PIC16C55A-20E/SO - 20MHz 8-Bit OTP MCU | Microchip | 28-SOIC
MPN: PIC16C55A-20E/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.92 | $8.92 |
| 10 | $8.05 | $80.50 |
| 100 | $7.1 | $710.00 |
| 500 | $6.3 | $3,150.00 |
| 1,000 | $5.65 | $5,650.00 |
PIC16C55A-20E/SO Overview
A microcontroller (MCU) is a single-chip computer that combines a CPU core, program memory, working RAM, and configurable I/O peripherals on one IC. The PIC16C5X family occupies the entry-level, cost-optimized branch of Microchip's 8-bit PIC portfolio, descending from the broader class of 8-bit microcontrollers -> microcontrollers -> embedded processors -> semiconductors. It uses a RISC instruction set with 33 single-cycle instructions, has no onboard peripherals beyond the core I/O and timer, and is intended for high-volume cost-sensitive applications where OTP programmability is acceptable.
Key features of the PIC16C55A-20E/SO include 768 bytes of OTP program memory, 24 bytes of RAM, four I/O ports (PORTB 8-bit, PORTC 8-bit, PORTD 4-bit plus RA 4-bit variant), a 20 MHz maximum oscillator frequency, and a wide 3.0 V to 5.5 V supply range. The 20 MHz clock enables a 200 ns instruction cycle at full speed; instructions are 12 bits wide, providing compact code density. The device uses an external oscillator and supports crystal, ceramic resonator, or RC clock inputs.
Architecturally, the PIC16C55A uses a Harvard RISC core with separate program and data paths, a 12-bit instruction word, and a 2-level hardware stack. Its reset and watchdog timing characteristics are defined in the manufacturer datasheet. There is no integrated UART, ADC, or interrupt controller beyond the basic external/port-change interrupt on PORTB, making this part one of the simplest members of the PIC16C5X family and the closest sibling of the PIC16C54A and PIC16C57C.
Typical applications for the PIC16C55A-20E/SO include low-cost consumer appliances, simple motor controllers, LED display drivers, automotive body controllers (using the -E temperature grade), battery chargers, remote-control transmitters, and any high-volume embedded design that requires OTP one-time programmable memory rather than flash. The PIC16C5X is often selected where field upgrades are unnecessary and unit cost is the primary driver.
When designing with this device, note that OTP memory cannot be rewritten in-circuit, so the firmware must be fully verified on EPROM-windowed samples (PIC16C55A-20/JW) before committing to OTP production. The lack of an internal oscillator means an external clock source must always be supplied, and the wide 0.295-inch SO body requires careful clearances in compact layouts.
This page synthesizes distributor pricing, drop-in OTP/EPROM and FLASH alternatives, and practical design notes not found in the standalone manufacturer datasheet.
Drop-in alternatives for PIC16C55A-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 PIC16C55A-20E/SO (same form factor and footprint) — differing in Program Memory Size, Program Memory Type, Core Architecture, Package, Number of Instructions.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55A-20/SO
✅ Drop-In✓ In Stock
$2.9 / Unit
View Datasheet →PIC16C55A-04E/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C57C-20/SO
✅ Drop-In✓ In Stock
$2.89 / Unit
View Datasheet →PIC16F54-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C54A-20I/SO
✅ Drop-In✓ In Stock
$1.15 / Unit
View Datasheet →PIC16C55A-20E/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC RISC (Harvard) |
| Family | PIC16C5X (PIC16C55A) |
| Program Memory Type | OTP (One-Time Programmable) EPROM |
| Program Memory Size | 768 B (512 x 12 words) |
| RAM Size | 24 B |
| Instruction Word Width | 12 bits |
| Number of Instructions | 33 (single-cycle) |
| Max CPU Frequency | 20 MHz |
| Instruction Cycle Time | 200 ns @ 20 MHz |
| I/O Pins | 20 |
| Supply Voltage (Vdd) | 3.0 V to 5.5 V |
| Oscillator Type | External (XT, HS, LP, RC) |
| Operating Temperature | -40 C to +125 C (E grade) |
| Package | 28-SOIC (0.295 in / 7.50 mm width, SO) |
| Mounting Type | Surface Mount |
PIC16C55A-20E/SO Pin Configuration
| Pin 1 | VDD — Positive supply voltage (3.0 V to 5.5 V) |
| Pin 2 | RA0 — I/O port A bit 0 |
| Pin 3 | RA1 — I/O port A bit 1 |
| Pin 4 | RA2 — I/O port A bit 2 |
| Pin 5 | RA3 — I/O port A bit 3 |
