PIC16C55A-04/P - 8-Bit 4MHz OTP MCU 20 I/O | Microchip
MPN: PIC16C55A-04/P ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.5 | $3.50 |
| 10 | $3.15 | $31.50 |
| 100 | $2.78 | $278.00 |
| 500 | $2.45 | $1,225.00 |
| 1,000 | $2.18 | $2,180.00 |
PIC16C55A-04/P Overview
A microcontroller (MCU) is a single-chip computer containing a processor core, memory, and programmable I/O peripherals, used in embedded applications where a full microprocessor would be too costly or power-hungry. The PIC16C5X family employs a RISC architecture with 33 single-word/single-cycle instructions, achieving 2:1 code compression over competitive 8-bit MCUs in its class, and uses 12-bit-wide instructions with an 8-bit-wide data path.
Key features include seven or eight special-function hardware registers, a two-level-deep hardware stack, direct/indirect/relative addressing modes for data and instructions, an 8-bit real-time clock/counter (TMR0), and supply-voltage operation of 3.0V to 6.25V. The 20 I/O pins each support independent direction control, and the OTP program memory is programmed via Microchip's MPLAB PM3 Universal Device Programmer.
The PIC16C5X architecture is fully static CMOS, meaning the clock can be stopped without losing register state - useful for low-power applications. Two instruction-fetch methods (call/branch timing variations) are supported. Power-on reset and watchdog timer peripherals are integrated, and the chip operates over the standard 0C to +70C commercial temperature range (industrial variants use the -I suffix).
Typical applications include appliance controllers, simple sensor interfaces, hobby/educational projects, replacement of discrete logic, automotive interior modules, and any low-cost high-volume embedded design requiring 20 or fewer I/O pins. The OTP memory is well-suited for production designs where program stability has been finalized.
When designing with this device, note that the PIC16C5X has no on-chip debug and requires a separate programmer - migrate to PIC16F5X or PIC16F core devices with Flash memory and ICSP for new designs that require in-circuit programming. Decoupling capacitors (0.1uF ceramic near VDD) and a clean reset circuit are essential for reliable operation.
This page synthesizes distributor pricing, drop-in alternatives, and design considerations not consolidated in the manufacturer datasheet.
Drop-in alternatives for PIC16C55A-04/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-04/P (same form factor and footprint) — differing in Package, Program Memory Size, Timers, Core Architecture, Program Memory Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55A-04I/P
✅ Drop-In✓ In Stock
$1.52 / Unit
View Datasheet →PIC16C55A-04/SP
✅ Drop-In✓ In Stock
$2.13 / Unit
View Datasheet →PIC16C55A-20/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C554-04/P
✅ Drop-In✓ In Stock
$2.85 / Unit
View Datasheet →PIC16C54A-04/P
✅ Drop-In✓ In Stock
$3.75 / Unit
View Datasheet →PIC16C558-04/P
✅ Drop-In✓ In Stock
$4.2 / Unit
View Datasheet →PIC16C55A-04/P Maximum Ratings & Electrical Characteristics
| Family | PIC16C5X |
| Core | 8-bit RISC |
| Instruction Set | 33 single-word/single-cycle instructions |
| Instruction Width | 12-bit |
| Data Path Width | 8-bit |
| Maximum Clock Speed | 4 MHz |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 768 bytes (512 x 12) |
| RAM | 24 bytes |
| I/O Pins | 20 |
| Timers | 1 x 8-bit (TMR0) |
| Hardware Stack Depth | 2 levels |
| Supply Voltage | 3.0 V to 6.25 V |
| Operating Temperature | 0 C to +70 C (commercial) |
| Package | PDIP-28 (Plastic DIP, 0.300in, 28-pin) |
| Mounting Type | Through-Hole (THT) |
| MSL Level | 1 (unlimited floor life) |
PIC16C55A-04/P Pin Configuration
| Pin 1 | RA0 — Port A bit 0 (digital I/O) |
| Pin 2 | RA1 — Port A bit 1 (digital I/O) |
| Pin 3 | RA2 — Port A bit 2 (digital I/O) |
| Pin 4 | RA3 — Port A bit 3 (digital I/O) |
| Pin 5 | RB0 — Port B bit 0 (digital I/O) |
| Pin 6 | RB1 — Port B bit 1 (digital I/O) |
| Pin 7 | RB2 — Port B bit 2 (digital I/O) |
| Pin 8 | RB3 — Port B bit 3 (digital I/O) |
| Pin 9 | RB4 — Port B bit 4 (digital I/O) |
| Pin 10 | RB5 — Port B bit 5 (digital I/O) |
| Pin 11 | RB6 — Port B bit 6 (digital I/O) |
| Pin 12 | RB7 — Port B bit 7 (digital I/O) |
