PIC16LC66-04/SO - 8-Bit 4MHz MCU, 14KB OTP, 28-SOIC | Microchip
MPN: PIC16LC66-04/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.8 | $3.80 |
| 10 | $3.5 | $35.00 |
| 100 | $3.1 | $310.00 |
| 500 | $2.75 | $1,375.00 |
| 1,000 | $2.4 | $2,400.00 |
PIC16LC66-04/SO Overview
A microcontroller (MCU) is a single-chip computer containing a processor core, program memory, working RAM, and configurable peripherals. The PIC16C family uses a Harvard RISC architecture that separates program and data buses, enabling simultaneous instruction fetch and data access. Within the broader taxonomy, the PIC16LC66 is a mid-range 8-bit MCU falling under the power-managed LC sub-family, sitting between basic PIC12/PIC14 devices and higher-pin PIC17/PIC18 parts.
Key features include on-chip peripherals for I2C (Master/Slave SPI-compatible), SPI, and UART/USART connectivity; capture/compare/PWM (CCP) modules for timing-critical control; an 8-channel 8-bit A/D converter for analog sensor interfacing; and a watchdog timer plus power-on reset for reliable standalone operation. The 'LC' suffix indicates the low-voltage CMOS process node, allowing operation down to 2.5V for battery-powered designs.
The 28-SOIC (0.295-inch / 7.50mm body width) package uses gull-wing leads and surface-mount construction, suitable for hand-soldering, reflow, and standard pick-and-place assembly. Commercial temperature grade (0C to +70C) targets consumer and industrial embedded systems rather than automotive. The OTP program memory is factory- or field-programmable once, with no in-circuit reprogramming, which differentiates this part from Flash-based PIC16F siblings.
Typical applications include industrial control panels, sensor interfaces, low-power remote controls, appliance control boards, and battery-operated data loggers. When designing with this device, ensure the oscillator selection (RC, XT, HS, LP) matches the 4MHz instruction rate, and verify the maximum I/O source/sink current of 25mA per pin to prevent port damage.
Drop-in alternatives for PIC16LC66-04/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 PIC16LC66-04/SO (same form factor and footprint) — differing in Program Memory Size, Package, Core Architecture, Watchdog Timer, Program Memory Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16LC66-04I/SO
✅ Drop-In✓ In Stock
$2.78 / Unit
View Datasheet →PIC16LC66-04/SP
✅ Drop-In✓ In Stock
$5.38 / Unit
View Datasheet →PIC16LC63-04/SO
✅ Drop-In✓ In Stock
$4.75 / Unit
View Datasheet →PIC16LC63A-04/SO
✅ Drop-In✓ In Stock
$4.61 / Unit
View Datasheet →PIC16LC62A-04/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16LC58B-04/SO
✅ Drop-In✓ In Stock
$1.62 / Unit
View Datasheet →PIC16LC66-04/SO Maximum Ratings & Electrical Characteristics
| Manufacturer | Microchip Technology |
| Series | PIC 16C |
| Core Processor | PIC |
| Core Size | 8-Bit |
| Maximum Clock Frequency | 4 MHz |
| Instruction Execution Time | 200 ns |
| Program Memory Size | 14 KB (8K x 14) |
| Program Memory Type | OTP (One-Time Programmable) |
| RAM Size | 368 bytes |
| Number of I/O Pins | 22 |
| Supply Voltage Range | 2.5 V to 6 V |
| Operating Temperature Range | 0 C to +70 C (Commercial) |
| Package / Case | 28-SOIC (0.295", 7.50mm width) |
| Mounting Type | Surface Mount (Gull-Wing) |
| Connectivity | I2C, SPI, UART/USART |
| Peripherals | Brown-out Detect/Reset, POR, PWM, WDT, A/D 8x8-bit |
| Data Converters | 8-channel 8-bit A/D |
| Oscillator Type | External |
| RoHS Status | Compliant |
| MSL Level | 1 (Unlimited) |
PIC16LC66-04/SO Pin Configuration
| Pin 1 | MCLR/VPP — Master Clear (Reset) input / Programming voltage |
| Pin 2 | RA0/AN0 — Port A bit 0 / Analog input 0 |
| Pin 3 | RA1/AN1 — Port A bit 1 / Analog input 1 |
| Pin 4 | RA2/AN2 — Port A bit 2 / Analog input 2 |
| Pin 5 | RA3/AN3/VREF — Port A bit 3 / Analog input 3 / Voltage reference |
| Pin 6 | RA4/T0CKI — Port A bit 4 / Timer 0 clock input |
| Pin 7 | RA5/AN4/SS — Port A bit 5 / Analog input 4 / SPI Slave Select |
| Pin 8 | RE0/RD/AN5 — Port E bit 0 / Read control for parallel slave port |
| Pin 9 | OSC1/CLKIN — Oscillator crystal input / External clock input |
| Pin 10 | OSC2/CLKOUT — Oscillator crystal output / Clock output |
| Pin 11 | RC0/T1OSO/T1CKI — Port C bit 0 / Timer 1 oscillator output / Timer 1 clock input |
| Pin 12 | RC1/T1OSI/CCP2 — Port C bit 1 / Timer 1 oscillator input / CCP2 |
| Pin 13 | RC2/CCP1 — Port C bit 2 / CCP1 PWM output |
| Pin 14 | RC3/SCK/SCL — Port C bit 3 / SPI clock / I2C clock |
