PIC16C55AT-20E/SO - 8-Bit 20MHz OTP MCU 768B | Microchip
MPN: PIC16C55AT-20E/SO ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.2 | $3.20 |
| 10 | $2.88 | $28.80 |
| 100 | $2.55 | $255.00 |
| 500 | $2.21 | $1,105.00 |
| 1,000 | $1.95 | $1,950.00 |
PIC16C55AT-20E/SO Overview
A PIC microcontroller (Programmable Interface Controller) is a family of low-cost, high-performance, 8-bit fully static, EPROM/ROM-based CMOS microcontrollers built around a Reduced Instruction Set Computer (RISC) architecture. Within the broader semiconductor taxonomy, a PIC MCU belongs to: microcontroller -> embedded processor -> integrated circuit -> semiconductor device. The PIC16C5X family pioneered Microchip's OTP and windowed EPROM product lines, offering a Harvard architecture with separate program and data buses for predictable instruction timing.
Key differentiating features include 768 bytes of OTP program memory (sufficient for ~512 single-word instructions), 25 bytes of general-purpose RAM, and a 12-bit instruction word. The part operates from a 5V supply at 20MHz, supports the standard 28-pin PIC16C5X peripheral set (I/O ports, Timer0, watchdog timer), and provides the extended automotive temperature profile indicated by the 'E' suffix in the order code.
Technically, the PIC16C55A employs a RISC core with a fixed 12-bit instruction set, a 2-level hardware stack, and direct/indirect addressing modes. Its 8-bit ALU, working register (W), and 25-byte register file are mapped into a single linear address space, simplifying compiler code generation. The device's low power consumption and CMOS static design allow operation across the full industrial/automotive temperature range, with all I/O pins capable of sourcing/sinking typical CMOS loads.
Typical applications include automotive body controllers, simple sensor interfaces, appliance control boards, LED drivers, hobbyist/educational development platforms, and replacement of legacy 8051 designs. The 28-SOIC footprint allows hand-soldering and breadboard-friendly prototyping in low-volume production.
When designing with this part, plan for OTP-only programming: code must be fully verified before programming, as OTP cannot be erased. Place a 0.1uF decoupling capacitor as close as possible to VDD/VSS, and ensure MCLR is held high during normal operation. For new designs, modern Flash-based PIC16F equivalents offer reprogrammability at similar cost.
This page synthesizes distributor pricing, drop-in same-package alternatives, and design notes not found in the standalone Microchip datasheet, with focus on automotive-temperature PIC16C5X family variants.
Drop-in alternatives for PIC16C55AT-20E/SO — 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-20E/SO (same form factor and footprint) — differing in Package, Program Memory Size, RAM Size, Mounting Type, Timers.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55AT-04E/SO
✅ Drop-In✓ In Stock
$1.67 / Unit
View Datasheet →PIC16C55A-20I/SS
✅ Drop-In✓ In Stock
$1.04 / Unit
View Datasheet →PIC16C55A-20I/SP
✅ Drop-In✓ In Stock
$3.01 / Unit
View Datasheet →PIC16C55A-20I/P
✅ Drop-In✓ In Stock
$1.6 / Unit
View Datasheet →PIC16C55A-04E/P
✅ Drop-In✓ In Stock
$3.15 / Unit
View Datasheet →PIC16C55AT-20E/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC RISC |
| Series | PIC 16C |
| Core Subfamily | PIC16C5X (PIC16C55A) |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 768 bytes (512 x 12-bit words) |
| RAM Size | 25 x 8 bytes |
| Maximum Clock Speed | 20 MHz |
| Supply Voltage | 5 V |
| Number of Pins | 28 |
| Package | 28-SOIC (7.50mm / 0.295" width) |
