PIC16C55A-40/SS - 8-bit 40MHz OTP MCU, 768B Code | Microchip
MPN: PIC16C55A-40/SS β End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.71 | $1.71 |
| 10 | $1.62 | $16.20 |
| 100 | $1.5 | $150.00 |
| 500 | $1.42 | $710.00 |
| 1,000 | $1.35 | $1,350.00 |
PIC16C55A-40/SS Overview
What is a microcontroller (MCU)? A microcontroller is a single-chip computer that integrates a CPU core, memory (program + data), and peripheral interfaces (I/O, timers, etc.) into one IC. Within that hierarchy, the PIC16C5X sits in the baseline 12-bit-instruction family, which later expanded into the enhanced mid-range (14-bit) and PIC18 (16-bit) families. The 12-bit wide instructions deliver high code density - typically 2:1 compression versus competing 8-bit MCUs - allowing more functionality to fit in the small on-chip OTP memory.
Key features of the PIC16C55A-40/SS include 768 bytes of EPROM program memory (OTP), 24 bytes of data RAM, a 4 MHz internal RC oscillator option (selected at programming), a 40 MHz maximum external clock input, and 20 bidirectional digital I/O pins across two ports (RA, RB). The device has only 28 instructions, enabling fast learning curves, and provides a watchdog timer with on-chip RC oscillator for reliable unattended operation.
Architecturally, the PIC16C55A uses a Harvard architecture with separate program and data buses, a single accumulator-based ALU, and a deep hardware stack for subroutine nesting. The 12-bit instruction width and 8-bit data path balance code density against silicon cost, which is why this family remains popular in high-volume appliance and consumer products where BOM cost dominates.
Typical applications include remote controls, small appliance controllers (toasters, coffee machines, fan controllers), security keypads, sensor signal conditioning, LED chaser/sequencer lights, and simple battery-operated toys. Its 20 I/O pins are sufficient to scan 4x4 keypads while driving multiplexed displays.
When designing with this part, plan for one-time programming: the EPROM memory cannot be erased. For prototype work, use a windowed (JW) variant or a pin-compatible Flash MCU (PIC16F) for in-circuit reprogramming. The 28-pin SSOP footprint is shared with the PIC16C55, PIC16C554, and PIC16C558 families, simplifying PCB layout reuse across product variants.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes - information not consolidated on any single distributor or manufacturer page. All specifications are sourced from the Microchip PIC16C55A datasheet and distributor listings verified as of 2026-09-16.
Drop-in alternatives for PIC16C55A-40/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 PIC16C55A-40/SS (same form factor and footprint) β differing in Architecture, Maximum Clock Frequency, Package, Program Memory Size, Program Memory Type.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
PIC16C55A-04/SS
β Drop-Inβ In Stock
$2.25 / Unit
View Datasheet βPIC16C55A-20/SS
β Drop-Inπ Reference alternative (not in catalog)
PIC16C55A-20I/SS
β Drop-Inβ In Stock
$1.04 / Unit
View Datasheet βPIC16F54-I/SS
β Drop-Inπ Reference alternative (not in catalog)
PIC16C554-04/SS
β Drop-Inβ In Stock
$1.55 / Unit
View Datasheet βPIC16C558-04/SS
β Drop-Inπ Reference alternative (not in catalog)
PIC16C55A-40/SS Maximum Ratings & Electrical Characteristics
| Family | PIC16C5X (Baseline, 12-bit instruction) |
| Architecture | 8-bit RISC, Harvard |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 768 bytes (0.75 KB) |
| Data RAM | 24 bytes |
| Data EEPROM | Not present |
| Maximum Clock Frequency | 40 MHz |
| Instruction Count | 28 |
| I/O Pins | 20 |
| Package | SSOP-28 (gull-wing) |
| Temperature Grade | Commercial |
| Operating Temperature | 0C to +70C (commercial) |
