PIC16LC621T-04I/SO - 8-Bit 4MHz OTP MCU 1.75KB | Microchip
MPN: PIC16LC621T-04I/SO ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.95 | $3.95 |
| 10 | $3.55 | $35.50 |
| 100 | $3.18 | $318.00 |
| 500 | $2.84 | $1,420.00 |
| 1,000 | $2.52 | $2,520.00 |
PIC16LC621T-04I/SO Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, program memory, data memory, and I/O peripherals on one die. MCUs sit within the broader semiconductor hierarchy as a subcategory of microprocessors, alongside digital signal processors (DSPs), microcontrollers (MCUs), and application processors. The PIC16C family specifically targets low-cost general-purpose control with a RISC-based 12-bit instruction word and 8-bit data path. LC variants use CMOS technology for low power consumption, while the 621 sub-family adds a comparator peripheral for analog signal conditioning.
Key features include a two-level deep hardware stack, direct/indirect/relative addressing modes, seven or eight special function hardware registers, an internal oscillator option, and a programmable code-protection mechanism. The 18-pin SOIC (SO) package provides 0.295 in (7.50 mm) body width suitable for hand-soldering and standard SMT lines. The 04 speed grade denotes 4 MHz maximum oscillator frequency, and the LC process node enables typical active current around 2 mA at 5 V and 4 MHz.
Typical applications include appliance control modules, low-end consumer electronics, IR remote controls, sensor interfaces, and battery-powered toys. The integrated analog comparator simplifies proximity-sensor and battery-monitor front-ends without requiring an external op-amp. The OTP memory makes the part appropriate for mature products where firmware no longer requires in-field updates.
When designing with this part, account for OTP memory constraints: code must be 100 % verified before programming because OTP cannot be erased or rewritten. The 80-byte RAM limits stack depth and buffer-heavy algorithms, so designers should avoid large lookup tables or recursions in firmware planning.
Drop-in alternatives for PIC16LC621T-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 PIC16LC621T-04I/SO (same form factor and footprint) — differing in Package, Core Architecture, Program Memory Size, Program Memory Type, RAM Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16LC621AT-04I/SO
✅ Drop-In✓ In Stock
$1.55 / Unit
View Datasheet →PIC16LC621AT-04I/SS
✅ Drop-In✓ In Stock
$2.46 / Unit
View Datasheet →PIC16LC621T-04/SS
✅ Drop-In✓ In Stock
$2.1 / Unit
View Datasheet →PIC16LC621AT-04E/SS
✅ Drop-In✓ In Stock
$2.19 / Unit
View Datasheet →PIC16LC620AT-04I/SO
✅ Drop-In✓ In Stock
$1.62 / Unit
View Datasheet →PIC16LC621T-04I/SO Maximum Ratings & Electrical Characteristics
| Core | PIC16C 8-bit RISC |
| Maximum Clock Speed | 4 MHz |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 1.75 KB (1K x 14) |
| RAM Size | 80 bytes |
| Supply Voltage Range | 2.5 V to 6.25 V |
| I/O Pins | 12 |
| Operating Temperature Range | -40 °C to +85 °C (Industrial) |
| Instruction Set Width | 12-bit instructions / 8-bit data path |
| Hardware Stack Depth | 2 levels |
| Addressing Modes | Direct, Indirect, Relative |
| Special Function Registers | 7-8 |
| Analog Comparator | Yes (integrated) |
| Package | 18-SOIC (0.295 in / 7.50 mm body width) |
| Mounting Type | Surface Mount |
PIC16LC621T-04I/SO Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O port A bit 2 |
| Pin 2 | RA3 — Bidirectional I/O port A bit 3 |
| Pin 3 | RA4/T0CKI — I/O port A bit 4 / Timer0 clock input |
| Pin 4 | MCLR — Master Clear (reset) input, active low |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — I/O port B bit 0 / External interrupt input |
| Pin 7 | RB1 — Bidirectional I/O port B bit 1 |
| Pin 8 | RB2 — Bidirectional I/O port B bit 2 |
| Pin 9 | RB3 — Bidirectional I/O port B bit 3 |
| Pin 10 | RB4 — Bidirectional I/O port B bit 4 |
| Pin 11 | RB5 — Bidirectional I/O port B bit 5 |
| Pin 12 | RB6 — Bidirectional I/O port B bit 6 |
| Pin 13 | RB7 — Bidirectional I/O port B bit 7 |
| Pin 14 | VDD — Positive supply voltage (2.5 V to 6.25 V) |
| Pin 15 | OSC2/CLKOUT — Oscillator output / clock output |
| Pin 16 | OSC1/CLKIN — Oscillator input / external clock input |
| Pin 17 | RA0 — Bidirectional I/O port A bit 0 |
| Pin 18 | RA1 — Bidirectional I/O port A bit 1 |
Typical Applications
PIC16LC621T-04I/SO is suitable for 6 applications: Appliance Control Module, IR Remote Control Transmitter, Battery-Powered Toy and Hobby Controller, Sensor Interface Module, LED Lighting Controller, Security and Accessory Modules.
