PIC16LC65B-04/L - 4MHz 8-Bit OTP MCU 7KB | Microchip | 44-PLCC
MPN: PIC16LC65B-04/L ✓ ActivePIC16LC65B-04/L Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory, working RAM, and peripheral interfaces onto one IC. The PIC16C65B belongs to the mid-range PIC architecture that sits hierarchically between simple PIC10/12/14 baseline parts and the higher-pin-count PIC17/18 families. LC-series parts specifically target battery-friendly portable and industrial applications where the standard PIC16C65B's 4.5 V minimum would be too high. Within the broader taxonomy: 8-bit microcontroller -> RISC MCU -> microcontroller -> embedded IC -> semiconductor.
Key features include 33 digital I/O pins, a hardware USART, MSSP (SPI/I2C), two 8-bit timers plus one 16-bit timer with capture/compare/PWM, a 10-bit multi-channel ADC, and the standard PIC mid-range 35-instruction RISC core executing instructions in one instruction cycle (except branches, which take two). The 44-PLCC package gives generous PCB real estate for legacy through-hole designs and educational platforms where socketed replacement is desirable.
Typical applications include industrial control panels, HVAC thermostats, security alarm keypads, appliance user-interface boards, point-of-sale terminals, and legacy embedded systems where the 16C mid-range toolchain is well understood. Designers choose this part when migrating older PIC16C65 designs to a lower-voltage supply rail, or when a robust OTP MCU is needed for production runs that do not require re-programmability. Designers favor the LC variant specifically for portable instrumentation where dropping the supply to 3.3 V is needed to extend battery life without leaving the PIC ecosystem.
When designing with this part, verify that the chosen crystal or resonator meets the 4 MHz maximum at the in-circuit temperature extreme and budget adequate decoupling (100 nF plus 10 µF bulk) close to the VDD pins. The OTP nature of program memory means firmware must be fully validated before final programming, and unused I/O pins should be configured as outputs to minimize current draw.
Drop-in alternatives for PIC16LC65B-04/L — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
PIC16C65B-04/L
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16LC65B-04I/L
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16LC65B-04/L Maximum Ratings & Electrical Characteristics
| Core | PIC 16C RISC 8-bit |
| Instruction Set | 35 single-word instructions |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 7 KB (4K x 14) |
| RAM | 192 bytes |
| Maximum CPU Frequency | 4 MHz |
| Supply Voltage (VDD) | 3.0 V to 5.5 V |
| I/O Pins | 33 |
| Timers | 2 x 8-bit + 1 x 16-bit (CCP) |
| Communication | USART + MSSP (SPI / I2C) |
| Package | 44-PLCC (16.59 x 16.59 mm), J-Lead, through-hole |
| Operating Temperature | 0 °C to +70 °C (commercial) |
| Mounting Type | Through-Hole (PLCC socket compatible) |
PIC16LC65B-04/L Pin Configuration
| Pin 1 | MCLR — Master Clear (active-low reset input) |
| Pin 2 | RA0/AN0 — PORTA bit 0 / ADC input 0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / ADC input 1 |
| Pin 4 | RA2/AN2 — PORTA bit 2 / ADC input 2 |
| Pin 5 | RA3/AN3/VREF — PORTA bit 3 / ADC input 3 / VREF+ |
