PIC16C55-LPI/SS - 768B OTP 8-bit MCU, 20 I/O, SSOP-28 | Microchip
MPN: PIC16C55-LPI/SS β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.3836 | $4.38 |
| 10 | $4.05 | $40.50 |
| 100 | $3.62 | $362.00 |
| 500 | $3.2 | $1,600.00 |
| 1,000 | $2.85 | $2,850.00 |
PIC16C55-LPI/SS Overview
What is an 8-bit OTP microcontroller? An 8-bit OTP MCU is a small RISC processor with an 8-bit ALU and 8-bit data bus, packaged with non-volatile program memory that can be written exactly once during production programming - making it a cost-optimized alternative to UV-erasable EPROM MCUs and a more secure option than Flash for low-to-medium volume products. Within the embedded hierarchy, the PIC16C5X sits below PIC16 enhanced cores and PIC18, targeting cost-sensitive applications that need deterministic timing and a tiny footprint rather than large code space.
The PIC16C55-LPI variant is specified for the LP oscillator range (typically 200 kHz to 4 MHz crystal) with industrial-grade -40C to +85C operation and low-power quiescent characteristics, distinguishing it from the XT, HS, and RC variants in the same family. Hardware features include an 8-bit real-time clock/counter (TMR0) with programmable prescaler, a two-level deep hardware stack, direct/indirect/relative addressing modes, seven or eight special-function hardware registers, a watchdog timer, power-on reset, and brown-out / power-on reset circuitry. The SSOP-28 footprint and pinout allow direct substitution with other PIC16C5X 28-pin SSOP variants.
Typical applications include low-cost consumer appliances, white-goods user-interface boards, simple sensor front-ends, automotive body controllers, industrial timers and counters, and battery-powered metering nodes. The combination of 20 I/O lines, 768-byte OTP, and a sub-2 mA active current makes it suitable for cost-sensitive designs where the PIC ecosystem (MPLAB IDE, MPASM assembler, MPLAB PM3 programmer) is preferred over more complex ARM Cortex-M parts.
A key design consideration is OTP memory programming: code must be committed at the production line using a Microchip device programmer (e.g., MPLAB PM3) because OTP cannot be erased in-circuit; engineers should plan for firmware-revision discipline and use the JW UV-erasable variant during development. For new designs, Microchip generally recommends Flash-based successors such as PIC16F54 in the same package.
This page synthesizes distributor pricing, drop-in PIC16C5X SSOP-28 alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for PIC16C55-LPI/SS β 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/SS (same form factor and footprint) β differing in Program Memory Size, Program Memory Type, Package, Series, Timers.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
PIC16C55A-04I/SS
β Drop-Inπ Reference alternative (not in catalog)
PIC16C55-LPE/SS
β Drop-Inπ Reference alternative (not in catalog)
PIC16C55T-LPI/SS
β Drop-Inβ In Stock
$1.75 / Unit
View Datasheet βPIC16C55-10I/SS
β Drop-Inβ In Stock
$2.55 / Unit
View Datasheet βPIC16C54-LPI/SS
β Drop-Inβ In Stock
$2.41 / Unit
View Datasheet βPIC16F54-I/SS
β Drop-Inπ Reference alternative (not in catalog)
PIC16C55-LPI/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC RISC |
| Family | PIC16C5X |
| Series | PIC16C55 |
| Program Memory Type | OTP (One-Time-Programmable) EPROM |
| Program Memory Size | 512 x 12 words (768 bytes) |
| Data RAM | 24 bytes |
| Instruction Width | 12-bit |
| Data Path Width | 8-bit |
| Maximum I/O Pins | 20 |
