PIC16LC54AT-04I/SO - 4MHz 8-Bit OTP MCU, 768B | Microchip
MPN: PIC16LC54AT-04I/SO ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.95 | $2.95 |
| 10 | $2.66 | $26.60 |
| 100 | $2.36 | $236.00 |
| 500 | $2.07 | $1,035.00 |
| 1,000 | $1.78 | $1,780.00 |
PIC16LC54AT-04I/SO Overview
What is an OTP microcontroller? An OTP (One-Time Programmable) microcontroller is a class of MCU whose program memory is implemented as user-programmable non-volatile memory (EPROM/UV-EPROM based) that can be written only once after manufacture using a device programmer. Once programmed, the code becomes permanent; unlike Flash microcontrollers, the program memory cannot be erased or rewritten in-circuit. OTPs occupy a hypernym hierarchy of: microcontroller -> embedded MCU -> CMOS digital IC. They are widely used in high-volume cost-sensitive products where firmware is final, such as appliance controllers, sensor nodes, and disposable consumer devices.
Key features of the PIC16LC54AT-04I/SO include a two-level deep hardware call stack, 12-bit wide instructions with 8-bit data path, direct/indirect/relative addressing modes, a single 8-bit timer/counter (TMR0), and seven special function hardware registers. The PIC16C5X core delivers roughly twice the code density of competing 8-bit MCUs thanks to its highly orthogonal 12-bit instruction set, which reduces overall program memory consumption by approximately 2:1 versus 8-bit instruction-set MCUs of the same era.
Architecturally, the PIC16LC54A uses a Harvard architecture with separate program and data buses, fully static CMOS design for low quiescent current, and a watchdog timer option on the wider PIC16C5X family. The "A" suffix denotes the improved silicon revision that fixes early silicon errata of the original PIC16C54 and adds the high-end OTP variants. The 18-SOIC (300-mil) package offers a familiar through-hole-compatible footprint for legacy designs.
Typical applications include low-cost consumer appliances, simple LED controllers, remote key fobs, basic sensor signal conditioning, educational development platforms, and industrial timer/counter modules where the OTP memory suffices and Flash is unnecessary. The 3 V to 6.25 V supply range and 4 MHz clock are sufficient for slow control loops and human-interface polling tasks.
When designing with this MCU, plan program memory carefully: the 768-byte (512 x 12) OTP must hold your entire firmware. Use MPLAB X IDE with MPASMX assembler or XC8 compiler (legacy support) for code development. For new designs, consider migrating to the Flash-based PIC16F54 drop-in equivalent which retains the same pinout and instruction set while adding in-circuit reprogrammability.
This page synthesizes distributor stock, parametric alternatives, and design migration paths not found in the manufacturer datasheet, including Flash drop-in replacements and same-package PIC16C5X family variants.
Drop-in alternatives for PIC16LC54AT-04I/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 PIC16LC54AT-04I/SO (same form factor and footprint) — differing in Core, Package, Instruction Set, Program Memory Type, Watchdog Timer.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16LC54A-04I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C54A-04I/SO
✅ Drop-In✓ In Stock
$2.55 / Unit
View Datasheet →PIC16C54C-04I/SO
✅ Drop-In✓ In Stock
$2.18 / Unit
View Datasheet →PIC16F54-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16CR54A-04I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16LC54AT-04I/SO Maximum Ratings & Electrical Characteristics
| Architecture | PIC16C5X 8-bit Harvard |
| Core | PIC16C5X (RISC) |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 768 bytes (512 x 12 bits) |
| RAM Size | 25 x 8 bytes |
| Data EEPROM | Not present |
| Maximum Clock Speed | 4 MHz |
| Instruction Width | 12 bits |
| Supply Voltage (Vdd) | 3.0 V to 6.25 V |
| I/O Pins | 12 |
| Timers | 1 x 8-bit (TMR0) |
| Hardware Stack | 2 levels deep |
| Watchdog Timer | Present (family feature) |
| ADC | None |
| Operating Temperature | -40C to +85C (Industrial grade) |
| Package | 18-pin SOIC (300 mil, SO) |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited floor life) |
