PIC16C55AT-04/SO - 8-Bit 4MHz OTP MCU 768B | Microchip
MPN: PIC16C55AT-04/SO β End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.11 | $1.11 |
| 10 | $1.05 | $10.50 |
| 100 | $0.95 | $95.00 |
| 500 | $0.86 | $430.00 |
| 1,000 | $0.79 | $790.00 |
PIC16C55AT-04/SO Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, program memory, data RAM, and I/O peripherals on a single silicon die. The PIC16C5X family uses a 12-bit-wide instruction word with a RISC (Reduced Instruction Set Computer) architecture that delivers roughly 2:1 code compression versus other 8-bit MCUs in its class, enabling simpler firmware development. Within the broader taxonomy, this part is a microcontroller (MCU) -> embedded controller -> semiconductor device, designed for cost-sensitive embedded control where deterministic instruction timing and minimal external components are priorities.
Key features of the PIC16C55AT-04/SO include a 4 MHz internal/external clock input, 33 single-word instructions, a two-level hardware stack, 20 bidirectional I/O pins organized into three ports (RA, RB, RC), and a programmable Watchdog Timer (WDT) with on-chip RC oscillator. The OTP program memory is programmed once via Microchip's standard ICSP-compatible serial programming interface. Power consumption is typically 2 mA at 5V/4 MHz, with sleep/idle current under typical CMOS standby levels.
The device is built on a baseline PIC architecture using static CMOS logic, meaning the clock can be stopped without losing internal register state - useful for power-saving designs. It supports interrupt-driven control via the global interrupt enable and individual peripheral flags, and includes a Power-on Reset (POR), power-up Timer (PWRT), and Oscillator Start-up Timer (OST) for reliable cold-start behavior without external reset circuitry.
Typical applications include appliance control, automotive body electronics (non-safety), LED display drivers, simple sensor interfaces, and remote transmitters/receivers. The wide SOIC-28 footprint is suitable for hand-soldered prototypes as well as high-volume SMT production lines.
When designing with the PIC16C55AT-04/SO, note that OTP memory cannot be erased or reprogrammed - firmware bugs require physical part replacement. Engineers targeting field updates should consider the flash-based PIC16F5X family instead. The /SO suffix indicates the SOIC-28 wide-body tape-and-reel packaging for SMT assembly.
This page synthesizes distributor pricing, drop-in alternatives, comparison data, and practical design notes not found in the manufacturer datasheet, helping engineers source and integrate this legacy OTP MCU efficiently.
Drop-in alternatives for PIC16C55AT-04/SO 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 PIC16C55AT-04/SO (same form factor and footprint) β differing in Core Architecture, Package, Program Memory Size, Program Memory Type, Watchdog Timer.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
PIC16C55AT-04I/SO
β Drop-Inπ Reference alternative (not in catalog)
PIC16C55A-04/SO
β Drop-Inβ In Stock
$1.48 / Unit
View Datasheet βPIC16C54A-04/SO
β Drop-Inβ In Stock
$1.4 / Unit
View Datasheet βPIC16F54-I/SO
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
PIC16C554T-04/SO
β Drop-Inβ In Stock
$1.15 / Unit
View Datasheet βPIC16C558-04/SO
β Drop-Inπ Reference alternative (not in catalog)
PIC16C55AT-04/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit RISC PIC16C5X |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 768 B (512 x 12 words) |
| RAM | 24 B |
| Maximum Clock Frequency | 4 MHz |
| Instruction Set | 33 single-word instructions, 12-bit opcode |
| Number of I/O Pins | 20 |
| Supply Voltage | 5 V (nominal) |
| Package | 28-pin SOIC wide-body (7.50 mm) |
| Mounting Type | Surface Mount |
| Operating Temperature | 0C to +70C (commercial) |
| Watchdog Timer | Yes (software-enabled) |
