PIC16LC54CT-04/SO - 8-Bit 4MHz OTP MCU 768B | Microchip
MPN: PIC16LC54CT-04/SO ✗ End of LifePIC16LC54CT-04/SO Overview
What is an 8-bit OTP microcontroller? An 8-bit OTP MCU is a small, single-chip computer whose program memory can be written only once after manufacture using a programmer, after which the code is permanent. Within the broader semiconductor taxonomy, it sits below flash-based MCUs and above purely hardwired logic, falling under the embedded microcontrollers > microcontroller IC > integrated circuit hierarchy. The PIC16C5x family from Microchip is a foundational architecture that established the now-ubiquitous RISC instruction set in low-cost 8-bit devices.
Key features include a 12-bit wide instruction word for compact code density, a RISC core with 33 single-word instructions, two 8-bit timer/counters, a watchdog timer with its own on-chip RC oscillator, and an internal power-on reset circuit. The device operates from a 2.5V to 6.0V supply, drawing typical quiescent current in the low milliamp range. Sleep mode further reduces power for battery-sensitive applications.
Technically, the PIC16LC54C uses a Harvard architecture with separate program and data buses, enabling simultaneous instruction fetch and data access. The OTP memory cell is implemented with standard EPROM technology, retaining bits for decades when operated within the datasheet specifications. The 4MHz instruction rate translates to a 1 microsecond instruction cycle because the PIC divides the oscillator by four internally, providing predictable timing for assembly-level bit manipulation.
Typical applications include appliance control boards, simple sensor interfaces, LED driver sequencers, low-end remote controls, and replacement of discrete logic in cost-sensitive embedded products. The 18-SOIC package is convenient for hand-soldered prototypes and small-batch production runs where through-hole PDIP variants are too large.
When designing with this device, note that OTP cannot be re-programmed; verify your firmware on a windowed (JW) or flash-equivalent PIC16F5x part first. The lack of an analog comparator or ADC on the original PIC16C54 means external conditioning is required for any analog signal acquisition.
This page synthesizes distributor pricing, pin-compatible drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone, helping engineers evaluate second-source options and lifecycle risk for legacy designs.
Drop-in alternatives for PIC16LC54CT-04/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 PIC16LC54CT-04/SO (same form factor and footprint) — differing in Program Memory Size, Program Memory Type, RAM Size, Package, Timers.
PIC16LC54AT-04/SO
✅ Drop-InContact for price
View Datasheet →PIC16LC54C-04I/SO
✅ Drop-InContact for price
View Datasheet →PIC16C54C-04/SO
✅ Drop-InContact for price
View Datasheet →PIC16LC54A-04E/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F54-I/SO
✅ Drop-InContact for price
View Datasheet →PIC16LC54CT-04/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC RISC |
| Series | PIC® 16C |
| Program Memory Type | OTP (One-Time Programmable EPROM) |
| Program Memory Size | 768 B (512 x 12 words) |
| RAM Size | 25 B |
| Maximum CPU Frequency | 4 MHz |
| Instruction Cycle | 4 oscillator cycles (1 us at 4 MHz) |
| Supply Voltage (Vdd) | 2.5 V to 6.0 V |
| I/O Pins | 12 |
| Timers | 2 x 8-bit |
| Watchdog Timer | Yes (independent on-chip RC oscillator) |
| Package / Case | 18-SOIC (0.295", 7.50 mm width) |
| Mounting Type | Surface Mount |
| Operating Temperature | 0 C to +70 C (commercial grade) |
PIC16LC54CT-04/SO Pin Configuration
