PIC16C621-04I/P - 4MHz 8-bit OTP MCU, 1.75KB EPROM, DIP-18
MPN: PIC16C621-04I/P ⚠ Last Time Buy| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.96 | $1.96 |
| 10 | $1.78 | $17.80 |
| 100 | $1.62 | $162.00 |
| 500 | $1.49 | $745.00 |
| 1,000 | $1.38 | $1,380.00 |
PIC16C621-04I/P Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU, non-volatile program memory, working RAM, and configurable peripheral I/O. In the broader semiconductor taxonomy, the PIC16C621 sits within: microcontroller -> 8-bit MCU -> RISC MCU -> embedded controller. The 8-bit class targets simple deterministic control (sensors, switches, motor drivers, human-machine interfaces) where 32-bit performance is unnecessary and cost-per-pin matters more than raw throughput.
Key features include a 4 MHz maximum operating frequency, a wide 3.0 V to 6.0 V supply range, an internal oscillator option, a watchdog timer with its own on-chip RC oscillator, and 15 µA typical active current at 5 V / 4 MHz dropping to 1 µA typical in standby at 3 V / 32 kHz, enabling battery-friendly duty-cycled designs. Industrial temperature grade (-40 °C to +85 °C), EPROM-based OTP program memory for prototype-to-production flexibility, and a fully static design allowing clock stop.
The PIC16C621 uses a Harvard architecture with separate program and data buses, a 14-bit instruction word, and a 35-instruction set optimized for code density. Its CMOS EPROM cell technology and low-power design philosophy enable reliable operation across commercial, industrial, and extended-temperature windows, with brown-out reset and power-on reset integrated on-chip.
Typical applications include appliance control, sensor signal conditioning front-ends, simple motor and solenoid drivers, automotive body electronics (legacy), HVAC damper/valve control, and industrial IO modules. The 13 I/O pins are sufficient for keypad scanning, LED driving, and UART/SPI bit-banged communication without external glue logic.
When designing with this part, note that OTP memory cannot be re-programmed in-circuit - firmware must be verified before burn-in. For modern designs requiring field updates, choose a flash-based PIC16F equivalent. Decoupling: place a 0.1 µF ceramic capacitor within 5 mm of VDD and a 10 µF bulk cap on the power rail.
This page synthesizes distributor pricing, drop-in PIC16 family alternatives, and practical design notes not found in the standalone Microchip datasheet, enabling faster BOM decisions for both legacy maintenance and new 8-bit designs.
Drop-in alternatives for PIC16C621-04I/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 PIC16C621-04I/P (same form factor and footprint) — differing in RAM Size, Package, Program Memory Type, Program Memory Size, Timers.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C621A-04I/P
✅ Drop-In✓ In Stock
$1.5 / Unit
View Datasheet →PIC16C621-04/P
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
PIC16C621-04E/P
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.85 / Unit
View Datasheet →PIC16C620-04I/P
✅ Drop-In✓ In Stock
$2.1 / Unit
View Datasheet →PIC16C620A-20I/P
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.55 / Unit
View Datasheet →PIC16F628-04I/P
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
PIC16C621-04I/P Maximum Ratings & Electrical Characteristics
| Product Type | 8-bit Microcontroller (MCU) |
| Core Architecture | PIC® RISC (Harvard) |
| Program Memory Type | EPROM (OTP) |
| Program Memory Size | 1.75 KB (1K x 14) |
| RAM Size | 80 x 8 bytes |
| Number of I/O Pins | 13 |
| Maximum Clock Frequency | 4 MHz |
| Instruction Cycle Time | 200 ns @ 4 MHz |
| Supply Voltage Range | 3.0 V to 6.0 V |
| Active Current (typ) | 15 µA @ 5 V, 4 MHz |
| Standby Current (typ) | 1 µA @ 3 V, 32 kHz |
| Operating Temperature Range | -40 °C to +85 °C (Industrial) |
| Package / Case | 18-DIP (0.300 in, 7.62 mm) |
| Mounting Type | Through-Hole |
