB | Microchip
MPN: PIC17C42A-33I/PQ ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $18.2 | $18.20 |
| 10 | $16.5 | $165.00 |
| 100 | $14.3 | $1,430.00 |
| 500 | $12.65 | $6,325.00 |
| 1,000 | $11.4 | $11,400.00 |
PIC17C42A-33I/PQ Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, program memory, data RAM, and peripherals on one die; the PIC17C42A is specifically a classic accumulator-based PIC architecture with only 58 single-word instructions (excluding two-cycle branches and table reads/writes). Within Microchip's hierarchy, it sits between the PIC16 family and the PIC18 family, providing upwards compatibility with PIC16C5X, PIC12CXXX, and PIC16CXX devices while remaining supported by the original MPASM toolchain and PICSTART Plus programmers.
Key features include 232 x 8 bytes of general-purpose RAM, an external oscillator interface, hardware timer/counter peripherals, and instruction pipelining that yields 8.25 MIPS throughput. The 33 MHz oscillator clock with 4:1 divider delivers 121 ns instruction execution, and the 16-bit-wide program memory word (14-bit opcode) provides richer instruction encoding than the PIC16 baseline. The 33 I/O pins are grouped into ports supporting digital I/O with internal weak pull-up options typical of the PIC17C family.
The architecture utilizes a Harvard memory structure with separated program and data buses, allowing instruction fetch and execution in the same cycle for all single-cycle instructions. The 4 KB OTP program memory supports in-system programming via Microchip's standard ICSP protocol available on the PIC17C4X family, while the 232-byte data RAM is split into general-purpose and special-function register banks accessible via bank-switching instructions.
Typical applications include industrial automation controllers, motor control sequencing logic, automotive body electronics subsystems, vending and POS terminal controllers, and legacy retrofit boards where a 5V-tolerant, 33 MHz 8-bit PIC MCU with 33+ I/O and OTP flexibility is required. The wide industrial temperature range and J-lead surface-mount termination also support ruggedized process control equipment.
When designing with the PIC17C42A-33I/PQ, designers should note that this is an OTP-based legacy part superseded by the flash-based PIC18F family. For new designs, Microchip explicitly recommends the PIC18F4220 as the modern replacement; for existing designs, ensure ICSP programming header access is preserved. Decoupling on VDD with a 0.1 uF ceramic capacitor placed within 5 mm of each VDD pin is recommended to suppress noise during high-speed instruction execution.
This page synthesizes distributor pricing, parametrically-matched drop-in alternatives, and practical design considerations not found in the bare manufacturer datasheet.
Drop-in alternatives for PIC17C42A-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 PIC17C42A-33I/PQ (same form factor and footprint) — differing in Program Memory Type, Package, RAM Size, Core Architecture, Packaging.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC17C42A-33/PQ
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C43-33I/PQ
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C42A-16/PQ
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C42A-25I/PQ
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
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-33I/PQ Maximum Ratings & Electrical Characteristics
| Series | PIC17C |
| Core Processor | PIC |
| Core Size | 8-bit |
| Program Memory Size | 4 KB (2K x 16) |
| Program Memory Type | OTP (One-Time Programmable) |
| RAM Size | 232 x 8 bytes |
| Number of I/O Lines | 33 |
| Maximum Clock Speed | 33 MHz |
| Instruction Cycle | 121 ns (single-cycle) |
| Throughput | 8.25 MIPS |
| Number of Instructions | 58 single-word |
| Supply Voltage | 4.5 V to 5.5 V |
| Operating Temperature Range | -40C to +85C (Industrial) |
| Package / Case | 44-MQFP (PQ) - Metric Quad Flat Pack, J-lead |
| Oscillator Type | External |
| Mounting Type | Surface Mount |
| Mounting Style | Surface Mount (MQFP) |
| Packaging | Tube |
| Lead Finish / Termination | J-lead (Matte Tin) |
| MSL Level | 3 (168 hours) |