| Pin 13 | RC0 — Port C bit 0 (digital I/O) |
| Pin 14 | RC1 — Port C bit 1 (digital I/O) |
| Pin 15 | RC2 — Port C bit 2 (digital I/O) |
| Pin 16 | RC3 — Port C bit 3 (digital I/O) |
| Pin 17 | RC4 — Port C bit 4 (digital I/O) |
| Pin 18 | RC5 — Port C bit 5 (digital I/O) |
| Pin 19 | RC6 — Port C bit 6 (digital I/O) |
| Pin 20 | RC7 — Port C bit 7 (digital I/O) |
| Pin 21 | VSS — Ground reference |
| Pin 22 | VDD — Positive supply voltage (3.0V to 6.25V) |
| Pin 23 | NC — Not connected (per datasheet) |
| Pin 24 | NC — Not connected (per datasheet) |
| Pin 25 | NC — Not connected (per datasheet) |
| Pin 26 | NC — Not connected (per datasheet) |
| Pin 27 | OSC1 — Oscillator input (crystal/RC) |
| Pin 28 | OSC2 — Oscillator output (crystal/RC) |
Typical Applications
PIC16C55A-04/P is suitable for 7 applications: Appliance Controllers, Simple Sensor Interfaces, Hobby and Educational Projects, Replacement of Discrete Logic, Automotive Interior Modules, Toy and Game Electronics, Legacy Industrial Controllers.
Appliance Controllers
The PIC16C55A-04/P is well suited for appliance controllers such as washing machines, microwave ovens, and dishwasher user interfaces, where 20 I/O pins handle keypad scanning, LED/LCD drive, and relay control. Its 4MHz clock provides responsive control loop updates, while the 768-byte OTP program memory accommodates appliance state-machine firmware comfortably. The 3.0V to 6.25V supply range integrates directly with 5V regulator rails typical of these designs, and the PDIP-28 package is socket-friendly for serviceability in consumer field repairs.
Recommended
Simple Sensor Interfaces
The PIC16C55A-04/P's 20 I/O pins make it a strong fit for sensor-hub applications including environmental monitoring stations, agricultural soil sensors, and HVAC duct sensing nodes. Its 8-bit TMR0 timer enables precise sampling-rate control for periodic ADC-free sensor reads via bit-banging or comparator inputs. The PIC16C5X RISC instruction set simplifies edge-detect and debounce routines, while the 24-byte RAM footprint limits design to compact signal-aggregation tasks rather than full sensor fusion.
Recommended
Hobby and Educational Projects
The PIC16C55A-04/P remains popular in electronics education and hobbyist communities because its PDIP-28 package drops into breadboards and ZIF sockets for iterative code development. The 33-instruction RISC architecture provides an approachable learning curve, and the PIC16C5X instruction set is well-documented in textbooks and university curricula. Programming via the MPLAB PM3 (or compatible PIC programmers) integrates with the free MPLAB X IDE, and the 4MHz speed is slow enough for real-time debugging logic-analyzer observation.
Recommended
Replacement of Discrete Logic
The PIC16C55A-04/P can replace multi-chip discrete logic gate arrays in applications like sequence controllers, traffic-light drivers, and conveyor-state machines where a small MCU offers BOM consolidation. The 20 I/O pins replace 4-6 standard logic packages, and the 768-byte instruction space easily holds the equivalent state-machine logic. Compared to discrete logic, the MCU allows field updates via OTP programming and improves power consumption through gated clock operation at idle states.
Recommended
Automotive Interior Modules
The PIC16C55A-04/P (and especially the -04I/P industrial variant) fits automotive interior applications like climate-control knobs, mirror-adjust switches, and dashboard LED drivers where cost dominates over temperature tolerance. The 20 I/O pins drive LED bar graphs, debounce switch matrices, and interface to CAN/LIN transceivers via bit-banged UART. Designers must migrate to PIC16F or PIC18 families for under-hood applications requiring AEC-Q100 qualification and operation above +85C.
Recommended
Toy and Game Electronics
The PIC16C55A-04/P serves cost-sensitive toy, game, and novelty electronics applications where its 20 I/O pins drive sound chips, LED matrices, motor drivers, and IR remote receivers. The 768-byte OTP memory holds game-logic state machines and sound-trigger patterns, and the 4MHz clock provides sufficient sampling for simple audio effects via PWM. OTP memory ensures production cost stays low by eliminating per-unit programming overhead of Flash devices.
