PIC16C55A-20E/P - 8-Bit 20MHz OTP MCU, 768B, 28-PDIP | Microchip
MPN: PIC16C55A-20E/P ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.45 | $3.45 |
| 10 | $3.1 | $31.00 |
| 100 | $2.62 | $262.00 |
| 500 | $2.25 | $1,125.00 |
| 1,000 | $1.95 | $1,950.00 |
PIC16C55A-20E/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 is positioned at the entry level of the 8-bit RISC MCU taxonomy: PIC16C5X -> PIC16C family -> PIC microcontrollers -> 8-bit microcontrollers -> microcontrollers -> embedded ICs. The 12-bit wide instruction set provides 2:1 code compression over competing 8-bit MCUs, allowing more functionality in fewer bytes of program memory.
Key features include a 33-instruction set, 12-bit wide instructions, 2:1 code compression versus competitors, 8-bit data path, 20 MHz maximum clock frequency, and one-time programmable (OTP) program memory. The 28-pin PDIP package provides breadboard-friendly through-hole mounting suitable for prototyping, education, and legacy industrial systems.
Architecturally, the PIC16C55A uses a Harvard-architecture RISC core with separate program and data buses. The OTP memory is programmed once and cannot be erased, making the device well-suited to high-volume, cost-sensitive applications where firmware is finalized at production. The automotive temperature grade extends operating range to -40C to +125C, distinguishing the 'E' suffix from commercial-grade variants.
Typical applications include automotive embedded controllers, legacy industrial control systems, appliance control boards, prototyping platforms, educational development boards, and cost-sensitive replacement designs. The 28-pin PDIP form factor remains popular for through-hole manufacturing lines and hobbyist development.
When designing with this device, note that OTP memory cannot be field-updated - any firmware bug requires physical IC replacement. Use the parallel programming mode and a Microchip-approved device programmer (such as the MPLAB PM3) for production programming.
This page synthesizes distributor pricing from DigiKey/Mouser, automotive-grade drop-in alternatives in the same 28-PDIP footprint, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for PIC16C55A-20E/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-20E/P (same form factor and footprint) — differing in Program Memory Size, Core, Package, Timers, Watchdog Timer.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55A-20/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55A-04E/P
✅ Drop-In✓ In Stock
$3.15 / Unit
View Datasheet →PIC16C55A-04I/P
✅ Drop-In✓ In Stock
$1.52 / Unit
View Datasheet →PIC16C55-10I/P
✅ Drop-In✓ In Stock
$2.58 / Unit
View Datasheet →PIC16C55-10/SP
✅ Drop-In✓ In Stock
$2.45 / Unit
View Datasheet →PIC16C55A-20E/P Maximum Ratings & Electrical Characteristics
| Core | 8-bit RISC (PIC16C5X family) |
| Instruction Set | 33 instructions, 12-bit wide |
| Maximum Clock Frequency | 20 MHz |
| Program Memory Size | 768 B (512 x 12) OTP |
| Program Memory Type | OTP (One-Time Programmable) |
| RAM Size | 25 x 8 bytes |
| Number of I/O Pins | 20 |
| Data Bus Width | 8-bit |
| Supply Voltage Typical | 5 V |
| Temperature Grade | Automotive (-40C to +125C) |
| Package | 28-pin PDIP (0.600 inch, 15.24 mm) |
| Mounting Type | Through-Hole |
| Terminal Form | Through-Hole |
| Number of Terminals | 28 |
| Package Code | DIP |
| Package Shape | Rectangular |
| Architecture | Harvard (separate program/data buses) |
| Code Compression vs 8-bit class | 2:1 |
| RoHS Status | unknown |
PIC16C55A-20E/P Pin Configuration
| Pin 1 | RA0 — Port A bit 0 (bidirectional I/O) |
| Pin 2 | RA1 — Port A bit 1 (bidirectional I/O) |
| Pin 3 | RA2 — Port A bit 2 (bidirectional I/O) |
| Pin 4 | RA3 — Port A bit 3 (bidirectional I/O) |
| Pin 5 | RA4/RTCC — Port A bit 4 / RTCC timer input (bidirectional I/O, open-drain) |
| Pin 6 | OSC1/CLKIN — Oscillator input / external clock input |
| Pin 7 | OSC2/CLKOUT — Oscillator output / clock output (4x instruction frequency) |
| Pin 8 | MCLR/VPP — Master clear reset (active low) / programming voltage input |
| Pin 9 | VSS — Ground reference |
| Pin 10 | VDD — Positive supply voltage |
| Pin 11 | RB0 — Port B bit 0 (bidirectional I/O) |
| Pin 12 | RB1 — Port B bit 1 (bidirectional I/O) |
| Pin 13 | RB2 — Port B bit 2 (bidirectional I/O) |
| Pin 14 | RB3 — Port B bit 3 (bidirectional I/O) |
