PIC16C55A-04I/P - 4MHz 8-Bit OTP MCU, 768B, 28-PDIP | Microchip
MPN: PIC16C55A-04I/P ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.45 | $2.45 |
| 10 | $2.18 | $21.80 |
| 100 | $1.92 | $192.00 |
| 500 | $1.71 | $855.00 |
| 1,000 | $1.52 | $1,520.00 |
PIC16C55A-04I/P Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, RAM, non-volatile program memory, and peripheral I/O on one die. In the component taxonomy, an MCU belongs to the broader class of microcontrollers -> embedded processors -> digital ICs -> semiconductors. The PIC16C5x family pioneered Microchip's RISC architecture for low-cost, high-volume embedded control, and it is the direct ancestor of today's PIC16 and PIC18 families.
Key features of the PIC16C55A-04I/P include 33 single-word single-cycle RISC instructions providing 2:1 code compression over CISC 8-bit MCUs of its era, a two-level deep hardware stack, an 8-bit real-time counter (TMR0) with an 8-bit programmable prescaler, direct/indirect/relative addressing, and seven or eight special function hardware registers. The OTP program memory allows one-time factory or field programming, making the part well suited to mature production runs where firmware is fixed.
Architecturally, the device uses a Harvard-style separated program/data bus, 12-bit instruction width, and CMOS process technology for low power. It runs from a single 3.0V to 6.25V supply (commercial/industrial variants) at up to 4 MHz, producing 1 MIPS throughput. The 8-bit data path with 12-bit opcodes yields compact code density that fits easily within the 512-word OTP space.
Typical applications include appliance controls, low-end consumer products, simple sensor interfaces, battery chargers, LED drivers, and industrial timers where a small, inexpensive, deterministic 8-bit core is preferred over a 16-/32-bit MCU. The industrial temperature grade extends deployment into factory and outdoor equipment.
When designing with this part, choose an external 4 MHz crystal or resonator for clock accuracy, drive MCLR with a proper reset circuit, and reserve RA0-RA3 digital I/O pins carefully because some packages multiplex analog functions onto them. The OTP memory cannot be erased, so use a PIC16F55 flash equivalent for prototyping.
Drop-in alternatives for PIC16C55A-04I/P — 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-04I/P (same form factor and footprint) — differing in Program Memory Size, Timers, Mounting Type, Program Memory Type, Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55A-04/P
✅ Drop-In✓ In Stock
$2.18 / Unit
View Datasheet →PIC16C55A-04E/P
✅ Drop-In✓ In Stock
$3.15 / Unit
View Datasheet →PIC16C55-10I/P
✅ Drop-In✓ In Stock
$2.58 / Unit
View Datasheet →PIC16C55A-04I/SO
✅ Drop-In✓ In Stock
$2.05 / Unit
View Datasheet →PIC16C55A-04I/P Maximum Ratings & Electrical Characteristics
| Core | PIC16C5x 8-bit RISC |
| Data Bus Width | 8-bit |
| Instruction Width | 12-bit |
| Max Clock Frequency | 4 MHz |
| Program Memory Size | 768 B (512 x 12 OTP) |
| Program Memory Type | OTP (One-Time Programmable) |
| RAM Size | 24 B |
| Number of I/O Pins | 20 |
| Timers | 1 x 8-bit (TMR0) with prescaler |
| Stack Depth | 2 levels (hardware) |
| Supply Voltage (Vdd) | 3.0 V to 6.25 V |
| Operating Temperature | -40 C to +85 C (Industrial) |
| Package / Case | 28-DIP (0.600 in / 15.24 mm) |
| Mounting Type | Through-Hole |
| RoHS Status | Compliant |
PIC16C55A-04I/P Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O port A bit 2 |
| Pin 2 | RA3 — Bidirectional I/O port A bit 3 |
| Pin 3 | RA4/T0CKI — Bidirectional I/O port A bit 4 / TMR0 clock input |
| Pin 4 | MCLR/Vpp — Master Clear reset input / programming voltage |
| Pin 5 | Vss — Ground reference |
| Pin 6 | OSC1/CLKIN — Crystal oscillator input / external clock input |
| Pin 7 | OSC2/CLKOUT — Crystal oscillator output / clock output |
| Pin 8 | RB0 — Bidirectional I/O port B bit 0 |