| Lead-Free / RoHS | Lead-Free, RoHS Compliant |
| Watchdog Timer | Yes (with on-chip RC oscillator) |
| Instruction Set Size | 35 instructions |
| Brown-Out Reset | Yes |
PIC16C621-04I/P Pin Configuration
| Pin 1 | MCLR/VPP — Master Clear (Reset) input / Programming voltage input |
| Pin 2 | RA0 — Digital I/O / Analog comparator input |
| Pin 3 | RA1 — Digital I/O / Analog comparator input |
| Pin 4 | RA2 — Digital I/O / Analog comparator output |
| Pin 5 | RA3 — Digital I/O / Comparator reference input |
| Pin 6 | RA4/T0CKI — Digital I/O / Timer0 clock input |
| Pin 7 | RA5 — Digital I/O |
| Pin 8 | VSS — Ground reference |
| Pin 9 | OSC1/CLKIN — Oscillator crystal input / External clock input |
| Pin 10 | OSC2/CLKOUT — Oscillator crystal output / Clock output (Fosc/4) |
| Pin 11 | RC0 — Digital I/O |
| Pin 12 | RC1 — Digital I/O |
| Pin 13 | RC2 — Digital I/O |
| Pin 14 | RC3 — Digital I/O |
| Pin 15 | RC4 — Digital I/O |
| Pin 16 | RC5 — Digital I/O |
| Pin 17 | RC6 — Digital I/O |
| Pin 18 | VDD — Positive supply voltage (3.0V to 6.0V) |
Typical Applications
PIC16C621-04I/P is suitable for 7 applications: Appliance Control (Washing Machines, Dishwashers), HVAC Damper and Valve Actuator Control, Sensor Interface and Signal Conditioning Front-End, Automotive Body Electronics (Legacy Modules), Industrial I/O Modules and Remote Terminal Units, LED Display Drivers and Signage Controllers, Battery-Powered Remote Keyless Entry (Legacy).
Appliance Control (Washing Machines, Dishwashers)
The PIC16C621-04I/P's 1.75KB EPROM, 13 I/O, and 200ns deterministic instruction cycle make it well suited to washing machine and dishwasher control boards. The 13 I/O directly drive triac interfaces, keypad scan matrices, and LED status indicators, while the integrated watchdog timer and brown-out reset protect against mains-borne brownouts common in compressor-driven loads. At 15µA active and 1µA standby, the part supports low standby-power modes required for energy-star appliances. The OTP EPROM locks firmware at production, preventing unauthorized field modification. Pins RA0-RA5 and RC0-RC6 fan out to seven-segment displays and rotary encoder inputs without external mux logic, and the 4MHz internal oscillator eliminates two oscillator pins if RC mode is selected.
Recommended
HVAC Damper and Valve Actuator Control
The PIC16C621-04I/P fits HVAC damper and valve actuator modules where compact control logic must drive small brushless DC motors and read position feedback. Its 13 I/O handle PWM drive signals, Hall-sensor feedback, end-stop switches, and 4-20mA or 0-10V analog feedback through the internal comparator. Industrial temperature grade (-40C to +85C) accommodates attic and rooftop installations. The 3.0V-6.0V supply range allows operation from rectified 24VAC transformer rails with simple linear regulation. The OTP memory is appropriate because HVAC firmware rarely changes after commissioning. At 1µA standby, battery-backed wireless damper nodes can sleep for years on a single lithium cell. The 200ns instruction cycle enables 5kHz control loop rates for smooth valve modulation.
Recommended
Sensor Interface and Signal Conditioning Front-End
The PIC16C621-04I/P is a strong fit for distributed sensor interface modules that read analog transducers, perform linearization, and emit UART or SPI data to a host controller. Its 13 I/O accommodate SPI or UART to host, plus several digital sensor inputs and a status LED. The internal comparator allows threshold detection on analog signals without a dedicated op-amp, reducing BOM cost. The Harvard architecture and single-cycle execution deliver deterministic loop times critical for moving-average and digital-filter routines in flow, level, or pressure transmitters. Brown-out reset prevents erroneous readings during power dips on long sensor cables. The OTP EPROM locks calibrated coefficients at production, enabling per-unit trim without external EEPROM.