| Pin 6 | RA4/T0CKI — PORTA bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4/SS — PORTA bit 5 / ADC input 4 / SPI slave select |
| Pin 8 | RE0/RD/AN5 — PORTE bit 0 / Read control / ADC input 5 |
| Pin 9 | RE1/WR/AN6 — PORTE bit 1 / Write control / ADC input 6 |
| Pin 10 | RE2/CS/AN7 — PORTE bit 2 / Chip select / ADC input 7 |
| Pin 11 | VDD — Positive supply (3.0 V to 5.5 V) |
| Pin 12 | VSS — Ground |
| Pin 13 | OSC1/CLKIN — Crystal oscillator input / external clock in |
| Pin 14 | OSC2/CLKOUT — Crystal oscillator output / Fosc/4 out |
| Pin 15 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator output / T1 clock in |
| Pin 16 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator input / CCP2 |
| Pin 17 | RC2/CCP1 — PORTC bit 2 / Capture/Compare/PWM 1 |
| Pin 18 | RC3/SCK/SCL — PORTC bit 3 / SPI SCK / I2C SCL |
| Pin 19 | RD0/PSP0 — PORTD bit 0 / Parallel Slave Port bit 0 |
| Pin 20 | RD1/PSP1 — PORTD bit 1 / Parallel Slave Port bit 1 |
| Pin 21 | RD2/PSP2 — PORTD bit 2 / Parallel Slave Port bit 2 |
| Pin 22 | RD3/PSP3 — PORTD bit 3 / Parallel Slave Port bit 3 |
| Pin 23 | RC4/SDI/SDA — PORTC bit 4 / SPI data in / I2C data |
| Pin 24 | RC5/SDO — PORTC bit 5 / SPI data out |
| Pin 25 | RC6/TX/CK — PORTC bit 6 / USART TX / USART clock |
| Pin 26 | RC7/RX/DT — PORTC bit 7 / USART RX / USART data |
| Pin 27 | RD4/PSP4 — PORTD bit 4 / Parallel Slave Port bit 4 |
| Pin 28 | RD5/PSP5 — PORTD bit 5 / Parallel Slave Port bit 5 |
| Pin 29 | RD6/PSP6 — PORTD bit 6 / Parallel Slave Port bit 6 |
| Pin 30 | RD7/PSP7 — PORTD bit 7 / Parallel Slave Port bit 7 |
| Pin 31 | VSS — Ground |
| Pin 32 | VDD — Positive supply (3.0 V to 5.5 V) |
| Pin 33 | RB0/INT — PORTB bit 0 / external interrupt |
| Pin 34 | RB1 — PORTB bit 1 |
| Pin 35 | RB2 — PORTB bit 2 |
| Pin 36 | RB3 — PORTB bit 3 |
| Pin 37 | RB4 — PORTB bit 4 |
| Pin 38 | RB5 — PORTB bit 5 |
| Pin 39 | RB6/PGC — PORTB bit 6 / ICSP clock |
| Pin 40 | RB7/PGD — PORTB bit 7 / ICSP data |
| Pin 41 | NC — Not connected |
| Pin 42 | NC — Not connected |
| Pin 43 | NC — Not connected |
| Pin 44 | NC — Not connected |
Typical Applications
PIC16LC65B-04/L is suitable for 6 applications: Industrial Control Panels, HVAC Thermostats and Climate Controllers, Security Alarm Keypads, Appliance User Interface Boards, Point-of-Sale Terminals and Cash Drawers, Legacy Embedded Systems and Educational Platforms.
Industrial Control Panels
The PIC16LC65B-04/L is well matched to industrial control panels because its 33 I/O pins can drive 7-segment displays, keypad matrices, status LEDs, and relay banks without external glue logic. The 4 MHz CPU clock is sufficient for scanning user inputs, debouncing switches, and updating indicator outputs in real time at sub-millisecond cadence. The 3.0 V to 5.5 V LC variant accepts the 24 V industrial bus stepped down to 5 V or 3.3 V. The 192-byte SRAM is enough for menu state machines and timer variables. The 7 KB OTP memory holds control tables and operator interface strings. The hardware USART links to a host PLC or HMI for supervisory control. Engineers choose this part over a CPLD because of its integrated timers, ADC, and serial peripherals in one package, reducing BOM cost and PCB area in panel-mounted designs.
