PIC17C42AT-25/PQ - 8-Bit 25MHz 4KB OTP MCU | Microchip PIC17C
MPN： PIC17C42AT-25/PQ ✗ 停產PIC17C42AT-25/PQ 概覽
An 8-bit microcontroller (MCU) is a single-chip computer that combines a CPU, program memory, data RAM, I/O peripherals, and timers on one CMOS die. The PIC17C family sits above the baseline PIC16 line and below the PIC18 line, adding a wider 16-bit instruction word, a 16-bit data path, hardware multiply, and external memory expansion. The category hierarchy is: 8-bit MCU -> microcontroller -> embedded processor -> semiconductor. PIC17C parts target industrial control, instrumentation, and motor-control applications where the 16-bit instruction word simplifies C compiler code density versus legacy PIC16 designs.
Key features of the PIC17C42AT-25/PQ include 58 single-word instructions, single-cycle (121 ns) execution on most opcodes (program branches and table reads/writes are two-cycle), UART/USART serial connectivity, and a 4.5V to 6V supply range with commercial-grade temperature rating. The 33 MHz maximum clock input supports high-throughput bit-banging and interrupt-heavy control loops, while 232 bytes of RAM allow modest local data buffers and stack depth suitable for small real-time operating kernels.
The device's CMOS EPROM/ROM process provides high noise immunity and low power consumption relative to NMOS predecessors of the early 1990s. Its Harvard architecture separates program and data buses, enabling simultaneous instruction fetch and operand access on most cycles. The PIC17C42A is the successor die revision of the original PIC17C42, improving peripheral behavior and adding OTP variants (the 'A' suffix marks the OTP/EPROM-revised revision).
Typical applications include industrial control systems, motor drive interfaces, instrumentation front ends, sensor signal conditioning, and embedded communication bridges. The 33 I/O pins and UART/USART make it suitable for bridging legacy peripherals to RS-232/RS-485 networks in factory automation, while the 4KB OTP memory suits cost-sensitive production runs where in-circuit reprogramming is unnecessary.
When designing with this MCU, allocate sufficient program memory headroom because the 16-bit instruction word consumes 2 bytes per opcode compared to PIC14's 12-bit word. Plan for a quartz crystal or ceramic resonator plus two load capacitors on OSC1/OSC2, and reserve one I/O pin for MCLR reset if in-circuit programming or intentional external reset is required.
This page synthesizes distributor pricing, drop-in alternative MPNs in the same MQFP-44 footprint, and practical design notes not consolidated in the manufacturer datasheet, supporting faster sourcing decisions for engineers maintaining legacy PIC17C designs.
直接替換替代品，適用於 PIC17C42AT-25/PQ — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： PIC17C42AT-25/PQ （相同外形與佔位） — 差異在於 Package, Program Memory Type, Peripherals, Program Memory Size, RAM Size.
PIC17C42A-33I/PQ
✅ 直接替換聯絡詢價
查看資料表 →PIC17C42A-33/PT
✅ 直接替換聯絡詢價
查看資料表 →PIC17C42A-25E/P
✅ 直接替換聯絡詢價
查看資料表 →PIC17C42AT-25/PQ 最大額定值與電氣特性
| Core Architecture | 8-bit PIC RISC |
| Family | PIC17C |
| Program Memory Type | OTP (One-Time Programmable) EPROM |
| Program Memory Size | 4 KB (2K x 16) |
| RAM Size | 232 bytes |
| Maximum Clock Input | 33 MHz |
| Instruction Cycle Time | 121 ns (single cycle) |
| Operating Frequency (rated) | 25 MHz |
| 供應電壓 | 4.5 V to 6 V |
| I/O Pins | 33 |
| Communication Interfaces | UART/USART |
| Instruction Set Size | 58 single-word instructions |
| 資料匯流排寬度 | 16-bit (instruction word) |
| 封裝 | 44-MQFP (PQ) 10x10 mm |
| Temperature Grade | Commercial |
| 安裝類型 | Surface Mount |
| Terminal Form | Gull Wing |
| Lifecycle Stage | Obsolete (per digchip datasheet entry) |
PIC17C42AT-25/PQ 腳位配置
| 腳位 1 | RA0/AN0 — PORTA bit 0 / analog input 0 |