| Hardware Stack Levels | 2 |
| Timers | 1 x 8-bit (TMR0 with prescaler) |
| Oscillator Type | LP (Low-Power Crystal, ~200 kHz-4 MHz input) |
| Supply Voltage | 3.0 V to 6.25 V (typical 5 V operation) |
| Maximum Clock Frequency | 4 MHz oscillator input (LP grade) |
| Operating Temperature | -40C to +85C (Industrial) |
| Package | 28-pin SSOP (0.209 inch / 5.30 mm width) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant (verify by lot - some OTP PIC16C5X SKUs are non-RoHS) |
| Lead-Free | Yes (per Microchip marking convention) |
PIC16C55-LPI/SS Pin Configuration
| Pin 1 | RA2 β Bidirectional I/O port A bit 2 |
| Pin 2 | RA3 β Bidirectional I/O port A bit 3 |
| Pin 3 | T0CKI β Timer0 clock input (shared with RA4) |
| Pin 4 | RA4 β Bidirectional I/O port A bit 4 / T0CKI |
| Pin 5 | MCLR β Master Clear (reset) input, active low |
| Pin 6 | VSS β Ground reference |
| Pin 7 | OSC1 β Oscillator crystal input / external clock |
| Pin 8 | OSC2 β Oscillator crystal output |
| Pin 9 | RB0 β Bidirectional I/O port B bit 0 |
| Pin 10 | RB1 β Bidirectional I/O port B bit 1 |
| Pin 11 | RB2 β Bidirectional I/O port B bit 2 |
| Pin 12 | RB3 β Bidirectional I/O port B bit 3 |
| Pin 13 | RB4 β Bidirectional I/O port B bit 4 |
| Pin 14 | RB5 β Bidirectional I/O port B bit 5 |
| Pin 15 | RB6 β Bidirectional I/O port B bit 6 |
| Pin 16 | RB7 β Bidirectional I/O port B bit 7 |
| Pin 17 | RC0 β Bidirectional I/O port C bit 0 |
| Pin 18 | RC1 β Bidirectional I/O port C bit 1 |
| Pin 19 | RC2 β Bidirectional I/O port C bit 2 |
| Pin 20 | RC3 β Bidirectional I/O port C bit 3 |
| Pin 21 | RC4 β Bidirectional I/O port C bit 4 |
| Pin 22 | RC5 β Bidirectional I/O port C bit 5 |
| Pin 23 | RC6 β Bidirectional I/O port C bit 6 |
| Pin 24 | RC7 β Bidirectional I/O port C bit 7 |
| Pin 25 | RD0 β Bidirectional I/O port D bit 0 |
| Pin 26 | RD1 β Bidirectional I/O port D bit 1 |
| Pin 27 | RD2 β Bidirectional I/O port D bit 2 |
| Pin 28 | VDD β Positive supply (3.0 V to 6.25 V, typically 5 V) |
Typical Applications
PIC16C55-LPI/SS is suitable for 7 applications: Consumer Appliance Control Boards, Industrial Timers and Counters, Automotive Body Electronics, Battery-Powered Sensor Front-Ends, LED Display and Sign Controllers, Educational and Hobbyist Microcontroller Kits, Remote Control and IR Receiver Boards.
Consumer Appliance Control Boards
The PIC16C55-LPI/SS is well suited to low-cost user-interface boards in white goods such as microwave ovens, washing machines, and rice cookers, where its 20 digital I/O pins can directly drive 7-segment LED displays, keypad matrix scanning, and relay/MOSFET control outputs. The 768-byte OTP program memory holds typical appliance state machines and timing routines comfortably, while the LP oscillator grade keeps standby current low for Energy Star compliance. Combined with its 5 V operation and small SSOP-28 footprint, it enables compact PCBAs at BOM cost below $1.50 in volume.
Recommended
Industrial Timers and Counters
In industrial timer, counter, and sequence-controller modules the PIC16C55-LPI/SS provides a deterministic 8-bit RISC core with a hardware TMR0 timer/counter and programmable prescaler that handles pulse counting and time-base generation without software overhead. The 24-byte RAM and 768-byte OTP are sufficient for simple ladder-logic replacements, while the -40C to +85C industrial temperature range supports factory-floor deployment. The SSOP-28 package and 5 V supply integrate easily with existing 24V->5V logic-level interface boards.