Recommended
HVAC Thermostats and Climate Controllers
The PIC16LC65B-04/L fits HVAC thermostat designs that need temperature sensing, relay control, and a user keypad with display. Its 10-bit ADC combined with the 3.0 V to 5.5 V LC supply range allows direct interfacing to thermistor bridges and 24 VAC-derived DC rails without level shifters. The 16-bit CCP timer drives triac zero-crossing detection for accurate power control of compressor contactors and blower motors. The 4 MHz CPU bandwidth handles PID calculation for closed-loop temperature regulation while servicing a real-time clock interrupt every 1 ms. The 192-byte SRAM is adequate for storing setpoint history and scheduling data. The 7 KB OTP memory stores multi-stage control firmware, day/night setpoints, and fault logging. The 44-PLCC package is socket-friendly for serviceability in field-deployed thermostat units.
Recommended
Security Alarm Keypads
The PIC16LC65B-04/L is a strong fit for security alarm keypads because it can simultaneously scan a 4x4 key matrix, drive a 2-line LCD module, blink arm/disarm LEDs, and supervise a backup-battery charger. Its 33 I/O pins cover key rows/columns, an LCD bus interface, a piezo buzzer driver, and a tamper input, all without external logic. The USART enables connection to the main alarm panel for status reporting. The 3.0 V to 5.5 V LC range matches the 3.6 V NiMH backup battery stack during mains failure, ensuring continuous operation for hours. The 4 MHz CPU bandwidth handles scan loops, debouncing, and buzzer tone generation in interrupt-driven firmware. The OTP 7 KB memory stores encrypted zone codes and arming sequences. The 44-PLCC through-hole socket simplifies field service and board rework for OEM production runs.
Recommended
Appliance User Interface Boards
The PIC16LC65B-04/L is well suited for washing machine, dishwasher, and oven display boards that combine a multi-segment LCD, a rotary encoder, and several capacitive or mechanical buttons. Its 33 I/O pins drive 4-bit LCD data plus control lines, encoder A/B inputs, and motor-control relay drivers via optocouplers. The 16-bit CCP timer precisely measures encoder rotation speed and generates PWM buzzer tones. The 10-bit ADC reads temperature and water-level sensors for display and safety interlocks. The 3.0 V to 5.5 V LC supply accommodates universal mains-derived 5 V rails and 3.3 V logic-level variants. The 192-byte SRAM supports cycle state tracking and fault history. The 7 KB OTP memory holds multi-language UI strings and cycle-program firmware. The 44-PLCC package allows drop-in replacement between appliance models.
Recommended
Point-of-Sale Terminals and Cash Drawers
The PIC16LC65B-04/L is ideal for low-cost POS peripherals such as cash drawers, customer-facing displays, and barcode scanner interfaces because it consolidates keypad scanning, USART communication, and relay control into a single chip. Its USART links to the main POS terminal at 9600 to 115200 baud while its 33 I/O lines drive the cash-drawer solenoid driver, status LEDs, and a 2x16 character LCD. The MSSP peripheral supports SPI barcode readers and I2C EEPROMs for storing terminal IDs and transaction logs. The 4 MHz CPU bandwidth handles protocol framing and CRC checking without timing pressure. The 3.0 V to 5.5 V LC variant is usable on USB-powered 5 V or regulated 3.3 V POS rails. The 7 KB OTP memory stores secure bootloaders and configuration. The 44-PLCC facilitates compliance upgrades and firmware revisions during long production cycles.
Recommended
Legacy Embedded Systems and Educational Platforms
The PIC16LC65B-04/L is favored in legacy industrial controllers and university embedded courses because the PIC16C mid-range architecture has decades of documentation, example code, and trained engineers behind it. Its 35-instruction RISC core is widely taught, and its instruction-cycle-based timing is straightforward to reason about at 4 MHz. The 44-PLCC socket-friendly package allows students and field engineers to swap chips without soldering. The 3.0 V to 5.5 V LC supply runs from common benchtop power supplies and battery packs used in teaching labs. The 7 KB OTP memory holds lab assignments and instrument-control code without requiring in-circuit reprogramming capability. The 33 I/O pins give plenty of breadboard-friendly signals for experiments with sensors, displays, and serial peripherals. This is also a typical replacement target for older PIC16C65B boards migrating to a 3.3 V supply.