| RoHS Status | Compliant |
| Lead-Free | Yes |
PIC16LC54AT-04I/SO Pin Configuration
| Pin 1 | /MCLR — Master Clear (reset, active low) |
| Pin 2 | RA0 — Port A bit 0 (digital I/O) |
| Pin 3 | RA1 — Port A bit 1 (digital I/O) |
| Pin 4 | RA2 — Port A bit 2 (digital I/O) |
| Pin 5 | RA3 — Port A bit 3 (digital I/O) |
| Pin 6 | RB0 — Port B bit 0 (digital I/O) |
| Pin 7 | RB1 — Port B bit 1 (digital I/O) |
| Pin 8 | Vss — Ground reference |
| Pin 9 | OSC1 — Oscillator input / external clock |
| Pin 10 | OSC2 — Oscillator output (crystal mode) |
| Pin 11 | RB2 — Port B bit 2 (digital I/O) |
| Pin 12 | RB3 — Port B bit 3 (digital I/O) |
| Pin 13 | RB4 — Port B bit 4 (digital I/O) |
| Pin 14 | Vdd — Positive supply (3.0-6.25 V) |
| Pin 15 | RB5 — Port B bit 5 (digital I/O) |
| Pin 16 | RB6 — Port B bit 6 (digital I/O) |
| Pin 17 | RB7 — Port B bit 7 (digital I/O) |
| Pin 18 | NC — Not connected (per datasheet) |
Typical Applications
PIC16LC54AT-04I/SO is suitable for 6 applications: Low-Cost Consumer Appliance Controller, Remote Key Fob and RF Encoder, Industrial Timer / Counter Module, Educational Microcontroller Trainer, LED Lighting Sequencer / Chaser, Simple Sensor Signal Conditioning Front-End.
Low-Cost Consumer Appliance Controller
The PIC16LC54AT-04I/SO fits low-cost consumer appliances such as toasters, coffee makers, and rice cookers because its 768-byte OTP program memory is sufficient for fixed-function control firmware, and the 3.0-6.25 V supply range allows direct connection to rectified 5 V or 3.3 V rails without additional regulators. With 12 I/O pins the MCU can directly drive relays, read keypad matrix inputs, and multiplex 7-segment or LED displays via the RB port. The 4 MHz instruction rate yields a 1 us instruction cycle, which is fast enough for polled button debounce and slow PWM-like control loops without needing interrupt overhead.
Recommended
Remote Key Fob and RF Encoder
The PIC16LC54AT-04I/SO is well-suited for simple RF remote-control key fobs because its 25-byte RAM and 768-byte OTP are adequate for storing fixed transmission codes and basic button debounce logic. The PIC16C5X core's predictable 1 us instruction cycle at 4 MHz allows tight timing control of encoder pulse widths without crystal precision drift, and the 3 V low-voltage operation matches coin-cell battery packs directly. Its 12 I/O pins comfortably interface 2-4 buttons plus an ASK/OOK transmitter module such as the MICRF102.
Recommended
Industrial Timer / Counter Module
Industrial timer modules benefit from the PIC16LC54AT-04I/SO's industrial -40C to +85C operating range, 4 MHz clock for second-to-hour timing, and the single 8-bit TMR0 that can be prescaled for long interval counting. The OTP memory is ideal for fixed time-range products where firmware is locked once deployed. The 18-SOIC package fits compact DIN-rail-mounted timer enclosures, and the 3-6.25 V supply accommodates 5 V industrial rails without additional regulation.
Recommended
Educational Microcontroller Trainer
Hobbyist and educational microcontroller trainer boards use the PIC16LC54AT-04I/SO to teach fundamental 8-bit embedded programming because of its simple PIC16C5X instruction set, small 768-byte program memory that forces students to write efficient code, and 12 accessible I/O pins for breadboard experimentation. The 3-6.25 V supply range means it runs from a 9 V battery with a simple 7805 regulator. Its low cost (under USD 3 at qty 1) makes it attractive for inclusion in starter kits, and MPLAB X IDE with the XC8 compiler fully supports it.
Recommended
LED Lighting Sequencer / Chaser
Decorative LED chasers and sequencer modules pair well with the PIC16LC54AT-04I/SO because the 12 I/O pins can directly drive up to 12 individual LEDs (with current-limiting resistors) or multiplex a larger array in a charlieplex/charlie-LED configuration. The 768-byte OTP holds multiple chase-pattern look-up tables, and the 4 MHz clock delivers smooth visual transitions. The 3-6.25 V supply lets the chip run directly from a 5 V USB or battery pack, and the OTP memory prevents accidental code corruption during power glitches.