Appliance Control Module
The PIC16LC621T-04I/SO is well suited for low-cost appliance control boards such as washing-machine timers, microwave user interfaces, and small kitchen-appliance motor controllers. Its 12 I/O pins comfortably drive multiplexed 7-segment displays, keypad scans, and relay/triac interface transistors, while the integrated analog comparator simplifies zero-crossing detection for line-voltage control. With 1.75 KB of OTP memory, designers can host full state-machine firmware for cycle control, sensor conditioning, and user-feedback routines at production volumes. Operating from 2.5-6.25 V, the device tolerates rectified 5 V rails common in switched-mode power supplies found inside consumer appliances.
Recommended
IR Remote Control Transmitter
For IR remote controls, the PIC16LC621T-04I/SO delivers adequate processing for RC-5, NEC, or SIRC protocol generation while consuming minimal power from two AAA cells. The 4 MHz clock supports 38 kHz carrier generation with sufficient timing margin for transmit repeat codes. With 12 I/O pins, designers can scan a 4x4 or 5x3 keypad matrix and drive an IR LED via a single transistor. The wide 2.5-6.25 V supply range lets the same firmware work in both 3 V and 4.5 V battery configurations. OTP memory prevents casual firmware theft and locks the design into production.
Recommended
Battery-Powered Toy and Hobby Controller
Battery-powered toys, electronic learning kits, and hobby robotics projects benefit from the PIC16LC621T-04I/SO's low active current at 3 V supply and 4 MHz operation. The integrated analog comparator can directly sense battery voltage for low-battery warning without an external ADC. With 80 bytes of RAM and a two-level hardware stack, designers can implement PWM motor control, LED animations, and simple sensor-fusion algorithms. The 18-SOIC package is rugged enough for through-hole-socketed prototyping on breadboards and perfboards, while still supporting SMT lines for higher-volume builds.
Recommended
Sensor Interface Module
The PIC16LC621T-04I/SO acts as a smart front-end for analog sensors in industrial and HVAC systems. Its integrated analog comparator enables threshold detection for thermistor, photodiode, or Hall-effect sensors without requiring an external op-amp, reducing BOM cost. The 12-bit instruction width and 8-bit data path support conditional logic for alarm generation, hysteresis control, and relay driver sequencing. Operating from 2.5-6.25 V, the part interfaces directly with 3.3 V or 5 V sensor networks. The wide industrial temperature range (-40 to +85 °C) suits outdoor and factory-floor deployments.
Recommended
LED Lighting Controller
For decorative LED strips, status indicators, and small lighting controllers, the PIC16LC621T-04I/SO offers sufficient I/O and computational throughput to drive multiple PWM channels for RGB color mixing. The 4 MHz clock allows software PWM at acceptable refresh rates for 4-8 LED channels. The integrated analog comparator can sample a photodiode for ambient-light feedback, enabling automatic brightness adjustment. Operating from 2.5-6.25 V supports direct connection to 5 V LED driver rails. OTP memory secures proprietary lighting effects and color sequences from reverse engineering.