Recommended
Recommended Products Summary
Engineering reference data for PIC16LC65B-04/L — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C65B-04/L | PIC16LC65B-04I/L | PIC16LC65B-04/PT |
|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 44-PLCC (16.59 x 16.59 mm) | 44-PLCC (same) | 44-PLCC (same) | 44-TQFP (SMT, different footprint) |
| Core | PIC 16C 8-bit RISC | PIC 16C 8-bit RISC | PIC 16C 8-bit RISC | PIC 16C 8-bit RISC |
| Program Memory | 7 KB OTP (4K x 14) | 7 KB OTP | 7 KB OTP | 7 KB OTP |
| RAM | 192 bytes | 192 bytes | 192 bytes | 192 bytes |
| Max CPU Frequency | 4 MHz | 4 MHz | 4 MHz | 4 MHz |
| Supply Voltage | 3.0 V to 5.5 V (LC) | 4.5 V to 5.5 V (C, narrower) | 3.0 V to 5.5 V (LC, same) | 3.0 V to 5.5 V (LC, same) |
| Operating Temperature | 0 °C to +70 °C (commercial) | 0 °C to +70 °C (same) | -40 °C to +85 °C (industrial) | 0 °C to +70 °C (same) |
| I/O Pins | 33 | 33 | 33 | 33 |
Key Differentiators
- Wide 3.0 V to 5.5 V supply including 3.3 V operation (vs PIC16C65B-04/L)
- Industrial-temperature sibling with same pinout (vs PIC16LC65B-04I/L differs by only the -40C to +85C range)
- Through-hole PLCC socket-friendly packaging (vs PIC16LC65B-04/PT (44-TQFP SMD))
Design Notes
Estimated: at 4 MHz CPU and 5 V supply, the PIC16LC65B-04/L typically draws 2-5 mA of active current; in sleep mode this drops below 5 µA. Place a 100 nF ceramic decoupling capacitor as close as possible to each VDD pin (pins 11 and 32); add a 10 µF bulk tantalum or ceramic at the supply entry point. For battery designs running from a 3.3 V rail, verify brown-out-reset thresholds in the device configuration to prevent partial-Vdd register corruption during power dips.
Estimated: at 4 MHz and 5 V, internal power dissipation is roughly 25 mW maximum. The 44-PLCC package has a theta_JA around 50 C/W, giving a junction rise of only 1-2 °C above ambient - no heatsink is required. Designers running the part near its 70 °C upper commercial limit should still ensure airflow or thermal relief around the socket to prevent longevity reduction.
OTP program memory means the PIC16LC65B-04/L can be programmed only once; an in-circuit misconfiguration (e.g., wrong oscillator mode, disabled MCLR, or wrong watchdog setting) is not recoverable without a fresh device. Fully validate firmware with a flash-equivalent PIC16F-series emulator before committing to OTP production units. Also, the LC supply minimum is 3.0 V - designs running from a nominal 3.3 V rail must include bulk decoupling to avoid dipping below 3.0 V during transient load steps.
Keep the crystal or resonator leads short and symmetrical, with the load capacitors grounded to the nearest VSS pin. Place decoupling capacitors within 3 mm of each VDD/VSS pair. The 44-PLCC socket should sit on a generous ground pour to provide a low-impedance return path. For in-circuit serial programming (ICSP), ensure the PGC/PGD pins (RB6/RB7) are accessible through test points or a 2-pin header for production programming.
Compliance Information
RoHS and lead-free status not specified in the verified web data for the 44-PLCC variant of the PIC16LC65B-04/L. Contact Microchip directly for certificate of compliance.
