PIC16LC621A-04E/P - 8-Bit 4MHz OTP MCU 1.75KB | Microchip
MPN: PIC16LC621A-04E/P ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.95 | $2.95 |
| 10 | $2.65 | $26.50 |
| 100 | $2.34 | $234.00 |
| 500 | $2.05 | $1,025.00 |
| 1,000 | $1.78 | $1,780.00 |
PIC16LC621A-04E/P Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU, program memory, data RAM, and programmable I/O peripherals. The PIC16C family specifically uses a RISC architecture with only 35 single-word instructions, making it well suited to embedded control applications where deterministic timing and a small code footprint are priorities. PIC16LC621A-04E/P sits at the entry level of the PIC16C62x lineup, providing just enough program memory and I/O for cost-sensitive control loops.
Key features include 12 I/O pins distributed across two ports (PORTA 5-bit, PORTB 8-bit with programmable weak pull-ups), 80 bytes of data RAM, a two-level hardware stack, and seven special function registers. The core executes one instruction per 200 ns cycle (except program branches, which are two-cycle) and supports direct, indirect, and relative addressing modes for efficient peripheral and register access. A 4 MHz internal oscillator can be selected via configuration fuse to eliminate external clock hardware.
Architecturally, the PIC16C62x is built around a Harvard-style split-bus design with 14-bit wide instructions and 8-bit data, paired with a 200 ns instruction pipeline that gives the family its deterministic interrupt and timing behavior. The PIC16LC621A specifically targets applications that need the analog comparator peripheral of the PIC16C62x family but do not require the on-chip ADC of the larger PIC16C622/PIC16C622A variants, keeping cost and silicon area minimal.
Typical applications include appliance control, sensor signal conditioning, simple PWM fan or motor control loops, low-cost LED lighting controllers, and white-goods user-interface modules. The wide 2.5 V to 6.25 V supply range allows direct connection to 3.3 V or 5 V rails without external level shifters. Industrial-grade parts with the 'E' suffix support -40 °C to +125 °C operating temperatures, which is required for outdoor, automotive-cabin, and factory-floor deployments.
When designing with this MCU, reserve one of the PORTA pins for the analog comparator and configure the MCLR pin with a proper external pull-up, since this family does not provide an internal MCLR pull-up. Allow at least 4 ms Vdd rise time at power-up so the internal power-on-reset circuit releases the part cleanly into user code.
Drop-in alternatives for PIC16LC621A-04E/P — 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/P (same form factor and footprint) — differing in Operating Temperature Range, Package, Program Memory Size, Program Memory Type, I/O Pins.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16LC621A-04/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16LC621A-04I/P
✅ Drop-In✓ In Stock
$1.01 / Unit
View Datasheet →PIC16LC621-04E/P
✅ Drop-In✓ In Stock
$2.46 / Unit
View Datasheet →PIC16LC620A-04E/P
✅ Drop-In✓ In Stock
$1.85 / Unit
View Datasheet →PIC16F628A-I/P
✅ Drop-In✓ In Stock
$1.62 / Unit
View Datasheet →PIC16LC621A-04E/P Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC (Harvard) |
| Family | PIC® 16C |
| Program Memory Type | OTP (EPROM-based) |
| Program Memory Size | 1.75 KB (1K x 14) |
| Data RAM | 80 bytes |
| Maximum Clock Frequency | 4 MHz |
| Instruction Cycle | 200 ns (4 MHz) |
| Supply Voltage (Vdd) | 2.5 V to 6.25 V |
| I/O Pins | 12 |
| Package | 18-PDIP (0.300 inch, 7.62 mm) |
| Operating Temperature Range | -40 °C to +125 °C (industrial, 'E' suffix) |
| Number of Instructions | 35 |
| Hardware Stack Depth | 2 levels |
| Special Function Registers | 7-8 |
| Mounting Type | Through-Hole (THT) |
PIC16LC621A-04E/P Pin Configuration
| Pin 1 | RA2 — PORTA bit 2 (bidirectional I/O, analog comparator input) |
| Pin 2 | RA3 — PORTA bit 3 (bidirectional I/O, analog comparator input) |