| Pin 1 | RA0 — Bidirectional I/O, Port A bit 0 |
| Pin 2 | RA1 — Bidirectional I/O, Port A bit 1 |
| Pin 3 | RA2 — Bidirectional I/O, Port A bit 2 |
| Pin 4 | RA3/MCLR/Vpp — Bidirectional I/O, Master Clear reset, OTP programming voltage |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0 — Bidirectional I/O, Port B bit 0 |
| Pin 7 | RB1 — Bidirectional I/O, Port B bit 1 |
| Pin 8 | RB2 — Bidirectional I/O, Port B bit 2 |
| Pin 9 | RB3 — Bidirectional I/O, Port B bit 3 |
| Pin 10 | RB4 — Bidirectional I/O, Port B bit 4 |
| Pin 11 | RB5 — Bidirectional I/O, Port B bit 5 |
| Pin 12 | RB6 — Bidirectional I/O, Port B bit 6 |
| Pin 13 | RB7 — Bidirectional I/O, Port B bit 7 |
| Pin 14 | VDD — Positive supply (2.5 V to 6.0 V) |
| Pin 15 | OSC2/RA6 — Oscillator output / Port A bit 6 |
| Pin 16 | OSC1/RA7 — Oscillator input / Port A bit 7 |
| Pin 17 | RA4 — Bidirectional I/O, Port A bit 4 |
| Pin 18 | RA5 — Bidirectional I/O, Port A bit 5 |
Typical Applications
PIC16LC54CT-04/SO is suitable for 6 applications: Appliance Control Boards, LED Sequencer / Chaser Light, Remote Control Transmitter, Sensor Interface / Signal Conditioning, Replacement of Discrete Logic (Glue Logic Consolidation), Battery-Powered Timing Module.
Appliance Control Boards
The PIC16LC54CT-04/SO fits appliance control boards because its 12 CMOS I/O pins are sufficient to drive relays, triacs, LEDs, and keypads found in washing machines, dishwashers, and microwave ovens. The 768 B OTP memory holds typical appliance firmware such as mode sequencers and timing loops. The 2.5 V to 6.0 V supply range allows direct connection to rectified 5 V or 3.3 V rails. Place a 100 nF decoupling capacitor within 5 mm of Vdd pin 14, and use a 4 MHz ceramic resonator on OSC1/OSC2 with built-in load capacitors to minimize BOM count.
Recommended
LED Sequencer / Chaser Light
The PIC16LC54CT-04/SO is well suited to LED sequencer and chaser lighting products where cost dominates. Two 8-bit timers multiplex up to 16 LEDs through the RA and RB ports at refresh rates well above 100 Hz, eliminating visible flicker. The 1 us instruction cycle at 4 MHz handles bit-banged patterns such as Knight Rider, fade sequences, and holiday-light controllers without external driver ICs. Use a 4 MHz crystal rather than the internal RC to keep timing precise across temperature, and place current-limit resistors on every LED line to protect the I/O pins.
Recommended
Remote Control Transmitter
The PIC16LC54CT-04/SO serves as the encoder in low-cost infrared or RF remote controls. Its low power consumption and small code footprint allow 768 B of OTP to store button-scan routines and protocol packets such as RC-5 or Sony SIRC. The 12 I/O pins connect to a 4x4 keypad matrix and to a 38 kHz carrier output feeding an IR LED driver transistor. Brownout detection via the power-on reset circuit prevents corrupted transmissions when the battery is weak. Migrate to PIC16LF54 for 1.8 V operation if extended battery life is required.
Recommended
Sensor Interface / Signal Conditioning
The PIC16LC54CT-04/SO works as a simple sensor interface where no analog-to-digital conversion is required on-chip, such as counting pulses from a flow meter, reading quadrature encoders, or debouncing mechanical switches. The 25 B RAM and two 8-bit timers capture timing events with microsecond resolution at 4 MHz, sufficient for rate measurement in HVAC or process-control applications. Connect sensors to RB0-RB7 with external Schmitt-trigger buffers to clean noisy signals before they reach the MCU. The OTP memory guarantees firmware integrity in fielded units.