| Mounting Type | Surface Mount |
| Temperature Grade | Automotive (E suffix) |
| Terminal Form | GULL WING |
| Package Code | SOP |
| Package Shape | RECTANGULAR |
PIC16C55AT-20E/SO Pin Configuration
| Pin 1 | RA0 — Port A bit 0 (I/O) |
| Pin 2 | RA1 — Port A bit 1 (I/O) |
| Pin 3 | RA2 — Port A bit 2 (I/O) |
| Pin 4 | RA3 — Port A bit 3 (I/O) |
| Pin 5 | MCLR — Master Clear (reset, active low) |
| Pin 6 | VSS — Ground reference |
| Pin 7 | RB0 — Port B bit 0 (I/O) |
| Pin 8 | RB1 — Port B bit 1 (I/O) |
| Pin 9 | RB2 — Port B bit 2 (I/O) |
| Pin 10 | RB3 — Port B bit 3 (I/O) |
| Pin 11 | VDD — Positive supply (5V) |
| Pin 12 | RB4 — Port B bit 4 (I/O) |
| Pin 13 | RB5 — Port B bit 5 (I/O) |
| Pin 14 | RB6 — Port B bit 6 (I/O) |
| Pin 15 | RB7 — Port B bit 7 (I/O) |
| Pin 16 | OSC1 — Oscillator input |
| Pin 17 | OSC2 — Oscillator output |
| Pin 18 | RC0 — Port C bit 0 (I/O) |
| Pin 19 | RC1 — Port C bit 1 (I/O) |
| Pin 20 | RC2 — Port C bit 2 (I/O) |
| Pin 21 | RC3 — Port C bit 3 (I/O) |
| Pin 22 | RC4 — Port C bit 4 (I/O) |
| Pin 23 | RC5 — Port C bit 5 (I/O) |
| Pin 24 | RC6 — Port C bit 6 (I/O) |
| Pin 25 | RC7 — Port C bit 7 (I/O) |
| Pin 26 | RD0 — Port D bit 0 (I/O) |
| Pin 27 | RD1 — Port D bit 1 (I/O) |
| Pin 28 | RD2 — Port D bit 2 (I/O) |
Typical Applications
PIC16C55AT-20E/SO is suitable for 6 applications: Automotive Body Control Modules, Appliance Control Boards, Simple Sensor Interface Modules, Hobbyist and Educational Development, LED Driver and Display Controllers, Legacy 8051 Replacement.
Automotive Body Control Modules
The PIC16C55AT-20E/SO is well-suited to automotive body control applications such as simple lighting drivers, seat-position switches, and mirror-fold actuators. The 'E' temperature grade designation supports under-hood and cabin environments across -40C to +125C, while the 8-bit RISC core and 25-byte RAM are sufficient for state-machine-based control logic with deterministic instruction timing. The 20MHz clock provides the throughput needed for PWM generation at audio-band frequencies for motor control.
Recommended
Appliance Control Boards
In appliance control boards for washers, dryers, and dishwashers, the PIC16C55AT-20E/SO can serve as a low-cost secondary controller for sensor multiplexing, button-debounce logic, and LED indicator driving. The 768-byte OTP program memory holds tight state-machine firmware, and the 28-SOIC footprint allows automated SMT assembly in high-volume appliance lines. Designers benefit from the mature baseline PIC16C5X toolchain (MPASM, MPLAB SIM) for predictable development.
Recommended
Simple Sensor Interface Modules
For low-bandwidth sensor interface modules reading temperature, humidity, or contact-closure inputs, the PIC16C55AT-20E/SO provides ample processing power with its 20MHz instruction rate. The 25-byte RAM accommodates small data buffers, and the OTP program memory holds calibration constants and lookup tables. The industrial/automotive temperature grade supports deployment in unconditioned enclosures, factory floors, and outdoor sensor housings.
Recommended
Hobbyist and Educational Development
The PIC16C55AT-20E/SO remains popular in hobbyist and educational contexts because the baseline PIC16C5X architecture is the simplest PIC to learn - only 33 instructions, 2-level hardware stack, and direct/indirect addressing. The 28-SOIC package is breadboard-friendly with adapter boards, and the OTP memory constraint teaches firmware-completion discipline. Universities teaching embedded systems use this part to demonstrate Harvard architecture fundamentals.