| Pin 9 | RB1 — Bidirectional I/O port B bit 1 |
| Pin 10 | RB2 — Bidirectional I/O port B bit 2 |
| Pin 11 | RB3 — Bidirectional I/O port B bit 3 |
| Pin 12 | RB4 — Bidirectional I/O port B bit 4 |
| Pin 13 | RB5 — Bidirectional I/O port B bit 5 |
| Pin 14 | RB6 — Bidirectional I/O port B bit 6 |
| Pin 15 | RB7 — Bidirectional I/O port B bit 7 |
| Pin 16 | RC0 — Bidirectional I/O port C bit 0 |
| Pin 17 | RC1 — Bidirectional I/O port C bit 1 |
| Pin 18 | RC2 — Bidirectional I/O port C bit 2 |
| Pin 19 | RC3 — Bidirectional I/O port C bit 3 |
| Pin 20 | RC4 — Bidirectional I/O port C bit 4 |
| Pin 21 | RC5 — Bidirectional I/O port C bit 5 |
| Pin 22 | RC6 — Bidirectional I/O port C bit 6 |
| Pin 23 | RC7 — Bidirectional I/O port C bit 7 |
| Pin 24 | RD0 — Bidirectional I/O port D bit 0 |
| Pin 25 | RD1 — Bidirectional I/O port D bit 1 |
| Pin 26 | RD2 — Bidirectional I/O port D bit 2 |
| Pin 27 | RD3 — Bidirectional I/O port D bit 3 |
| Pin 28 | Vdd — Positive supply voltage |
Typical Applications
PIC16C55A-04I/P is suitable for 6 applications: Appliance Control Board, Battery Charger Control, Industrial Timer / Sequencer, LED Lighting Controller, Simple Sensor Interface Module, Consumer Remote Control.
Appliance Control Board
The PIC16C55A-04I/P suits low-cost appliance controllers such as microwave oven keypads, washing-machine cycle timers, and coffee-maker user interfaces. Its 4 MHz RISC core delivers deterministic 1 MIPS throughput, allowing real-time control of relays, triacs, and seven-segment LED or LCD displays without an RTOS. The 768-byte OTP program memory fits typical appliance firmware (state machines, button debouncing, buzzer patterns) while keeping unit cost under $2.50. Industrial -40C to +85C temperature grade supports refrigerator and dishwasher compartments. MCLR, TMR0, and 20 I/O pins enable direct drive of matrix keypads and indicator LEDs with minimal external logic, reducing BOM cost and PCB area.
Recommended
Battery Charger Control
The PIC16C55A-04I/P is well-matched to lead-acid or NiMH charger controllers in the 1A-5A range. TMR0 with programmable prescaler provides accurate charge-time and -dT/dt termination timing, while the 20 I/O pins drive MOSFET gate drivers, status LEDs, and temperature-sensor inputs. The 3.0V-6.25V supply range allows direct connection to a 6V or 12V battery rail through a small linear regulator. OTP program memory locks the charging algorithm at production time, preventing field firmware drift in safety-critical applications. Low power consumption and the industrial temperature range support unattended battery-backed installations and outdoor solar charger enclosures.
Recommended
Industrial Timer / Sequencer
Factory-floor timer and sequencer modules benefit from the PIC16C55A-04I/P's deterministic 8-bit core and rugged PDIP package. The device can scan 4x4 matrix keypads, drive 7-segment displays via discrete transistors, and sequence up to eight relay outputs through optical isolation. The -40C to +85C industrial temperature grade handles unheated cabinets and outdoor enclosures. OTP memory is ideal for fixed-cycle production equipment where firmware is finalized and never updated. PIC16C5x instruction-set compatibility means hundreds of legacy timer/sequencer designs can be re-implemented without retraining.
Recommended
LED Lighting Controller
Decorative and architectural LED controllers use the PIC16C55A-04I/P to generate PWM dimming, chase patterns, and color-mixing sequences across RGB LED strings. The 8-bit TMR0 with prescaler creates accurate PWM frequencies above 100 Hz to avoid visible flicker, and 20 I/O pins multiplex dozens of LED channels through constant-current drivers like the WS2801 or TLC5940. OTP memory locks lighting patterns at production - perfect for fixed-scene installations in retail, signage, and stage lighting. Low cost and industrial temperature range suit 24/7 commercial installations.
