PIC16C55-XTI/SP - 8-Bit 4MHz OTP MCU 768B | 28-SPDIP Microchip
MPN: PIC16C55-XTI/SP ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.85 | $2.85 |
| 10 | $2.56 | $25.60 |
| 100 | $2.27 | $227.00 |
| 500 | $2.04 | $1,020.00 |
| 1,000 | $1.82 | $1,820.00 |
PIC16C55-XTI/SP Overview
A microcontroller (MCU) is a single-chip computer that contains a processor core, memory, and programmable I/O peripherals. The PIC16C5X family belongs to the original 8-bit PIC architecture, sitting in the hierarchy: PIC16C5X -> PIC16 family -> PICmicro -> 8-bit microcontroller -> embedded MCU. These parts use 12-bit-wide instructions with an 8-bit data path, achieving roughly 2:1 code compression versus competitive 8-bit MCUs of the same era. The PIC16C5X remains popular for cost-sensitive, low-complexity designs such as appliance controls, sensor interfaces, and hobbyist projects.
Key features of the PIC16C55-XTI/SP include a 4 MHz maximum clock, 768B OTP program memory (one-time programmable), 24B SRAM, 20 digital I/O pins arranged across multiple ports, an 8-bit real-time clock/counter (TMR0), a two-level deep hardware stack, and direct, indirect, and relative addressing modes for both data and instructions. Seven or eight special function hardware registers manage peripherals and core state. The industrial temperature grade (-40C to +85C) and through-hole SPDIP-28 form factor make it suitable for legacy, hand-soldered, or ruggedized equipment.
Typical applications for the PIC16C55-XTI/SP include simple motor control, LED driving, appliance control boards, sensor signal conditioning front-ends, and educational MCU platforms. The wide operating voltage range and low pin count support battery-powered or wall-powered designs with minimal external components.
When designing with the PIC16C55-XTI/SP, remember that OTP memory cannot be reprogrammed - the firmware must be fully verified before burning. In-system programming is not available; a device programmer such as the MPLAB PM3 is required. Provide adequate decoupling (0.1uF ceramic) close to VDD, and reserve unused I/O pins to defined states to minimize current consumption.
This page synthesizes current distributor pricing, a drop-in alternative cross-reference matrix, and practical design considerations not consolidated on any single manufacturer page.
Drop-in alternatives for PIC16C55-XTI/SP — 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 PIC16C55-XTI/SP (same form factor and footprint) — differing in Package, Operating Temperature, Timers, Watchdog Timer, I/O Pins.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55-XT/P
✅ Drop-In✓ In Stock
$4.05 / Unit
View Datasheet →PIC16C55-XTE/P
✅ Drop-In✓ In Stock
$1.9 / Unit
View Datasheet →PIC16C55A-20I/SP
✅ Drop-In✓ In Stock
$3.01 / Unit
View Datasheet →PIC16C55A-04I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55-HSI/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55-10/SP
✅ Drop-In✓ In Stock
$2.45 / Unit
View Datasheet →PIC16C55-XTI/SP Maximum Ratings & Electrical Characteristics
| Core | PIC 8-bit (PIC16C5X family) |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 768 B (512 x 12 words) |
| Data RAM | 24 B |
| Maximum CPU Frequency | 4 MHz |
| Instruction Width | 12 bits |
| Data Bus Width | 8 bits |
| I/O Pins | 20 |
| Timers | 1 x 8-bit (TMR0) |
| Hardware Stack | 2 levels |
| Addressing Modes | Direct, Indirect, Relative |
| Special Function Registers | 7-8 |
| Package | 28-SPDIP (through-hole) |
| Pin Count | 28 |
| Operating Temperature | -40C to +85C (Industrial) |
| Mounting Type | Through-Hole |
