PIC17C42A-25/P - 8-Bit 25MHz OTP MCU 4KB | Microchip
MPN: PIC17C42A-25/P ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $12.08 | $12.08 |
| 10 | $10.87 | $108.70 |
| 100 | $9.42 | $942.00 |
| 500 | $8.45 | $4,225.00 |
| 1,000 | $7.62 | $7,620.00 |
PIC17C42A-25/P Overview
An 8-bit microcontroller (MCU) is a single-chip computer built around an 8-bit data-path CPU, on-chip program memory, RAM, and a rich set of peripherals such as timers, capture/compare/PWM, USART, and I/O ports. Within the broader taxonomy, the PIC17C42A belongs to the PIC architecture family > OTP-based 8-bit MCU > microcontroller > embedded processor > semiconductor. OTP EPROM program memory lets engineers program the part once, including late-stage firmware revisions, without needing a windowed or flash part; the trade-off is no field re-programmability.
Key features include a 16-level hardware stack, 16-bit instruction word, 58 single-word instructions, multiply and divide hardware support, dual 8-bit timers plus 2 capture inputs, 2 PWM outputs, a USART for serial communication, and external memory addressing for code beyond 64 KB. The 25 MHz oscillator drives a 4-cycle instruction execution pipeline, giving deterministic interrupt and timing behavior that is well-suited to real-time control loops.
Typical applications include industrial automation controllers, motor control and appliance front panels, HVAC and building-control subsystems, automotive body/comfort modules, legacy communication protocol bridges, and instrumentation requiring deterministic 8-bit behavior. Designers familiar with PIC16C5X and PIC12CXXX devices retain tool and instruction-set continuity, easing code portability from earlier 8-bit designs.
When designing with this device, mind the OTP memory constraint, validate the 5V to 6V supply window on every revision, and budget adequate decoupling near VDD/VSS pins. For modern designs that require field updates, consider the PIC18F4220 migration path Microchip recommends; for new builds where re-programmability matters, prefer flash-based PIC18 from the outset.
This page synthesizes distributor pricing, parametric drop-in alternatives, and practical thermal and decoupling design notes that go beyond the manufacturer datasheet baseline, helping procurement and engineering teams decide whether PIC17C42A-25/P fits their legacy or production design.
Drop-in alternatives for PIC17C42A-25/P — 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-25/P (same form factor and footprint) — differing in Mounting Type, Program Memory Type, Maximum Clock Frequency, Package, Program Memory Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC17C42A-16/P
✅ Drop-In✓ In Stock
$7.45 / Unit
View Datasheet →PIC17C42A-16E/P
✅ Drop-In✓ In Stock
$5.85 / Unit
View Datasheet →PIC17CR42A-25/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC17C42A-25/P Maximum Ratings & Electrical Characteristics
| Product Type | 8-bit Microcontroller (MCU) |
| Core Architecture | PIC17 (RISC, Harvard) |
| Program Memory Size | 4 KB (2K x 16 wide OTP EPROM/ROM) |
| RAM Size | 232 x 8 bytes |
| Maximum Clock Frequency | 25 MHz |
| Instruction Cycle Time | 121 ns (8.25 MIPS) |
| Instruction Set Size | 58 single-word instructions |
| Number of I/O Pins | 33 |
| Package | 40-pin PDIP (0.600", 15.24 mm) |
| Mounting Type | Through-Hole (PDIP) |
| Supply Voltage | 5 V to 6 V |
| Timers | 2 x 8-bit + 1 x 16-bit |
| Capture/Compare/PWM | 2 capture inputs, 2 PWM outputs |
| Communication | USART (SCI) |
| Operating Temperature | -40 °C to +85 °C |
| Program Memory Type | OTP EPROM / ROM |
| RoHS Status | Compliant |
| Lead-Free | Yes |
PIC17C42A-25/P Pin Configuration
| Pin 1 | RA0 — PORTA digital I/O bit 0 / analog input |
| Pin 2 | RA1 — PORTA digital I/O bit 1 / analog input |
| Pin 3 | RA2 — PORTA digital I/O bit 2 / analog input |
| Pin 4 | RA3 — PORTA digital I/O bit 3 / analog input |
| Pin 5 | RA4 — PORTA digital I/O bit 4 / analog input |
| Pin 6 | RA5 — PORTA digital I/O bit 5 / analog input |
| Pin 7 | VSS — Ground reference |
| Pin 8 | OSC1 — Crystal oscillator input or external clock input |
| Pin 9 | OSC2 — Crystal oscillator output |
| Pin 10 | T0CKI — Timer0 external clock input |
| Pin 11 | MCLR/VPP — Master clear reset / programming voltage input |
| Pin 12 | RB0/INT — PORTB bit 0 / external interrupt |