| Hardware Stack | 2 levels |
| Power-on Reset / PWRT / OST | Yes (built-in) |
| MSL Level | 1 (per JEDEC J-STD-020) |
PIC16C55AT-04/SO 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 / RA4 |
| Pin 4 | MCLR β Master Clear (reset) input, active low |
| Pin 5 | VSS β Ground reference |
| Pin 6 | OSC1/CLKIN β Oscillator input / external clock input |
| Pin 7 | OSC2/CLKOUT β Oscillator output / clock output |
| 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 β Bidirectional I/O, Port C bit 3 |
| Pin 12 | RC4 β Bidirectional I/O, Port C bit 4 |
| Pin 13 | RC5 β Bidirectional I/O, Port C bit 5 |
| Pin 14 | RC6 β Bidirectional I/O, Port C bit 6 |
| Pin 15 | RC7 β Bidirectional I/O, Port C bit 7 |
| Pin 16 | RB0/INT β Bidirectional I/O, Port B bit 0 / external interrupt |
| Pin 17 | RB1 β Bidirectional I/O, Port B bit 1 |
| Pin 18 | RB2 β Bidirectional I/O, Port B bit 2 |
| Pin 19 | RB3 β Bidirectional I/O, Port B bit 3 |
| Pin 20 | RB4 β Bidirectional I/O, Port B bit 4 |
| Pin 21 | RB5 β Bidirectional I/O, Port B bit 5 |
| Pin 22 | RB6 β Bidirectional I/O, Port B bit 6 |
| Pin 23 | RB7 β Bidirectional I/O, Port B bit 7 |
| Pin 24 | VDD β Positive supply voltage (+5V) |
| Pin 25 | RA0 β Bidirectional I/O, Port A bit 0 |
| Pin 26 | RA1 β Bidirectional I/O, Port A bit 1 |
| Pin 27 | NC β Not connected (per datasheet) |
| Pin 28 | NC β Not connected (per datasheet) |
Typical Applications
PIC16C55AT-04/SO is suitable for 6 applications: Appliance Control Panels, LED Display Drivers, Remote Control Transmitters, Automotive Body Electronics (Non-Safety), Industrial Sensor Interfaces, Toy and Hobby Electronics.
Appliance Control Panels
The PIC16C55AT-04/SO is well suited to appliance control panels such as washing machines, microwave ovens, and small kitchen devices where 20 I/O pins are sufficient for keypad scanning, LED/LCD segment driving, and relay or triac control. Its 768B OTP program memory is enough to encode state-machine-based control firmware, and its 4 MHz execution provides adequate response time for user-interface debouncing, motor sequencing, and timer-based cycles. The SOIC-28 wide-body footprint supports both hand-prototype assembly and high-volume SMT lines typical of consumer appliance manufacturing.
Recommended
LED Display Drivers
The PIC16C55AT-04/SO can directly drive multiplexed 7-segment LED displays using its 20 I/O pins, each capable of 25 mA source/sink per the Microchip datasheet. By mapping segment and digit lines to ports RA/RB/RC and time-multiplexing in firmware, the MCU can refresh 4-6 digit displays without external driver ICs, reducing BOM cost in digital clocks, counters, and simple instrumentation. The 4 MHz instruction rate easily sustains 100+ Hz multiplex refresh to avoid visible flicker.
Recommended
Remote Control Transmitters
Battery-powered remote controls benefit from the PIC16C55AT-04/SO's low sleep current, 4 MHz execution speed, and small SOIC-28 footprint. Firmware generates IR or RF carrier modulation via timer-driven port toggling, while the Watchdog Timer with on-chip RC oscillator wakes the MCU periodically to check inputs. The static CMOS core allows the system clock to be stopped between user events to extend battery life to multi-year levels in intermittent-use applications.
Recommended
Automotive Body Electronics (Non-Safety)
Within non-safety body electronics such as interior lighting controllers, seat-position memory modules, or HVAC damper actuators, the PIC16C55AT-04/SO provides the I/O count and deterministic timing needed for relay and stepper-motor sequencing. The industrial-temperature variant PIC16C55AT-04I/SO supports -40C to +85C cabin environments. Although automotive safety-critical functions now require newer parts, legacy 12V body modules continue to use this PIC16C5X family due to long-term firmware stability and supply-chain maturity.
