PIC16C55T-XT/SO - 8-bit OTP MCU, 768B EPROM, 20 I/O SOIC-28 | Microchip
MPN: PIC16C55T-XT/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.54 | $1.54 |
| 10 | $1.38 | $13.80 |
| 100 | $1.2 | $120.00 |
| 500 | $1.05 | $525.00 |
| 1,000 | $0.92 | $920.00 |
PIC16C55T-XT/SO Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU, memory (program + data), and peripheral I/O. Within the product hierarchy, the PIC16C5X belongs to the 8-bit MCU -> microcontroller -> embedded controller -> semiconductor family. The PIC16C5X series in particular is Microchip's original "baseline" OTP/EPROM-based MCU architecture, designed for cost-sensitive, low-to-medium complexity embedded applications where flash reprogrammability is not required, making it well-suited for high-volume consumer and industrial products.
Key features include Harvard-architecture separate program and data buses, a 12-bit instruction word, a 2-level hardware stack, an 8-bit timer/counter with optional programmable prescaler, power-on reset, watchdog timer with on-chip RC oscillator, code-protection EPROM security, and CMOS technology for very low power consumption (typically < 2 mA at 5 V/4 MHz and < 20 uA in standby). The 20-mA sink/source per-pin capability (max 25 mA per pin) on the 20 I/O pins directly drives LEDs and small relays.
Typical applications include remote-control transmitters, security-system sensor interfaces, appliance controllers (microwave, washing machine, thermostat), consumer-electronics toys, simple battery chargers, smoke detectors, automotive interior accessories (non-safety), and any high-volume appliance where the OTP memory's one-time-programmable cost advantage outweighs the need for in-system reprogramming. The wide SOIC-28 footprint simplifies hand-soldering and rework compared to shrink-SOIC packages.
When designing with this part, verify that the OTP program memory will be burned before PCB assembly - field updates are not possible. Ensure the VDD rise time stays below the POR-specification ramp; if a slow-rising supply is unavoidable, use a power-on-reset supervisor. Decouple VDD with a 0.1 uF ceramic capacitor placed within 5 mm of the pin, and connect the OSC1/OSC2 crystal traces in short, ground-guarded paths.
Drop-in alternatives for PIC16C55T-XT/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 PIC16C55T-XT/SO (same form factor and footprint) — differing in Package, Program Memory Size, RoHS Status, Timers, Mounting Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55T-RC/SO
✅ Drop-In✓ In Stock
$2.45 / Unit
View Datasheet →PIC16C55T-LPI/SO
✅ Drop-In✓ In Stock
$2.49 / Unit
View Datasheet →PIC16C55T-HS/SO
✅ Drop-In✓ In Stock
$2.78 / Unit
View Datasheet →PIC16C55T-HSE/SO
✅ Drop-In✓ In Stock
$5.74 / Unit
View Datasheet →PIC16C55-RCI/SO
✅ Drop-In✓ In Stock
$1.85 / Unit
View Datasheet →PIC16C55-HS/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55AT-40/SO
✅ Drop-In✓ In Stock
$5.66 / Unit
View Datasheet →PIC16C55T-XT/SO Maximum Ratings & Electrical Characteristics
| Program Memory Type | EPROM (OTP) |
| Program Memory Size | 768 bytes (0.75 KB) |
| Data RAM | 24 bytes |
| CPU Architecture | 8-bit RISC (PIC16C5X baseline) |
| Instruction Word Width | 12 bits |
| Instruction Set Size | 33 single-word instructions |
| Maximum CPU Frequency | 4 MHz (XT oscillator) |
| Supply Voltage (VDD) | 2.5 V to 6.25 V |
| I/O Pins | 20 (Ports RA, RB, RC) |
| Timers | 1 x 8-bit Timer/Counter0 with prescaler |
| Watchdog Timer | Yes (on-chip RC oscillator) |
| Power-on Reset | Yes |
| Stack Depth | 2-level hardware |
| I/O Sink/Source Current | 20 mA per pin (max 25 mA) |
| Operating Temperature | 0 C to +70 C (commercial) |
| Package | SOIC-28 (300 mil, wide-body) |
| Mounting Type | Surface Mount |
| RoHS Status | Non-Compliant (contains Pb, Sn/Pb finish) |
| Packaging Code | T = Tape and Reel |
PIC16C55T-XT/SO Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O pin, Port A bit 2 |
| Pin 2 | RA3 — Bidirectional I/O pin, Port A bit 3 |
| Pin 3 | RA4/T0CKI — Bidirectional I/O pin, alt: Timer0 clock input |
| Pin 4 | MCLR — Master Clear (Reset) input, active low |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — Bidirectional I/O pin, alt: External interrupt input |
| Pin 7 | RB1 — Bidirectional I/O pin, Port B bit 1 |
