PIC16LC781-I/SO - 8-Bit 20MHz MCU 1.75KB OTP | Microchip
MPN: PIC16LC781-I/SO β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.95 | $3.95 |
| 10 | $3.55 | $35.50 |
| 100 | $3.15 | $315.00 |
| 500 | $2.78 | $1,390.00 |
| 1,000 | $2.46 | $2,460.00 |
PIC16LC781-I/SO Overview
What is an OTP microcontroller? An OTP (One-Time-Programmable) MCU is a class of microcontroller whose internal program memory is based on EPROM cells - they can be programmed exactly once after packaging, then erased only by strong UV light through a quartz window. Compared to flash-based MCUs, OTP variants typically cost less per unit and offer slightly better radiation tolerance, which is why PIC16LC781 is commonly used in cost-sensitive, high-volume industrial and appliance applications. PIC16LC781 sits within the Microchip PIC16 family -> 8-bit MCU -> microcontroller -> embedded processing -> semiconductor hierarchy.
Key differentiating features include a wide 2.5 V to 5.5 V supply-voltage range, an integrated brown-out reset (BOR), a programmable watchdog timer (WDT), an in-circuit serial programming (ICSP) interface, and Microchip's nanoWatt technology for low-power sleep modes. The on-chip 10-bit ADC supports up to 8 input channels, providing direct connection to sensors without an external ADC. Two analog comparators with programmable reference voltages simplify power-supply and signal-conditioning tasks.
Typical applications include appliance control boards, battery chargers, sensor interfaces, low-end SMPS controllers, and small motor drivers. Because the part is OTP-based, the code is fixed at production time, so it is best suited to products that ship in large volumes with no field firmware updates.
When designing with PIC16LC781, leave the ICSP pins (RB6/RB7) accessible on the PCB even if in-circuit programming is not planned during production - this dramatically simplifies lab bring-up and debugging. Because the part is OTP, ensure your firmware is fully validated before mask-programming the final order.
Drop-in alternatives for PIC16LC781-I/SO β 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 PIC16LC781-I/SO (same form factor and footprint) β differing in ADC, Analog Comparators, Data EEPROM, In-Circuit Programming, Instruction Set.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
PIC16LC781T-I/SO
β Drop-Inπ Reference alternative (not in catalog)
PIC16F630-I/SO
β Drop-Inπ Reference alternative (not in catalog)
PIC16LC781-I/SO Maximum Ratings & Electrical Characteristics
| Product Type | 8-bit Microcontroller (MCU) |
| Family | PIC16C / PIC16LC |
| Program Memory Type | OTP (One-Time-Programmable EPROM) |
| Program Memory Size | 1.75 KB (1K x 14) |
| Data RAM | 128 bytes |
| Data EEPROM | Not present (ROM-less data area) |
| CPU Clock Speed (max) | 20 MHz |
| Supply Voltage Range | 2.5 V to 5.5 V (LC variant, 3.0 V to 5.5 V at 20 MHz) |
| Number of I/O Pins | 16 |
| ADC | 10-bit, up to 8 channels |
| Analog Comparators | 2 (programmable reference) |
| Serial Interface | USART/SCI (asynchronous/synchronous) |
| Timers | Timer0 (8-bit), Timer1 (16-bit), Timer2 (8-bit with PWM) |
| Capture/Compare/PWM | 1 CCP module |
| Watchdog Timer | Yes (programmable WDT) |
| Brown-Out Reset | Yes |
| In-Circuit Programming | Yes (ICSP, 2-wire) |
| Instruction Set | 35 instructions, 14-bit opcode |
| Package | 20-pin SOIC (SO) |
| Operating Temperature | -40 C to +85 C (Industrial 'I' grade) |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited floor life at <30 C/85 % RH) |
| RoHS Status | Compliant (lead-free SOIC package) |
PIC16LC781-I/SO Pin Configuration
| Pin 1 | RA2/AN2 β Bidirectional I/O / analog input channel 2 |
| Pin 2 | RA3/AN3/VREF+ β Bidirectional I/O / analog input 3 / ADC reference positive |
| Pin 3 | RA4/AN4 β Bidirectional I/O / analog input channel 4 |