| Pin 3 | RA4/T0CKI — PORTA bit 4 / Timer0 external clock input |
| Pin 4 | MCLR — Master clear reset (active-low, external pull-up required) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — PORTB bit 0 / external interrupt input |
| Pin 7 | RB1 — PORTB bit 1 (bidirectional I/O) |
| Pin 8 | RB2 — PORTB bit 2 (bidirectional I/O) |
| Pin 9 | RB3 — PORTB bit 3 (bidirectional I/O) |
| Pin 10 | RB4 — PORTB bit 4 (interrupt-on-change, weak pull-up) |
| Pin 11 | RB5 — PORTB bit 5 (interrupt-on-change, weak pull-up) |
| Pin 12 | RB6 — PORTB bit 6 (interrupt-on-change, weak pull-up) |
| Pin 13 | RB7 — PORTB bit 7 (interrupt-on-change, weak pull-up) |
| Pin 14 | VDD — Positive supply voltage (2.5 V to 6.25 V) |
| Pin 15 | OSC2/CLKOUT — Oscillator crystal output / CLKOUT when RC mode selected |
| Pin 16 | OSC1/CLKIN — Oscillator crystal input / external clock input |
| Pin 17 | RA0 — PORTA bit 0 (analog comparator input) |
| Pin 18 | RA1 — PORTA bit 1 (analog comparator input) |
Typical Applications
PIC16LC621A-04E/P is suitable for 6 applications: White Goods Appliance Control, Sensor Signal Conditioning Hub, Low-Cost LED Lighting Controller, User-Interface Keypad Decoder, Battery-Powered Remote Control, Industrial Sensor Transmitter.
White Goods Appliance Control
The PIC16LC621A-04E/P's 1.75 KB OTP memory, 12 I/O pins, and industrial -40C to +125C temperature range make it a practical fit for washing-machine, dishwasher, and refrigerator control boards. Its 200 ns instruction cycle is sufficient to drive relay sequencing, door-lock interlocks, and rotary-encoder user inputs while leaving CPU bandwidth for a simple finite-state-machine user interface. The 2.5 V to 6.25 V supply range lets the same part run directly from 5 V rails or a regulated 3.3 V supply, and the analog comparator on PORTA can read NTC temperature sensors without an external op-amp. Compared with newer PIC16F1xxx parts it is lower cost and supported by legacy toolchains still used in white-goods manufacturing.
Recommended
Sensor Signal Conditioning Hub
With 12 I/O and an analog comparator on PORTA, the PIC16LC621A-04E/P can read a small array of analog sensors, threshold-detect them, and drive digital outputs. The 'LC' low-voltage process lets the part run from 2.5 V, matching modern 1.5-cell battery or boost-converter-rail designs. PORTA pins RA0-RA3 can each be routed to the analog comparator, allowing up to four sensor thresholds to be monitored without an external analog front end. Industrial temperature grading (-40C to +125C) supports outdoor and factory installations. The 200 ns instruction cycle is fast enough to scan all sensors within typical 10 ms control loops.
Recommended
Low-Cost LED Lighting Controller
The PIC16LC621A-04E/P can drive multiple LED channels via PWM generated in software on its 12 I/O pins, supporting dimming, color-mixing, and simple show patterns for under-cabinet, accent, or decorative lighting. The 4 MHz clock and 200 ns instruction cycle comfortably handle 8-bit PWM at 1 kHz refresh across several channels. The 2.5 V minimum supply lets the part operate from a single Li-ion cell when paired with a small boost converter. Industrial temperature grading is sufficient for outdoor luminaires and refrigerator/freezer compartments. Pairing with MOSFET drivers like the MCP14-series gives PWM fan or LED control at higher currents.
Recommended
User-Interface Keypad Decoder
The PIC16LC621A-04E/P's PORTB weak pull-ups and 8-bit width make it an efficient 4x4 or smaller matrix-keypad scanner with native interrupt-on-change support. The 200 ns instruction cycle allows the MCU to debounce and decode matrix scans at 50 Hz or faster with negligible CPU load. The 12 I/O pins provide enough headroom for up to 16 matrix keys plus a few indicator LEDs. Industrial temperature grading ensures reliable operation in outdoor kiosks and industrial control panels. The internal watchdog timer catches keypad scan lockups without external components.