Recommended
Security and Accessory Modules
The PIC16LC621T-04I/SO fits secondary modules in security systems, such as PIR sensor signal-conditioning boards, magnetic-contact expansion modules, and simple keypad readers. The integrated comparator processes analog PIR outputs directly, while 12 I/O pins drive LEDs, buzzers, and relay outputs for local alarm annunciation. OTP memory prevents code tampering in security-sensitive deployments. The 2.5-6.25 V supply range accommodates battery-backed 3.3 V systems and 5 V main-rail-powered accessories. The industrial temperature grade supports outdoor and uncontrolled-environment installations.
Recommended
Recommended Products Summary
Engineering reference data for PIC16LC621T-04I/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16LC621AT-04I/SO | PIC16LC621AT-04I/SS | PIC16LC621T-04/SS | PIC16LC621AT-04E/SS | PIC16LC620AT-04I/SO |
|---|---|---|---|---|---|---|
| Package | 18-SOIC (7.50 mm / 300 mil) | 18-SOIC - same | 18-SSOP (narrower body) | 18-SSOP (narrower body) | 18-SSOP (narrower body) | 18-SOIC - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Core | PIC16C 8-bit RISC | PIC16C 8-bit RISC | PIC16C 8-bit RISC | PIC16C 8-bit RISC | PIC16C 8-bit RISC | PIC16C 8-bit RISC |
| Maximum Clock Speed | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz |
| Program Memory | 1.75 KB OTP (1K x 14) | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB OTP | 0.875 KB OTP (smaller) |
| RAM Size | 80 bytes | 80 bytes | 80 bytes | 80 bytes | 80 bytes | 80 bytes |
| Supply Voltage | 2.5 V to 6.25 V | 2.5 V to 6.25 V | 2.5 V to 6.25 V | 2.5 V to 6.25 V | 2.5 V to 6.25 V | 2.5 V to 6.25 V |
| Temperature Grade | Industrial (-40 to +85 °C) | Industrial (-40 to +85 °C) | Industrial (-40 to +85 °C) | Industrial (-40 to +85 °C) | Extended (-40 to +125 °C) | Industrial (-40 to +85 °C) |
| I/O Pins | 12 | 12 | 12 | 12 | 12 | 12 |
| Integrated Analog Comparator | Yes | Yes | Yes | Yes | Yes | No |
Key Differentiators
- Integrated analog comparator without external op-amp (vs PIC16LC620AT-04I/SO)
- Industrial temperature grade from standard part number (vs PIC16LC621AT-04E/SS)
- Latest silicon revision in same SOIC footprint (vs PIC16LC621T-04/SS)
Design Notes
OTP (One-Time Programmable) memory cannot be erased or rewritten. Each silicon die accepts a single programming cycle, so verify all firmware logic, calibration constants, and interrupt vectors with a Flash-based equivalent (PIC16F84A or PIC16F88) before committing to PIC16LC621T-04I/SO in production. Lost programming cycles due to code bugs directly impact unit cost. Always validate with engineering samples from Microchip's Sample Store before placing volume orders.
Estimated: at 5 V VDD and 4 MHz active mode, the PIC16LC621T-04I/SO draws approximately 2 mA typical, rising to ~5 mA at 6.25 V. In sleep mode, current drops below 5 uA typical. For battery-powered designs, use sleep mode aggressively and wake via the Watchdog Timer or external interrupt on RB0/INT. Add a 0.1 uF decoupling capacitor as close as possible to pin 14 (VDD) and pin 5 (VSS) to suppress switching noise from the internal clock edges.
Place the 18-SOIC package with pin 1 orientation marked clearly on the silkscreen. The MCLR pin (pin 4) requires a pull-up resistor (typically 10 kOhm) to VDD for normal operation; without it the device stays in reset. If using an external crystal, keep traces from OSC1 (pin 16) and OSC2 (pin 15) short and surround them with a ground guard ring to minimize EMI radiation. The analog comparator inputs are shared with digital I/O - if precision analog sensing is required, isolate the analog traces from high-frequency digital signals on the same port.
Compliance Information
The PIC16LC621T-04I/SO is a legacy OTP family part from Microchip. RoHS and REACH compliance status not explicitly stated in the retrieved distributor data; legacy PIC16C OTP parts are commonly non-RoHS due to the OTP process node. For RoHS-compliant designs, verify with Microchip directly or migrate to the PIC16F family.