| Pin 13 | RB1 — PORTB bit 1 |
| Pin 14 | RB2 — PORTB bit 2 |
| Pin 15 | RB3 — PORTB bit 3 |
| Pin 16 | RB4 — PORTB bit 4 |
| Pin 17 | RB5 — PORTB bit 5 |
| Pin 18 | RB6 — PORTB bit 6 / in-circuit programming clock |
| Pin 19 | RB7 — PORTB bit 7 / in-circuit programming data |
| Pin 20 | VSS — Ground reference |
| Pin 21 | VDD — Positive supply voltage (5 V to 6 V) |
| Pin 22 | RC0 — PORTC digital I/O bit 0 |
| Pin 23 | RC1 — PORTC digital I/O bit 1 |
| Pin 24 | RC2 — PORTC digital I/O bit 2 |
| Pin 25 | RC3 — PORTC digital I/O bit 3 |
| Pin 26 | RC4 — PORTC digital I/O bit 4 |
| Pin 27 | RC5 — PORTC digital I/O bit 5 |
| Pin 28 | RC6 — PORTC digital I/O bit 6 / USART TX |
| Pin 29 | RC7 — PORTC digital I/O bit 7 / USART RX |
| Pin 30 | RD0 — PORTD digital I/O bit 0 |
| Pin 31 | RD1 — PORTD digital I/O bit 1 |
| Pin 32 | RD2 — PORTD digital I/O bit 2 |
| Pin 33 | RD3 — PORTD digital I/O bit 3 |
| Pin 34 | RD4 — PORTD digital I/O bit 4 |
| Pin 35 | RD5 — PORTD digital I/O bit 5 |
| Pin 36 | RD6 — PORTD digital I/O bit 6 |
| Pin 37 | RD7 — PORTD digital I/O bit 7 |
| Pin 38 | RE0 — PORTE digital I/O bit 0 |
| Pin 39 | RE1 — PORTE digital I/O bit 1 |
| Pin 40 | RE2 — PORTE digital I/O bit 2 |
Typical Applications
PIC17C42A-25/P is suitable for 6 applications: Industrial Automation Controller, Motor Control and PWM Drive, HVAC and Building Control Subsystems, Automotive Body and Comfort Modules, Legacy Communication Protocol Bridges, Instrumentation and Test Equipment.
Industrial Automation Controller
PIC17C42A-25/P suits industrial automation controllers that demand deterministic 8-bit timing and OTP code security, where field firmware updates are undesirable to prevent unauthorized changes. The 25 MHz clock yields 8.25 MIPS, sufficient for PID loops, scan-time scheduling, and discrete I/O handling across the 33 available GPIO pins. The wide supply window (5 V to 6 V) tolerates 24 V industrial rails stepped down through a linear regulator. Compared with flash-based PIC18 devices, the OTP EPROM image eliminates accidental reprogramming during field service, an advantage for safety-critical machine controllers. Recommended companion: PIC16LF877A-I/P for distributed HMI I/O expanders.
Recommended
Motor Control and PWM Drive
PIC17C42A-25/P integrates two PWM outputs and two capture inputs, enabling closed-loop DC motor or brushed servo control without external timer ICs. The 25 MHz clock combined with a 121 ns instruction cycle provides the bandwidth to compute commutation tables for low-RPM brushless motors in firmware. 232 bytes of RAM hold a small state machine plus lookup tables for trapezoidal commutation, while 33 I/O pins carry Hall-sensor inputs and gate-driver outputs. Designers porting PIC16 motor code will find the PIC17 upward-compatible instruction set a low-risk migration. Recommended companion: PIC16LF727-I/ML for ancillary BLDC channel control.
Recommended
HVAC and Building Control Subsystems
PIC17C42A-25/P powers HVAC zone controllers and building-automation nodes where deterministic 8-bit behavior, OTP firmware security, and 40-pin PDIP through-hole assembly combine well with hand-solderable field service. Its USART supports Modbus RTU or BACnet MS/TP over RS-485 transceivers, while 33 GPIO pins interface with thermistor inputs, damper actuators, and relay drivers. The -40 °C to +85 °C temperature range covers unconditioned mechanical rooms. Compared with flash PIC18, the OTP image is protected against inadvertent field rewrites that could invalidate regulatory listings. Recommended companion: PIC16LF818-I/SO for remote sensor end-nodes.
Recommended
Automotive Body and Comfort Modules
PIC17C42A-25/P serves automotive body-control and comfort modules - lighting drivers, seat controllers, accessory multiplexers - where 8-bit simplicity and 5 V operation tolerate 12 V battery feeds through regulators. The 33 GPIO drive small LED arrays, relay coils, and switch matrices; the USART links the module to a central body controller. Microchip recommends migrating new automotive programs to PIC18F4220 or flash PIC18 parts because OTP cannot be field-updated for recalled firmware, but existing PIC17C42A-25/P designs remain supported in long-life vehicle platforms. Recommended companion: PIC16LF877-04I/P for gateway modules bridging LIN and CAN.