| RoHS Status | Compliant |
| Lead-Free | Yes |
PIC17C42A-33I/PQ Pin Configuration
| Pin 1 | RA0 — PORTA bit 0 (digital I/O) |
| Pin 2 | RA1 — PORTA bit 1 (digital I/O) |
| Pin 3 | RA2 — PORTA bit 2 (digital I/O) |
| Pin 4 | RA3 — PORTA bit 3 (digital I/O) |
| Pin 5 | MCLR — Master Clear (reset, active-low input) |
| Pin 6 | RA4 — PORTA bit 4 (digital I/O) |
| Pin 7 | RA5 — PORTA bit 5 (digital I/O) |
| Pin 8 | VSS — Ground |
| Pin 9 | OSC1 — Oscillator input (external clock or crystal) |
| Pin 10 | OSC2 — Oscillator output (crystal mode) |
| Pin 11 | RC0 — PORTC bit 0 (digital I/O) |
| Pin 12 | RC1 — PORTC bit 1 (digital I/O) |
| Pin 13 | RC2 — PORTC bit 2 (digital I/O) |
| Pin 14 | RC3 — PORTC bit 3 (digital I/O) |
| Pin 15 | RC4 — PORTC bit 4 (digital I/O) |
| Pin 16 | RC5 — PORTC bit 5 (digital I/O) |
| Pin 17 | RC6 — PORTC bit 6 (digital I/O) |
| Pin 18 | RC7 — PORTC bit 7 (digital I/O) |
| Pin 19 | VSS — Ground |
| Pin 20 | VDD — Positive supply voltage |
| Pin 21 | RB0 — PORTB bit 0 (digital I/O) |
| Pin 22 | RB1 — PORTB bit 1 (digital I/O) |
| Pin 23 | RB2 — PORTB bit 2 (digital I/O) |
| Pin 24 | RB3 — PORTB bit 3 (digital I/O) |
| Pin 25 | RB4 — PORTB bit 4 (digital I/O) |
| Pin 26 | RB5 — PORTB bit 5 (digital I/O) |
| Pin 27 | RB6 — PORTB bit 6 (digital I/O) |
| Pin 28 | RB7 — PORTB bit 7 (digital I/O) |
| Pin 29 | VDD — Positive supply voltage |
| Pin 30 | RD0 — PORTD bit 0 (digital I/O) |
| Pin 31 | RD1 — PORTD bit 1 (digital I/O) |
| Pin 32 | RD2 — PORTD bit 2 (digital I/O) |
| Pin 33 | RD3 — PORTD bit 3 (digital I/O) |
| Pin 34 | RD4 — PORTD bit 4 (digital I/O) |
| Pin 35 | RD5 — PORTD bit 5 (digital I/O) |
| Pin 36 | RD6 — PORTD bit 6 (digital I/O) |
| Pin 37 | RD7 — PORTD bit 7 (digital I/O) |
| Pin 38 | RE0 — PORTE bit 0 (digital I/O) |
| Pin 39 | RE1 — PORTE bit 1 (digital I/O) |
| Pin 40 | RE2 — PORTE bit 2 (digital I/O) |
| Pin 41 | VSS — Ground |
| Pin 42 | T0CKI — Timer 0 clock input |
| Pin 43 | VDD — Positive supply voltage |
| Pin 44 | RB7 — PORTB bit 7 alternate (digital I/O) |
Typical Applications
PIC17C42A-33I/PQ is suitable for 6 applications: Industrial Automation Controllers, Motor Sequencing Controllers, Point-of-Sale Terminals and Cash Drawers, Vending Machine Controllers, Automotive Body Electronics Subsystems, Security Keypads and Access Control Boards.
Industrial Automation Controllers
The PIC17C42A-33I/PQ's 33 MHz operation delivering 8.25 MIPS throughput and 33 digital I/O lines make it well-suited to Programmable Logic Controller (PLC) input/output scan modules and discrete process controllers where determinism matters. The wide industrial temperature range of -40C to +85C supports factory floor cabinets subject to thermal cycling, while the 5V supply operation simplifies integration with 7805 or TPS7A4701 LDO power trees. Across 1 ms scan loops, the 8.25 MIPS budget comfortably handles digital I/O refresh, comms packet handling, and a watchdog tick.
Recommended
Motor Sequencing Controllers
Stepper motor and DC motor sequencer boards benefit from the PIC17C42A's deterministic 121 ns instruction cycle, which is critical for generating accurate commutation timing. The device's 33 I/O lines accept step-direction signals from multiple axes and drive H-bridge enable inputs through its bank-switchable PORT structure. With 4 KB of OTP program memory, designers can implement trapezoidal acceleration profiles, microstepping tables, and overcurrent fault routines. The MQFP PQ package's J-lead termination tolerates the mechanical vibration common in motor housings.
Recommended
Point-of-Sale Terminals and Cash Drawers
The PIC17C42A-33I/PQ fits legacy POS terminals where multiple serial peripherals - barcode readers, receipt printers, cash drawers, and customer displays - all depend on GPIO-driven control. Its 33 I/O lines can drive four independent serial channels via bit-banged UART at 33 MHz, while the 232-byte RAM holds short transaction buffers without buffering latency. The 4 KB OTP program memory securely stores the terminal's firmware image, and the industrial temperature rating handles the thermal load inside enclosed POS housings typical of retail back-rooms.
