PIC16LC621-04E/SO - 4MHz 1.75KB OTP 8-bit MCU 18SOIC | Microchip
MPN: PIC16LC621-04E/SO ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.63 | $1.63 |
| 10 | $1.55 | $15.50 |
| 100 | $1.42 | $142.00 |
| 500 | $1.3 | $650.00 |
| 1,000 | $1.18 | $1,180.00 |
PIC16LC621-04E/SO Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory, working RAM, and programmable peripherals. The PIC16C/LC family belongs to Microchip's classic baseline PIC16 architecture, which uses a RISC-style Harvard design with 12-bit wide instructions, an 8-bit wide data path, and only 35 single-cycle instructions to learn. This compact instruction set and deterministic execution model are the foundation of the PIC platform used in millions of embedded products.
Key features of the PIC16LC621-04E/SO include a 200ns instruction cycle time, seven or eight special-function hardware registers, a two-level deep hardware stack, and three addressing modes (direct, indirect, and relative). The LC designation indicates a low-voltage CMOS process that allows operation down to 2.5V for battery-powered designs. The /SO suffix designates the wide-body 0.300-inch SOIC-18 (300 mil) package for surface-mount assembly.
Typical applications span industrial control, automotive body electronics, consumer white goods, and low-power sensor interfaces where cost-sensitive 8-bit processing is sufficient. The 4MHz clock and 1.75KB OTP program memory suit applications such as appliance user-interface controllers, simple motor drivers, and remote sensor transmitters.
When designing with this part, note that OTP memory is one-time programmable - firmware must be fully validated before programming, as code cannot be revised. Engineers migrating to flash-based alternatives should consider the PIC16F family, which offers identical peripherals and footprints with in-circuit reprogrammability.
Drop-in alternatives for PIC16LC621-04E/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 PIC16LC621-04E/SO (same form factor and footprint) — differing in Program Memory Size, Core Architecture, Operating Temperature Range, Package, Program Memory Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16LC621-04I/SO
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
PIC16LC621T-04E/SO
✅ Drop-In✓ In Stock
$2.62 / Unit
View Datasheet →PIC16C621A-04E/SO
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.75 / Unit
View Datasheet →PIC16LC620A-04E/SO
✅ Drop-In✓ In Stock
$2.07 / Unit
View Datasheet →PIC16LC620AT-04E/SO
✅ Drop-In✓ In Stock
$2.25 / Unit
View Datasheet →PIC16C621AT-04E/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16LC621-04E/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC16C 8-bit RISC |
| Program Memory Type | OTP |
| Program Memory Size | 1.75KB (1K x 14) |
| Data RAM | 80 bytes |
| Maximum CPU Clock | 4 MHz |
| Instruction Cycle Time | 200 ns (single-cycle) |
| Instruction Set Size | 35 instructions |
| Supply Voltage Range | 2.5 V to 6 V |
| I/O Pins | 13 |
| Stack Depth | 2 levels (hardware) |
| Oscillator Type | External |
| Package | 18-SOIC (0.300 inch, 300 mil) |
| Operating Temperature Range | -40C to +125C |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited floor life) |
| RoHS Status | Compliant |
PIC16LC621-04E/SO Pin Configuration
| Pin 1 | RA2 — Digital I/O / analog comparator input |
| Pin 2 | RA3 — Digital I/O / analog comparator input |
| Pin 3 | RA4 — Digital I/O / Timer0 clock input |
| Pin 4 | MCLR — Master clear (reset) input, active low |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — Digital I/O / external interrupt input |
| Pin 7 | RB1 — Digital I/O |
| Pin 8 | RB2 — Digital I/O |
| Pin 9 | RB3 — Digital I/O |
| Pin 10 | RB4 — Digital I/O |
| Pin 11 | RB5 — Digital I/O |
| Pin 12 | RB6 — Digital I/O / serial programming clock |
| Pin 13 | RB7 — Digital I/O / serial programming data |
| Pin 14 | VDD — Positive supply voltage (2.5V to 6.0V) |
| Pin 15 | OSC2 — External oscillator output |
| Pin 16 | OSC1 — External oscillator input |
| Pin 17 | RA0 — Digital I/O |
| Pin 18 | RA1 — Digital I/O |
Typical Applications
PIC16LC621-04E/SO is suitable for 6 applications: Appliance User-Interface Controllers, Automotive Body Electronics Modules, Low-Power Sensor Interface Nodes, Simple Motor Driver Controllers, Remote Control Transmitter Encoder, Industrial Control Panel Logic.
