PIC16C55A-04/SO - 8-Bit 4MHz OTP MCU 768B | Microchip | SOIC-28
MPN: PIC16C55A-04/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.45 | $2.45 |
| 10 | $2.2 | $22.00 |
| 100 | $1.95 | $195.00 |
| 500 | $1.72 | $860.00 |
| 1,000 | $1.48 | $1,480.00 |
PIC16C55A-04/SO Overview
An 8-bit microcontroller (MCU) is a single-chip computer integrating a CPU, RAM, program memory (ROM/EPROM/Flash/OTP), and peripherals such as I/O ports, timers, and communication interfaces on one die. Within the broader power management and embedded hierarchy, MCUs sit alongside DSPs, FPGAs, and microprocessors as programmable logic devices. The PIC16C5x family occupies the low-cost, high-performance niche for cost-sensitive appliance, automotive accessory, and industrial sensor applications.
Key features of the PIC16C55A-04/SO include 20 digital I/O pins, a 12-bit instruction word with 8-bit data path, an operating voltage range of 3.0V to 6.25V, and CMOS fully-static design that allows clock rates down to DC for low-power standby. The 4 MHz version (the "/04" suffix) targets applications where 1 microsecond instruction execution is sufficient. It supports in-circuit serial programming via Microchip's legacy tools and provides power-on reset and watchdog timer functionality in the baseline PIC16C5x feature set.
Architecturally, the PIC16C55A uses a Harvard memory layout with separate program and data buses, a 2-level hardware stack, and direct/indirect addressing modes. The device is fabricated on a CMOS process optimized for low quiescent current, and its 4 MHz speed grade is the most common production variant. According to Microchip's documentation, the PIC16C5x series is the foundation on which later PIC16 and PIC18 architectures were developed.
Typical applications include appliance control boards, LED display drivers, simple sensor interfaces, remote controls, and low-cost industrial timers. Its wide 3.0V-6.25V supply range also makes it compatible with legacy 5V logic designs and unregulated supplies in cost-optimized products.
When designing with this part, note that the OTP memory cannot be erased - code must be verified before programming. Engineers should reserve engineering samples for development and use windowed ceramic or Flash-based PIC16F parts during prototyping before locking in the OTP variant for production.
This page synthesizes distributor pricing, same-family drop-in alternatives, and practical design notes not found in the standalone manufacturer datasheet, including guidance on migrating from the C variant to the lower-cost F (Flash) versions.
Drop-in alternatives for PIC16C55A-04/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 PIC16C55A-04/SO (same form factor and footprint) — differing in Program Memory Size, Core Architecture, Instruction Set, Program Memory Type, Operating Temperature Range.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55A-04I/SO
✅ Drop-In✓ In Stock
$2.05 / Unit
View Datasheet →PIC16C55A-04E/SO
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
PIC16C558-04/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 →PIC16F54-I/SO
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
PIC16C554-04/SO
✅ Drop-In✓ In Stock
$1.62 / Unit
View Datasheet →PIC16C55A-04/SO Maximum Ratings & Electrical Characteristics
| Series | PIC16C5x |
| Core Processor | PIC |
| Core Size | 8-Bit |
| Maximum Clock Speed | 4 MHz |
| Program Memory Size | 768 B (512 x 12) |
| Program Memory Type | OTP (One-Time-Programmable) |
| RAM Size | 24 B |
| Number of I/O | 20 |
| Supply Voltage Range | 3.0 V to 6.25 V |
| Operating Temperature Range | -40C to +85C (commercial SO) |
| Package / Case | 28-SOIC (7.50 mm wide) |
| Mounting Type | Surface Mount |
| Oscillator Type | External |
| ROM Type | OTP EPROM |
| Instruction Set | 33 single-word/single-cycle instructions |
| RoHS Status | Compliant |
| Lead-Free | Yes |
PIC16C55A-04/SO Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O port A bit 2 |
| Pin 2 | RA3 — Bidirectional I/O port A bit 3 |
| Pin 3 | RTCC — Real-Time Clock/Counter external input |