| Programming Method | External device programmer (e.g. MPLAB PM3) |
PIC16C55-XTI/SP Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O, Port A bit 2 |
| Pin 2 | RA3 — Bidirectional I/O, Port A bit 3 |
| Pin 3 | RA0 — Bidirectional I/O, Port A bit 0 |
| Pin 4 | RA1 — Bidirectional I/O, Port A bit 1 |
| Pin 5 | VSS — Ground reference |
| Pin 6 | OSC2 — Oscillator output (crystal/RC) |
| Pin 7 | OSC1 — Oscillator input (crystal/RC/external clock) |
| Pin 8 | RC0 — Bidirectional I/O, Port C bit 0 |
| Pin 9 | RC1 — Bidirectional I/O, Port C bit 1 |
| Pin 10 | RC2 — Bidirectional I/O, Port C bit 2 |
| Pin 11 | RC3 — Bidirectional I/O, Port C bit 3 |
| Pin 12 | RC4 — Bidirectional I/O, Port C bit 4 |
| Pin 13 | RC5 — Bidirectional I/O, Port C bit 5 |
| Pin 14 | RC6 — Bidirectional I/O, Port C bit 6 |
| Pin 15 | RC7 — Bidirectional I/O, Port C bit 7 |
| Pin 16 | VSS — Ground reference |
| Pin 17 | VDD — Positive supply voltage |
| Pin 18 | RB0 — Bidirectional I/O, Port B bit 0 (interrupt capable) |
| Pin 19 | RB1 — Bidirectional I/O, Port B bit 1 |
| Pin 20 | RB2 — Bidirectional I/O, Port B bit 2 |
| Pin 21 | RB3 — Bidirectional I/O, Port B bit 3 |
| Pin 22 | RB4 — Bidirectional I/O, Port B bit 4 |
| Pin 23 | RB5 — Bidirectional I/O, Port B bit 5 |
| Pin 24 | RB6 — Bidirectional I/O, Port B bit 6 |
| Pin 25 | RB7 — Bidirectional I/O, Port B bit 7 |
| Pin 26 | T0CKI — Timer0 clock input |
| Pin 27 | /MCLR — Master Clear (active-low reset) |
| Pin 28 | VDD — Positive supply voltage |
Typical Applications
PIC16C55-XTI/SP is suitable for 7 applications: Appliance Control Boards, Sensor Signal Conditioning Front-End, LED Display and Lighting Controllers, Educational Microcontroller Trainer Boards, Simple Motor Control (DC, Stepper, Brushed), Automotive Accessory Controllers (Non-Safety), Industrial Control Logic Replacement.
Appliance Control Boards
The PIC16C55-XTI/SP's 20 digital I/O pins, 768B OTP program memory, and 4 MHz CPU make it well-suited for low-cost appliance control boards such as coffee makers, toaster ovens, washing-machine user interfaces, and small fan controllers. Its 768B code budget fits the typical state-machine logic for sensor readout, button debouncing, and triac/relay control. The OTP memory enforces firmware lockdown, protecting manufacturers from reverse engineering. The industrial -40C to +85C temperature range covers most kitchen and laundry environments, and the through-hole SPDIP-28 package survives hand-soldered assembly in low-volume appliance production. Pair it with a UL-recognized power supply and an optoisolated triac driver for line-voltage switching. The PIC16C55-XTI/SP typically replaces older bipolar logic with a single chip, reducing BOM count by 8-12 components.
Recommended
Sensor Signal Conditioning Front-End
The PIC16C55-XTI/SP serves as a low-cost front-end MCU for sensor signal conditioning boards reading thermistors, photodiodes, Hall-effect sensors, or simple switch contacts. Its 8-bit ADC-free architecture (note: PIC16C5X lacks integrated ADC) works best with analog sensors feeding external comparator or op-amp front-ends; the MCU then performs thresholding, linearization, and serial transmission. With 4 MHz CPU clock, conversion and digital filtering routines execute in well under 100us per channel. The 24B data RAM constrains the sample buffer, but for slow-changing sensor signals (1 Hz to 1 kHz update rates), this is rarely a bottleneck. Industrial temperature grade allows deployment in factory and outdoor cabinets. Use 0.1uF ceramic decoupling close to VDD to keep digital switching noise out of analog input traces.