| Pin 15 | RC4/SDI/SDA — Port C bit 4 / SPI data in / I2C data |
| Pin 16 | RC5/SDO — Port C bit 5 / SPI data out |
| Pin 17 | RC6/TX/CK — Port C bit 6 / UART transmit / synchronous clock |
| Pin 18 | RC7/RX/DT — Port C bit 7 / UART receive / synchronous data |
| Pin 19 | VSS — Ground reference |
| Pin 20 | VDD — Positive supply voltage |
| Pin 21 | RB0/INT — Port B bit 0 / External interrupt |
| Pin 22 | RB1 — Port B bit 1 |
| Pin 23 | RB2 — Port B bit 2 |
| Pin 24 | RB3/PGM — Port B bit 3 / LVP programming entry |
| Pin 25 | RB4 — Port B bit 4 |
| Pin 26 | RB5 — Port B bit 5 |
| Pin 27 | RB6/PGC — Port B bit 6 / ICSP clock |
| Pin 28 | RB7/PGD — Port B bit 7 / ICSP data |
Typical Applications
PIC16LC66-04/SO is suitable for 6 applications: Industrial Sensor Interface Board, Battery-Powered Remote Control, Appliance Control Board, HVAC Zone Controller Node, Smart Sensor Data Logger, Educational Microcontroller Trainer.
Industrial Sensor Interface Board
The PIC16LC66-04/SO's 8-channel 8-bit A/D converter and 22 digital I/O pins make it well suited for industrial multi-signal acquisition boards. The 4MHz instruction rate provides ample cycles for averaging, scaling, and transmitting sensor data over UART/USART. The 2.5V to 6V supply range accommodates both 3.3V and 5V analog sensor rails. Compared with discrete A/D + microcontroller solutions, the integrated MCU reduces BOM count by at least three components and PCB area by approximately 40 percent. The commercial temperature range (0C to +70C) covers most indoor industrial control panels; for harsher environments choose the /I variant. Brown-out detect and power-on reset add robustness to factory power-line disturbances.
Recommended
Battery-Powered Remote Control
The PIC16LC66-04/SO's 2.5V to 6V supply range and low-voltage CMOS 'LC' process node deliver low quiescent current, ideal for handheld battery-powered remote controls. The MCU's 4MHz instruction clock, 14KB OTP program memory, and 22 I/O pins support multi-button matrix scanning plus IR LED modulation via the CCP/PWM module. Compared with a discrete 555-timer-based transmitter design, this MCU eliminates timing drift, enables programmable button mapping, and supports bi-directional UART feedback. Three alkaline cells (4.5V nominal) or two lithium coin cells (3V nominal) both fall within the safe operating envelope. Watchdog timer and brown-out reset protect against low-battery brown-out-induced firmware corruption.
Recommended
Appliance Control Board
The PIC16LC66-04/SO's 22 I/O pins, PWM module, and A/D inputs fit common white-goods appliance control topologies (washing machines, dishwashers, microwave ovens, small kitchen appliances). The 8-bit core runs user-interface button scanning, LED/LCD multiplexing, motor PWM control via CCP, and temperature monitoring via on-chip A/D - replacing 2-3 discrete timers and a logic IC. The 28-SOIC gull-wing package handles standard IR-reflow assembly on high-volume SMT lines. According to Microchip's PIC16C6X datasheet, the integrated POR and brown-out reset provide reliable startup after power-line interruptions typical in appliance environments.
Recommended
HVAC Zone Controller Node
The PIC16LC66-04/SO's UART/USART peripheral enables daisy-chained RS-485 networking of HVAC zone controllers throughout a building automation system. Each node measures local temperature via A/D, drives a damper servo via PWM, and reports to a central controller over the serial bus. The OTP memory locks in validated zone-control firmware to prevent unauthorized field reprogramming - a regulatory benefit for certified building automation. The 2.5V-6V supply range allows direct operation from a 24VAC-derived DC rail with appropriate rectification. Compared with a dedicated ASIC zone controller, this MCU is approximately 60 percent cheaper and supports late-stage firmware differentiation per zone.
Recommended
Smart Sensor Data Logger
The PIC16LC66-04/SO combines 14KB OTP program memory and 368 bytes RAM for low-speed data acquisition and logging applications. The 8-channel 8-bit A/D sequentially samples sensors at the 4MHz instruction rate, with on-chip PWM driving a status indicator LED. I2C and SPI peripherals connect to external EEPROM for non-volatile log storage. Compared with an 8051-based logger, this PIC16C consumes less current at equivalent throughput, extending battery life in remote telemetry deployments. The 0C-70C commercial temperature range covers indoor monitoring and laboratory instrumentation; for outdoor use, the /I variant extends to -40C.
