PIC16LC621A-04E/SS - 8-bit OTP MCU, 4MHz, 1.75KB EPROM | Microchip
MPN: PIC16LC621A-04E/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.83 | $2.83 |
| 10 | $2.55 | $25.50 |
| 100 | $2.1 | $210.00 |
| 500 | $1.75 | $875.00 |
| 1,000 | $1.45 | $1,450.00 |
PIC16LC621A-04E/SS Overview
What is an 8-bit OTP microcontroller? An 8-bit OTP MCU is a small, low-power RISC microcontroller that integrates CPU, non-volatile OTP program memory, RAM data memory, and digital peripherals on a single CMOS die. Within the broader hierarchy (8-bit microcontroller -> RISC microcontroller -> microcontroller -> embedded IC -> semiconductor), the PIC16LC62x sits at the lower end of Microchip's mid-range PIC16 architecture, designed for cost-sensitive, low-pin-count embedded control tasks where the firmware is finalized during development and not field-upgradable.
Key features of the PIC16LC621A-04E/SS include a 14-bit instruction word with only 35 single-cycle instructions to learn (excluding program branches, which take two cycles), a two-level deep hardware stack, direct/indirect/relative addressing modes, seven or eight special-function hardware registers, and an integrated watchdog timer, power-on reset, and brown-out reset. The "LC" voltage class supports 2.5 V to 6.25 V operation, allowing both 3.3 V and 5 V rails, while the "04" suffix denotes the 4 MHz speed grade. The "E" suffix designates the extended industrial temperature range (-40 °C to +125 °C).
The device architecture uses a Harvard-style separate program/data bus optimized for deterministic 200 ns instruction cycles, with a small but efficient interrupt structure. Twelve to thirteen GPIO pins share package pins with peripheral functions, and the on-chip RC oscillator option reduces external component count. Total I/O count and peripheral map vary slightly within the PIC16LC62x sub-family, but the 621A variant provides 12 I/O with analog comparator support.
Typical applications include low-cost consumer appliances, sensor interface modules, simple motor and relay control, LED driving and indicator panels, battery-powered handheld instruments, and industrial automation edge nodes where 8-bit processing headroom and minimal BOM are more important than connectivity or DSP performance.
When designing with this part, note that OTP memory cannot be reprogrammed in-circuit; for development cycles, use the windowed (JW) or flash-based PIC16F62x equivalent. Brown-out reset and watchdog timer configuration are controlled by configuration-word bits set during programming and cannot be changed at runtime. Always place a 0.1 µF decoupling capacitor within a few millimeters of VDD.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not found in the manufacturer datasheet, organized to help procurement and embedded engineers evaluate the PIC16LC621A-04E/SS quickly.
Drop-in alternatives for PIC16LC621A-04E/SS — 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 PIC16LC621A-04E/SS (same form factor and footprint) — differing in Program Memory Type, Package, Program Memory Size, Core Architecture, I/O Pins.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16LC621A-04/SS
✅ Drop-In✓ In Stock
$1.95 / Unit
View Datasheet →PIC16LC621A-04I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16LC621AT-04/SS
✅ Drop-In✓ In Stock
$1.22 / Unit
View Datasheet →PIC16LC620A-04E/SS
✅ Drop-In✓ In Stock
$2.54 / Unit
View Datasheet →PIC16LC620AT-04I/SS
✅ Drop-In✓ In Stock
$1.18 / Unit
View Datasheet →PIC16LC620A-04E/SO
✅ Drop-In✓ In Stock
$2.07 / Unit
View Datasheet →PIC16LC621A-04E/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC RISC |
| Program Memory Type | EPROM (OTP) |
| Program Memory Size | 1.75 KB |
| Data RAM | 96 bytes |
| Maximum Clock Frequency | 4 MHz |