| 腳位 2 | RA1/AN1 — PORTA bit 1 / analog input 1 |
| 腳位 3 | RA2/AN2 — PORTA bit 2 / analog input 2 |
| 腳位 4 | RA3/AN3 — PORTA bit 3 / analog input 3 |
| 腳位 5 | RA4/T0CKI — PORTA bit 4 / Timer 0 clock input |
| 腳位 6 | RA5 — PORTA bit 5 |
| 腳位 7 | RA6 — PORTA bit 6 |
| 腳位 8 | RA7 — PORTA bit 7 |
| 腳位 9 | OSC1 — Oscillator input / external clock |
| 腳位 10 | OSC2 — Oscillator output |
| 腳位 11 | RC0 — PORTC bit 0 |
| 腳位 12 | RC1 — PORTC bit 1 |
| 腳位 13 | RC2 — PORTC bit 2 |
| 腳位 14 | RC3 — PORTC bit 3 |
| 腳位 15 | RC4 — PORTC bit 4 |
| 腳位 16 | RC5 — PORTC bit 5 |
| 腳位 17 | RC6 — PORTC bit 6 |
| 腳位 18 | RC7 — PORTC bit 7 |
| 腳位 19 | VSS — Ground reference |
| 腳位 20 | VDD — Positive supply (4.5V to 6V) |
| 腳位 21 | RB0/INT — PORTB bit 0 / external interrupt |
| 腳位 22 | RB1 — PORTB bit 1 |
| 腳位 23 | RB2 — PORTB bit 2 |
| 腳位 24 | RB3 — PORTB bit 3 |
| 腳位 25 | RB4 — PORTB bit 4 |
| 腳位 26 | RB5 — PORTB bit 5 |
| 腳位 27 | RB6 — PORTB bit 6 |
| 腳位 28 | RB7 — PORTB bit 7 |
| 腳位 29 | MCLR/VPP — Master clear reset / programming voltage |
| 腳位 30 | RD0 — PORTD bit 0 |
| 腳位 31 | RD1 — PORTD bit 1 |
| 腳位 32 | RD2 — PORTD bit 2 |
| 腳位 33 | RD3 — PORTD bit 3 |
| 腳位 34 | RD4 — PORTD bit 4 |
| 腳位 35 | RD5 — PORTD bit 5 |
| 腳位 36 | RD6 — PORTD bit 6 |
| 腳位 37 | RD7 — PORTD bit 7 |
| 腳位 38 | RE0 — PORTE bit 0 |
| 腳位 39 | RE1 — PORTE bit 1 |
| 腳位 40 | RE2 — PORTE bit 2 |
| 腳位 41 | NC — Not connected (per datasheet) |
| 腳位 42 | NC — Not connected (per datasheet) |
| 腳位 43 | NC — Not connected (per datasheet) |
| 腳位 44 | NC — Not connected (per datasheet) |
典型應用
PIC17C42AT-25/PQ 適用於 6 應用s: Industrial Control Systems, Motor Drive Interfaces, Instrumentation Front Ends, Sensor Signal Conditioning Hubs, Embedded Communication Bridges, Legacy Embedded Replacement Boards.
Industrial Control Systems
The PIC17C42AT-25/PQ suits legacy industrial control systems where its 4KB OTP program memory and 33 I/O pins directly interface to relays, solenoid drivers, and discrete sensors. The 16-bit instruction word improves C-compiler code density versus PIC16, simplifying maintenance of PLC-style ladder replacements. With 121 ns single-cycle execution at 25 MHz the device delivers ~8.25 MIPS, adequate for PID loops sampled at sub-millisecond rates. The 4.5V to 6V supply aligns with 5V industrial backplanes, while the commercial temperature rating fits factory-floor enclosures. Drop-in compatible parts like PIC17C42A-33I/PQ extend service life into industrial-grade deployments.
推薦
Motor Drive Interfaces
For low-power DC motor and stepper drive interfaces, the PIC17C42AT-25/PQ provides the GPIO count and timing precision needed to generate PWM, monitor current-sense amplifiers, and execute commutation tables in software. Its 232-byte RAM is sufficient for trapezoidal profiles on small BLDC motors, and the 25 MHz instruction rate supports 10 kHz PWM updates with margin for housekeeping tasks. The hardware USART simplifies connection to host controllers or RS-485 drive networks. For designs requiring extended operation in harsh thermal environments, the industrial-temperature PIC17C42A-33I/PQ alternative provides a drop-in path.
推薦
Instrumentation Front Ends
The PIC17C42AT-25/PQ serves instrumentation front ends where moderate computation, multiple digital control lines, and serial telemetry are required. The Harvard architecture and 16-bit instructions enable efficient table-driven linearization of sensor readings, while the 33 I/O pins drive LCDs, keypads, and status LEDs simultaneously. With UART/USART, the device streams measurement data to host PCs or data loggers over RS-232/RS-485 links. The 4KB OTP program memory accommodates calibration constants and menu state machines typical of bench-top instruments, while the MQFP-44 footprint suits compact panel-mount enclosures.
