PIC16LC66T-04I/SO - 8-bit MCU, 14KB OTP, 4MHz, 28-SOIC | Microchip
MPN: PIC16LC66T-04I/SO ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.95 | $7.95 |
| 10 | $7.16 | $71.60 |
| 100 | $6.4 | $640.00 |
| 500 | $5.65 | $2,825.00 |
| 1,000 | $4.95 | $4,950.00 |
PIC16LC66T-04I/SO Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, RAM, non-volatile program memory, and peripherals such as timers, ADC, and I/O. PIC microcontrollers use a Harvard RISC architecture with a small, fixed instruction set, making them popular for embedded control, instrumentation, and legacy industrial systems. Within the broader semiconductor taxonomy, the PIC16LC66 sits at: 8-bit MCU -> microcontroller -> embedded processor -> semiconductor IC. Its ultra-low-power CMOS design positions it as a fit for battery-backed and power-constrained applications versus standard PIC16C6X parts.
Key features include 22 digital I/O pins organized across multiple ports (Port A, B, C), three timers (Timer0 8-bit with prescaler, Timer1 16-bit with sleep-mode crystal increment, Timer2 8-bit), a capture/compare/PWM (CCP) module, a 5-channel 8-bit ADC, and a universal synchronous/asynchronous receiver-transmitter (USART/SCI). The OTP program memory allows one-time factory or field programming, while 368 bytes of data RAM support runtime variables and stack operations.
Typical applications include industrial sensor interfaces, low-power remote controls, appliance controllers, building automation nodes, white-goods motor control, simple HMI panels, and legacy embedded control boards. The 28-SOIC package supports surface-mount assembly, enabling compact PCB designs in space-constrained products.
When designing with this part, ensure that code density and stack depth fit within 14KB / 8-level hardware stack. The PIC16LC66 uses One-Time Programmable memory, so firmware revisions require physical device replacement; consider PIC16F66 for Flash-based upgrades on the same pinout.
This page synthesizes distributor pricing, drop-in alternatives from the same PIC16C6X family, and practical design notes not found in a quick-datasheet summary. All pricing is quoted as of 2026-09-22.
Drop-in alternatives for PIC16LC66T-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 PIC16LC66T-04I/SO (same form factor and footprint) — differing in Package, Program Memory Size, Core Architecture, Timers, Mounting 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/SO
✅ Drop-In✓ In Stock
$2.4 / Unit
View Datasheet →PIC16F66-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C66-04I/SO
✅ Drop-In✓ In Stock
$5.1 / Unit
View Datasheet →PIC16LC66T-04I/SO Maximum Ratings & Electrical Characteristics
| Manufacturer | Microchip Technology |
| Series | PIC® 16C |
| Core Architecture | 8-bit RISC (Harvard) |
| Core Processor | PIC16C6X |
| Maximum Clock Speed | 4 MHz |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 14 KB (8K x 14) |
| Data RAM | 368 bytes |
| I/O Pins | 22 |
| Supply Voltage Range | 2.5 V to 5.5 V |
| Operating Temperature | -40 °C to +85 °C (Industrial) |
| Package | 28-SOIC (0.295", 7.50 mm width) |
| Mounting Type | Surface Mount |
| Timers | Timer0 (8-bit) + Timer1 (16-bit) + Timer2 (8-bit) |
| Communication | USART/SCI |
| Packaging Type | Tape & Reel ("T" suffix) |
PIC16LC66T-04I/SO Pin Configuration
| Pin 1 | RA2/AN2/VREF- — Port A bit 2 / ADC channel 2 / ADC negative reference |
| Pin 2 | RA3/AN3/VREF+ — Port A bit 3 / ADC channel 3 / ADC positive reference |
| Pin 3 | RA4/T0CKI — Port A bit 4 / Timer0 clock input |
| Pin 4 | RA5/AN4/SS — Port A bit 5 / ADC channel 4 / SPI slave select |
| Pin 5 | OSC1/CLKIN — Crystal oscillator input / external clock input |
| Pin 6 | OSC2/CLKOUT — Crystal oscillator output / clock output |
| Pin 7 | RC0/T1OSO/T1CKI — Port C bit 0 / Timer1 oscillator output / Timer1 clock input |
| Pin 8 | RC1/T1OSI/CCP2 — Port C bit 1 / Timer1 oscillator input / CCP2 |
| Pin 9 | RC2/CCP1 — Port C bit 2 / CCP1 PWM/capture/compare |
| Pin 10 | RC3/SCK/SCL — Port C bit 3 / SPI clock / I2C clock |
| Pin 11 | RC4/SDI/SDA — Port C bit 4 / SPI data in / I2C data |
| Pin 12 | RC5/SDO — Port C bit 5 / SPI data out |
| Pin 13 | RC6/TX/CK — Port C bit 6 / USART TX / USART clock |
| Pin 14 | RC7/RX/DT — Port C bit 7 / USART RX / USART data |
| Pin 15 | VSS — Ground reference |
| Pin 16 | VDD — Positive supply (2.5V to 5.5V) |
| Pin 17 | RB0/INT — Port B bit 0 / external interrupt |
| Pin 18 | RB1 — Port B bit 1 |
| Pin 19 | RB2 — Port B bit 2 |
| Pin 20 | RB3/PGM — Port B bit 3 / LVP programming |
| Pin 21 | RB4 — Port B bit 4 |
| Pin 22 | RB5 — Port B bit 5 |
| Pin 23 | RB6/PGC — Port B bit 6 / ICSP clock |
| Pin 24 | RB7/PGD — Port B bit 7 / ICSP data |
| Pin 25 | RA0/AN0 — Port A bit 0 / ADC channel 0 |
| Pin 26 | RA1/AN1 — Port A bit 1 / ADC channel 1 |
| Pin 27 | MCLR/VPP — Master clear reset / programming voltage |
| Pin 28 | VSS — Ground reference |
Typical Applications
PIC16LC66T-04I/SO is suitable for 6 applications: Industrial Sensor Interface Node, Battery-Backed Remote Control, White-Goods Appliance Controller, Building Automation Node, Simple HMI Display Panel, Legacy Embedded Control Board Replacement.