Recommended
Automotive Body Electronics
Inside automotive body controllers - window lift modules, mirror adjusters, seat controllers, and simple lighting drivers - the PIC16C55-LPI/SS delivers the deterministic interrupt response of the PIC16C5X core plus 20 I/O lines to read switches and drive small loads via external MOSFETs. The LP oscillator grade reduces quiescent current for always-on body modules, while the -40C to +85C industrial temperature range covers passenger-compartment environments. For under-hood deployment, Microchip recommends the AEC-Q100-qualified PIC16F series successors instead.
Recommended
Battery-Powered Sensor Front-Ends
Battery-powered sensor nodes such as remote thermostats, simple weather stations, and utility metering transmitters benefit from the PIC16C55-LPI/SS's LP oscillator grade, which supports 32.768 kHz watch-crystal operation for sub-100 uA active current. The 24-byte RAM is adequate for buffering periodic sensor readings before transmitting them via UART or simple GPIO bit-banging. The 768-byte OTP holds compact protocol stacks and calibration data, while the 28-pin SSOP keeps the PCB small enough to fit in standard AAA-battery enclosures.
Recommended
LED Display and Sign Controllers
Small LED matrix signs, channel-letter controllers, and decorative lighting drivers use the PIC16C55-LPI/SS to multiplex 8x8 LED arrays via its 20 I/O pins, with TMR0 generating the row-refresh interrupt for flicker-free persistence-of-vision operation. The 5 MIPS instruction throughput at 4 MHz oscillator is more than enough for Charlieplexing patterns and DMX-512-like bit-banged protocols. Its SSOP-28 footprint and 5 V operation simplify integration with constant-current LED driver ICs, while OTP memory protects the lighting pattern IP from casual copying.
Recommended
Educational and Hobbyist Microcontroller Kits
The PIC16C55-LPI/SS serves as a teaching platform in university embedded-systems courses and DIY maker projects thanks to its simple 12-bit PIC16C5X instruction set, single 5 V supply, and free MPLAB IDE plus MPASM assembler toolchain. Students can learn timer/counter fundamentals, GPIO bit manipulation, and interrupt-driven programming using only 24 bytes of RAM and 768 bytes of OTP, with code examples published in countless textbooks since the 1990s. The SSOP-28 breakout boards available from Microchip Direct and LCSC make hand-soldering feasible for advanced hobbyists.
Recommended
Remote Control and IR Receiver Boards
Universal remote controls, IR/RF receiver base stations, and simple garage-door keypads leverage the PIC16C55-LPI/SS's 8-bit TMR0 for accurate IR protocol timing (NEC, RC5, Sony SIRC) and its 20 I/O pins to scan 4x4 key matrices while driving status LEDs. The LP oscillator grade supports 32.768 kHz to 4 MHz crystals used in low-power IR receiver standby. With 768 bytes OTP, the device can store protocol libraries for 3-4 common IR formats plus user-configuration data, all in a tiny SSOP-28 PCB footprint.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55-LPI/SS β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55A-04I/SS | PIC16C55-LPE/SS | PIC16C55T-LPI/SS | PIC16C55-10I/SS | PIC16C54-LPI/SS | PIC16F54-I/SS |
|---|---|---|---|---|---|---|---|
| Package | 28-SSOP (0.209 inch) | 28-SSOP (0.209 inch) - same | 28-SSOP (0.209 inch) - same | 28-SSOP (0.209 inch) - same | 28-SSOP (0.209 inch) - same | 28-SSOP (0.209 inch) - same | 28-SSOP (0.209 inch) - same |
| Brand | Microchip Technology | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same |
| Program Memory | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP | 512 B OTP (smaller) | 512 B Flash (reprogrammable) |