Recommended
LED Display and Lighting Controllers
The PIC16C55-XTI/SP is a strong fit for LED display drivers and decorative lighting controllers, where its 20 I/O pins can directly multiplex up to a 4x5 LED matrix or drive 20 individual LEDs via charlieplexing. The 4 MHz CPU clock provides sufficient bandwidth to refresh LED matrices at 100+ Hz, eliminating visible flicker in human-eye response. Industrial temperature grade supports indoor commercial lighting and outdoor signage applications within its -40C to +85C envelope. OTP memory prevents end-users from modifying lighting patterns, which protects brand IP and safety-related limits. Power consumption stays below 10 mA at 5V, allowing battery or USB-powered installations. Pair with ULN2003A drivers for high-current LED strings and use 220-ohm series resistors to limit per-pin current to 20 mA maximum.
Recommended
Educational Microcontroller Trainer Boards
The PIC16C55-XTI/SP is widely used in university microcontroller courses and hobbyist trainer boards because its 28-SPDIP through-hole package is easy to socket, hand-solder, and replace in breadboard-style trainers. The 768B OTP memory teaches students the discipline of code budgeting, while the simple PIC16C5X instruction set (33 instructions) allows full assembly-language mastery within a single semester. Industrial temperature grade ensures lab benches and dorm-room environments are within spec. PIC16C55-XTI/SP trainers typically include a 4 MHz crystal, 0.1uF decoupling, an RS-232 level shifter, and a bank of 8 LEDs for output demonstration. The external programmer requirement (e.g. MPLAB PM3) introduces students to industry-standard MCU development workflows from day one.
Recommended
Simple Motor Control (DC, Stepper, Brushed)
The PIC16C55-XTI/SP can drive small brushed DC motors, unipolar stepper motors, and PWM-controlled fans through its 20 I/O pins and 4 MHz CPU clock. Software PWM at 1 kHz is achievable with timer TMR0 and software loops, sufficient for fan speed control and small DC motor speed regulation. Industrial temperature grade supports under-hood automotive accessories, HVAC dampers, and factory-floor stepper indexers. The OTP memory enforces firmware integrity for safety-related motor profiles. Pair with discrete MOSFET drivers such as the IRF540 or integrated H-bridge drivers for bi-directional control. With 24B RAM, the MCU can hold a small motion profile table (position, velocity) but not extended trajectory buffers; use external EEPROM for longer motion sequences.
Recommended
Automotive Accessory Controllers (Non-Safety)
The PIC16C55-XTI/SP fits non-safety automotive accessories such as ambient lighting controllers, seat-heater switches, mirror adjusters, and auxiliary gauge displays where industrial -40C to +85C is borderline acceptable for cabin applications. With 768B OTP and 4 MHz CPU, the MCU handles switch debouncing, LED dimming via software PWM, and simple serial communication to a body control module. For under-hood or extreme-temperature locations, upgrade to the PIC16C55-XTE/P (extended -40C to +125C). The through-hole SPDIP-28 package is favored in legacy automotive harness modules where vibration resistance of through-hole leads is critical. OTP memory prevents post-sale firmware tampering, an important consideration for warranty protection. Always add TVS diodes on supply and I/O lines for automotive transient protection.