Recommended
Replacement of Discrete Logic (Glue Logic Consolidation)
The PIC16LC54CT-04/SO replaces tens of 74-series TTL or HC logic gates by implementing state machines, custom counters, and protocol converters in software. At a unit price competitive with a single 74HC00 quad NAND, a single PIC MCU absorbs what would otherwise be 5-10 SSI/MSI packages, reducing PCB area and assembly cost. Use this approach when a board already requires firmware-driven behavior such as timeouts or sequencing. Ensure OTP programming is finalized before ordering the parts, since OTP cannot be rewritten.
Recommended
Battery-Powered Timing Module
The PIC16LC54CT-04/SO is appropriate for battery-powered timing modules such as intervalometers, parking meters, or simple data loggers because of its low-power CMOS design and sleep-mode support. At 4 MHz, the device draws only a few milliamps from a 3 V coin cell, extending service life to multiple years in pulsed-duty applications. The watchdog timer wakes the MCU from sleep on overflow, eliminating the need for an external RTC. Use a low-quiescent LDO such as MCP1700 to regulate the supply and minimize dark current.
Recommended
Recommended Products Summary
Engineering reference data for PIC16LC54CT-04/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16LC54AT-04/SO | PIC16LC54C-04I/SO | PIC16C54C-04/SO | PIC16LC54A-04E/SO | PIC16F54-I/SO |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 18-SOIC | 18-SOIC - same | 18-SOIC - same | 18-SOIC - same | 18-SOIC - same | 18-SOIC - same |
| Program Memory Type | OTP EPROM (768 B / 512 x 12) | Flash (768 B) | OTP EPROM (768 B) | OTP EPROM (768 B) | OTP EPROM (768 B) | Flash (768 B) |
| Maximum Frequency | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 20 MHz |
| RAM Size | 25 B | 25 B | 25 B | 25 B | 25 B | 25 B |
| I/O Pins | 12 | 12 | 12 | 12 | 12 | 12 |
| Supply Voltage | 2.5 V to 6.0 V | 2.5 V to 6.0 V | 2.5 V to 6.0 V | 3.0 V to 6.0 V | 2.5 V to 6.0 V | 2.0 V to 5.5 V |
| 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 +125 C | -40 C to +85 C |
Key Differentiators
- Industry-standard 18-SOIC footprint with multiple drop-in alternatives (vs PIC16F54-I/SO)
- Established NRND lifecycle status (vs PIC16LC54AT-04/SO)
- Low-voltage CMOS operation to 2.5 V (vs PIC16C54C-04/SO)
Design Notes
Place a 100 nF decoupling capacitor within 5 mm of the Vdd pin (14) and the Vss pin (5). For boards with multiple ICs, add a 10 uF bulk capacitor near the regulator. The PIC16LC54C draws transient currents of 10-20 mA during instruction execution; insufficient decoupling causes code-fetch errors and intermittent resets. Brownout is handled internally by the POR circuit, but adding an external reset supervisor (e.g., MCP100) is recommended in noisy industrial environments.
Route the crystal or ceramic resonator leads to OSC1/OSC2 as short as possible and keep them away from high-current traces. The exposed pad of the 18-SOIC is not present on this package, but copper pour under the device still aids thermal dissipation. If using an RC oscillator instead of a crystal, choose component values from the datasheet's RC table for stable operation across the 2.5 V to 6.0 V Vdd range. Always test oscillator start-up at minimum Vdd before committing the design to production.
Do not assume OTP can be re-programmed - once written, the PIC16LC54CT-04/SO is locked and must be discarded if firmware changes. Use a JW (windowed) package or the flash-based PIC16F54 for development. Another common pitfall is leaving the WDT enabled in battery-powered designs, which causes the MCU to reset every 18 ms; either disable WDT in the configuration word or service it in firmware. Finally, verify the /MCLR pin (pin 4) is tied to Vdd through a 10 kohm resistor; floating /MCLR results in random resets.
Compliance Information
RoHS, lead-free, and halogen-free status not confirmed in the verified web data; consult Microchip's product environmental compliance page before placing orders for markets requiring these certifications.