Recommended
Industrial Sensor Interfaces
Industrial sensor-interface boards with discrete digital inputs/outputs - such as limit-switch aggregators, simple counters, or contact-debounce modules - can use the PIC16C55AT-04/SO as a low-cost protocol converter or local aggregator. With 20 I/O pins, 24 bytes RAM, and a built-in Watchdog Timer for fault recovery, the part handles sensor polling, contact debouncing, and relay sequencing. The SOIC-28 package is industrial-friendly for hand rework on legacy DIN-rail equipment.
Recommended
Toy and Hobby Electronics
Cost-sensitive toy and hobby products - including model train controllers, electronic dice, sound-effect generators, and educational kits - leverage the PIC16C55AT-04/SO's low unit cost, simple RISC core, and 20 I/O pins for motor, LED, and speaker control. The OTP memory secures production firmware against easy duplication. With 33 single-word instructions, beginner firmware developers can quickly master the architecture and bring up working prototypes within a few days.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55AT-04/SO β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55AT-04I/SO | PIC16C55A-04/SO | PIC16F54-I/SO | PIC16C554T-04/SO |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | SOIC-28 (7.50 mm) | SOIC-28 (7.50 mm) - same | SOIC-28 (7.50 mm) - same | SOIC-28 (7.50 mm) - same | SOIC-28 (7.50 mm) - same |
| Program Memory | 768 B OTP | 768 B OTP | 768 B OTP | 768 B Flash | 768 B OTP |
| Memory Type | OTP (one-time programmable) | OTP | OTP | Flash (reprogrammable) | OTP |
| Maximum Clock Frequency | 4 MHz | 4 MHz | 4 MHz | 20 MHz (F-version) | 4 MHz |
| I/O Pins | 20 | 20 | 20 | 12 | 20 |
| UART/USART | No | No | No | No | Yes (SCI/UART) |
| Temperature Range | 0C to +70C (commercial) | -40C to +85C (industrial) | 0C to +70C (commercial) | -40C to +85C (industrial) | 0C to +70C (commercial) |
Key Differentiators
- Wide SOIC-28 footprint with 20 I/O pins (vs PIC16C54A-04/SO)
- Industrial temperature variant available in same package (vs PIC16F54-I/SO)
- Direct flash replacement available from same vendor (vs PIC16C554T-04/SO)
Design Notes
The PIC16C55AT-04/SO uses OTP EPROM technology - once programmed, firmware cannot be erased or reprogrammed. A firmware bug in production means scrapping all programmed devices. For prototypes and any design where iteration is expected, use the flash-based PIC16F54-I/SO in the same SOIC-28 footprint for development, then port the final code to PIC16C55AT-04/SO only for locked production. Always program at least 5-10% extra devices for engineering samples and rework.
The PIC16C55AT-04/SO requires a clean 5V supply (4.5V to 5.5V). Place a 0.1uF decoupling capacitor as close as possible to the VDD pin (pin 24) and a bulk capacitor (10uF or larger) at the board-level supply entry. The MCLR reset pin (pin 4) should be pulled up to VDD through a 10k resistor with a 0.1uF capacitor to ground for noise immunity - this RC network prevents false resets in electrically noisy environments such as motor-control applications.
The SOIC-28 wide-body (7.50 mm) package requires standard SMT land patterns per IPC-7351. Ensure each I/O pin trace can handle up to 25 mA source/sink current; use at least 0.2 mm trace width for low-current signals and 0.4 mm or wider for LED or relay drive lines. Place the oscillator crystal or resonator (typically 4 MHz) within 10 mm of pins 6-7 (OSC1/OSC2), and keep oscillator traces short and surrounded by a ground pour to reduce EMI susceptibility.
Compliance Information
RoHS, REACH, lead-free, halogen-free, and conflict-mineral statuses were NOT present in the verified web data and are marked as 'unknown'. Engineers should confirm compliance directly with Microchip before volume procurement. AEC-Q100 is not_applicable because this part is not marketed as automotive-qualified.