Appliance User-Interface Controllers
The PIC16LC621-04E/SO suits appliance user-interface controllers (microwave keypads, washing-machine displays, thermostat panels) because its 13 I/O pins can drive multiplexed 7-segment displays and key-scan matrices directly. The 1.75KB OTP holds typical UI state machines and indicator logic; the 2.5V-6.0V supply range simplifies interfacing with 3.3V LCD modules or 5V LED driver rails. Compared with Flash-based PIC16F parts, OTP locking prevents field firmware tampering and reduces per-unit cost in high-volume appliance production. The 200ns instruction cycle and 35-instruction RISC core deliver responsive key-debounce and display-refresh behavior at 4MHz. Industrial appliance environments also benefit from the -40C to +125C operating range, which covers unheated garages and outdoor enclosures. Per the Microchip PIC16C621 datasheet (30213E), the SOIC-18 300-mil package supports standard SMT reflow profiles for automated assembly lines.
Recommended
Automotive Body Electronics Modules
The PIC16LC621-04E/SO fits automotive body-electronics modules such as interior lighting controllers, seat-position switches, and rear-window defroster timers. The 13 I/O pins map cleanly to relay drivers, switch-sense inputs, and PWM channels for lamp dimming. The wide 2.5V-6.0V supply tolerates automotive load-dump transients when paired with an external TVS clamp. OTP memory locks the firmware at production time, eliminating recall risk from unintended field reprogramming. The 4MHz external oscillator keeps EMI predictable versus internal-RC parts and the -40C to +125C temperature range covers under-hood and cabin environments. Compared with PIC16F parts, the LC621's simpler peripheral set reduces silicon cost in body modules where UART and ADC are not required. Reference the Microchip PIC16C621 datasheet section on electrical characteristics for automotive-grade derating guidance.
Recommended
Low-Power Sensor Interface Nodes
The PIC16LC621-04E/SO operates in battery-powered sensor interface nodes for HVAC thermistors, smoke-detector front-ends, and remote weather stations. The 2.5V low-voltage capability lets the part run directly from two AA alkaline cells without a boost converter, extending service life. The 35-instruction RISC core executes periodic sensor reads and threshold comparisons in well under 1ms, leaving ample wake/sleep duty-cycle margin for multi-year battery operation. OTP memory locks calibration coefficients and decision thresholds to prevent end-user tampering in field-deployed sensors. The 13 I/O pins accommodate SPI sensor chips, digital-output sensors, and analog comparator inputs (the LC621 includes an on-chip comparator module). Per the Microchip datasheet, the LC621 draws under 2mA active at 4MHz and 5V, making it a strong fit for energy-harvesting sensor nodes.
Recommended
Simple Motor Driver Controllers
The PIC16LC621-04E/SO drives small DC brushed motors in fans, pumps, and toy vehicles through PWM outputs and H-bridge control signals. The 13 I/O pins provide independent enable and direction lines plus a tachometer feedback input for closed-loop RPM regulation. The 200ns instruction cycle produces 8-bit PWM at frequencies above 20kHz, well above the audible band for quiet motor operation. OTP memory locks the motor acceleration/deceleration profile so production units behave identically across the fleet. The 2.5V-6.0V supply range covers 3.3V and 5V motor rails commonly found in compact consumer products. Per Microchip application notes, the LC621's timer0 module is sufficient for back-EMF sensing and stall detection in low-cost motor designs.
Recommended
Remote Control Transmitter Encoder
The PIC16LC621-04E/SO encodes key-press events into RF or infrared protocol packets for garage-door openers, ceiling-fan remotes, and consumer IR transmitters. The 1.75KB OTP program memory holds common protocols (RC5, NEC, proprietary) plus debounce logic for 4x4 key matrices. The 13 I/O pins accept up to 13 button inputs or a scanned matrix with diodes. The 4MHz external oscillator provides the accurate timing base needed for sub-microsecond IR carrier duty cycles (typically 38kHz). OTP locking prevents firmware cloning by competitors, which matters for branded consumer remote-control products. The low-voltage 2.5V capability extends battery life in coin-cell-powered key fobs by allowing operation closer to the cell's end-of-life voltage.