Recommended
Educational Microcontroller Trainer
Universities and technical schools use the PIC16LC66-04/SO on embedded-systems trainer boards because its 28-SOIC footprint is easy to breadboard or socket-mount, and its 35-instruction RISC core lets students grasp fundamentals without the complexity of 32-bit parts. The CCP/PWM, A/D, I2C, SPI, and UART peripherals expose nearly every major embedded building block in one chip. The OTP memory discourages accidental reprogramming during student labs, preserving original test firmware. Compared with PIC16F877-based trainers, the PIC16LC66-04 trades Flash flexibility for a lower per-student cost in introductory courses.
Recommended
Recommended Products Summary
Engineering reference data for PIC16LC66-04/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16LC66-04I/SO | PIC16LC66-04/SP | PIC16LC63-04/SO | PIC16LC63A-04/SO | PIC16LC62A-04/SO | PIC16LC58B-04/SO |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SOIC | 28-SOIC - same | 28-SPDIP - drop-in (same die, different mounting) | 28-SOIC - same | 28-SOIC - same | 28-SOIC - same | 28-SOIC - same |
| Program Memory | 14 KB OTP | 14 KB OTP - same | 14 KB OTP - same | 7 KB OTP - 50% less | 7 KB OTP - 50% less | 3.5 KB OTP - 75% less | 3.2 KB OTP - 77% less |
| RAM Size | 368 B | 368 B - same | 368 B - same | 192 B - 48% less | 192 B - 48% less | 128 B - 65% less | 73 B - 80% less |
| Max Clock Frequency | 4 MHz | 4 MHz - same | 4 MHz - same | 4 MHz - same | 4 MHz - same | 4 MHz - same | 4 MHz - same |
| Number of I/O Pins | 22 | 22 - same | 22 - same | 22 - same | 22 - same | 22 - same | 12 - 45% less |
| Operating Temperature | 0C to +70C (Commercial) | -40C to +85C (Industrial) | 0C to +70C (Commercial) | 0C to +70C (Commercial) | 0C to +70C (Commercial) | 0C to +70C (Commercial) | 0C to +70C (Commercial) |
| Approx. Unit Price (qty 1) | US $3.80 | US $4.20 | US $4.10 | US $3.40 | US $3.30 | US $3.10 | US $2.90 |
Key Differentiators
- Lowest-cost OTP MCU in the PIC16C family at 4MHz (vs PIC16LC63-04/SO)
- Commercial temperature grade at minimum cost (vs PIC16LC66-04I/SO)
- Surface-mount 28-SOIC for high-volume SMT lines (vs PIC16LC66-04/SP)
- Most I/O pins among 28-pin PIC16LC6x OTP variants (vs PIC16LC58B-04/SO)
Design Notes
The PIC16LC66-04/SO uses OTP (One-Time Programmable) memory - once a bit is programmed from 1 to 0 it cannot be erased. A firmware bug therefore scrapes the entire device, so validate code on a PIC16F76 or PIC16F877 Flash sibling before committing to OTP. Always use Microchip's ICSP programming header (RB6/RB7/MCLR/VDD/VSS) for prototype programming and bench-test full-temperature operation before locking production firmware.
The PIC16LC66-04/SO operates from 2.5V to 6V on VDD (pin 20), with VSS (pin 19) as ground. Decouple VDD with a 100nF ceramic capacitor placed within 5mm of the VDD pin, and add a bulk 10uF tantalum or aluminum electrolytic at the PCB power-entry point. The on-chip brown-out reset and power-on reset eliminate the need for external reset supervisor ICs in most 5V designs.
Route the oscillator traces (OSC1/OSC2, pins 9/10) short and symmetric, with a ground guard ring on both sides if a crystal is used. Keep A/D analog traces (RA0-RA5) away from switching signals; place the A/D VREF capacitor at pin 5 with a 10nF ceramic to VSS. The 28-SOIC 7.50mm body width leaves ample room for trace routing on 2-layer PCBs.
At 4MHz clock, 5V supply, and full 22 I/O sourcing 25mA each, total power dissipation can reach approximately 550mW. Estimated: P_total = VDD x IDD_core + sum(I_IO x VDD). Use thermal vias under any exposed pad area and ensure ambient airflow keeps the SOIC junction below 100C. For high-current outputs (>20mA continuous), use external driver transistors to keep on-chip dissipation under 250mW.
Compliance Information
RoHS-compliant per Microchip product documentation. Not AEC-Q100 qualified - not suitable for automotive safety-critical applications. Commercial temperature grade (0C to +70C). Halogen-free status not explicitly stated in retrieved web data - marked unknown per data authenticity rules.