Industrial Sensor Interface Node
The PIC16LC66T-04I/SO's 2.5 V to 5.5 V low-voltage CMOS operation, 8-bit ADC, and 22 digital I/O make it a strong fit for industrial sensor interface nodes that read analog sensors and forward processed data via USART. Industrial-grade -40°C to +85C operation handles factory-floor temperature swings. The 14 KB OTP memory holds protocol stacks for Modbus RTU, simple state machines, and calibration tables. Estimated: at 4 MHz clock and typical sensor sampling loops, code easily fits 14 KB and 368 bytes RAM is sufficient for protocol buffers.
Recommended
Battery-Backed Remote Control
The PIC16LC66T-04I/SO's "LC" low-voltage CMOS process supports operation down to 2.5 V, ideal for 2xAA or coin-cell battery-powered remote controls. Timer1 with external crystal increment during sleep enables RTC-style wake-up with microamp quiescent current. The 22 I/O drive LED indicators, keypads, and IR transmitters; the USART/SCI provides wired comms to a base station. Estimated: at 4 MHz active and <1% duty cycle, average current draw is well under 100 uA, supporting multi-year battery life.
Recommended
White-Goods Appliance Controller
The PIC16LC66T-04I/SO is widely deployed in legacy washing-machine, dishwasher, and refrigerator control boards where the OTP memory and industrial temperature grade provide long-life reliability. The CCP module drives PWM outputs for motor and valve control, while the 8-bit ADC reads temperature, water level, and motor-current sensors. The 28-SOIC package is compatible with high-volume SMT assembly lines. According to the PIC16C6X datasheet, brown-out reset and watchdog timer are integrated, supporting IEC 60730 class B safety requirements for appliance control.
Recommended
Building Automation Node
The PIC16LC66T-04I/SO's USART/SCI, 22 I/O, and industrial temperature range make it suitable for HVAC zoning nodes, lighting controllers, and access-control sub-modules in building automation. The 14 KB OTP memory fits BACnet/Modbus slave stacks and relay-control logic, while the 8-bit ADC reads analog sensors (light, temperature, CO2). Estimated: typical building-automation node code is 6-10 KB, leaving 4 KB+ headroom in 14 KB OTP. Brown-out reset is critical for HVAC applications with unstable power.
Recommended
Simple HMI Display Panel
The PIC16LC66T-04I/SO drives small character-LCD or 7-segment LED displays in simple human-machine-interface panels such as instrument readouts, kiosk keypads, and vending-machine selectors. The CCP module generates PWM for LED backlight dimming, while the 8-bit ADC reads user potentiometers or touch sensors. The 22 I/O pins are sufficient to drive a 4x4 keypad and 8-digit 7-segment display via BCD decoders. The 28-SOIC footprint is easily laid out on a 2-layer PCB.
Recommended
Legacy Embedded Control Board Replacement
The PIC16LC66T-04I/SO is often specified for legacy industrial control board repair and re-manufacturing, where original equipment manufacturers must source the same silicon and footprint. The "T" tape-and-reel suffix supports modern SMT re-assembly; same 28-SOIC JEDEC footprint allows direct PCB drop-in. According to Microchip, the PIC16LC66 family has been in production for decades and remains ACTIVE (as of 2026-09-22), making it suitable for industrial OEMs with 10-20 year product support commitments.
