PIC16C55A-04E/P - 8-Bit 4MHz OTP MCU, 768B, 28-PDIP | Microchip
MPN: PIC16C55A-04E/P β End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.2 | $5.20 |
| 10 | $4.65 | $46.50 |
| 100 | $4.1 | $410.00 |
| 500 | $3.6 | $1,800.00 |
| 1,000 | $3.15 | $3,150.00 |
PIC16C55A-04E/P Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory, working RAM, and programmable I/O peripherals. The PIC16C5X family from Microchip is a classic baseline architecture employing a RISC instruction set with only 33 single-word, single-cycle instructions, achieving 2:1 code compression over competitive 8-bit microcontrollers in the same cost tier. Positioned within the broader semiconductor hierarchy, this device sits below modern PIC16 enhanced mid-range and PIC18 high-performance cores, but remains in production for long-life industrial and automotive designs that were qualified against the original PIC16C5X silicon.
Key features include 4 MHz operating frequency, 12-bit wide instruction words, an 8-bit data path, a programmable watchdog timer, power-on reset, and a programmable code-protection bit. The OTP (One-Time Programmable) EPROM cell technology allows the firmware to be written once and locked permanently, which simplifies production programming and protects intellectual property. I/O current sourcing and sinking capabilities are sufficient to drive LEDs and small relays directly without external buffers in many designs.
The PIC16C55A-04E architecture uses a Harvard-style separate program and data bus, single-cycle instruction fetch with two-stage pipelining, and a 2-level hardware stack that limits subroutine nesting depth. Compared with PIC16 enhanced cores, this baseline family lacks interrupts, so all real-time servicing must be performed via polled software loops - a key trade-off that benefits cost-sensitive applications where deterministic polling is acceptable. The 'E' suffix indicates the extended temperature grade (typically -40C to +125C), and 'P' designates the PDIP-28 package with through-hole leads.
Typical applications include automotive body controllers, industrial appliance control, simple sensor interfaces, LED driver controllers, and replacement of discrete logic in legacy equipment. The wide operating temperature range supports under-hood automotive modules and outdoor industrial enclosures where commercial-grade parts would fail.
When designing with this part, observe the maximum clock-versus-voltage constraint: at 5V VDD the device operates up to 4 MHz, while at lower supply voltages the maximum frequency decreases proportionally. Decouple VDD with a 0.1 uF ceramic capacitor placed close to the pin, and reserve the MCLR pin for a proper reset network unless it is disabled in configuration.
This page synthesizes distributor pricing, cross-reference alternatives, and practical engineering notes that complement the manufacturer datasheet.
Drop-in alternatives for PIC16C55A-04E/P 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-04E/P (same form factor and footprint) β differing in Core Architecture, Data RAM, Mounting Type, Package, Program Memory Size.
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PIC16C55A-04I/P
β Drop-Inβ In Stock
$1.52 / Unit
View Datasheet βPIC16C55A-04/P
β Drop-Inπ Reference alternative (not in catalog)
PIC16C55A-20/P
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
PIC16C55A-10/P
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PIC16C55A-04E/SP
β Drop-In β οΈ εζ°εΎ ιͺθ―β In Stock
$2.05 / Unit
View Datasheet βPIC16C55A-04E/P Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC16C5X (8-bit RISC baseline) |
| Program Memory Size | 768 bytes (512 x 12 words, OTP EPROM) |
| Data RAM | 25 x 8 bytes |
| Maximum Clock Frequency | 4 MHz |
| Instruction Set Size | 33 instructions, single-word, single-cycle |
| Instruction Width | 12 bits |
| Number of I/O Pins | 20 |
| Timers | 1 x 8-bit (TMR0 with prescaler) |
| Watchdog Timer | Yes (software-enabled) |
| Program Memory Type | OTP EPROM |
| Operating Voltage Range | 3.0 V to 6.0 V (extended range per datasheet family) |
| Operating Temperature Range | -40 C to +125 C (extended grade, 'E' suffix) |
| Package | 28-Pin PDIP (0.600 in / 15.24 mm) |
| Mounting Type | Through-Hole |
| Interrupts | No (polled operation only) |
| Hardware Stack Depth | 2 levels |
| Brown-out Reset | No (Power-on Reset only on baseline PIC16C5X) |
| RoHS Status | Compliant |
PIC16C55A-04E/P Pin Configuration
| Pin 1 | RA0 β Port A bit 0 (digital I/O) |
| Pin 2 | RA1 β Port A bit 1 (digital I/O) |
| Pin 3 | RA2 β Port A bit 2 (digital I/O) |
| Pin 4 | RA3 β Port A bit 3 (digital I/O) |
| Pin 5 | T0CKI β Timer0 clock input (also digital I/O on PIC16C55A 28-pin variants) |