推薦
Sensor Signal Conditioning Hubs
For multi-sensor hubs that aggregate thermocouple, RTD, or strain-gauge inputs, the PIC17C42AT-25/PQ provides the I/O density and serial bandwidth required. Its 33 I/O pins drive multiple analog mux chips via SPI-style bit-banging while the hardware USART reports preprocessed data to a central controller. The 232-byte RAM buffers scan sequences for 8 to 16 channels, and the 16-bit instruction word accelerates fixed-point math for cold-junction compensation. Drop-in compatibility with PIC17C42A-33I/PQ allows field upgrades to industrial-grade variants for outdoor installations.
推薦
Embedded Communication Bridges
The PIC17C42AT-25/PQ excels as an embedded communication bridge between legacy peripherals and modern fieldbuses. Its hardware USART handles RS-232/RS-485 traffic natively, while spare GPIO lines implement bit-banged I2C or SPI to talk to sensors or EEPROM memories. The 25 MHz instruction cycle (121 ns) keeps round-trip latency under 10 microseconds for short-frame protocols, and 232-byte RAM supports modest protocol stacks for Modbus RTU or vendor-proprietary framing. For designs moving to industrial environments, the PIC17C42A-33I/PQ drop-in upgrade extends thermal range.
推薦
Legacy Embedded Replacement Boards
The PIC17C42AT-25/PQ is commonly specified for legacy board-replacement manufacturing where the original MQFP-44 footprint must be retained for form-fit-function continuity. Production runs in mature industrial equipment (printers, test fixtures, HVAC controllers) often keep the PIC17C42A pinout to avoid respinning PCB artwork. The 'A' revision OTP variant offers cost-effective one-time programming for high-volume builds, while the in-system-programmable PIC17C42A-33I/PQ drop-in alternative serves field-service kits. Maintaining 4KB code density, 232B RAM, and 33 I/O pins preserves software compatibility across product generations.
推薦
推薦產品摘要
工程參考資料，適用於 PIC17C42AT-25/PQ — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | PIC17C42A-33I/PQ | PIC17C42A-33/PT | PIC17C42A-25E/P |
|---|---|---|---|---|
| Package | 44-MQFP (PQ) 10x10 mm | 44-MQFP (PQ) - identical | 44-TQFP (PT) - same pin count, different lead pitch | 40-PDIP (P) - different pin count and through-hole |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Max Clock Input | 25 MHz | 33 MHz (+32%) | 33 MHz (+32%) | 25 MHz (same) |
| Program Memory | 4 KB (2K x 16) OTP | 4 KB (2K x 16) OTP (same) | 4 KB (2K x 16) OTP (same) | 4 KB (2K x 16) OTP (same) |
| RAM Size | 232 bytes | 232 bytes (same) | 232 bytes (same) | 232 bytes (same) |
| I/O Pins | 33 | 33 (same) | 33 (same) | 33 (same) |
| Temperature Grade | Commercial (0C to +70C) | Industrial (-40C to +85C) | Commercial | Extended |
| Supply Voltage | 4.5 V to 6 V | 4.5 V to 6 V (same) | 4.5 V to 6 V (same) | 4.5 V to 6 V (same) |
主要差異化特點
- Higher instruction throughput than PIC16 predecessors (對比PIC16F84A-I/P)
- Larger I/O count in same package family (對比PIC16F877A-I/P)
- Industrial-grade drop-in path without PCB rework (對比PIC17C42AT-25/PQ itself (commercial grade))
設計說明
The PIC17C42AT-25/PQ operates from a single 4.5V to 6V supply. Place a 100 nF decoupling capacitor as close as possible to the VDD pin (20) and a 10 uF bulk capacitor on the same supply rail within 25 mm of the package. VSS (pin 19) must connect to a low-impedance ground plane; the 44-pin MQFP's central lead frame benefits from a via-stitched ground pad beneath the package for thermal and electrical return.
Route the OSC1 (pin 9) and OSC2 (pin 10) traces symmetrically and as short as possible, surrounded by ground pour. Keep digital signal traces at least 5 mm away from the oscillator traces to minimize capacitive loading and jitter. For 25 MHz operation at 121 ns cycle time, signal-integrity margin is adequate but traces longer than 50 mm on PORTB or PORTC should be series-terminated if driving capacitive loads above 25 pF.
Because the PIC17C42AT-25/PQ is OTP (One-Time Programmable), there is no second-chance reprogramming after the device leaves the programmer. Always verify firmware in a windowed PIC17C42A-25/PQ (UV-erasable prototype) or in MPLAB SIM before committing to OTP production parts. Also, MCLR (pin 29) must be pulled high through a 10 kohm resistor for normal operation; floating MCLR will randomly reset the part and corrupt UART framing.
合規資訊
Compliance data not explicitly stated in the verified web sources. The PIC17C42AT-25/PQ predates many current environmental compliance requirements; consult Microchip product page or distributor documentation for definitive compliance certificates.