| Pin 4 | RA5/MCLR/VPP β Bidirectional I/O / master clear reset (active low) / programming voltage |
| Pin 5 | VSS β Ground reference |
| Pin 6 | RB0/INT β Bidirectional I/O / external interrupt |
| Pin 7 | RB1 β Bidirectional I/O |
| Pin 8 | RB2 β Bidirectional I/O |
| Pin 9 | RB3 β Bidirectional I/O |
| Pin 10 | RB4 β Bidirectional I/O |
| Pin 11 | RB5 β Bidirectional I/O |
| Pin 12 | RB6/PGC β Bidirectional I/O / ICSP clock (programming) |
| Pin 13 | RB7/PGD β Bidirectional I/O / ICSP data (programming) |
| Pin 14 | VDD β Positive supply (2.5 V to 5.5 V) |
| Pin 15 | OSC1/CLKIN β Oscillator crystal / external clock input |
| Pin 16 | OSC2/CLKOUT β Oscillator crystal / 4 x Fosc clock output |
| Pin 17 | RA0/AN0 β Bidirectional I/O / analog input channel 0 |
| Pin 18 | RA1/AN1 β Bidirectional I/O / analog input channel 1 |
| Pin 19 | RA6/OSC2 (alt) β Bidirectional I/O / alternate oscillator output on LC77x die (NC on LC781) |
| Pin 20 | RA7/OSC1 (alt) β Bidirectional I/O / alternate oscillator input on LC77x die (NC on LC781) |
Typical Applications
PIC16LC781-I/SO is suitable for 6 applications: White Goods and Appliance Control, Battery Chargers and Power Management, Industrial Sensor Signal Conditioning, Low-End SMPS and PFC Controllers, Small Brushless DC and Stepper Motor Drivers, Cost-Sensitive Remote Control and Sensor Nodes.
White Goods and Appliance Control
The PIC16LC781-I/SO is a strong fit for white-goods controllers because its OTP program memory drops per-unit cost in high-volume runs while the integrated 10-bit ADC and two analog comparators directly sense temperature, water level, and line voltage. With 1.75 KB of code space and 16 I/O pins, the part can drive seven-segment displays, triac-fired heaters, and buzzer feedback from a single chip. The wide 2.5 V to 5.5 V supply tolerates rectified 5 V or 12 V rails, and the SOIC-20 footprint reflows cleanly on automated lines. nanoWatt sleep modes keep standby current under 1 uA, satisfying IEC 62301 standby limits for modern appliances.
Recommended
Battery Chargers and Power Management
In NiCd/NiMH/Li-ion charger designs, the PIC16LC781-I/SO provides the regulation loop, status indication, and safety timing from one chip. Its 10-bit ADC samples charge current and battery voltage with 4 mV resolution at 5 V, while the built-in analog comparator triggers fast over-current shutdown without software latency. The USART link to a host panel reports charge state and accepts charge profiles, and ICSP allows factory calibration of the ADC offset/gain before final programming. At 20 MHz the core runs the PID loop comfortably every 4 ms, leaving spare cycles for LED PWM on Timer2.
Recommended
Industrial Sensor Signal Conditioning
The PIC16LC781-I/SO integrates two analog comparators and a 10-bit ADC, allowing direct interface to bridge sensors, RTDs, and thermistors without a separate op-amp stage. Its 16 digital I/Os can drive LED bar-graphs, optocouplers, and 4-20 mA loop interfaces, while the USART streams digitized readings to a PLC or HMI. The industrial -40 C to +85 C temperature range supports factory-floor deployment, and the wide 2.5 V to 5.5 V supply operates directly from 24 V loops stepped down with a series resistor. Brown-out reset and watchdog timer harden the design against noisy industrial power rails.
Recommended
Low-End SMPS and PFC Controllers
The PIC16LC781-I/SO can run small switch-mode power supplies and active PFC pre-regulators thanks to its 20 MHz throughput and on-chip 10-bit ADC. The CCP module generates the PWM gate drive, while Timer1 captures zero-crossing timing for synchronous rectification. Two analog comparators implement cycle-by-cycle current limiting and brown-out protection with hardware latency measured in nanoseconds. OTP memory locks the firmware to the specific power-supply design, preventing accidental field re-flashing in safety-critical converters.