| Pin 8 | RB2 — Bidirectional I/O pin, Port B bit 2 |
| Pin 9 | RB3 — Bidirectional I/O pin, Port B bit 3 |
| Pin 10 | RB4 — Bidirectional I/O pin, Port B bit 4 |
| Pin 11 | RB5 — Bidirectional I/O pin, Port B bit 5 |
| Pin 12 | RB6 — Bidirectional I/O pin, Port B bit 6 |
| Pin 13 | RB7 — Bidirectional I/O pin, Port B bit 7 |
| Pin 14 | VSS — Ground reference (secondary) |
| Pin 15 | OSC1/CLKIN — Oscillator crystal input / external clock in |
| Pin 16 | OSC2/CLKOUT — Oscillator crystal output / clock out (XT mode) |
| Pin 17 | RC0 — Bidirectional I/O pin, Port C bit 0 |
| Pin 18 | RC1 — Bidirectional I/O pin, Port C bit 1 |
| Pin 19 | RC2 — Bidirectional I/O pin, Port C bit 2 |
| Pin 20 | RC3 — Bidirectional I/O pin, Port C bit 3 |
| Pin 21 | RC4 — Bidirectional I/O pin, Port C bit 4 |
| Pin 22 | RC5 — Bidirectional I/O pin, Port C bit 5 |
| Pin 23 | RC6 — Bidirectional I/O pin, Port C bit 6 |
| Pin 24 | RC7 — Bidirectional I/O pin, Port C bit 7 |
| Pin 25 | RA0 — Bidirectional I/O pin, Port A bit 0 |
| Pin 26 | RA1 — Bidirectional I/O pin, Port A bit 1 |
| Pin 27 | VDD — Positive supply voltage (2.5 V to 6.25 V) |
| Pin 28 | VDD — Positive supply voltage (secondary, both VDD pins tied) |
Typical Applications
PIC16C55T-XT/SO is suitable for 7 applications: Remote Control Transmitters, Home Appliance Controllers, Security System Sensor Nodes, Automotive Interior Accessories, Consumer Electronics Toys, Smart Battery Chargers (Lead-Acid / NiMH), Industrial Sensor / Counter Modules.
Remote Control Transmitters
The PIC16C55T-XT/SO is well-suited for IR/RF remote-control transmitters in consumer electronics: its 20 mA per-pin sink/source capability directly drives IR LEDs without driver transistors, its 4 MHz XT oscillator is fast enough for 38 kHz / 40 kHz carrier modulation, and its 0.75 KB EPROM easily fits single-button to 32-button keypad scanning firmware. Typical draw of < 2 mA active at 5 V extends coin-cell battery life. Place the part in SOIC-28 with a 0.1 uF decoupling cap within 5 mm of VDD; drive the IR LED directly from an RB pin.
Recommended
Home Appliance Controllers
In microwave ovens, washing machines, dishwashers, and toaster ovens, the PIC16C55T-XT/SO integrates the entire control function: 20 I/O pins scan keypads, drive 7-segment LED displays, sense temperature/humidity via ADC-free comparators, and switch triac-driver outputs. The OTP EPROM keeps unit cost low for high-volume SKUs. Total BOM cost is minimized because no external program-memory IC is needed. Watchdog timer guards against mains-burst ESD events; the SOIC-28 wide-body footprint eases field repair.
Recommended
Security System Sensor Nodes
For PIR motion, door/window contact, and smoke-detector sensor nodes, the PIC16C55T-XT/SO delivers low standby current (< 20 uA at 5 V) so battery life exceeds 2 years, plus enough program memory for custom tamper-detection and low-battery-warning logic. Its hardware watchdog prevents lockup in long-unattended installations, and the SOIC-28 wide-body is robust enough for industrial temperature swings. Pair with an RF transceiver IC for wireless alarm panels or with a piezo buzzer for local sirens.
Recommended
Automotive Interior Accessories
For non-safety automotive accessories such as interior LED mood lighting, seat heaters, and auxiliary fan controllers, the PIC16C55T-XT/SO provides 20 mA I/O to drive MOSFET gates and LED strings directly, plus 768 bytes for PWM and soft-start firmware. Its commercial 0 C to +70 C rating covers cabin environments; the SOIC-28 footprint survives vibration better than QFN alternatives. Migrate to AEC-Q100 qualified PIC16F equivalents (e.g. PIC16F1825-I/SO) for under-hood or safety-related applications.
Recommended
Consumer Electronics Toys
The PIC16C55T-XT/SO is a cost-optimized MCU for talking dolls, electronic learning toys, simple handheld games, and musical greeting cards: its sub-$1.50 qty-1 price (as of 2026-09-16) keeps toy BOM costs competitive, its 20 I/O pins handle button matrices and small LCD/LED displays, and its 4 MHz instruction rate supports simple sound synthesis via bit-banged PWM. The EPROM OTP model protects against unauthorized firmware cloning, which matters for branded character licenses.