| Data RAM | 24 B | 24 B | 24 B | 24 B | 24 B | 25 B | 25 B |
| I/O Pins | 20 | 20 | 20 | 20 | 20 | 12 (smaller port count) | 12-20 (variant dependent) |
| Oscillator Grade | LP (low-power, up to ~4 MHz) | 04 (4 MHz) | LP (low-power) | LP (low-power) | 10 MHz rated | LP (low-power) | Wide range with internal oscillator |
| Temperature Grade | Industrial -40C to +85C | Industrial -40C to +85C | Commercial 0C to +70C | Industrial -40C to +85C | Industrial -40C to +85C | Industrial -40C to +85C | Industrial -40C to +85C |
| Memory Type | OTP (one-time programmable) | OTP | OTP | OTP | OTP | OTP | Flash (re-programmable) |
| Supply Voltage | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 2.0 V to 5.5 V |
Key Differentiators
- Industrial -40C to +85C temperature grade in LP low-power oscillator variant (vs PIC16C55-LPE/SS)
- LP oscillator grade optimized for low-power 32.768 kHz watch-crystal operation (vs PIC16C55-10I/SS)
- 20 I/O pins in SSOP-28 footprint (vs PIC16C54-LPI/SS)
- Direct same-die SSOP-28 replacement with Flash reprogrammability (vs PIC16F54-I/SS)
Design Notes
OTP (one-time-programmable) memory can be written only once. Use the PIC16C55/JW UV-erasable CERDIP variant for firmware development and bring-up, then switch to the PIC16C55-LPI/SS only when the code is fully validated. Any code bug committed to OTP memory cannot be corrected in-circuit and requires mechanical replacement of the MCU on every faulty board, which destroys production yield and field-repair economics.
The PIC16C55-LPI/SS is designed for the LP low-power crystal oscillator grade; supply decoupling must include a 100 nF ceramic capacitor placed within 5 mm of VDD (pin 28) and a 10 uF bulk capacitor on the main 5 V rail. The MCLR pin (pin 5) requires an external 10 kohm pull-up to VDD plus a 100 nF decoupling cap to ground to prevent spurious resets during power-up brown-out events; do not leave MCLR floating.
For SSOP-28 layout, use 0.65 mm pitch land patterns with 0.4 mm wide pads and a 0.3 mm solder-mask opening. Route VDD/VSS as a 0.5 mm-wide power pair on the top layer with a continuous ground pour on layer 2 to provide a low-impedance return path for the oscillator. Place the LP crystal within 5 mm of OSC1 (pin 7) and OSC2 (pin 8) and guard the traces with a ground ring to reduce EMI pickup on the low-amplitude oscillator node.
The PIC16C55-LPI/SS in SSOP-28 has a thermal resistance (theta_JA) of approximately 100 C/W on a standard JEDEC 2S2P test board, meaning full-power continuous operation at 70C ambient will keep the junction below 90C at the worst-case 30 mA active current. In most cost-sensitive appliance designs total active dissipation stays below 150 mW, so no heatsink is required. Verify with on-board thermal profiling if the design forces 100% duty-cycle CPU activity.
Do not confuse the PIC16C55-LPI/SS (industrial -40C to +85C, LP oscillator) with the PIC16C55-LPE/SS (commercial 0C to +70C, LP oscillator) - both share the SSOP-28 footprint but the temperature grade difference can cause field failures in outdoor or automotive applications. The PIC16C5X instruction set is also incompatible with PIC16 enhanced cores (PIC16F1xxx); firmware written for PIC16C55 does not run on PIC16F690 without complete rewrite and re-assembly.
Compliance Information
RoHS and REACH compliance confirmed per Microchip PIC16C5X family product page; specific lot compliance certificates available on Microchip Direct. Not AEC-Q100 qualified; choose PIC16F-series automotive parts for under-hood deployments. Halogen-free status not explicitly stated in provided data - treat as 'unknown' until verified via manufacturer certificate of compliance.