Recommended
Small Brushless DC and Stepper Motor Drivers
For small motors under 50 W, the PIC16LC781-I/SO provides the commutation, current sensing, and PWM generation from one chip. The 10-bit ADC samples the back-EMF or shunt current, the two analog comparators detect zero-crossing or over-current events, and the CCP module drives the FET gate drivers at up to 20 kHz. Its nanoWatt sleep modes cut standby current to <1 uA, which extends battery life in cordless tools and toys. The 16 I/O pins handle direction, enable, tach feedback, and fault indicators without external logic.
Recommended
Cost-Sensitive Remote Control and Sensor Nodes
The PIC16LC781-I/SO is well matched to low-cost RF remote controls and one-way sensor nodes where OTP memory is acceptable and per-unit cost dominates. Its integrated USART can drive 315/433 MHz SAW-transmitter modules, while the 16 I/Os scan keypads or matrix sensors directly. nanoWatt sleep modes drop average current below 5 uA on duty-cycled transmissions, allowing coin-cell operation for years. Because the firmware is OTP-locked at the factory, the design is intrinsically secure against end-user firmware tampering.
Recommended
Recommended Products Summary
Engineering reference data for PIC16LC781-I/SO β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16LC781T-I/SO | PIC16F630-I/SO |
|---|---|---|---|
| Package | 20-pin SOIC (SO) | 20-pin SOIC (SO) - same | 20-pin SOIC (SO) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory Type | OTP (1.75 KB) | OTP (1.75 KB) | Flash (1 KB) |
| Program Memory Size | 1.75 KB (1K x 14) | 1.75 KB (1K x 14) | 1 KB (512 x 14) |
| CPU Clock (max) | 20 MHz | 20 MHz | 20 MHz |
| Data RAM | 128 B | 128 B | 64 B |
| I/O Pins | 16 | 16 | 12 |
| ADC | 10-bit, 8 ch | 10-bit, 8 ch | 10-bit, 4 ch |
| Comparators | 2 | 2 | 1 |
| Field Firmware Update | No (OTP) | No (OTP) | Yes (Flash) |
Key Differentiators
- More code space than PIC16F630-I/SO (vs PIC16F630-I/SO)
- Higher I/O count than PIC16F630-I/SO (vs PIC16F630-I/SO)
- Lower per-unit cost in high volume due to OTP memory (vs PIC16F630-I/SO)
- Two analog comparators vs one on PIC16F630 (vs PIC16F630-I/SO)
Design Notes
Estimated: keep the ICSP pins RB6 (PGC) and RB7 (PGD) accessible on the PCB even if in-circuit programming is not planned for production. A 4-pin 0.1 inch header or pogo-pad footprint dramatically simplifies lab bring-up, debugging, and field-recovery. Because the PIC16LC781 is OTP, production code must be fully validated before mask programming; the ICSP header lets you iterate on a flash equivalent during development and then port the final firmware to OTP for production.
The PIC16LC781-I/SO has an internal brown-out reset (BOR) that holds the MCU in reset when VDD drops below the configured threshold. Enable BOR in the configuration word to prevent code execution from corrupted memory during power-rail droops. Place a 100 nF decoupling capacitor within 5 mm of VDD (pin 14) and a 10 uF bulk capacitor on the main supply rail. For battery operation, the nanoWatt sleep mode reduces current to <1 uA, but verify the wake-up source (WDT, INT, or port change) is configured before entering sleep.
Place the oscillator crystal or resonator within 10 mm of OSC1 (pin 15) and OSC2 (pin 16), and route traces over a continuous ground plane to minimize EMI. Keep digital switching traces away from the analog inputs RA0-RA5 to avoid ADC noise coupling; a guard ring around AN0-AN4 improves ADC accuracy at the LSB level. Use separate analog and digital ground islands that join at a single point beneath the IC to prevent ground-loop injection into the ADC.
OTP program memory cannot be erased electrically; once the part is programmed, the firmware is permanent. Always program a development flash equivalent (e.g., PIC16F630-I/SO) first to validate your code, then transition to PIC16LC781 for production. Configuration word settings (WDT, BOR, oscillator mode, code protection) are also OTP - a wrong configuration word locks the part and the chip must be discarded. Sample at least 5 parts with your chosen configuration before committing to a full production run.
Compliance Information
Lead-free SOIC-20 package per Microchip RoHS statement. Not AEC-Q100 qualified - choose PIC16LC781T-I/SO or a PIC16F automotive grade for vehicle applications.
