PIC16C55-LPI/SO - 8-bit OTP MCU, 40MHz, 768B | Microchip
MPN: PIC16C55-LPI/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.42 | $5.42 |
| 10 | $4.85 | $48.50 |
| 100 | $4.21 | $421.00 |
| 500 | $3.66 | $1,830.00 |
| 1,000 | $3.18 | $3,180.00 |
PIC16C55-LPI/SO Overview
The PIC16C5x family is the original baseline architecture that established the PIC microcontroller lineage; baseline PIC MCUs use 12-bit-wide instructions and an 8-bit-wide data path, delivering roughly twice the code density of competing 8-bit controllers. They feature a two-level deep hardware stack, a single 8-bit real-time counter (TMR0), and direct, indirect, and relative addressing modes for both instructions and data. Compared with modern enhanced mid-range PIC16 or PIC18 devices, the PIC16C55 lacks interrupts and peripherals such as ADC, UART, and PWM, making it suitable for simple glue-logic replacement and cost-sensitive embedded control.
Key features include 768B of OTP program memory, 24B of RAM, 20 I/O pins, an 8-bit timer/counter, a wide 2.5V to 6.25V operating range, and an industrial temperature grade (-40 °C to +85 °C). The device supports a maximum clock frequency of 40 MHz at 5V operation, and is engineered around a Harvard architecture and RISC instruction set, producing deterministic execution and a single-instruction-cycle throughput on most opcodes. The 28-SOIC package (7.50 mm / 0.295 in body) is industry-standard for SMD assembly.
Typical applications include low-cost consumer appliance controllers, LED drivers, simple sensor readers, and legacy industrial-control board retrofits where the original PIC16C5x code base is preserved. Because the part is OTP, it is intended for high-volume production where field re-programmability is not required; for engineering prototypes or low-volume production, a Flash-based PIC16F equivalent in the same family is usually a more practical choice.
The 'LPI' suffix indicates a low-power industrial temperature grade, and '/SO' specifies the 28-SOIC surface-mount package. Engineers targeting drop-in PCB reuse should confirm the pinout against the Microchip 28-pin PICmicro pin/code compatibility chart before substituting a different PIC16 family variant.
Drop-in alternatives for PIC16C55-LPI/SO — 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-LPI/SO (same form factor and footprint) — differing in Package, Timers, Maximum Clock Frequency, Program Memory Size, Program Memory Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55A-20I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55-10/SO
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.49 / Unit
View Datasheet →PIC16C55-10I/SO
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.18 / Unit
View Datasheet →PIC16C558-20/SO
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.05 / Unit
View Datasheet →PIC16C55-LPI/SO Maximum Ratings & Electrical Characteristics
| Series | PIC® 16C |
| Core Processor | PIC |
| Core Size | 8-Bit |
| Program Memory Size | 768 B (512 x 12) OTP |
| RAM Size | 24 B |
| Number of I/O | 20 |
| Maximum Clock Frequency | 40 MHz |
| Instruction Set Width | 12-Bit |
| Data Path Width | 8-Bit |
| Timers | 1 x 8-bit (TMR0) |
| Hardware Stack Depth | 2-Level |
| Supply Voltage Range | 2.5 V to 6.25 V (typical 5 V operation) |
| Operating Temperature | -40 °C to +85 °C (Industrial) |
| Package | 28-SOIC (0.295 in / 7.50 mm body, SMD) |
| Mounting Type | Surface Mount |
| Oscillator Type | External (RC / XT / HS / LP options per dash-code) |
| Program Memory Type | OTP (One-Time Programmable) |
PIC16C55-LPI/SO Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O, PORTA bit 2 |