| Supply Voltage | 3.0 V to 6.25 V (typical 5 V) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
PIC16C55A-40/SS Pin Configuration
| Pin 1 | VDD β Positive supply voltage |
| Pin 2 | RA0 β Bidirectional I/O, Port A bit 0 |
| Pin 3 | RA1 β Bidirectional I/O, Port A bit 1 |
| Pin 4 | MCLR/VPP β Master Clear (reset) / Programming voltage |
| Pin 5 | RA2 β Bidirectional I/O, Port A bit 2 |
| Pin 6 | RA3 β Bidirectional I/O, Port A bit 3 |
| Pin 7 | RA4 β Bidirectional I/O, Port A bit 4 |
| Pin 8 | RC0 β Bidirectional I/O, Port C bit 0 |
| Pin 9 | RC1 β Bidirectional I/O, Port C bit 1 |
| Pin 10 | RC2 β Bidirectional I/O, Port C bit 2 |
| Pin 11 | RC3/T0CKI β Bidirectional I/O / Timer0 clock input |
| Pin 12 | RC4 β Bidirectional I/O, Port C bit 4 |
| Pin 13 | RC5 β Bidirectional I/O, Port C bit 5 |
| Pin 14 | VSS β Ground reference |
| Pin 15 | OSC1/CLKIN β Oscillator input / external clock in |
| Pin 16 | OSC2/CLKOUT β Oscillator output / clock out |
| Pin 17 | RC6 β Bidirectional I/O, Port C bit 6 |
| Pin 18 | RC7 β Bidirectional I/O, Port C bit 7 |
| Pin 19 | RB0 β Bidirectional I/O, Port B bit 0 (interrupt-on-change) |
| Pin 20 | RB1 β Bidirectional I/O, Port B bit 1 |
| Pin 21 | RB2 β Bidirectional I/O, Port B bit 2 |
| Pin 22 | RB3 β Bidirectional I/O, Port B bit 3 |
| Pin 23 | RB4 β Bidirectional I/O, Port B bit 4 |
| Pin 24 | RB5 β Bidirectional I/O, Port B bit 5 |
| Pin 25 | RB6 β Bidirectional I/O, Port B bit 6 |
| Pin 26 | RB7 β Bidirectional I/O, Port B bit 7 |
| Pin 27 | RA5/SS β Bidirectional I/O / Optional slave select |
| Pin 28 | RA6 β Bidirectional I/O, Port A bit 6 |
Typical Applications
PIC16C55A-40/SS is suitable for 6 applications: Remote Control and IR Transmitter, Small Appliance Controller (Toaster, Coffee Maker), Security Keypad and Access Controller, LED Chaser and Decorative Lighting Controller, Sensor Signal Conditioning and Threshold Detector, Battery-Operated Toys and Hobby Electronics.
Remote Control and IR Transmitter
The PIC16C55A-40/SS is well-suited for infrared remote control transmitters because its 20 I/O pins can drive a 4x4 keypad matrix plus an IR LED via PWM or simple bit-banging, while 768 bytes of OTP memory is sufficient for fixed RC5, NEC, or SIRC protocol code. The 40 MHz clock supports high carrier frequencies (e.g., 38 kHz or 56 kHz) without external divider hardware. The SSOP-28 footprint keeps the transmitter PCB small and low-cost. Because the code is OTP, the part is ideal for shipping production where firmware is locked - field returns cannot have firmware tampered with.
Recommended
Small Appliance Controller (Toaster, Coffee Maker)
The PIC16C55A-40/SS can act as the main controller in toasters, coffee machines, blenders, and similar small appliances, where its 20 I/O pins drive relays, triacs, key switches, and seven-segment LED displays. The 24 bytes of RAM is adequate for simple state machines (idle, heating, timing, done), and the 768 bytes of OTP code holds the appliance menu logic plus timing profiles. Commercial temperature grade (0C to +70C) covers kitchen environments, and the SSOP-28 footprint supports automated SMT assembly. OTP programming prevents warranty-fraud firmware modifications.
Recommended
Security Keypad and Access Controller
For PIN-code keypads and simple access control panels, the PIC16C55A-40/SS scans a 4x4 matrix keypad (16 keys), drives a status LED or beeper, and optionally interfaces with an electric strike via one of the GPIO outputs. The 768 bytes of OTP memory holds the comparison logic and lockout timers; 24 bytes of RAM tracks entry state. Because code is OTP, the master access code cannot be extracted via reprogramming - attackers cannot dump the firmware. SSOP-28 keeps the keypad PCB compact.