| Pin 4 | /MCLR — Master Clear (active-low reset) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0 — Bidirectional I/O port B bit 0 |
| Pin 7 | RB1 — Bidirectional I/O port B bit 1 |
| Pin 8 | RB2 — Bidirectional I/O port B bit 2 |
| Pin 9 | RB3 — Bidirectional I/O port B bit 3 |
| Pin 10 | RB4 — Bidirectional I/O port B bit 4 |
| Pin 11 | RB5 — Bidirectional I/O port B bit 5 |
| Pin 12 | RB6 — Bidirectional I/O port B bit 6 |
| Pin 13 | RB7 — Bidirectional I/O port B bit 7 |
| Pin 14 | VDD — Positive supply voltage |
| Pin 15 | OSC2 — Oscillator crystal output |
| Pin 16 | OSC1 — Oscillator crystal input / external clock |
| Pin 17 | RC0 — Bidirectional I/O port C bit 0 |
| Pin 18 | RC1 — Bidirectional I/O port C bit 1 |
| Pin 19 | RC2 — Bidirectional I/O port C bit 2 |
| Pin 20 | RC3 — Bidirectional I/O port C bit 3 |
| Pin 21 | RC4 — Bidirectional I/O port C bit 4 |
| Pin 22 | RC5 — Bidirectional I/O port C bit 5 |
| Pin 23 | RC6 — Bidirectional I/O port C bit 6 |
| Pin 24 | RC7 — Bidirectional I/O port C bit 7 |
| Pin 25 | RA0 — Bidirectional I/O port A bit 0 |
| Pin 26 | RA1 — Bidirectional I/O port A bit 1 |
| Pin 27 | VDD — Positive supply voltage (second pin) |
| Pin 28 | VSS — Ground reference (second pin) |
Typical Applications
PIC16C55A-04/SO is suitable for 6 applications: Appliance Control Boards, LED Display Drivers, Remote Control Transmitters, Industrial Timers and Counters, Sensor Interface Front-Ends, Automotive Accessory Modules.
Appliance Control Boards
The PIC16C55A-04/SO suits low-cost appliance controllers such as microwave ovens, washing machines, and toaster timers because its 20 I/O pins can drive 7-segment displays, keypads, and triac-based load switches. With 768 bytes of OTP program memory, the device holds a typical appliance state machine plus timer logic without external storage. Its 3.0V-6.25V supply range tolerates the unregulated rails common in white goods, and the 33-instruction RISC set simplifies field service for production volumes in the millions.
Recommended
LED Display Drivers
The PIC16C55A-04/SO drives multiplexed 7-segment or dot-matrix LED displays using its 20 I/O pins to scan rows and columns directly, eliminating the need for an external LED driver in small signage. At 4 MHz each instruction cycle is 1 microsecond, sufficient to refresh an 8-digit display at 60 Hz without flicker. The wide 3.0V-6.25V supply range lets it run directly from rectified mains or USB 5V rails, and the OTP memory ensures the firmware pattern is locked once the LED sequence is finalized.
Recommended
Remote Control Transmitters
The PIC16C55A-04/SO serves as the encoder MCU in IR/RF remote controls, using its 20 I/O pins for a keypad matrix and the carrier generator for the transmit LED or RF stage. The 4 MHz instruction rate generates accurate carrier frequencies for RC5, NEC, and SIRC protocols without external timing components. Its low cost at OTP volume pricing makes it economical for disposable universal remotes, and the CMOS design minimizes standby current for battery-powered operation.
Recommended
Industrial Timers and Counters
The PIC16C55A-04/SO fits compact industrial timer and event-counter modules where its 768B OTP holds a fixed delay schedule and its 20 I/O lines interface to relay drivers and sensor inputs. The 4 MHz clock provides millisecond resolution for typical PLC-style timing, and the 33 single-cycle instructions ensure deterministic response to external interrupts. Mounting in SOIC-28 supports conformal-coated industrial environments where DIP parts would be impractical.
Recommended
Sensor Interface Front-Ends
The PIC16C55A-04/SO conditions digital sensors such as Hall-effect switches, encoders, and simple switches, generating control signals for downstream systems. With 20 I/O pins it can read multiple sensor channels simultaneously and arbitrate priority logic in firmware. The 768B OTP program memory holds encoder-decoding routines, debounce filters, and fault-detection code. The wide supply tolerance lets it operate from 5V industrial rails or battery-backed 3.3V supplies without additional regulation.