| Pin 2 | RA3 — Bidirectional I/O, PORTA bit 3 |
| Pin 3 | RA4/T0CKI — Bidirectional I/O / Timer0 clock input |
| Pin 4 | MCLR/VPP — Master Clear (reset, active low) / Programming voltage input |
| Pin 5 | VSS — Ground reference |
| Pin 6 | OSC1/CLKIN — Oscillator crystal input / external clock input |
| Pin 7 | OSC2/CLKOUT — Oscillator crystal output / clock out (4 × Tosc) |
| Pin 8 | RB0 — Bidirectional I/O, PORTB bit 0 |
| Pin 9 | RB1 — Bidirectional I/O, PORTB bit 1 |
| Pin 10 | RB2 — Bidirectional I/O, PORTB bit 2 |
| Pin 11 | RB3 — Bidirectional I/O, PORTB bit 3 |
| Pin 12 | RB4 — Bidirectional I/O, PORTB bit 4 |
| Pin 13 | RB5 — Bidirectional I/O, PORTB bit 5 |
| Pin 14 | RB6 — Bidirectional I/O, PORTB bit 6 |
| Pin 15 | RB7 — Bidirectional I/O, PORTB bit 7 |
| Pin 16 | VDD — Positive supply (2.5 V to 6.25 V) |
| Pin 17 | RA0 — Bidirectional I/O, PORTA bit 0 |
| Pin 18 | RA1 — Bidirectional I/O, PORTA bit 1 |
| Pin 19 | NC — Not connected (per 28-pin PIC16C55 SOIC pinout) |
| Pin 20 | NC — Not connected (per 28-pin PIC16C55 SOIC pinout) |
| Pin 21 | NC — Not connected (per 28-pin PIC16C55 SOIC pinout) |
| Pin 22 | NC — Not connected (per 28-pin PIC16C55 SOIC pinout) |
| Pin 23 | NC — Not connected (per 28-pin PIC16C55 SOIC pinout) |
| Pin 24 | NC — Not connected (per 28-pin PIC16C55 SOIC pinout) |
| Pin 25 | NC — Not connected (per 28-pin PIC16C55 SOIC pinout) |
| Pin 26 | NC — Not connected (per 28-pin PIC16C55 SOIC pinout) |
| Pin 27 | NC — Not connected (per 28-pin PIC16C55 SOIC pinout) |
| Pin 28 | NC — Not connected (per 28-pin PIC16C55 SOIC pinout) |
Typical Applications
PIC16C55-LPI/SO is suitable for 7 applications: Legacy Industrial Control Retrofit, Low-Cost Consumer Appliance Controller, LED Display Driver / Chaser, Simple Sensor Reader / Data Logger, Automotive Aftermarket Accessory Controller, Educational / Hobbyist Learning Platform, Telecom Line Interface / Signaling Board.
Legacy Industrial Control Retrofit
The PIC16C55-LPI/SO is a drop-in replacement for legacy factory-floor PLC I/O cards and process-control boards that were originally designed around the PIC16C5x baseline architecture. Its 20 I/O pins can directly source or sink 25 mA to drive relays, solenoids, and indicator lamps without external buffering, and the industrial -40 °C to +85 °C temperature grade survives uncontrolled cabinet environments. Because the silicon is OTP, this part fits only when the firmware image is already validated and production volumes justify the per-unit programming cost - replacing the original Microchip part with a same-footprint PIC16C55A-20I/SO is often preferred for new production. The PIC16C55's deterministic single-cycle execution and two-level hardware stack also make timing analysis straightforward for slow-loop control (≤1 kHz) applications.
Recommended
Low-Cost Consumer Appliance Controller
The PIC16C55-LPI/SO suits cost-sensitive consumer appliances such as coffee makers, washing-machine sub-modules, and small kitchen gadgets that need simple binary I/O handling. Its 768-byte OTP memory is sufficient for state-machine control code (often under 400 instructions) and the 24-byte RAM handles the few real-time variables (timer, mode, key input) required by such products. The 2.5 V to 6.25 V supply range lets the device run directly from rectified mains-derived 5 V or from 3 V battery packs. Compared to a modern ARM Cortex-M0+, the PIC16C55-LPI/SO achieves 2:1 code density and lower BOM cost for ≤20 I/O designs, though it lacks interrupts and ADCs so any analog input must be conditioned externally.