Recommended
Simple Sensor Signal Conditioning Front-End
Simple sensor-conditioning front-ends for thermostats, soil-moisture probes, and basic level sensors use the PIC16LC54AT-04I/SO to digitize slow-changing analog signals via a comparator-based slope ADC, then drive indicator LEDs or relay outputs. The single 8-bit TMR0 with prescaler provides the time base for ratiometric measurements, and the OTP memory locks the calibration constants at production. The 3-6.25 V supply supports both 3.3 V sensor modules and 5 V industrial signal chains.
Recommended
Recommended Products Summary
Engineering reference data for PIC16LC54AT-04I/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16LC54A-04I/SO | PIC16C54A-04I/SO | PIC16C54C-04I/SO | PIC16F54-I/SO | PIC16CR54A-04I/SO |
|---|---|---|---|---|---|---|
| Package | 18-SOIC (300 mil) | 18-SOIC (300 mil) - same | 18-SOIC (300 mil) - same | 18-SOIC (300 mil) - same | 18-SOIC (300 mil) - same | 18-SOIC (300 mil) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 768 B OTP EPROM | 768 B OTP EPROM | 768 B OTP EPROM | 768 B OTP EPROM | 768 B Flash | 768 B Mask ROM |
| Max Clock Speed | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 20 MHz (Flash) | 4 MHz |
| Supply Voltage | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 4.0 V to 6.25 V | 3.0 V to 6.25 V | 2.0 V to 5.5 V | 3.0 V to 6.25 V |
| In-Circuit Reprogrammable | No (OTP) | No (OTP) | No (OTP) | No (OTP) | Yes (Flash, ICSP) | No (Mask ROM) |
| I/O Pins | 12 | 12 | 12 | 12 | 12 | 12 |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
Key Differentiators
- OTP EPROM retains firmware permanently even after power loss (vs PIC16F54-I/SO)
- Lower 3.0 V minimum supply enables 3.3 V direct operation (vs PIC16C54A-04I/SO)
- 12-bit RISC instruction set delivers ~2:1 code density vs competitors (vs PIC16F54-I/SO (also 12-bit))
Design Notes
Estimated: PIC16LC54AT-04I/SO quiescent current is typically 1-2 mA at 5 V and 4 MHz, but the device has no power-down or sleep mode because the PIC16C5X base architecture predates the SLP/IDLE instructions of later PIC families. For battery-powered designs, you must gate Vdd externally with a load switch and use the /MCLR pin to wake up. Add a 100 nF decoupling capacitor close to Vdd (pin 14) and a 10 uF bulk capacitor on the supply rail; the part can glitch on Vdd dips below 3.0 V which may corrupt OTP read mode operation.
Place the decoupling capacitor within 5 mm of the Vdd pin (pin 14) and the Vss pin (pin 8). Keep the oscillator traces short: connect a 4 MHz ceramic resonator with built-in capacitors (e.g., Murata CSTLS series) between OSC1 (pin 9) and OSC2 (pin 10), or use an external crystal with two 15-33 pF load capacitors. The /MCLR pin (pin 1) requires a 10 kohm pull-up to Vdd for normal operation; adding a momentary pushbutton to ground allows manual reset during development.
Critical: Once programmed, the PIC16LC54AT-04I/SO's OTP memory cannot be erased or rewritten. There is no in-circuit programming (ICSP) interface - the part must be programmed in a standalone device programmer (such as Microchip PICkit 1/2/3 in programmer-not-debugger mode, or a Universal Programmer like Dataman). Do not design firmware expecting field updates; if in-field updates are needed, migrate to the Flash-based PIC16F54-I/SO. Also note that the PIC16C5X has NO interrupt controller - all event handling must use polled loops. Programming voltage Vpp (typically 13 V on /MCLR) is required and not generated internally.
Compliance Information
RoHS compliant per Microchip product page. Industrial temperature grade -40C to +85C. Not AEC-Q100 qualified for automotive applications; use PIC16F54-E/SO or PIC16F54-I/SO for AEC-Q100 needs.