Recommended
Battery-Powered Remote Control
The PIC16LC621A-04E/P's 'LC' low-voltage process and 2.5 V minimum supply let it operate from a single CR2032 or two AA cells without a boost regulator, ideal for handheld remote controls. SLEEP-mode current in the microampere range extends battery life to years, and the watchdog timer wakes the MCU periodically to scan button inputs. PORTB weak pull-ups let button inputs be wired directly without external resistors. The 4 MHz internal oscillator mode eliminates external crystal cost. Industrial temperature rating covers outdoor garage-door openers and automotive-keyfob applications.
Recommended
Industrial Sensor Transmitter
The PIC16LC621A-04E/P can serve as the core of a 4-20 mA or simple digital sensor transmitter, digitizing sensor inputs and modulating a current loop or UART output. Its industrial -40C to +125C operating range meets harsh-environment sensor deployments on factory floors. The 12 I/O pins and analog comparator support both bridge-type sensors and threshold detection without additional analog components. The OTP memory prevents firmware modification after deployment, important for tamper-resistant industrial transmitters. Pairing with isolation devices like isolation transformers or digital isolators keeps the MCU safe on high-voltage field sides.
Recommended
Recommended Products Summary
Engineering reference data for PIC16LC621A-04E/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16LC621A-04/P | PIC16LC621A-04I/P | PIC16LC621-04E/P | PIC16LC620A-04E/P | PIC16F628A-I/P |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 18-PDIP (0.300 inch) | 18-PDIP (0.300 inch) - same | 18-PDIP (0.300 inch) - same | 18-PDIP (0.300 inch) - same | 18-PDIP (0.300 inch) - same | 18-PDIP (0.300 inch) - same |
| Program Memory | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB OTP | 0.875 KB OTP | 3.5 KB Flash |
| Maximum Clock | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 20 MHz (with internal 4 MHz) |
| Operating Temperature | -40C to +125C (E) | 0C to +70C (commercial) | -40C to +85C (I grade) | -40C to +125C (E) | -40C to +125C (E) | -40C to +85C (I) |
| Memory Type | OTP (one-time) | OTP | OTP | OTP | OTP | Flash (reprogrammable) |
| I/O Pins | 12 | 12 | 12 | 12 | 13 | 16 |
| Reprogrammable | No (OTP) | No | No | No | No | Yes (Flash, 1000 cycles) |
| Internal Peripherals | Analog comparator, Timer0, WDT | Same as target | Same as target | Same as target | Reduced (no analog comparator) | Adds USART, CCP, 128B EEPROM |
Key Differentiators
- Low-voltage CMOS process supports 2.5 V to 6.25 V operation (vs PIC16C621A (non-LC))
- Industrial temperature grade -40C to +125C included in stock part (vs PIC16LC621A-04/P (commercial 0-70C))
- PIC16C62x analog comparator with PORTA inputs (vs PIC16LC620A-04E/P)
Design Notes
The PIC16LC621A-04E/P requires a stable Vdd ramp at power-up to ensure the internal power-on reset releases the part cleanly into user code; hold Vdd rise time below 4 ms and add a 100 nF decoupling capacitor as close to the Vdd pin as possible. For battery operation, leverage the SLEEP mode and watchdog timer to drop average current into the microampere range. Place a 10 uF bulk capacitor on the board if the supply is shared with relays or other switching loads.
Route the crystal or resonator traces on the 18-PDIP between OSC1 (pin 16) and OSC2 (pin 15) as short as possible, with a guard ground on the surrounding copper to keep noise out of the oscillator. Keep high-current switching traces away from the MCLR pin (pin 4) to prevent spurious resets; place the MCLR pull-up resistor within 25 mm of the pin. PORTA analog comparator traces should be guarded from adjacent digital signals to avoid false comparator triggers.
The PIC16LC621A-04E/P is OTP, not flash - firmware bugs cannot be fixed after programming without physically replacing the part. Always order engineering samples and verify code in PIC16F628A-I/P or PIC16LC621A-04E/P emulation mode before committing to production programming. Configuration bits (oscillator selection, watchdog enable, MCLR enable, code protection) must be set correctly at programming time; an incorrect config can render the part undebuggable. PORTA pins default to analog mode on reset and must be explicitly configured for digital I/O via the CMCON register before use.
Compliance Information
RoHS / REACH / lead-free status not explicitly stated in the verified web data for this legacy PIC16C OTP part; confirm with Microchip before RoHS-restricted deployments. AEC-Q100 is not applicable (this is a legacy industrial-grade MCU without automotive qualification).