Recommended
LED Driver and Display Controllers
The PIC16C55AT-20E/SO can drive multiplexed 7-segment LED displays, simple dot-matrix indicators, or chase-light patterns in signage. With 20MHz operation, the MCU can refresh 8-digit displays without visible flicker, and the 25-byte RAM holds display buffer state. OTP programming locks the final lighting sequence at production time, preventing field tampering. The automotive temperature grade suits outdoor signage and vehicle interior lighting.
Recommended
Legacy 8051 Replacement
Engineers modernizing legacy 8051-based designs benefit from the PIC16C55AT-20E/SO's similar 8-bit processing model with predictable instruction timing and a smaller, more orthogonal instruction set. The PIC16C5X RISC core executes most instructions in one cycle versus the 8051's 12 cycles, delivering higher throughput at the same clock rate. The 28-SOIC package allows footprint-compatible PCB redesigns where pin-1-to-pin-28 mapping is re-routed.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55AT-20E/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55AT-04E/SO | PIC16C55A-20I/SS | PIC16C55A-20I/SP | PIC16C55A-20I/P | PIC16C55A-04E/P |
|---|---|---|---|---|---|---|
| Package | 28-SOIC | 28-SOIC - same | 28-SSOP | 28-SPDIP | 28-PDIP | 28-PDIP |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Maximum Clock Speed | 20 MHz | 4 MHz | 20 MHz | 20 MHz | 20 MHz | 4 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 | 25 x 8 bytes | 25 x 8 bytes | 25 x 8 bytes | 25 x 8 bytes | 25 x 8 bytes | 25 x 8 bytes |
| Core | 8-bit PIC RISC | 8-bit PIC RISC | 8-bit PIC RISC | 8-bit PIC RISC | 8-bit PIC RISC | 8-bit PIC RISC |
| Temperature Grade | Automotive (E) | Automotive (E) | Industrial (I) | Industrial (I) | Industrial (I) | Automotive (E) |
| Mounting Type | Surface Mount (SOIC) | Surface Mount (SOIC) | Surface Mount (SSOP) | Through-Hole (SPDIP) | Through-Hole (PDIP) | Through-Hole (PDIP) |
Key Differentiators
- Automotive temperature grade in 28-SOIC (vs PIC16C55A-20I/SO (industrial temp))
- 20MHz speed grade at 5V (vs PIC16C55AT-04E/SO (4MHz speed grade))
- Compact 28-SOIC footprint (vs PIC16C55A-20I/P (28-PDIP through-hole))
Design Notes
Place a 0.1uF ceramic decoupling capacitor as close as physically possible to the VDD pin (pin 11) with the ground return via the shortest path to VSS (pin 6). For designs with switching peripherals, add a bulk 10uF tantalum or aluminum electrolytic capacitor on the VDD rail. The PIC16C5X core draws only a few mA at 20MHz but supply noise can corrupt program counter fetch on this baseline architecture.
OTP memory cannot be erased or rewritten. Any bug in the firmware that reaches production OTP programming is permanent. Mitigate by (1) fully validating firmware on a Flash equivalent such as PIC16F54 or PIC16F57 in 28-SOIC, (2) using a windowed PIC16C55A JW part for prototype verification, and (3) implementing hardware watchdog timer to recover from firmware lockups in the field.
The 28-SOIC package has a 1.27mm pin pitch and 7.50mm body width. Maintain at least 0.2mm clearance between SOIC leads and adjacent traces, and use a ground plane on the bottom layer for EMI suppression. The exposed pad is not present on SOIC; thermal dissipation is through the leads only, sufficient for the PIC16C55A's low power dissipation.
Keep the OSC1/OSC2 crystal or resonator traces short (<5mm) and symmetric. For 20MHz operation, use a fundamental-mode crystal with 15-20pF load capacitors per the PIC16C5X datasheet's oscillator section. If using the internal RC oscillator (where supported by the specific part), connect OSC1 to ground and leave OSC2 floating per datasheet guidance.
Compliance Information
RoHS and lead-free status not stated in verified distributor data. The 'E' suffix denotes automotive temperature grade per Microchip ordering convention, not RoHS/lead-free. Confirm with Microchip material declaration or by selecting the 'NL' (no-lead) orderable suffix for RoHS-compliant variants.