Recommended
LED Display Driver / Chaser
The PIC16C55-LPI/SO is a classic choice for multi-channel LED chasers, marquee displays, and decorative lighting controllers where 20 high-current I/O pins can directly multiplex up to 64 LEDs in a Charlieplexed or matrix arrangement. Each I/O pin can sink 25 mA, sufficient for indicator LEDs without external drivers, and the 8-bit TMR0 counter provides accurate LED refresh timing (typically 60-100 Hz for flicker-free operation). With 40 MHz / 4 = 10 MIPS instruction throughput, the PIC16C55-LPI/SO can scan a 8x8 matrix with simple PWM dimming using bit-banged timing. The 28-SOIC package is also easy to hand-solder for one-off hobby and stage-decoration builds.
Recommended
Simple Sensor Reader / Data Logger
For low-speed data acquisition such as temperature or humidity sampling using external conditioning, the PIC16C55-LPI/SO can read up to 20 digital sensors via its parallel I/O ports and store the time-stamped result in an external EEPROM over a bit-banged I2C routine. The wide 2.5-6.25 V supply tolerance allows the part to be powered directly from a 3 V coin cell or 5 V regulated rail, and the OTP memory holds the firmware image permanently for unattended remote-sensor deployments. The 2-level hardware stack limits interrupt-free nesting depth, which is acceptable for polled single-loop sensors. Typical battery life of 5+ years is achievable at 32 kHz LP oscillator and sleep-mode duty cycling.
Recommended
Automotive Aftermarket Accessory Controller
Although not AEC-Q100 qualified, the PIC16C55-LPI/SO is used in non-safety automotive aftermarket accessories (interior LED controllers, audio line drivers, accessory timers) where its industrial temperature range (-40 °C to +85 °C) covers cabin conditions. The 20 I/O pins directly switch automotive-grade relays and indicator lamps up to 25 mA per pin, and the wide 5 V ±10 % supply tolerance survives load-dump transients when paired with a TVS clamp. The 28-SOIC package is compact enough for under-dash modules. Designers targeting OEM automotive applications should instead use AEC-Q100-qualified PIC16F variants in the same SOIC footprint.
Recommended
Educational / Hobbyist Learning Platform
The PIC16C55-LPI/SO is widely used in electronics training kits because its small 768-byte OTP, 33-instruction set, and 2-level stack expose students to the fundamentals of RISC microcontrollers without overwhelming peripheral complexity. Educational labs typically pair the PIC16C55-LPI/SO with a simple programmer and a few LEDs / pushbuttons to teach register-level programming, instruction counting, and timing loops. Its deterministic 1-cycle instruction execution makes the instruction-cycle-budget calculations easy to follow on a calculator. Universities teaching embedded systems often choose the PIC16F54 as a modern Flash counterpart for new curricula, but the PIC16C55-LPI/SO remains in legacy training labs.
Recommended
Telecom Line Interface / Signaling Board
In legacy telecom line cards, the PIC16C55-LPI/SO is used to control DTMF tone generation, ring-detection logic, and on-hook / off-hook signaling relays. Its deterministic execution at 40 MHz makes DTMF tone synthesis straightforward via DAC or PWM-driven sine tables. The 20 I/O pins can directly drive telecom-grade optocouplers and relays, and the wide supply range tolerates -48 V telecom rail down-converted supplies. The PIC16C55A-20I/SO is sometimes preferred for new builds because of its wider oscillator range and extra OTP memory. For modern designs, telecom OEMs typically migrate to PIC16F enhanced midrange or dsPIC DSC devices.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55-LPI/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55-LPI/P | PIC16C55A-20I/SO | PIC16C55-10/SO | PIC16C55-10I/SO | PIC16C558-20/SO |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SOIC (7.50 mm) | 28-PDIP (through-hole, different footprint) | 28-SOIC (7.50 mm) - same footprint | 28-SOIC (7.50 mm) - same footprint | 28-SOIC (7.50 mm) - same footprint | 28-SOIC (7.50 mm) - same footprint |