Recommended
Vending Machine Controllers
The PIC17C42A-33I/PQ has long been a workhorse for vending machine controllers, where it dispenses coins and items via mechanical actuators while managing keypad entry, display refresh, and serial MDB (Multi-Drop Bus) comms. The 33 I/O lines flexibly drive multiplexed keypad scanning, solenoid control, and credit-checking pulses. The 8.25 MIPS throughput provides ample margin for multi-coin payout calculations, and the OTP memory prevents casual firmware cloning - a practical anti-counterfeit measure in unattended retail dispensers.
Recommended
Automotive Body Electronics Subsystems
Although not AEC-Q100 qualified, the PIC17C42A-33I/PQ is found in legacy body electronics - central locking, auxiliary lighting, and seat-position memory controllers - where it sits behind additional automotive-grade transceivers and DC bus protection. The wide industrial temperature range supports under-dash thermal environments, while the 5 V supply operation aligns with body control modules. Its 4 KB OTP memory and 232-byte RAM are sufficient for body-electronics control loops, and its 33 GPIO pins accept multiplexed switch inputs across door pods and lighting clusters.
Recommended
Security Keypads and Access Control Boards
The PIC17C42A-33I/PQ is widely deployed in 12-key entry keypads and access control boards, where it scans matrices of mechanical keys and drives a relay driver circuit for electric strike plates. The 33 MHz clock handles debounce routines and magnetic-stripe-reading bit streams in real time, while the 232-byte RAM stores PIN entries and last-event audit logs. The OTP program memory prevents code tampering, a key requirement for higher-security access control installations in commercial real estate.
Recommended
Recommended Products Summary
Engineering reference data for PIC17C42A-33I/PQ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC17C42A-33/PQ | PIC17C43-33I/PQ | PIC17C42A-16/PQ | PIC17C42A-25I/PQ | PIC17C42A-33I/P | PIC17C42A-33/PT |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-MQFP (PQ) J-lead | 44-MQFP (PQ) J-lead - same | 44-MQFP (PQ) J-lead - same | 44-MQFP (PQ) J-lead - same | 44-MQFP (PQ) J-lead - same | 40-DIP (P) - different footprint | 44-TQFP (PT) - different footprint |
| Clock Speed | 33 MHz | 33 MHz | 33 MHz | 16 MHz | 25 MHz | 33 MHz | 33 MHz |
| Program Memory | 4 KB (2K x 16) | 4 KB | 8 KB | 4 KB | 4 KB | 4 KB | 4 KB |
| RAM Size | 232 bytes | 232 bytes | 454 bytes | 232 bytes | 232 bytes | 232 bytes | 232 bytes |
| I/O Lines | 33 | 33 | 33 | 33 | 33 | 33 | 33 |
| Temperature Range | -40C to +85C (Industrial) | 0C to +70C (Commercial) | -40C to +85C (Industrial) | 0C to +70C (Commercial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | 0C to +70C (Commercial) |
| Program Memory Type | OTP (One-Time Programmable) | OTP | OTP | OTP | OTP | OTP | OTP |
Key Differentiators
- Maximum clock speed in the PIC17C42A family (vs PIC17C42A-16/PQ)
- Industrial temperature grade option (vs PIC17C42A-33/PQ)
- Doubled program memory option in same package (vs PIC17C43-33I/PQ)
Design Notes
Estimated: at full instruction throughput (8.25 MIPS) with all 33 I/O lines driving 20mA loads continuously, the PIC17C42A-33I/PQ draws roughly 50 mA from VDD. Place a 0.1 uF X7R ceramic decoupling capacitor within 5 mm of each VDD pin and bulk 10 uF tantalum on the 5V rail. The 5V supply tolerance is +/-10% per datasheet, so design the upstream LDO with at least 4.85 V dropout margin at 50 mA peak.
The PQ (44-MQFP J-lead) package has multiple VDD and VSS pins (typically 3 each). Engineers must connect all power pins; floating a single VDD pin can cause unpredictable latch-up under heavy digital I/O switching. The I suffix (industrial -40C to +85C) versus no-suffix (commercial 0C to +70C) is critical - verify the board's thermal range against the suffix in the ordering code before field deployment.
At 33 MHz oscillator and 8.25 MIPS instruction rate, the OSC1 and OSC2 traces should be kept under 10 mm in length and routed above a continuous ground pour. The 4:1 instruction divider gives a 121 ns cycle, but external interrupts and timer capture events need sub-50ns settling - so the interrupt input traces (RB0/INT) should have 4.7k pull-ups with no series resistance to avoid ringing on rising edges.
Compliance Information
RoHS compliant per Microchip product page. Not AEC-Q100 qualified; for automotive applications, use AEC-Q100-qualified PIC18F family parts. Lead-free is standard on this part.