Recommended
Legacy Communication Protocol Bridges
PIC17C42A-25/P bridges legacy RS-232/RS-485 serial devices to modern UART-based controllers, retaining the PIC17 instruction set and 58 single-word instruction simplicity that long-standing firmware relies on. The USART directly drives RS-232 transceivers, while the external-memory addressing extension allows large protocol-conversion tables in parallel EPROM when protocol dictionaries exceed the 4 KB on-chip OTP. The 25 MHz clock sustains sustained protocol parsing without buffering overflow. Compared with 16-bit PIC24 or dsPIC33 alternatives, PIC17C42A-25/P maintains bit-banged firmware paths that legacy code already depends on. Recommended companion: PIC16LF818-I/SO for end-of-line protocol taps.
Recommended
Instrumentation and Test Equipment
PIC17C42A-25/P powers benchtop instrumentation front-panels and test fixtures that need a stable 8-bit core, ample GPIO for switch matrices, and a USART for PC-side SCPI command handling. The 4 KB OTP EPROM stores calibration constants and test sequences that must not drift after NIST-traceable calibration cycles. 232 bytes of RAM plus 33 I/O cover simple display-and-keypad UIs without external logic. Compared with flash PIC18F4220, OTP EPROM provides tamper-resistance during factory calibration, an advantage for certified measurement products. Recommended companion: PIC16LF872-I/SO for keypad-scan co-processors.
Recommended
Recommended Products Summary
Engineering reference data for PIC17C42A-25/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC17C42A-16/P | PIC17C42A-16E/P | PIC17CR42A-25/P |
|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 40-pin PDIP | 40-pin PDIP | 40-pin PDIP | 40-pin PDIP |
| Maximum Clock Frequency | 25 MHz | 16 MHz | 16 MHz | 25 MHz |
| Program Memory Size | 4 KB (2K x 16 OTP EPROM) | 4 KB (2K x 16 OTP EPROM) | 4 KB (2K x 16 OTP EPROM) | 4 KB (2K x 16 ROM) |
| RAM Size | 232 bytes | 232 bytes | 232 bytes | 232 bytes |
| Number of I/O Pins | 33 | 33 | 33 | 33 |
| Supply Voltage | 5 V to 6 V | 5 V to 6 V | 5 V to 6 V | 5 V to 6 V |
| Operating Temperature | -40 °C to +85 °C | 0 °C to +70 °C (commercial) | -40 °C to +125 °C (extended) | -40 °C to +85 °C |
| Program Memory Type | OTP EPROM | OTP EPROM | OTP EPROM | Mask ROM |
| Lifecycle Status | NRND | NRND | NRND | NRND |
Key Differentiators
- One-Time-Programmable EPROM security model (vs PIC17C42A-16E/P)
- 40-pin PDIP through-hole form factor (vs PIC17C42A-25/L (PLCC))
- PIC17 family upward compatibility (vs PIC18F4220)
Design Notes
Estimated: with VDD at 5.0 V and active current near 25 mA at 25 MHz, the device dissipates approximately 125 mW. Place a 100 nF X7R ceramic decoupling capacitor within 5 mm of the VDD pin and a bulk 10 µF tantalum or aluminum-polymer capacitor on the same supply node. According to the Microchip PIC17C4X datasheet (DS30412C), the supply tolerance is 5 V to 6 V; design the upstream regulator for 5.0 V to leave margin for transient dips during MCLR resets.
Estimated: route the 25 MHz crystal traces from OSC1/OSC2 (pins 8 and 9) as short, matched-length stubs with a continuous ground pour on the opposite layer. Keep digital signal traces more than 5 mm away from the crystal to minimize capacitive loading. A grounded guard ring around the crystal cans reduces EMI pickup. The MCLR/VPP pin (pin 11) needs an external pull-up to VDD through a 10 kΩ resistor and a 100 nF cap to ground for noise immunity during reset.
Because PIC17C42A-25/P is OTP EPROM (one-time-programmable), firmware mistakes during in-system programming are irreversible; always verify the code image in an emulator window or socket-replaceable device before committing to the production programmer. The 16-bit instruction width differs from PIC16's 14-bit words, so binary code is not portable. Per the Microchip datasheet, exceeding 6 V on VDD stresses internal EPROM cells and may corrupt code even after a successful program/verify cycle.
Compliance Information
RoHS compliance per Microchip product documentation. Not AEC-Q100 qualified for automotive designs requiring that certification; for AEC-Q100 designs use flash-based PIC18 parts. Lead-free yes. Halogen-free status not surfaced in Verified Web Data - [DATA_NEEDED: halogen_free verification].
