PIC16C621-04/SO Microchip Integrated Circuit (Small Outline Packages) In Stock
The PIC16C621-04/SO is an 8-bit OTP microcontroller from Microchip running at up to 4 MHz (20 MHz capable), featuring 2 KB OTP program memory, 128 bytes SRAM, and 18 I/O pins in an 18-pin SOIC package. Suited for cost-sensitive consumer appliance control, sequential timing, and sensor interface applications.
- Manufacturer
- Microchip
- Package
- Small Outline Packages
- Pin Count
- 18
- Lifecycle
- NOT RECOMMENDED
- Datasheet
- PIC16C621-04/SO Datasheet PDF
- Category
- Integrated Circuit
- Temp Range
- ?°C to 70.0°C
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- 8-bit PIC16 RISC core with 35-instruction set running at up to 4 MHz
- 2 KB one-time-programmable (OTP) program Flash memory
- 128 bytes on-chip SRAM for variable and stack storage
- 18 configurable I/O pins with individual direction control
- Integrated Timer0 and Timer1 modules for accurate timing
- Hardware watchdog timer for fault-tolerant operation
- 18-pin SOIC SMT package for automated board assembly
- Wide operating voltage: 2.0 V to 6.0 V for battery and USB designs
Applications
The PIC16C621-04/SO is a cost-effective solution for household appliance control panels, keypad decoders, and low-speed sensor interfaces where firmware is fixed at manufacturing and BOM cost per unit is critical. Its 18 I/O pins allow direct interfacing with relay drivers, LED indicators, and UART-level signals without external port expanders. Designers maintaining legacy embedded systems will find the PIC16C621-04/SO a drop-in OTP replacement compatible with existing PIC16C6xx firmware and PCB footprints.
Specifications
| Pbfree Code | Yes |
| Factory Lead Time | 111Weeks |
| Date Of Intro | 1990-01-01 |
| YTEOL | 3 |
| Has ADC | NO |
| Bit Size | 8 |
| Boundary Scan | NO |
| CPU Family | PIC16 |
| Clock Frequency-Max | 20MHz |
| DAC Channels | NO |
| DMA Channels | NO |
| Format | FIXED POINT |
| Integrated Cache | NO |
| JESD-30 Code | R-PDSO-G18 |
| JESD-609 Code | e3 |
| Low Power Mode | YES |
| Number of External Interrupts | 1 |
| Number of I/O Lines | 13 |
| Number of Timers | 3 |
| On Chip Data RAM Width | 8 |
| On Chip Program ROM Width | 14 |
| PWM Channels | NO |
| Package Body Material | PLASTIC/EPOXY |
| Package Equivalence Code | SOP18,.4 |
| Package Shape | RECTANGULAR |
| Package Style | SMALL OUTLINE |
| Peak Reflow Temperature (Cel) | 260 |
| Qualification Status | Not Qualified |
| RAM (bytes) | 80 |
| ROM (words) | 1024 |
| ROM Programmability | OTPROM |
| Speed | 40MHz |
| Supply Current-Max | 3.3mA |
| Supply Voltage-Max | 5.5V |
| Supply Voltage-Min | 5V |
| Supply Voltage-Nom | 5V |
| Surface Mount | YES |
| Technology | CMOS |
| Temperature Grade | COMMERCIAL |
| Terminal Finish | Matte Tin (Sn) |
| Terminal Form | GULL WING |
| Terminal Pitch | 1.27mm |
| Terminal Position | DUAL |
| uPs/uCs/Peripheral ICs Type | MICROCONTROLLER, RISC |
| Package | Small Outline Packages |
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
| Moisture Sensitivity Level | MSL 1 |
| HTS Code | 8542.31.00.15 |
| Country of Origin | Thailand |
Alternate & Equivalent Parts
Compatible alternatives and drop-in replacements for PIC16C621-04/SO:
RISC Microcontroller, 8-Bit, OTPROM, PIC16 CPU, 20MHz, CMOS, PDSO18
Frequently Asked Questions
What is the maximum clock speed of the PIC16C621-04/SO and how does the -04 suffix describe its speed grade?
The -04 speed grade suffix on the PIC16C621-04/SO indicates a 4 MHz maximum crystal/clock oscillator frequency for its DC-to-4 MHz operating range, while the underlying silicon can physically support up to 20 MHz in other speed variants. At 4 MHz the device executes approximately 1 million instructions per second, sufficient for simple control loops and timer tasks.
How much SRAM does the PIC16C621-04/SO provide and how does this constrain firmware stack depth?
The PIC16C621-04/SO integrates 128 bytes of on-chip SRAM shared between user variables and the hardware call stack, which supports up to 8 nested subroutine levels on the PIC16 architecture. This is adequate for sequential appliance control firmware but may require careful stack management in interrupt-driven applications with more than 4 nesting levels.
What supply voltage range does the PIC16C621-04/SO accept and what battery types can power it directly?
The PIC16C621-04/SO operates from 2.0 V to 6.0 V, allowing it to run directly from 2 AA alkaline cells at 3 V, a 3.6 V Li primary cell, or a regulated 5 V wall adapter. This broad range eliminates the need for a dedicated LDO regulator in many battery-powered consumer products.
For a legacy product that uses the PIC16C621-04/SO, what is the closest modern pin-compatible replacement?
The PIC16F628A is the closest pin-compatible Flash-based replacement for the PIC16C621-04/SO, offering the same 18-pin DIP and SOIC footprint, 2 KB program memory, and 128 bytes SRAM while adding reprogrammable Flash memory and a built-in 4 MHz internal oscillator. Migrating to the PIC16F628A removes the OTP programming constraint and enables in-field firmware updates.
How many I/O pins does the PIC16C621-04/SO offer and what peripheral interfaces do they support?
The PIC16C621-04/SO provides 18 general-purpose I/O pins organized across 2 ports, capable of sourcing or sinking 25 mA per pin. These pins can be configured for UART serial communication, SPI/I2C with software bit-banging, PWM output, or direct LED and relay driving without external current-limiting transistors in many low-current designs.
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