| Pin 6 | RB0 β Port B bit 0 (digital I/O) |
| Pin 7 | RB1 β Port B bit 1 (digital I/O) |
| Pin 8 | RB2 β Port B bit 2 (digital I/O) |
| Pin 9 | RB3 β Port B bit 3 (digital I/O) |
| Pin 10 | RB4 β Port B bit 4 (digital I/O) |
| Pin 11 | RB5 β Port B bit 5 (digital I/O) |
| Pin 12 | RB6 β Port B bit 6 (digital I/O) |
| Pin 13 | RB7 β Port B bit 7 (digital I/O) |
| Pin 14 | VSS β Ground reference |
| Pin 15 | OSC2 β Oscillator output (crystal/ceramic resonator) |
| Pin 16 | OSC1 β Oscillator input (crystal/ceramic resonator or external clock) |
| Pin 17 | RC0 β Port C bit 0 (digital I/O) |
| Pin 18 | RC1 β Port C bit 1 (digital I/O) |
| Pin 19 | RC2 β Port C bit 2 (digital I/O) |
| Pin 20 | RC3 β Port C bit 3 (digital I/O) |
| Pin 21 | RC4 β Port C bit 4 (digital I/O) |
| Pin 22 | RC5 β Port C bit 5 (digital I/O) |
| Pin 23 | RC6 β Port C bit 6 (digital I/O) |
| Pin 24 | RC7 β Port C bit 7 (digital I/O) |
| Pin 25 | VDD β Positive supply voltage (3.0 V to 6.0 V) |
| Pin 26 | NC β Not connected (per datasheet) |
| Pin 27 | NC β Not connected (per datasheet) |
| Pin 28 | MCLR β Master Clear reset input (active low) |
Typical Applications
PIC16C55A-04E/P is suitable for 6 applications: Automotive Body Control Module, Industrial Appliance Control, LED Display and Signage Controller, Sensor Interface and Signal Conditioning, Replacement of Discrete TTL/CMOS Logic, Hobbyist and Educational Embedded Platform.
Automotive Body Control Module
The PIC16C55A-04E/P's extended -40C to +125C temperature grade and 20 digital I/O make it a long-proven choice for automotive body controllers managing lighting, mirror adjustment, and simple accessory switching. Its 768 bytes of OTP program memory comfortably holds the small state machines used for door-lock sequencing or wiper-interval logic, while the 4 MHz RISC core executes the 33-instruction PIC16C5X set fast enough for polled I/O without external interrupt controllers. The 28-PDIP through-hole package is also well suited to automotive harness-mounted ECU assemblies where hand-soldering and field replacement remain desirable. When compared with newer PIC16F parts, the lack of interrupts is acceptable because body-control loops are inherently slow (tens of milliseconds).
Recommended
Industrial Appliance Control
Washing machines, dishwashers, and small industrial pumps frequently use the PIC16C55A-04E/P as the supervisory MCU for motor-start sequencing, sensor polling, and front-panel indicator driving. The 20 available I/O pins connect directly to mains-isolated relay drivers, triac interfaces, and LED bar-graph displays, while the 25-byte RAM accommodates timers and counters without external expansion. OTP EPROM prevents accidental firmware tampering in field-deployed units, an important consideration for commercial appliances. The extended temperature grade supports under-cabinet installations where ambient may rise above 70C. Compared to PIC16 enhanced cores, this part's polled execution model simplifies real-time analysis because every instruction cycle is fully deterministic.
Recommended
LED Display and Signage Controller
The PIC16C55A-04E/P drives multiplexed LED matrix panels and scrolling signage where simple row/column scanning replaces complex graphics processing. Twenty I/O pins map directly to a 5x7 LED matrix plus row-select lines, while the 4 MHz CPU clock is more than sufficient for refresh rates above 100 Hz to eliminate visible flicker. OTP storage locks in the message table at production time, preventing end-user modification of commercial signage content. The 28-PDIP package eases hand-prototyping of custom message firmware, and the extended temperature grade allows outdoor enclosure deployment without additional thermal protection. Engineers can program the device using Microchip's MPLAB PM3 universal programmer, which supports the entire PIC16C5X OTP family.
Recommended
Sensor Interface and Signal Conditioning
In distributed sensor nodes the PIC16C55A-04E/P reads contact closures, thermistor dividers, and low-frequency analog levels through comparator-based slope conversion rather than a true ADC. The 20 I/O pins accept multiple parallel sensor inputs, with the single 8-bit TMR0 plus watchdog providing debounce and time-stamping functions. Extended temperature operation allows deployment in industrial chillers, HVAC ductwork, and outdoor weather stations where commercial-grade parts would drift. OTP code protection prevents unauthorized recalibration of metrology firmware in commercial sensor products. The deterministic polled loop is well suited to slow-changing physical parameters (temperature, pressure) where latency tolerance is in the millisecond range.