Recommended
Recommended Products Summary
Engineering reference data for PIC16LC66T-04I/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16LC66-04I/SO | PIC16LC66-04/SO | PIC16F66-I/SO | PIC16C66-04I/SO | PIC16LC66-04I/SP |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SOIC (0.295") | 28-SOIC (0.295") - same | 28-SOIC (0.295") - same | 28-SOIC (0.295") - same | 28-SOIC (0.295") - same | 28-SPDIP (0.300") - different footprint |
| Core Architecture | 8-bit PIC RISC | 8-bit PIC RISC | 8-bit PIC RISC | 8-bit PIC RISC | 8-bit PIC RISC | 8-bit PIC RISC |
| Max Clock Speed | 4 MHz | 4 MHz | 4 MHz | 20 MHz | 4 MHz | 4 MHz |
| Program Memory | 14 KB OTP | 14 KB OTP | 14 KB OTP | 14 KB Flash | 14 KB OTP | 14 KB OTP |
| Data RAM | 368 bytes | 368 bytes | 368 bytes | 368 bytes | 368 bytes | 368 bytes |
| Supply Voltage Range | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V | 2.0 V to 5.5 V | 4.0 V to 6.0 V | 2.5 V to 5.5 V |
| Operating Temperature | -40°C to +85°C (Industrial) | -40°C to +85°C | 0°C to +70°C | -40°C to +85°C | -40°C to +85°C | -40°C to +85°C |
| I/O Pins | 22 | 22 | 22 | 22 | 22 | 22 |
Key Differentiators
- Low-voltage CMOS ("LC") process variant (vs PIC16C66-04I/SO)
- Tape-and-reel packaging ("T" suffix) for high-volume SMT (vs PIC16LC66-04I/SO)
- Industrial temperature grade (-40°C to +85°C) (vs PIC16LC66-04/SO)
- OTP memory for low per-unit cost and security (vs PIC16F66-I/SO)
Design Notes
The PIC16LC66T-04I/SO "LC" variant supports 2.5 V to 5.5 V operation versus 4.0 V to 6.0 V for the original PIC16C66. For designs migrating between the two, confirm brown-out-reset thresholds in the electrical characteristics table and verify that any 5 V-only peripherals are tolerant of the lower Vdd. A 100 nF decoupling capacitor must be placed within 5 mm of the VDD pin (pin 16) with a low-impedance ground return to pin 15 or 28; add a bulk 10 uF tantalum or ceramic near the IC. Estimated: at 4 MHz clock and 5 V supply, active current is approximately 2 mA per the PIC16C6X datasheet family curves.
The PIC16LC66T-04I/SO uses OTP (One-Time Programmable) memory, not Flash. Once programmed, the firmware cannot be erased or rewritten. For prototypes and design iterations, use the Flash-based PIC16F66-I/SO or PIC16F877A in the same development environment; do not waste OTP parts during bring-up. The MCLR pin (pin 27) requires a 10 kohm pull-up to VDD; if left floating, the device will randomly enter reset. The ICSP clock (RB6/PGC, pin 23) and ICSP data (RB7/PGD, pin 24) must be accessible in the final PCB layout to allow factory programming.
The 28-SOIC package uses the JEDEC MS-013 standard footprint with 1.27 mm pin pitch and 7.50 mm body width. Reserve at least 0.5 mm clearance between the SOIC body and adjacent traces for pick-and-place nozzles. Decoupling: place a 100 nF X7R ceramic between VDD (pin 16) and VSS (pin 15 or 28) with trace length under 2 mm. The crystal oscillator pins (OSC1/CLKIN pin 5, OSC2/CLKOUT pin 6) should be guarded with a ground ring; keep crystal traces short and symmetric to avoid EMI. Estimated: SOIC thermal resistance theta_JA is approximately 70 C/W in still air, sufficient for the 2 mA active current at 4 MHz without heatsinking.
The 8-bit ADC on the PIC16LC66T-04I/SO has 5 channels multiplexed to RA0-RA4. To achieve rated ADC accuracy, the source impedance should be under 10 kohm, and acquisition time should follow the PIC16C6X datasheet equation (typically 19.7 us minimum at 4 MHz). For noisy analog inputs (e.g., motor current sensing), add an external RC filter (1 kohm + 100 nF = 10 kHz cutoff) and average multiple ADC readings in firmware. The analog reference pins (RA3/VREF+ pin 2, RA2/VREF- pin 1) should be bypassed with 100 nF capacitors; use a low-noise reference such as MCP1525 for precision measurements.
Compliance Information
Lead-free finish is standard per Microchip's product page; explicit RoHS/REACH certificates require request to Microchip. Not AEC-Q100 qualified (not an automotive-grade MCU). [DATA_NEEDED: latest RoHS/REACH compliance certificate from Microchip]