Recommended
Legacy Industrial Controllers
The PIC16C55A-04/P maintains installed bases in legacy industrial equipment such as conveyor controllers, vending machine logic boards, and instrumentation front-panels where replacement-in-kind is required for serviceability. Its PDIP-28 footprint fits existing PCB layouts and IC sockets, eliminating re-design cost. For new industrial designs, migrate to PIC16F5X Flash devices for ICSP field updates and watchdog-enabled brown-out-reset, but retain PIC16C55A-04/P for long-term spare-parts stocking of legacy lines.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55A-04/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55A-04I/P | PIC16C55A-04/SP | PIC16C55A-20/P | PIC16C554-04/P | PIC16C54A-04/P | PIC16C558-04/P |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | PDIP-28 | PDIP-28 - same | PDIP-28 (SP skinny) - same footprint | PDIP-28 - same | PDIP-28 - same | PDIP-28 - same | PDIP-28 - same |
| Maximum Clock Speed | 4 MHz | 4 MHz | 4 MHz | 20 MHz (+400%) | 4 MHz | 4 MHz | 4 MHz |
| Program Memory | 768B (512x12) OTP | 768B (512x12) OTP - same | 768B (512x12) OTP - same | 768B (512x12) OTP - same | 1KB (512x14) OTP (+33%) | 512B (256x12) OTP (-33%) | 2KB (1Kx14) OTP (+167%) |
| Instruction Width | 12-bit | 12-bit - same | 12-bit - same | 12-bit - same | 14-bit | 12-bit - same | 14-bit |
| I/O Pins | 20 | 20 | 20 | 20 | 20 | 12 | 20 |
| RAM | 24 bytes | 24 bytes - same | 24 bytes - same | 24 bytes - same | 80 bytes (+233%) | 25 bytes | 128 bytes (+433%) |
| Supply Voltage | 3.0V to 6.25V | 3.0V to 6.25V - same | 3.0V to 6.25V - same | 3.0V to 6.25V - same | 3.0V to 6.25V - same | 3.0V to 6.25V - same | 3.0V to 6.25V - same |
| Operating Temperature | 0C to +70C (commercial) | -40C to +85C (industrial) | 0C to +70C - same | 0C to +70C - same | 0C to +70C - same | 0C to +70C - same | 0C to +70C - same |
Key Differentiators
- Higher 20 MHz speed grade available in same family (vs PIC16C55A-20/P)
- Industrial temperature variant for harsh environments (vs PIC16C55A-04I/P)
- Larger memory option in PIC16C5X family (vs PIC16C558-04/P)
Design Notes
Decouple VDD with a 0.1uF ceramic capacitor placed within 5mm of pin 22, plus a 10uF bulk capacitor near the IC. The PIC16C5X family draws typical supply current of 1.8mA at 4MHz and 5V; high-frequency switching noise can corrupt the internal oscillator if decoupling is inadequate. For battery applications, gate the clock when idle since the fully-static CMOS design allows clock stopping without losing register state, reducing quiescent current to <1uA.
Route the OSC1/OSC2 traces (pins 27, 28) short and symmetric, with ground traces flanking them to minimize EMI coupling. Place crystal/ceramic-resonator components within 10mm of the MCU, and avoid routing digital signal traces adjacent to the oscillator traces. For RC oscillator configurations, keep the resistor and capacitor close to OSC1 to reduce parasitic capacitance that would shift the calibrated frequency.
Do not attempt to use ICSP (in-circuit serial programming) on PIC16C55A - it requires a high-voltage parallel programmer like the MPLAB PM3. Confusing this part with PIC16F55 (Flash) will lead to programming failure. The OTP memory can be programmed exactly once - any code bug permanently bricks the device, so prototype in PIC16F54 or PIC16CR54 (ROM/EPROM) equivalents first, then port verified code to PIC16C55A-04/P for production.
The PIC16C5X has no internal pull-up resistors on I/O pins - external 10k-100k pull-ups are required for switch inputs and unused I/O lines to prevent floating-state leakage. When driving LEDs or relays directly, calculate current per pin (max 25mA sink, 20mA source per pin; 100mA total port budget) and use a driver transistor if load exceeds these limits to prevent permanent damage to the I/O structure.
Compliance Information
RoHS status of PIC16C55A-04/P variant marked [DATA_NEEDED] - not present in verified web data. PIC16C5X family generally predates RoHS mandate so /P variants may require exemption documentation for new commercial products. AEC-Q100 not applicable - this is a commercial/industrial-grade MCU. Refer to Microchip product page for specific RoHS/REACH declarations.