| Pin 6 | RTCC — Real-time clock/counter input |
| Pin 7 | VSS — Ground reference |
| Pin 8 | OSC2 — Oscillator output (crystal/RC) |
| Pin 9 | OSC1 — Oscillator input (crystal/external clock) |
| Pin 10 | RC0 — I/O port C bit 0 |
| Pin 11 | RC1 — I/O port C bit 1 |
| Pin 12 | RC2 — I/O port C bit 2 |
| Pin 13 | RC3 — I/O port C bit 3 |
| Pin 14 | RC4 — I/O port C bit 4 |
| Pin 15 | RC5 — I/O port C bit 5 |
| Pin 16 | RC6 — I/O port C bit 6 |
| Pin 17 | RC7 — I/O port C bit 7 |
| Pin 18 | RD0 — I/O port D bit 0 |
| Pin 19 | RD1 — I/O port D bit 1 |
| Pin 20 | RD2 — I/O port D bit 2 |
| Pin 21 | RD3 — I/O port D bit 3 |
| Pin 22 | RB0 — I/O port B bit 0 (interrupt-on-change capable) |
| Pin 23 | RB1 — I/O port B bit 1 (interrupt-on-change capable) |
| Pin 24 | RB2 — I/O port B bit 2 (interrupt-on-change capable) |
| Pin 25 | RB3 — I/O port B bit 3 (interrupt-on-change capable) |
| Pin 26 | RB4 — I/O port B bit 4 (interrupt-on-change capable) |
| Pin 27 | RB5 — I/O port B bit 5 (interrupt-on-change capable) |
| Pin 28 | RB6 — I/O port B bit 6 (interrupt-on-change capable) |
Typical Applications
PIC16C55A-20E/SO is suitable for 6 applications: Low-Cost Consumer Appliance Controller, Automotive Body Control Modules, LED Display and Sign Drivers, Remote Control and RF Encoder, Simple Battery Charger Controller, Industrial Sensor Interface / Signal Conditioner.
Low-Cost Consumer Appliance Controller
The PIC16C55A-20E/SO fits low-cost consumer appliance controllers because its 768-byte OTP program memory covers typical state-machine firmware, its 20 MHz clock delivers 200 ns instruction cycles for fast timer-driven PWM and debounce tasks, and the 28-SOIC surface-mount package keeps board cost low. With 20 I/O pins split across multiple ports the MCU can directly drive 7-segment displays, keypad scan matrices, relay coils, and indicator LEDs without external expanders. At 5 V supply the 20 MHz speed is comfortably within the spec's 3.0 V to 5.5 V range. The extended temperature grade supports appliance environments with hot enclosures.
Recommended
Automotive Body Control Modules
The PIC16C55A-20E/SO is well-suited to automotive body controllers (window lift, mirror adjust, simple lighting) where the extended -40 C to +125 C temperature grade is mandatory. The 20 MHz clock provides sufficient throughput for CAN/LIN bit-banging or low-speed serial protocols common in entry-level BCMs, and the 768-byte OTP holds the entire BCM state-machine. The 28-SOIC package withstands automotive soldering profiles and the wide 0.295-inch body improves manufacturability. Note that AEC-Q100 qualification is not explicitly stated in the verified data, so OEMs requiring full AEC-Q100 should select an automotive-grade variant.
Recommended
LED Display and Sign Drivers
The PIC16C55A-20E/SO drives multiplexed LED displays well thanks to its 20 I/O pins (enough for an 8-digit 7-segment + 8 column-driver matrix) and 20 MHz throughput that handles multiplex refresh with timing headroom. The 24-byte RAM accommodates a small display buffer, and the 768-byte OTP program memory holds segment lookup tables and dimming state machines. The 28-SOIC package supports automated pick-and-place assembly for high-volume signage production.
Recommended
Remote Control and RF Encoder
In low-cost RF remote controls and IR encoders the PIC16C55A-20E/SO provides 20 MHz speed for tight bit timing of 38 kHz carrier modulation, 768 bytes of OTP for key-scanning and protocol state, and 20 I/O for matrix keypads. The wide supply range (3.0 V to 5.5 V) lets the same board accept 2 x AA alkaline (3 V) or regulated 5 V supplies. The 28-SOIC footprint supports slim handheld plastic enclosures. Power consumption is low enough for battery operation with external sleep/wake.
Recommended
Simple Battery Charger Controller
The PIC16C55A-20E/SO acts as a state-machine controller in entry-level NiCd/NiMH/Li-ion chargers where its 20 MHz clock monitors V/I sense inputs through digital I/O and times charge phases (precharge, fast-charge, top-off, terminate). The 768-byte OTP holds the charger algorithm, the 28-SOIC footprint is compatible with wave-soldered or reflow production, and the extended -40 C to +125 C grade handles warm charger enclosures. Designers should add external ADC circuitry because this MCU has no integrated ADC.