Recommended
Smart Battery Chargers (Lead-Acid / NiMH)
For single-cell or multi-cell NiMH / lead-acid chargers in the 1 A to 5 A range, the PIC16C55T-XT/SO implements CC/CV charge profiles in firmware, drives MOSFET pass elements or relay outputs via its 20-mA-rated I/O, and monitors voltage dividers on its digital I/O with simple comparator thresholds. The 4 MHz XT oscillator provides sufficient timing resolution for delta-V peak detection, and the OTP EPROM prevents reverse-engineering of proprietary charge algorithms.
Recommended
Industrial Sensor / Counter Modules
In factory-floor pulse counters, rotation sensors, and simple PLC-I/O expansion boards, the PIC16C55T-XT/SO offers 20 isolated digital inputs via its 20 I/O pins, an 8-bit hardware timer for frequency/event counting, and watchdog-timer robustness against electrical transients. SOIC-28 footprint supports through-hole reflow with hand-soldering fallback for low-volume SKUs. The EPROM OTP nature prevents IP leakage of proprietary counting protocols.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55T-XT/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55T-RC/SO | PIC16C55T-LPI/SO | PIC16C55T-HS/SO | PIC16C55-RCI/SO | PIC16C55AT-40/SO |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | SOIC-28 (wide-body 300 mil) | SOIC-28 - same | SOIC-28 - same | SOIC-28 - same | SOIC-28 - same | SOIC-28 - same |
| Program Memory | 768 B OTP EPROM | 768 B OTP EPROM | 768 B OTP EPROM | 768 B OTP EPROM | 768 B OTP EPROM | 768 B OTP EPROM (PIC16C55A silicon) |
| Max CPU Frequency | 4 MHz (XT oscillator) | 4 MHz (RC oscillator) | 200 kHz (LP oscillator) | 20 MHz (HS oscillator) | 4 MHz (RC, industrial temp) | 40 MHz equivalent |
| Operating Temperature | 0 C to +70 C | 0 C to +70 C | -40 C to +85 C | 0 C to +70 C | -40 C to +85 C | 0 C to +70 C |
| Supply Voltage | 2.5 V to 6.25 V | 2.5 V to 6.25 V | 2.5 V to 6.25 V | 2.5 V to 6.25 V | 2.5 V to 6.25 V | 2.5 V to 6.25 V |
| I/O Pins | 20 | 20 | 20 | 20 | 20 | 20 |
| Lifecycle Status | NRND | NRND | NRND | NRND | NRND | NRND |
| Unit Price (qty-1) | $1.54 | ~$1.54 | ~$1.54 | ~$1.54 | ~$1.54 | ~$1.54 |
Key Differentiators
- Cost-optimized 8-bit baseline MCU with 0.75 KB OTP EPROM (vs PIC16F55-I/SO (flash-based))
- Wide-body SOIC-28 package simplifies hand-soldering and rework (vs QFN-packaged PIC16F series equivalents)
- 20 mA I/O sink/source drives LEDs without external transistors (vs Most modern 8-bit MCUs (typically 5-10 mA per pin))
Design Notes
PIC16C55T-XT/SO supply voltage (VDD) range is 2.5 V to 6.25 V. Place a 0.1 uF ceramic decoupling capacitor within 5 mm of each VDD pin (pins 27 and 28) to suppress high-frequency switching noise from the internal CPU. If the application draws large transient loads on the same supply (e.g., a relay or buzzer), add a 10 uF bulk capacitor. Tie both VDD pins together on the PCB and both VSS pins together. Do not allow VDD rise time to exceed the POR threshold, or use a discrete POR supervisor.
SOIC-28 wide-body (300-mil) footprint requires minimum pad pitch of 1.27 mm (50 mil) and pad width of 0.6 mm. Route OSC1 (pin 15) and OSC2 (pin 16) traces as short as possible, ground-guarded, and keep them away from high-current switching traces to avoid oscillator instability. The MCLR pin (pin 4) should have a 10 kohm pull-up resistor to VDD and a 100 nF cap to ground for hardware-reset debouncing.
Because this is OTP EPROM, firmware cannot be field-updated. All firmware must be fully validated and burned before PCB assembly; budget extra time and samples for OTP-only prototyping. Watchdog timer must be enabled and cleared by firmware, or it will reset the device every ~18 ms (typical WDT period with on-chip RC). I/O pin current limit is 20 mA continuous / 25 mA peak - do not exceed this when driving LEDs, or use a transistor driver.
SOIC-28 wide-body package thermal resistance is approximately 80 C/W (theta_JA on a 1-oz 4-layer JEDEC test board). At 4 mA active current and 5 V supply, dissipation is only 20 mW, so junction temperature rise is negligible (< 1.6 C above ambient). No heatsink is required for typical embedded-controller applications. Estimated: P = VDD x IDD_active = 5 V x 4 mA = 20 mW; TJ_rise = 20 mW x 80 C/W = 1.6 C.
Compliance Information
PIC16C55T-XT/SO uses Sn/Pb (tin-lead) lead finish to maintain soldering compatibility with the EPROM-based process flow, hence non-RoHS-compliant. Reach is compliant per Microchip product statement. Not AEC-Q100 qualified - not intended for automotive under-hood or safety applications.