| Pin 15 | RB4 — Port B bit 4 (bidirectional I/O) |
| Pin 16 | RB5 — Port B bit 5 (bidirectional I/O) |
| Pin 17 | RB6 — Port B bit 6 (bidirectional I/O) |
| Pin 18 | RB7 — Port B bit 7 (bidirectional I/O) |
| Pin 19 | VSS — Ground reference |
| Pin 20 | VDD — Positive supply voltage |
| Pin 21 | RC0 — Port C bit 0 (bidirectional I/O) |
| Pin 22 | RC1 — Port C bit 1 (bidirectional I/O) |
| Pin 23 | RC2 — Port C bit 2 (bidirectional I/O) |
| Pin 24 | RC3 — Port C bit 3 (bidirectional I/O) |
| Pin 25 | RC4 — Port C bit 4 (bidirectional I/O) |
| Pin 26 | RC5 — Port C bit 5 (bidirectional I/O) |
| Pin 27 | RC6 — Port C bit 6 (bidirectional I/O) |
| Pin 28 | RC7 — Port C bit 7 (bidirectional I/O) |
Typical Applications
PIC16C55A-20E/P is suitable for 6 applications: Automotive Embedded Controllers, Legacy Industrial Control Systems, Appliance Control Boards, Prototyping and Educational Development, Cost-Sensitive Replacement Designs, Hobbyist and Maker Projects.
Automotive Embedded Controllers
The PIC16C55A-20E/P fits automotive embedded controller designs because its -40C to +125C automotive temperature grade ('E' suffix) handles under-hood and cabin module thermal swings without derating. Its 20 MHz clock, 768B OTP program memory, and 20 GPIO pins are sufficient for body controllers, lighting sequencers, and sensor interfaces that run fixed, validated firmware. The 28-PDIP package suits automotive through-hole manufacturing lines. Key fit: 2:1 code compression extends 768B OTP to roughly equivalent 1.5 kB on competing 8-bit cores, and the 33-instruction RISC set keeps firmware development time low. Use it where the BOM cost of an MCU dominates and firmware is finalized at production.
Recommended
Legacy Industrial Control Systems
The PIC16C55A-20E/P is a strong fit for legacy industrial control system retrofits and replacements because of its automotive temperature grade and proven long-life-cycle PIC16C5X core. With 20 GPIO pins, the MCU can directly drive relays, LED indicators, keypad matrices, and discrete sensor inputs in a PLC-style controller board. The 25-byte RAM is sufficient for state-machine logic without a heap. The 28-PDIP through-hole package simplifies hand-soldered field repairs and is robust to vibration in industrial cabinets. Trade-off: OTP memory means firmware changes require IC replacement; budget for spares in field-service kits.
Recommended
Appliance Control Boards
The PIC16C55A-20E/P suits appliance control boards (washers, dishwashers, microwaves) where the 8-bit RISC core delivers predictable deterministic execution for timing-critical sequencing, and the 20 MHz clock provides enough MIPS for motor-control PWM generation in software. The 768B OTP program memory holds complete appliance state machines with diagnostic logging, while the 20 GPIO pins interface directly to triacs, opto-isolated line-voltage drivers, and keypad scanners. Automotive-grade temperature tolerance handles appliance thermal environments. OTP prevents unauthorized firmware copying, a key concern for appliance OEMs.
Recommended
Prototyping and Educational Development
The PIC16C55A-20E/P is well-suited to prototyping and educational development because the 28-PDIP package drops into standard 0.1-inch pitch breadboards and IC sockets, allowing rapid hardware iteration. The 33-instruction RISC set is small enough to teach in a single semester, and the 12-bit instruction width is documented in classic Microchip textbooks. With 20 GPIO pins and a single timer, students can implement counters, PWM, key debouncing, and serial bit-banging. The automotive temperature grade means student designs work across hobby and lab environments.
Recommended
Cost-Sensitive Replacement Designs
The PIC16C55A-20E/P fits cost-sensitive replacement designs where the BOM is dominated by a sub-$2 MCU and firmware is locked at production. OTP memory eliminates the flash-memory silicon cost premium, while the 8-bit RISC core and 33-instruction set minimize code size, reducing verification effort. The automotive temperature grade allows the same SKU to serve both consumer and industrial customers, simplifying inventory. Use it in disposable sensor tags, single-function controllers, and high-volume consumable electronics where per-unit cost matters more than field upgradability.