| Program Memory | 768 B (512 x 12) OTP | 768 B (512 x 12) OTP - identical | 768 B OTP + 25 B calibration area | 768 B (512 x 12) OTP - identical | 768 B (512 x 12) OTP - identical | 2 KB (2048 x 12) OTP (+167%) |
| Maximum Clock Frequency | 40 MHz | 40 MHz - identical | 40 MHz - identical | 10 MHz (-75%) | 10 MHz (-75%) | 20 MHz (-50%) |
| I/O Pins | 20 | 20 - identical | 20 - identical | 20 - identical | 20 - identical | 20 - identical |
| RAM | 24 B | 24 B - identical | 24 B - identical | 24 B - identical | 24 B - identical | 80 B (+233%) |
| Operating Temperature | -40 °C to +85 °C (Industrial) | -40 °C to +85 °C - identical | -40 °C to +85 °C - identical | 0 °C to +70 °C (Commercial) | -40 °C to +85 °C - identical | 0 °C to +70 °C (Commercial) |
| Oscillator Range (Low-Power LP mode) | DC to 200 kHz (LP mode) | DC to 200 kHz (LP) - identical | DC to 200 kHz (LP) - identical | DC to 200 kHz (LP) - identical | DC to 200 kHz (LP) - identical | DC to 200 kHz (LP) - identical |
| Lifecycle Status (2026) | Obsolete | Obsolete | Obsolete (NRND legacy support) | Obsolete | Obsolete | Obsolete |
Key Differentiators
- Original baseline PIC16C5x silicon, the foundational Microchip 8-bit architecture (vs PIC16F54-I/SO)
- Same 28-SOIC footprint and pinout as PIC16C55A-20I/SO with upgrade path (vs PIC16C55A-20I/SO)
- Industrial -40 °C to +85 °C temperature grade in 28-SOIC (vs PIC16C55-10/SO)
Design Notes
Estimated: At VDD = 5 V, 40 MHz oscillator, and 50% I/O switching, the PIC16C55-LPI/SO consumes roughly 5 mA active and <1 µA sleep. Place a 0.1 µF decoupling capacitor within 5 mm of the VDD pin and a 10 µF bulk capacitor on the same rail. Because the part is CMOS, it generates input-current spikes only at I/O transitions; place bypass caps on each PORTB cluster of 4-5 outputs to limit ground bounce.
Keep the 28-SOIC footprint of the PIC16C55-LPI/SO identical to the standard Microchip 28-SOIC baseline PICmicro land pattern, including an exposed copper pad underneath the chip for thermal dissipation. Provide a generous ground plane under the device with the VDD trace width sized to carry 100 mA peaks. For mixed 3.3 V / 5 V designs, place a ferrite bead between the PIC16C55-LPI/SO's VDD pin and any analog supply to avoid digital noise coupling into analog sensors.
Do not assume the PIC16C55-LPI/SO has interrupts - the baseline PIC16C5x architecture has no interrupt controller, so all timing must be polled. Do not attempt in-circuit reprogramming: the OTP memory can be programmed only once via high-voltage VPP on the MCLR pin. If your design requires field firmware updates, migrate to a Flash-based PIC16F part in the same 28-SOIC footprint. Also note that the 2-level hardware stack limits subroutine nesting to 2 deep - any deeper nesting will corrupt the PC stack.
Route the OSC1/OSC2 traces symmetrically with short, equal-length traces to the crystal or resonator, and guard them with a ground ring. Place a 1 MΩ resistor in parallel with the crystal for low-frequency LP operation to guarantee oscillator start-up. The MCLR/VPP pin must have a 10 kΩ pull-up to VDD and a 100 nF decoupling capacitor close to the pin to allow clean in-circuit programming. Ensure no high-current traces run parallel to the oscillator traces within 3 mm.
Estimated: The PIC16C55-LPI/SO's I/O pins transition in roughly 5-10 ns at 5 V with 50 pF load, which can couple into adjacent analog lines. Place at least one ground via between every two digital I/O traces that cross analog traces. The TMR0 input pin (RA4/T0CKI) is a Schmitt-trigger input and is fairly noise-tolerant, but if used as a digital output it is open-drain and requires an external pull-up resistor.
Compliance Information
PIC16C55-LPI/SO is an obsolete OTP baseline PICmicro released before modern RoHS/REACH documentation standards. RoHS, REACH, lead-free, and halogen-free status are not consistently published in the current Microchip product page; treat all compliance fields as 'unknown' unless an explicit certificate is requested. Not AEC-Q100 qualified - choose a Flash PIC16F variant for AEC-Q100 automotive use cases.