Recommended
Industrial Control Logic Replacement
The PIC16C55-XTI/SP is commonly used to replace legacy 7400-series glue logic in industrial control panels, consolidating 5-15 discrete logic gates into a single programmable MCU. With 768B OTP and 4 MHz CPU, the MCU can scan 20 input buttons, drive 20 output indicators, and implement interlock logic with state-machine code well within memory limits. Industrial -40C to +85C temperature range covers factory floor and outdoor cabinet installations. The 28-SPDIP package fits legacy through-hole PCB footprints originally designed for 74HC logic, simplifying retrofit boards. OTP memory prevents unauthorized logic modification, important for safety-rated industrial systems. Use opto-isolated inputs and relay-driver outputs to interface with industrial 24V signal levels safely.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55-XTI/SP — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55-XT/P | PIC16C55-XTE/P | PIC16C55A-20I/SP | PIC16C55-HSI/SP |
|---|---|---|---|---|---|
| Package | 28-SPDIP | 28-SPDIP - same | 28-SPDIP - same | 28-SPDIP - same | 28-SPDIP - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| CPU Speed | 4 MHz | 4 MHz | 4 MHz | 20 MHz | 4 MHz |
| Program Memory | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP |
| Data RAM | 24 B | 24 B | 24 B | 24 B | 24 B |
| Operating Temperature | -40C to +85C (Industrial) | 0C to +70C (Commercial) | -40C to +125C (Extended) | -40C to +85C (Industrial) | -40C to +85C (Industrial) |
| I/O Pins | 20 | 20 | 20 | 20 | 20 |
| Program Memory Type | OTP | OTP | OTP | OTP | OTP |
| Mounting Type | Through-Hole | Through-Hole | Through-Hole | Through-Hole | Through-Hole |
Key Differentiators
- Industrial temperature grade in original-cost OTP silicon (vs PIC16C55-XT/P)
- Through-hole SPDIP-28 footprint for hand-repairable legacy designs (vs PIC16C55T-XT/SS (SSOP-28 surface-mount))
- OTP firmware lockdown prevents end-user modification (vs PIC16F54 (Flash-based))
Design Notes
The PIC16C55-XTI/SP uses OTP (One-Time Programmable) memory - once programmed, firmware cannot be erased or rewritten. All firmware verification must be completed on a windowed PIC16C55JW prototype before committing to OTP parts. A single firmware bug in production translates to scrap parts at full unit cost, so design a final-test plan that can detect and rework (depopulate and replace) failed boards before shipping. For prototypes and low-volume runs, prefer a socketed PIC16C55A or PIC16F54 alongside the PIC16C55-XTI/SP for development.
Place a 0.1uF ceramic decoupling capacitor as close as possible to the VDD pin (pin 17 and pin 28 are both VDD on the 28-SPDIP). Add a bulk electrolytic capacitor (10-47uF) on the board's main supply rail to handle inrush during programming and transient load steps. The PIC16C55-XTI/SP draws approximately 2-5 mA active at 4 MHz and 5V; sleep current drops below 1 uA with the watchdog disabled. If the design must survive brownouts, implement external voltage supervision on /MCLR (pin 27) rather than relying on internal brownout, since early PIC16C5X devices do not include internal BOR.
The 28-SPDIP through-hole footprint uses 0.100 inch (2.54 mm) pin pitch and a 0.600 inch (15.24 mm) row spacing, identical to all standard 28-pin DIP packages. Route high-current traces (motor drivers, relay coils) away from the oscillator pins (OSC1/OSC2) and the /MCLR reset pin to avoid injected noise. Keep the crystal or ceramic resonator within 0.5 inch (12 mm) of OSC1 and OSC2, with a ground plane underneath for noise shielding. Unused I/O pins should be configured as outputs and tied low to minimize supply current; floating inputs can draw several hundred microamps each due to CMOS input structure.
Estimated: for a 28-SPDIP board carrying the PIC16C55-XTI/SP and a 4 MHz fundamental-mode crystal, route the OSC1/OSC2 traces as short, parallel, length-matched nets and place load capacitors (typically 15-33 pF for a 4 MHz crystal) between each oscillator pin and ground. Keep digital switching traces (port B/C toggling) at least 3 trace-widths away from the oscillator traces to minimize capacitive coupling. If the design includes a T0CKI external clock input, route it perpendicular to the oscillator traces to further reduce crosstalk. A continuous ground plane under the MCU is recommended for EMI suppression.
The PIC16C55-XTI/SP in 28-SPDIP package typically exhibits theta_JA around 70 C/W in still air on a standard FR-4 board. At 5V supply, 4 MHz active operation, and 5 mA active current, power dissipation is approximately 25 mW, yielding a junction temperature rise of 1.75 C above ambient - negligible. Even at extended temperature (125C) with 10 mA active current, junction temperature rise is well within the 150C absolute maximum. No special thermal management is required for typical PIC16C55-XTI/SP designs; this is one of the lowest-power 8-bit MCUs in production.
Compliance Information
Compliance status not stated in the provided Verified Web Data snippets. PIC16C5X family is not AEC-Q100 qualified. Contact Microchip for current RoHS/REACH compliance certificates.