Recommended
Industrial Sensor Interface / Signal Conditioner
The PIC16C55A-20E/SO is used as a low-cost front-end MCU in industrial signal-conditioning modules where it scans digital sensor inputs, performs linearization or threshold logic in firmware, and drives isolated outputs. The 20 MHz throughput handles 1 kHz sample loops for simple digital filtering, the 20 digital I/Os are sufficient to read multiple sensor channels, and the wide operating temperature grade (-40 C to +125 C) suits factory-floor environments. The 28-SOIC package is compatible with conformal-coated industrial PCBs.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55A-20E/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55A-20/SO | PIC16C55A-04E/SO | PIC16C57C-20/SO | PIC16F54-I/SO | PIC16C54A-20I/SO |
|---|---|---|---|---|---|---|
| Package | 28-SOIC (SO, 0.295 in) | 28-SOIC (SO, 0.295 in) - same | 28-SOIC (SO, 0.295 in) - same | 28-SOIC (SO, 0.295 in) - same | 28-SOIC (SO, 0.295 in) - same | 28-SOIC (SO, 0.295 in) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Max Clock Frequency | 20 MHz | 20 MHz | 4 MHz | 20 MHz | 20 MHz | 20 MHz |
| Program Memory | 768 B (512 x 12 OTP) | 768 B (512 x 12 OTP) | 768 B (512 x 12 OTP) | 1536 B (1024 x 12 OTP) | 768 B FLASH | 512 B (384 x 12 OTP) |
| RAM Size | 24 B | 24 B | 24 B | 72 B | 25 B | 25 B |
| Memory Type | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | FLASH (reprogrammable) | OTP EPROM |
| Operating Temperature | -40 C to +125 C (E grade) | 0 C to +70 C | -40 C to +125 C (E grade) | 0 C to +70 C | -40 C to +85 C (I grade) | -40 C to +85 C (I grade) |
| Supply Voltage | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 3.0 V to 5.5 V | 2.0 V to 5.5 V | 3.0 V to 5.5 V |
| Lifecycle Status | NRND | NRND | NRND | NRND | Active | NRND |
| Oscillator | External (XT/HS/LP/RC) | External (XT/HS/LP/RC) | External (XT/HS/LP/RC) | External (XT/HS/LP/RC) | External | External (XT/HS/LP/RC) |
Key Differentiators
- Extended temperature grade in same SOIC footprint (vs PIC16C55A-20/SO)
- 20 MHz max clock vs 4 MHz alternative (vs PIC16C55A-04E/SO)
- FLASH-based upgrade path available (vs PIC16F54-I/SO)
- Larger program memory than PIC16C54A (vs PIC16C54A-20I/SO)
Design Notes
OTP memory cannot be erased or rewritten - firmware must be fully validated on EPROM-windowed samples (PIC16C55A-20/JW) or a FLASH-based sister part (PIC16F54-I/SO) before committing to OTP volume production. A single firmware bug in production requires scrapping all programmed parts. For new designs, prefer PIC16F54-I/SO (FLASH, in-circuit reprogrammable) over the OTP PIC16C55A.
Place the external crystal or resonator as close as possible to the OSC1/OSC2 pins (pins 8-9) and keep the trace lengths matched and short. Use a ground plane under the oscillator area to reduce EMI pickup. The 28-SOIC (0.295 in) body is wider than the standard 0.150 mm SOIC-8 footprint family, so confirm pad geometry and keep-out spacing against the actual land pattern recommended in the Microchip packaging specification (document 00049H).
Decouple VDD (pin 1) with a 100 nF ceramic capacitor as close as possible to the pin, plus a bulk capacitor (1-10 uF) within 10 mm. The PIC16C55A core draws low current at 20 MHz (typically <5 mA active), so power-rail sizing is straightforward, but switching I/O loads driven by the MCU may inject noise - separate analog and digital supplies if the board also hosts precision analog circuitry. The supply range is 3.0 V to 5.5 V; operation below 3.0 V is not guaranteed.
Unused I/O pins on ports B, C, and D should be configured as outputs and tied either high or low in firmware to avoid floating inputs that consume extra current. PORTB has interrupt-on-change capability on RB0-RB7; if interrupts are not used, disable the RBIE flag to prevent spurious wakeups. The PIC16C55A does not include an integrated ADC, so analog measurements require external ADC chips or a comparator circuit built from external transistors.
Compliance Information
PIC16C55A family predates current RoHS directives and Microchip does not publish RoHS compliance data for this part in the verified web sources. AEC-Q100 not explicitly qualified per Microchip product page; the -E temperature grade is not a substitute for AEC-Q100. Compliance info marked [DATA_NEEDED] should be confirmed with Microchip before automotive or EU-volume production.