Recommended
LED Chaser and Decorative Lighting Controller
The PIC16C55A-40/SS can sequence multiple LED strings for decorative lighting, holiday lights, and signage, using up to 20 GPIO pins to drive LED strings directly (with transistors) or to control addressable LED driver chips (e.g., WS2811). The 40 MHz clock supports fast pattern updates without visible flicker. OTP memory locks the lighting sequence for production, preventing unauthorized modifications in commercial installations.
Recommended
Sensor Signal Conditioning and Threshold Detector
The PIC16C55A-40/SS can read analog sensors (via external ADC or comparator), apply threshold logic, and drive relays or displays in industrial sensor-conditioning modules. The 20 I/O pins allow multiple sensor inputs and isolated outputs. Because the part is OTP, calibration constants and threshold tables are locked into firmware, eliminating the risk of field tampering with calibration. The SSOP-28 footprint is industrial-standard for DIN-rail mount modules.
Recommended
Battery-Operated Toys and Hobby Electronics
The PIC16C55A-40/SS can drive simple motorized toys, sound effects, and hobby projects where the BOM cost dominates. With 20 I/O pins, it can control two DC motors (via H-bridge), sound chips, and LED indicators. The 768-byte code memory holds motion profiles and sound triggers. OTP programming protects the toy designer's intellectual property from being cloned easily, and the SSOP-28 footprint supports automated assembly for volume production.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55A-40/SS β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55A-04/SS | PIC16C55A-20/SS | PIC16F54-I/SS | PIC16C554-04/SS |
|---|---|---|---|---|---|
| Package | SSOP-28 | SSOP-28 (same) | SSOP-28 (same) | SSOP-28 (same) | SSOP-28 (same) |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 768 bytes OTP | 768 bytes OTP (same) | 768 bytes OTP (same) | 768 bytes Flash | 896 bytes OTP |
| Max Clock Frequency | 40 MHz | 4 MHz | 20 MHz | 20 MHz | 4 MHz |
| RAM | 24 bytes | 24 bytes (same) | 24 bytes (same) | 25 bytes | 80 bytes |
| Memory Programmability | OTP (one-time) | OTP (same) | OTP (same) | Flash (reprogrammable) | OTP (one-time) |
| I/O Pins | 20 | 20 (same) | 20 (same) | 12 | 13 |
| Lifecycle Status | NRND | NRND | NRND | Active | NRND |
Key Differentiators
- Highest clock speed in PIC16C55A SSOP-28 family (vs PIC16C55A-04/SS)
- 20 I/O pins vs 12 on PIC16F54 (vs PIC16F54-I/SS)
- OTP locks firmware against cloning and warranty fraud (vs PIC16F54-I/SS)
- Smaller code size vs PIC16C554 (vs PIC16C554-04/SS)
Design Notes
The PIC16C55A-40/SS uses OTP EPROM, not Flash - once programmed, the firmware cannot be changed. Prototype builds should use the PIC16F54-I/SS (Flash, same SSOP-28 footprint) for iteration cycles, then move to PIC16C55A-40/SS for production lock-down. Do not rely on Microchip to relaunch the OTP line if supply is disrupted.
The SSOP-28 footprint has 0.65 mm pitch leads - keep solder paste stencil apertures between 0.3-0.4 mm wide for reliable reflow. Place a 100 nF decoupling capacitor within 5 mm of the VDD pin (pin 1) and a 10 uF bulk capacitor on the supply rail. The MCLR/VPP pin (pin 4) requires a 10 kohm pull-up to VDD for normal operation; during ICSP programming, this pin receives the high-voltage programming pulse.
The internal RC oscillator on PIC16C55A is calibrated at programming time and varies with VDD and temperature. For timing-critical applications (UART, IR carrier generation), use an external crystal or resonator on OSC1/OSC2 (pins 15, 16). The 4-clock-per-instruction cycle means effective throughput is Fosc/4 - at 40 MHz the CPU executes 10 MIPS.
Compliance Information
RoHS compliant per Microchip product page. Not AEC-Q100 qualified - choose PIC16C55A-20I/SS (industrial) or AEC-Q100-qualified PIC variants for automotive. NRND lifecycle per Microchip product page.