Recommended
Replacement of Discrete TTL/CMOS Logic
Designers often use the PIC16C55A-04E/P to replace boards of 74-series glue logic with a single programmable part that can be re-architecturally optimized without PCB rework. Twenty I/O pins, 768 bytes of OTP, and a 33-instruction RISC core can replace dozens of standard logic gates while adding configurable behavior - counter modes, sequence generators, and PWM emulators. The 28-PDIP through-hole form factor matches the original DIP-logic footprints, easing retrofit designs. Extended temperature grade lets legacy industrial equipment operate reliably in factory-floor environments. This application exploits the baseline PIC16C5X architecture's lack of interrupts, which actually simplifies timing analysis versus modern interrupt-driven MCUs.
Recommended
Hobbyist and Educational Embedded Platform
The PIC16C55A-04E/P is widely used in university embedded-systems courses and hobbyist projects because its 28-PDIP through-hole package is breadboard-friendly and its PIC16C5X baseline architecture exposes every internal register directly in assembly. Students learn timer/counter programming, watchdog-driven fail-safe design, and OTP programming workflow using a low-cost PICkit or MPLAB PM3 programmer. Twenty I/O pins connect directly to standard 7-segment displays, character LCDs (in 4-bit mode), and hobby servos, while 768 bytes of code space accommodates complete semester projects. The extended temperature rating is irrelevant for indoor use but does not affect the learning value. For educational budgets, the commercial-temp PIC16C55A-04/P is often substituted at lower cost.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55A-04E/P β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55A-04I/P | PIC16C55A-04/P | PIC16C55A-20/P | PIC16C55A-10/P | PIC16C55A-04E/SP |
|---|---|---|---|---|---|---|
| Package | 28-PDIP (through-hole) | 28-PDIP (through-hole) - same | 28-PDIP (through-hole) - same | 28-PDIP (through-hole) - same | 28-PDIP (through-hole) - same | 28-SPDIP (through-hole) - same lead pitch |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Maximum Clock Frequency | 4 MHz | 4 MHz | 4 MHz | 20 MHz | 10 MHz | 4 MHz |
| Program Memory (OTP) | 768 bytes (512 x 12) | 768 bytes | 768 bytes | 768 bytes | 768 bytes | 768 bytes |
| Data RAM | 25 bytes | 25 bytes | 25 bytes | 25 bytes | 25 bytes | 25 bytes |
| I/O Pins | 20 | 20 | 20 | 20 | 20 | 20 |
| Temperature Grade | Extended -40C to +125C | Industrial -40C to +85C | Commercial 0C to +70C | Commercial 0C to +70C (typical) | Commercial 0C to +70C (typical) | Extended -40C to +125C |
| Lifecycle Status | NRND (Not Recommended for New Designs) | NRND | NRND | NRND | NRND | NRND |
Key Differentiators
- 20 I/O pins and 768-byte OTP in a 28-PDIP baseline RISC core (vs PIC16C54A)
- Extended automotive temperature grade in through-hole package (vs PIC16C55A-04/P)
- 4 MHz speed grade optimized for lower EMI in noisy environments (vs PIC16C55A-20/P)
Design Notes
Estimated: at 5 V VDD, 4 MHz oscillator, and typical I/O loading the PIC16C55A-04E/P draws roughly 2-5 mA active. Decouple VDD with a 0.1 uF ceramic capacitor placed within 5 mm of the VDD pin, and add a bulk 10 uF electrolytic or tantalum on the supply rail if the source impedance is above 1 ohm. The MCLR pin should connect to VDD through a 10 kohm pull-up and to ground through a 100 nF capacitor for proper Power-on Reset timing per the PIC16C5X datasheet recommendation.
Route the crystal or resonator traces to OSC1/OSC2 as short as possible (under 10 mm preferred) and guard them with a ground ring to reduce noise coupling into the oscillator. Keep switching signals (relay drivers, triac zero-cross) physically separated from the oscillator loop. Place the VDD decoupling capacitor adjacent to the VDD pin before any via to the ground plane. Because the 28-PDIP package has through-hole leads, allow at least 0.6 mm annular ring and standard 2.54 mm drill pads in the PCB layout.
Do not assume the PIC16C55A-04E/P supports interrupts - the PIC16C5X baseline architecture is polled only and writing interrupt vectors will produce unexpected behavior. Also avoid configuring MCLR as a digital I/O (it is not available as GPIO on this baseline family). When migrating code from PIC16 enhanced cores (such as PIC16F84 or PIC16F877), remember the hardware stack is only 2 levels deep - deep subroutine nesting will overwrite the return addresses and cause erratic resets.
Compliance Information
RoHS and lead-free compliance per Microchip product page. The 'E' suffix denotes the extended temperature grade (-40C to +125C), which is commonly used in automotive applications but does not constitute formal AEC-Q100 qualification - new automotive designs should consider PIC16F or dsPIC Q-graded variants.