Recommended
Hobbyist and Maker Projects
The PIC16C55A-20E/P is a solid match for hobbyist and maker projects because the 28-PDIP package works in breadboards and ZIF sockets, and the 20 MHz clock supports responsive interactive projects (LED cubes, model railroad controllers, robotics). The 20 GPIO pins are enough for typical sensor-and-actuator projects without multiplexers. PIC16C5X assembly language is well-documented in older Microchip application notes and the public PICList archives. Caveat: OTP means burned parts cannot be re-flashed; consider a PIC16F54 or PIC16F84A for projects that will iterate through many firmware versions.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55A-20E/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55A-20/P | PIC16C55A-04E/P | PIC16C55A-04I/P | PIC16C55-10I/P | PIC16C55-10/SP |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-PDIP | 28-PDIP - same | 28-PDIP - same | 28-PDIP - same | 28-PDIP - same | 28-SPDIP (Skinny PDIP) - same footprint |
| Maximum Clock Frequency | 20 MHz | 20 MHz | 4 MHz | 4 MHz | 10 MHz | 10 MHz |
| Program Memory | 768 B (512 x 12) OTP | 768 B (512 x 12) OTP | 768 B (512 x 12) OTP | 768 B (512 x 12) OTP | 768 B (512 x 12) OTP | 768 B (512 x 12) OTP |
| RAM Size | 25 bytes | 25 bytes | 25 bytes | 25 bytes | 25 bytes | 25 bytes |
| GPIO Pins | 20 | 20 | 20 | 20 | 20 | 20 |
| Temperature Grade | Automotive (-40C to +125C) | Commercial (0C to +70C) | Automotive (-40C to +125C) | Industrial (-40C to +85C) | Industrial (-40C to +85C) | Commercial (0C to +70C) |
Key Differentiators
- Automotive temperature grade in 28-PDIP (vs PIC16C55A-20/P)
- Higher maximum clock than 04-grade siblings (vs PIC16C55A-04E/P)
- Larger program memory than PIC16C54A (vs PIC16C54A-20E/P)
Design Notes
OTP memory cannot be field-updated. Verify firmware with an OTP-equivalent windowed sample (e.g., PIC16C55A-20/JW) before committing to the programmed PIC16C55A-20E/P. A single bit error requires physical IC replacement; budget for spare units in production runs and field-service kits. Use Microchip's MPLAB PM3 programmer in high-voltage parallel mode to program the /P variants.
Estimated: at 5V VDD and 20 MHz clock, the PIC16C55A-20E/P typically draws 5-15 mA active, depending on I/O loading. Decouple VDD (pin 10 and pin 20) with 100 nF ceramic capacitors placed within 5 mm of each supply pin, plus a 10 uF bulk capacitor on the board. The two VSS pins (9 and 19) must both be connected to a low-impedance ground plane to avoid ground-bounce during port transitions.
Keep the oscillator traces (OSC1/OSC2, pins 6 and 7) short and surrounded by ground pour to minimize EMI pickup that can corrupt timing-sensitive peripherals. For crystal operation, place load capacitors (typically 15-33 pF) within 5 mm of the OSC pins. Avoid routing high-frequency switching signals (relay coils, triac outputs) parallel to the oscillator traces; a 4 mm clearance is recommended.
At maximum 20 MHz clock and full I/O load, junction temperature rise above ambient is negligible (estimated <5 C/W x 0.2 W ~= 1 C rise) due to the low-power CMOS core. The 28-PDIP package provides adequate thermal dissipation for the modest active currents. No heatsink is required even at +125C ambient, but the surrounding board should still provide airflow for surrounding analog components.
RA4 (pin 5) is an open-drain output and requires an external pull-up resistor (typically 4.7 kohm to VDD) for high-level output. All other RA, RB, and RC pins are TTL-compatible push-pull outputs. To avoid bus contention in bidirectional designs, configure TRIS bits before reading PORT latches and always disable interrupts during bit-banging sequences that touch the I/O port used by the ISR.
Compliance Information
Operating temperature grade 'E' (automotive -40C to +125C) is confirmed per verified web data and Microchip PIC16C5X datasheet. RoHS/REACH/lead-free status is not stated in the verified data and remains unknown. AEC-Q100 qualification is not separately attested; the automotive temperature grade alone does not imply AEC-Q100 compliance.