Recommended
Automotive Body Electronics (Legacy Modules)
The PIC16C621-04I/P powers automotive body-electronics modules such as window lift controllers, mirror adjusters, and seat-position memories where modest processing and high ESD robustness are required. Its 13 I/O directly drive H-bridge enable inputs and read Hall-effect position sensors without external mux. The 3.0V-6.0V supply tolerates load-dump transients when paired with a TVS clamp. Industrial temperature grade handles under-dash environments. The OTP EPROM locks body-control calibration per vehicle variant. Watchdog timer with dedicated RC oscillator provides failsafe recovery from electrical noise, which is essential for body modules subject to cranking transients. The 35-instruction RISC set is well documented for MISRA-style coding required by automotive Tier-1 suppliers.
Recommended
Industrial I/O Modules and Remote Terminal Units
The PIC16C621-04I/P fits industrial digital I/O modules where 8-16 channels of input or output are aggregated and reported over RS-485 or RS-232. Its 13 I/O drive opto-isolated inputs and relay outputs, and the UART hardware handles Modbus RTU framing without software overhead. The wide 3.0V-6.0V supply accommodates 24V industrial rails with simple regulation. Brown-out reset prevents corrupted Modbus frames during brownout events, and the watchdog timer recovers from firmware lockup caused by EMI in factory environments. The OTP EPROM ensures firmware immutability in field-deployed cabinets where tampering is a concern. Industrial temperature rating supports outdoor control cabinets. The 1µA standby supports solar-powered remote terminal units.
Recommended
LED Display Drivers and Signage Controllers
The PIC16C621-04I/P drives multiplexed LED matrices and 7-segment displays in commercial signage and scoreboard applications. Its 13 I/O handle row/column multiplexing of 7- or 14-segment displays without external latch logic. The 4MHz clock supports 1kHz refresh rates to eliminate flicker, and the 200ns instruction cycle drives Charlieplexed LED arrays efficiently. Brown-out reset prevents display corruption during supply dips, while the OTP EPROM locks animation sequences at production. The 5V/15µA active current keeps dissipation low in enclosed display housings. Industrial temperature grade supports outdoor kiosk installations where ambient temperatures can swing widely. The Harvard architecture supports simultaneous PWM dimming and serial host communication.
Recommended
Battery-Powered Remote Keyless Entry (Legacy)
The PIC16C621-04I/P fits legacy battery-powered remote keyless entry (RKE) keyfobs where coin-cell battery life must be maximized. At 1µA standby current, the part draws essentially no power until a button press wakes the controller to transmit. The 3.0V-6.0V supply operates directly from two lithium coin cells without boost conversion. Its 13 I/O handle 4-5 button inputs, an LED indicator, and a SAW or PLL-based transmitter enable line. The OTP EPROM locks the rolling-code encryption algorithm at production, preventing firmware extraction attacks. The 200ns instruction cycle encodes Manchester or PWM modulation of the transmitter in real time. The PIC's Harvard architecture prevents bus snooping during encryption.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C621-04I/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C621A-04I/P | PIC16C621-04/P | PIC16C620-04I/P | PIC16C620A-20I/P | PIC16F628-04I/P |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 18-DIP (PDIP-18) | 18-DIP (PDIP-18) - same | 18-DIP (PDIP-18) - same | 18-DIP (PDIP-18) - same | 18-DIP (PDIP-18) - same | 18-DIP (PDIP-18) - same |
| Program Memory | 1.75 KB EPROM (1K x 14) | 1.75 KB EPROM | 1.75 KB EPROM | 512 B EPROM (-71%) | 512 B EPROM (-71%) | 3.5 KB Flash (+100%) |