| Instruction Cycle Time | 200 ns (single-cycle instructions) |
| Instruction Word Width | 14 bits |
| Number of Instructions | 35 |
| Supply Voltage (LC class) | 2.5 V to 6.25 V |
| I/O Pins | 13 |
| Operating Temperature Range | -40 °C to +125 °C (Extended, "E") |
| Package | 20-pin SSOP (5.30 mm body width) |
| Mounting Type | Surface Mount |
| Hardware Stack | 2 levels deep |
| Peripherals | Watchdog Timer, Power-On Reset, Brown-Out Reset, Analog Comparator |
PIC16LC621A-04E/SS Pin Configuration
| Pin 1 | MCLR/VPP — Master clear reset input / programming voltage |
| Pin 2 | RA0/AN0 — Digital I/O / analog comparator input |
| Pin 3 | RA1/AN1 — Digital I/O / analog comparator input |
| Pin 4 | RA2/AN2/VREF — Digital I/O / analog comparator / voltage reference |
| Pin 5 | RA3/AN3 — Digital I/O / analog comparator input |
| Pin 6 | RA4/T0CKI — Digital I/O / Timer0 clock input (open-drain) |
| Pin 7 | RA5/SS/AN4 — Digital I/O / SPI slave select / analog comparator |
| Pin 8 | OSC2/CLKOUT — Crystal oscillator output / clock out |
| Pin 9 | OSC1/CLKIN — Crystal oscillator input / external clock |
| Pin 10 | RC0 — Digital I/O port C |
| Pin 11 | RC1 — Digital I/O port C |
| Pin 12 | RC2 — Digital I/O port C |
| Pin 13 | RC3 — Digital I/O port C |
| Pin 14 | RC4 — Digital I/O port C |
| Pin 15 | RC5 — Digital I/O port C |
| Pin 16 | RC6 — Digital I/O port C |
| Pin 17 | RC7 — Digital I/O port C |
| Pin 18 | RB0/INT — Digital I/O port B / external interrupt |
| Pin 19 | VSS — Ground reference |
| Pin 20 | VDD — Positive supply voltage (2.5V to 6.25V) |
Typical Applications
PIC16LC621A-04E/SS is suitable for 6 applications: Consumer Appliance Control, Battery-Powered Sensor Module, LED Lighting Driver Controller, Industrial Automation Edge Node, Automotive Interior Switch Panel, Simple Motor Speed Controller.
Consumer Appliance Control
The PIC16LC621A-04E/SS fits consumer appliance control with its 1.75 KB OTP program memory and 200 ns single-cycle instruction execution at 4 MHz, enabling responsive keypad/display polling. Brown-out reset and watchdog timer protect against mains brown-outs and firmware lock-ups, while the 13 I/O pins drive relays, triac optocouplers, and seven-segment displays. Compared with a flash MCU, the OTP variant reduces unit cost in high-volume appliance production runs.
Recommended
Battery-Powered Sensor Module
The PIC16LC621A-04E/SS suits battery-powered sensor modules thanks to its 2.5 V to 6.25 V supply range supporting 3.3 V lithium chemistry and low CMOS sleep current. The 4 MHz internal RC oscillator eliminates the external crystal, reducing quiescent draw and BOM cost for remote sensor nodes. With 96 bytes of RAM and 13 I/O, it handles periodic ADC reads from the analog comparator and basic threshold-based decision logic.
Recommended
LED Lighting Driver Controller
The PIC16LC621A-04E/SS drives LED lighting controllers via PWM-on-software, using one or more of its 13 I/O pins with the 200 ns instruction cycle to generate accurate PWM dimming signals at low frequencies. The 1.75 KB OTP stores color-mixing lookup tables and fade curves for architectural lighting. Extended -40C to +125C temperature operation supports outdoor or industrial fixture environments with high ambient heat.
Recommended
Industrial Automation Edge Node
In industrial automation edge nodes, the PIC16LC621A-04E/SS reads discrete sensor inputs and drives optoisolated outputs while the 4 MHz clock and 200 ns instruction cycle provide deterministic loop times for PLC-style control. Brown-out reset and watchdog timer protect against ESD-induced brown-outs on factory floors, while extended -40C to +125C operation supports unheated enclosures. The 20-pin SSOP package suits compact DIN-rail terminal form factors.