Recommended
Automotive Accessory Modules
The PIC16C55A-04/SO appears in non-safety automotive accessories such as interior lighting controllers, seat-position memory modules, and aftermarket gauge drivers. Its 20 I/O pins can drive LED indicators and read switch matrices, while the OTP memory holds the fixed personality of each vehicle trim. The 3.0V-6.25V supply tolerance accommodates 12V battery transients when paired with external regulation, and the part's automotive-grade variants extend temperature coverage. For safety-critical functions, migrate to AEC-Q100-qualified PIC16F or PIC18 families.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55A-04/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55A-04I/SO | PIC16C558-04/SO | PIC16C55-10/SO | PIC16F54-I/SO |
|---|---|---|---|---|---|
| Package | SOIC-28 | SOIC-28 - same | SOIC-28 - same | SOIC-28 - same | SOIC-28 - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Core / Architecture | PIC16C5x 8-bit RISC | PIC16C5x 8-bit RISC | PIC16C5x 8-bit RISC (enhanced) | PIC16C5x 8-bit RISC | PIC16F5x 8-bit RISC (Flash) |
| Maximum Clock Speed | 4 MHz | 4 MHz | 4 MHz | 10 MHz | 20 MHz |
| Program Memory Size | 768 B (512 x 12) OTP | 768 B OTP | 768 B OTP | 768 B OTP | 512 B Flash |
| Program Memory Type | OTP | OTP | OTP | OTP | Flash (re-programmable) |
| Supply Voltage Range | 3.0V to 6.25V | 3.0V to 6.25V | 3.0V to 6.25V | 3.0V to 6.25V | 2.0V to 5.5V |
| Operating Temperature | 0C to +70C (commercial) | -40C to +85C (industrial) | 0C to +70C (commercial) | 0C to +70C (commercial) | -40C to +85C (industrial) |
| Lifecycle Status | NRND | NRND | Active | Active | Active |
Key Differentiators
- Industrial temperature drop-in replacement within the PIC16C5x family (vs PIC16C55A-04I/SO)
- Enhanced C5x with comparator and additional interrupts, same footprint (vs PIC16C558-04/SO)
- Speed-grade upgrade path within the same footprint (vs PIC16C55-10/SO)
- Migration to Flash memory for new designs (vs PIC16F54-I/SO)
Design Notes
Estimated: The PIC16C55A uses OTP memory - once a cell is programmed it cannot be erased. Always verify code on a windowed ceramic or Flash equivalent (PIC16F54, PIC16F57) before committing to the OTP PIC16C55A. Reserve engineering samples of the OTP part for final production lock-in only, and use the Flash variant (PIC16F54-I/SO) during prototyping to allow iterative code development. Also note that the PIC16C5x core uses a 12-bit instruction word - be aware that the smaller program memory address space limits algorithm complexity.
Estimated: For designs drawing power from unregulated rails, add a 100 nF decoupling capacitor between VDD (pin 14 or 27) and VSS (pin 5 or 28), placed as close to the package as possible. The PIC16C55A's 3.0V-6.25V supply tolerance accommodates some ripple, but the VDD pin should remain above 3.0V during all operating conditions to avoid brown-out reset events. If long wire runs to VDD are unavoidable, add a 10 uF bulk capacitor near the IC.
Estimated: For oscillator stability with a crystal oscillator or ceramic resonator on OSC1 (pin 16) and OSC2 (pin 15), keep the oscillator traces short and surround them with a ground guard ring. Capacitive loading above the specified load capacitance degrades frequency accuracy. For RC oscillator configurations, place the timing resistor and capacitor close to the OSC1 pin and route the OSC2 pin to a quiet ground. I/O traces should be routed to minimize crosstalk with the oscillator section.
Compliance Information
RoHS compliance confirmed by Microchip product page. The PIC16C55A family is not AEC-Q100 qualified; for automotive safety applications migrate to AEC-Q100-qualified PIC16F or PIC18 family members.