Recommended
Simple Sensor Interface Module
Sensor-interface modules for HVAC, environmental monitoring, and industrial gauges use the PIC16C55A-04I/P to read analog signals via external ADC, apply linearization or thresholding, and drive 4-20 mA or RS-232 outputs. The small 24-byte RAM and 768-byte OTP are sufficient for lookup-table calibration of thermistor, RTD, or load-cell signals. Wide supply range (3.0-6.25V) supports both 3.3V and 5V sensor buses, and the industrial temperature grade covers outdoor installations. OTP prevents accidental field modification that could shift calibrated outputs.
Recommended
Consumer Remote Control
Universal remote controls, garage-door openers, and toy controllers use the PIC16C55A-04I/P for low-cost IR or RF transmission with matrix-scanned keypads. TMR0 generates accurate carrier frequencies (38 kHz IR, 315/433 MHz RF) and protocol bit-timings, while the 20 I/O pins directly drive keypad rows/columns and transmitter-enable lines. OTP memory locks the protocol decoder at production, preventing user modification. The 4 MHz clock is sufficient for all common IR (RC5, NEC, SIRC) and simple RF encoders without jitter issues, and the PDIP package simplifies hand-soldering during small-batch production.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55A-04I/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55A-04/P | PIC16C55A-04E/P | PIC16C55-10I/P |
|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-PDIP | 28-PDIP - same | 28-PDIP - same | 28-PDIP - same |
| Max Clock Frequency | 4 MHz | 4 MHz | 4 MHz | 10 MHz |
| Program Memory | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP |
| RAM | 24 B | 24 B | 24 B | 24 B |
| Operating Temperature | -40C to +85C (Industrial) | 0C to +70C (Commercial) | -40C to +125C (Extended) | -40C to +85C (Industrial) |
| Instruction Set | 33 RISC instructions, 12-bit wide | 33 RISC instructions, 12-bit wide | 33 RISC instructions, 12-bit wide | 33 RISC instructions, 12-bit wide |
| Number of I/O Pins | 20 | 20 | 20 | 20 |
Key Differentiators
- Industrial temperature grade for harsh environments (vs PIC16C55A-04/P)
- Maximum community familiarity and tooling support (vs PIC16C54A-04I/P)
- Cost-optimized OTP for high-volume mature products (vs PIC16F55-I/P)
Design Notes
The PIC16C55A-04I/P uses OTP (One-Time Programmable) memory that cannot be erased. Always prototype with a flash-based equivalent such as PIC16F57 or PIC16F59, then port the validated HEX file to the OTP part for production. Per Microchip datasheet DS30400D, blank OTP devices read as 0xFFF, so unprogrammed code space will execute NOP-equivalent instructions - always fill unused program memory with NOPs or jump-to-reset patterns to ensure safe recovery from any code path glitch.
Estimated: At Vdd = 5.0 V and a 4 MHz oscillator, the PIC16C55A-04I/P draws approximately 2 mA active and <1 uA in sleep mode. Provide a 100 nF decoupling capacitor within 5 mm of Vdd (pin 28) and a 10 uF bulk capacitor near the IC for noisy industrial environments. The MCLR/Vpp pin (pin 4) requires a 10 kohm pull-up to Vdd and a 100 nF capacitor to ground for proper reset - omitting this is the most common boot failure source on PIC16C5x designs.
Route the 4 MHz crystal traces (OSC1 pin 6, OSC2 pin 7) symmetrically and keep them short (<10 mm) and away from switching nodes. Add a grounded guard ring around the crystal to reduce EMI pickup. The 28-PDIP through-hole footprint allows easy hand-soldering and rework, but for high-vibration industrial environments consider the SOIC-28 (PIC16C55A-04I/SO) or SSOP-28 (PIC16C55A-04I/SS) surface-mount alternatives for better mechanical reliability.
Compliance Information
RoHS and REACH compliant per Microchip product page. Lead-free (Pb-free) PDIP package. Industrial temperature grade -40C to +85C. Not AEC-Q100 qualified; for automotive applications consult Microchip's PIC16F automotive family.