Recommended
Automotive Interior Switch Panel
The PIC16LC621A-04E/SS works in non-safety automotive interior switch panels (window switches, mirror controls, seat adjusters) where its -40C to +125C extended temperature rating handles cabin thermal extremes. The 13 I/O pins scan matrix keypads and drive LED backlights via PWM, while 1.75 KB EPROM holds debounce logic and indicator patterns. Note that AEC-Q100 qualification is not documented in the verified data, so it should not be used in safety-critical automotive ECUs.
Recommended
Simple Motor Speed Controller
The PIC16LC621A-04E/SS implements closed-loop DC motor speed control by measuring tachometer pulses on a digital input and generating PWM on a GPIO, using the 200 ns instruction cycle to compute PI control loops in software. The 1.75 KB EPROM stores calibration constants and ramp profiles, while 13 I/O handle direction, brake, and enable signals. Extended temperature operation supports motor-driver PCB thermal rise in enclosed appliances.
Recommended
Recommended Products Summary
Engineering reference data for PIC16LC621A-04E/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16LC621A-04/SS | PIC16LC621A-04I/SS | PIC16LC621AT-04/SS | PIC16LC620A-04E/SS | PIC16LC620AT-04I/SS | PIC16LC620A-04E/SO |
|---|---|---|---|---|---|---|---|
| Package | 20-pin SSOP | 20-pin SSOP | 20-pin SSOP | 20-pin SSOP | 20-pin SSOP | 20-pin SSOP | 20-pin SSOP |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 1.75 KB EPROM | 1.75 KB EPROM | 1.75 KB EPROM | 1.75 KB EPROM | 512 B EPROM | 512 B EPROM | 512 B EPROM |
| RAM | 96 bytes | 96 bytes | 96 bytes | 96 bytes | 68 bytes | 68 bytes | 68 bytes |
| Max Clock | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz |
| Operating Temperature | -40C to +125C (E) | 0C to +70C | -40C to +85C | 0C to +70C | -40C to +125C | -40C to +85C | -40C to +125C |
| 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 | 2.5 V to 6.25 V |
| I/O Pins | 13 | 13 | 13 | 13 | 13 | 13 | 13 |
Key Differentiators
- Extended industrial temperature range (vs PIC16LC621A-04/SS)
- 1.75 KB EPROM for more complex firmware (vs PIC16LC620A-04E/SS)
- 96 bytes RAM for larger buffers (vs PIC16LC620A-04E/SS)
Design Notes
Place a 0.1 µF ceramic decoupling capacitor within 3 mm of the VDD pin (pin 20) and an additional 10 µF bulk capacitor at the regulator output. The PIC16LC621A-04E/SS operates from 2.5 V to 6.25 V; for 5 V rails use a low-dropout regulator such as MCP1700 with at least 100 mV headroom above the regulated output to avoid dropout during motor inrush events.
The PIC16LC621A-04E/SS uses OTP EPROM and cannot be re-flashed after programming; the SSOP package has no UV-erase window. For development cycles, program a flash-based PIC16F62x or PIC16F628 equivalent first, then qualify the OTP variant for production. Configuration-word bits for watchdog, brown-out, and oscillator mode are set once during programming and cannot be changed at runtime.
Route the MCLR/VPP pin (pin 1) directly to a dedicated reset pull-up resistor (typically 10 kΩ to VDD) and avoid long traces that pick up noise; capacitive loading above 50 pF on MCLR can prevent reliable in-circuit serial programming. Keep the crystal traces between OSC1 (pin 9) and OSC2 (pin 8) short and symmetric, with a ground guard ring if operating above 4 MHz in noisy environments.
Compliance Information
RoHS, REACH, lead-free, and halogen-free status not explicitly stated in verified web data; flagged as [DATA_NEEDED]. AEC-Q100 not documented for this part - select PIC16F or PIC18F automotive-grade MCUs for safety-critical automotive ECUs. Microchip publishes a Conflict Minerals Report compliant with the Dodd-Frank Act covering the PIC16 family.