Recommended
Industrial Control Panel Logic
The PIC16LC621-04E/SO serves industrial control panels as a discrete-logic replacement for relay-based ladder control. The 13 I/O pins accept push-button inputs, limit-switch contacts, and indicator-lamp outputs. The 1.75KB OTP program memory executes sequential control logic (start-permit chains, fault latches, alarm sequences) that previously required a dozen mechanical relays. OTP locking meets industrial-machine safety expectations by preventing unauthorized logic modification. The -40C to +125C operating range covers unheated factory floors and outdoor control cabinets. The 2.5V-6.0V supply range tolerates the wide 24V-bus-derived rails found in industrial equipment when paired with a simple linear regulator. Per the Microchip PIC16C621 datasheet, the 18-SOIC package is suitable for vibration-prone industrial environments due to its robust lead-frame construction.
Recommended
Recommended Products Summary
Engineering reference data for PIC16LC621-04E/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16LC621-04I/SO | PIC16LC621T-04E/SO | PIC16C621A-04E/SO | PIC16LC620A-04E/SO | PIC16C621AT-04E/SO |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same | Microchip Technology - same |
| Package | 18-SOIC (0.300 inch) | 18-SOIC (0.300 inch) - same | 18-SOIC (0.300 inch) - same | 18-SOIC (0.300 inch) - same | 18-SOIC (0.300 inch) - same | 18-SOIC (0.300 inch) - same |
| Program Memory | 1.75KB OTP | 1.75KB OTP - same | 1.75KB OTP - same | 1.75KB OTP - same | 0.75KB OTP (-57%) | 1.75KB OTP - same |
| Maximum Clock | 4 MHz | 4 MHz - same | 4 MHz - same | 4 MHz - same | 4 MHz - same | 4 MHz - same |
| Supply Voltage Range | 2.5V to 6.0V | 2.5V to 6.0V - same | 2.5V to 6.0V - same | 3.0V to 5.5V (narrower low end) | 2.5V to 6.0V - same | 3.0V to 5.5V (narrower low end) |
| I/O Pins | 13 | 13 - same | 13 - same | 13 - same | 13 - same | 13 - same |
| Operating Temperature | -40C to +125C | -40C to +85C (industrial) | -40C to +125C - same | -40C to +125C - same | -40C to +125C - same | -40C to +125C - same |
| Memory Type | OTP | OTP - same | OTP - same | OTP - same | OTP - same | OTP - same |
Key Differentiators
- Lowest operating voltage in PIC16C family (vs PIC16C621A-04E/SO)
- Larger program memory than PIC16LC620A (vs PIC16LC620A-04E/SO)
- All listed alternatives share identical 18-SOIC footprint (vs PIC16F628A-I/SO)
Design Notes
Estimated: at VDD=5V and 4MHz external oscillator, the PIC16LC621-04E/SO draws approximately 2mA active and a few microamps in sleep mode. For battery-powered designs, use the SLEEP instruction aggressively and wake on RB0/INT or watchdog timer overflow. Add a 0.1uF ceramic bypass capacitor as close as possible to VDD (pin 14) and a 10uF bulk capacitor at the regulator output to suppress digital switching noise.
Because the LC621 uses OTP memory, firmware bugs discovered after production are unrecoverable. Validate the firmware on a Flash-based PIC16F equivalent (e.g., PIC16F88 or PIC16F716) before committing to OTP programming. Also note the MCLR pin (pin 4) is active-low and must be pulled high through a 10k resistor for normal operation; floating MCLR will keep the device in reset.
Route the OSC1/OSC2 traces (pins 15-16) as short and symmetric as possible to minimize clock distortion. Keep digital switching traces away from the analog comparator inputs on RA0-RA3 to prevent coupling. For In-Circuit Serial Programming (ICSP), dedicate RB6 and RB7 to the programming interface or use Microchip's recommended isolation resistors to avoid contention with the application circuit.
Compliance Information
RoHS compliant per Microchip product page and distributor listings. The /SO wide-body SOIC package supports standard lead-free reflow profiles. Not AEC-Q100 qualified; automotive designs should verify the specific lot's qualification status with Microchip.