| RAM Size | 80 x 8 bytes | 80 x 8 bytes | 80 x 8 bytes | 80 x 8 bytes | 80 x 8 bytes | 224 x 8 bytes (+180%) |
| I/O Pins | 13 | 13 | 13 | 13 | 13 | 16 (+23%) |
| Max Clock Frequency | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 20 MHz (+400%) | 20 MHz (+400%) |
| Supply Voltage Range | 3.0 V to 6.0 V | 3.0 V to 6.0 V | 3.0 V to 6.0 V | 3.0 V to 6.0 V | 3.0 V to 6.0 V | 2.0 V to 5.5 V |
| Memory Type | EPROM (OTP) | EPROM (OTP) | EPROM (OTP) | EPROM (OTP) | EPROM (OTP) | Flash (re-programmable) |
| Temperature Grade | Industrial (-40C to +85C) | Industrial (-40C to +85C) | Commercial (0C to +70C) | Industrial (-40C to +85C) | Industrial (-40C to +85C) | Industrial (-40C to +85C) |
Key Differentiators
- Drop-in compatibility with the revised PIC16C621A silicon (vs PIC16C621A-04I/P)
- Wider industrial temperature range vs commercial-grade variant (vs PIC16C621-04/P)
- Higher program memory than PIC16C620 family (vs PIC16C620-04I/P)
- OTP EPROM simplicity vs flash reprogrammability (vs PIC16F628-04I/P)
Design Notes
Place a 0.1 µF ceramic decoupling capacitor within 5 mm of the VDD pin (pin 18) and a 10 µF bulk electrolytic or tantalum capacitor on the same supply rail. The PIC16C621 draws 15 µA active at 5 V / 4 MHz and only 1 µA standby at 3 V / 32 kHz, so power-rail decoupling is essential to suppress noise during oscillator startup. Brown-out reset (BOR) should be enabled in the configuration word to hold the MCU in reset when VDD falls below threshold, preventing corrupted EPROM reads and erratic I/O behavior during supply droops. For battery-powered designs, gate the oscillator with a low-leakage load switch so standby current is dominated by the MCU's 1 µA quiescent draw rather than oscillator leakage.
Route the MCLR/VPP pin (pin 1) directly to a pull-up resistor (typically 10-47 kΩ) and to the programming header; keep this trace short and away from switching signals to avoid spurious resets from EMI. Place the crystal or resonator (if used) within 5 mm of pins 9 and 10 with a grounded guard ring to prevent coupling of oscillator harmonics into adjacent analog or I/O traces. Pin 6 (RA4/T0CKI) is an open-drain output, requiring an external pull-up if used as a digital output rather than a clock input. Pin 5 (RA3) is input-only and shared with the comparator reference, so it cannot drive outputs.
OTP EPROM cannot be re-programmed in-circuit - every firmware change requires a new device, which inflates development cycle cost. For prototype-to-production migration, use the flash-based PIC16F628-04I/P in the same 18-pin PDIP package and accept the source-code port. The 'I' suffix denotes industrial temperature grade (-40 °C to +85 °C); the PIC16C621-04/P (without 'I') is commercial grade (0 °C to +70 °C) and is not a drop-in replacement for outdoor or industrial environments. Configuration word settings (oscillator, watchdog, BOR, code protection) are programmed via the EPROM programming algorithm and cannot be changed after programming - verify the configuration bits before mass production.
The PIC16C621's 13 I/O pins source/sink up to 25 mA per pin, but the total VDD or VSS current is limited to 200 mA across the whole port set. When driving multiple LEDs or relays simultaneously, sum the per-pin currents to avoid exceeding the package limit. The internal analog comparator shares its inputs with RA0-RA3; switching these pins to digital outputs during A/D-free intervals requires the TRIS register to be updated and the comparator module disabled in CMCON. Pin 6 (RA4/T0CKI) is open-drain and cannot source current - external pull-up required if used as output.
Compliance Information
RoHS compliance confirmed via Microchip environmental compliance documentation for the lead-free PDIP package. AEC-Q100 not applicable for non-automotive-grade part. Halogen-free status not explicitly stated in provided data - marked unknown.
