PIC16C621T-20I/SS - 8-Bit 20MHz OTP MCU 1.75KB | Microchip
MPN: PIC16C621T-20I/SS ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.5 | $3.50 |
| 10 | $3.2 | $32.00 |
| 100 | $2.85 | $285.00 |
| 500 | $2.55 | $1,275.00 |
| 1,000 | $2.3 | $2,300.00 |
PIC16C621T-20I/SS Overview
An 8-bit PIC microcontroller is a compact, deterministic Reduced Instruction Set Computer (RISC) core designed for embedded control. The PIC16C62x family sits in the hierarchy of PIC microcontrollers -> 8-bit microcontrollers -> microcontrollers -> microcontrollers (MCU) -> integrated circuits -> semiconductors, where it bridges the entry-level PIC10/12/16 families and the higher-performance PIC17/18 families. The OTP program memory allows the part to be programmed once in production and used in cost-sensitive applications where firmware is fully matured and field updates are not required.
Key features include 13 digital I/O pins across multiple ports, support for an external oscillator or internal RC oscillator option, low-power SLEEP mode, an in-circuit serial programming interface (for compatible variants), and industrial-grade temperature qualification. The OTP memory architecture provides faster read access and higher reliability than EPROM in equivalent packages, while the SSOP form factor balances board-space savings with hand-solder-friendly lead pitch. Together, these features deliver a self-contained compute platform for low-cost embedded controllers.
The PIC16C621T-20I/SS implements a Harvard-architecture RISC core with a 14-bit instruction word, single-cycle instruction execution (except branches), and a hardware stack for subroutine nesting. Its integrated analog comparator enables direct interface with analog sensors without external op-amps, while the CCP module supports timing-critical control loops such as motor drive and SMPS feedback. Industrial -40C to +85C qualification plus BOR/POR/WDT make this part suitable for unattended equipment.
Typical applications include white-goods and appliance control, industrial sensor interfaces, low-cost motor control, automotive body electronics (non-safety), and consumer remote controls. The integrated analog comparator is particularly useful for threshold detection on temperature, light, or position sensors, while the CCP module drives PWM-controlled loads.
When designing with this part, note that OTP devices cannot be re-programmed - confirm firmware stability before committing to OTP. The 'T' suffix denotes tape-and-reel packaging for high-volume SMT assembly, and the 'I' suffix designates the industrial temperature grade (-40C to +85C).
This page synthesizes distributor pricing, drop-in alternatives drawn from the same PIC16C family, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for PIC16C621T-20I/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 PIC16C621T-20I/SS (same form factor and footprint) — differing in Package, Program Memory Type, Core Architecture, Operating Temperature, Program Memory Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C621A-20E/SS
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$4.12 / Unit
View Datasheet →PIC16C621AT-20I/SS
✅ Drop-In✓ In Stock
$0.81 / Unit
View Datasheet →PIC16C620A-20I/SS
✅ Drop-In✓ In Stock
$2.15 / Unit
View Datasheet →PIC16C621-20I/P
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$3.05 / Unit
View Datasheet →PIC16F621-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F628A-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C621T-20I/SS Maximum Ratings & Electrical Characteristics
| Product Family | PIC16C62x |
| Core Architecture | PIC 8-bit RISC |
| Core Size | 8-bit |
| Max CPU Speed | 20 MHz |
| Program Memory Type | OTP (One-Time Programmable EPROM) |
| Program Memory Size | 1.75 KB (1K x 14) |
| RAM Size | 80 x 8 bytes |
| Number of I/O Pins | 13 |
| Package / Case | 20-SSOP (0.209 inch, 5.30 mm width) |
| Mounting Type | Surface Mount |
| Operating Temperature | -40C to +85C (Industrial) |
| Supply Voltage Range | 2.5 V to 6.0 V (per PIC16C62x family) |
| Peripherals | Brown-Out Detect/Reset, Power-On Reset, Watchdog Timer, Analog Comparator, CCP |
| Oscillator Type | External |
| MSL Level | 1 (unlimited) |
PIC16C621T-20I/SS Pin Configuration
| Pin 1 | RA2/AN2 — Port A bit 2 / analog comparator input |
| Pin 2 | RA3/AN3 — Port A bit 3 / analog comparator input |
| Pin 3 | RA4/T0CKI — Port A bit 4 / Timer 0 clock input |
| Pin 4 | MCLR — Master clear reset input (active low) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — Port B bit 0 / external interrupt |
| Pin 7 | RB1 — Port B bit 1 |
| Pin 8 | RB2 — Port B bit 2 |
| Pin 9 | RB3 — Port B bit 3 |
| Pin 10 | RB4 — Port B bit 4 |
| Pin 11 | RB5 — Port B bit 5 |
| Pin 12 | RB6 — Port B bit 6 / serial programming clock |
| Pin 13 | RB7 — Port B bit 7 / serial programming data |
| Pin 14 | VDD — Positive supply voltage |
| Pin 15 | OSC2/CLKOUT — Oscillator output / clock out |
| Pin 16 | OSC1/CLKIN — Oscillator input / external clock in |
| Pin 17 | RA0/AN0 — Port A bit 0 / analog comparator input |
| Pin 18 | RA1/AN1 — Port A bit 1 / analog comparator input |
| Pin 19 | RA5/SS — Port A bit 5 / slave select |
| Pin 20 | RC0 — Port C bit 0 (per PIC16C62x family) |
Typical Applications
PIC16C621T-20I/SS is suitable for 6 applications: White-Goods and Appliance Control, Industrial Sensor Interface Module, Low-Cost Motor Control (BLDC / Fan), Consumer Remote Control and IR Transmitter, Automotive Body Electronics (Non-Safety), HVAC Thermostat and Building Control.
White-Goods and Appliance Control
The PIC16C621T-20I/SS is well-suited for white-goods controllers in washing machines, dishwashers, and microwave ovens where cost-optimized 8-bit processing is essential. Its 1.75 KB OTP memory holds fixed appliance firmware such as cycle timers, sensor polling loops, and user-interface debounce routines. The integrated analog comparator directly senses temperature thermistors or water-level probes without external op-amps, reducing BOM cost. The 20 MHz CPU clock provides sufficient throughput for 50/60 Hz zero-cross detection and PWM-controlled load drivers. Industrial -40C to +85C temperature qualification ensures operation across the hot/cold extremes typical of laundry rooms and kitchens. Brown-Out Reset and Watchdog Timer protect unattended appliance operation across mains-brownout events.
Recommended
Industrial Sensor Interface Module
In industrial sensor-interface boards the PIC16C621T-20I/SS provides signal conditioning, threshold detection, and digital output formatting in a compact 20-SSOP footprint. The integrated analog comparator monitors analog sensor outputs against on-chip voltage references, producing interrupt-driven threshold events without external ADC complexity. The 13 digital I/O pins drive status LEDs, accept digital inputs, and communicate via UART bit-banging or SPI to a host controller. The 1.75 KB OTP memory stores calibration constants and protocol handlers for sensor-specific data formatting. BOR and WDT ensure the module recovers gracefully from industrial electrical noise and supply transients, supporting reliable 24/7 factory-floor operation.
Recommended
Low-Cost Motor Control (BLDC / Fan)
The PIC16C621T-20I/SS handles low-cost BLDC and brushed-DC motor control loops in consumer fans, small pumps, and PC case ventilation. The CCP module generates PWM drive signals at switching frequencies up to 20 kHz, well above the audible band for silent operation. The integrated analog comparator implements back-EMF zero-cross detection in sensorless BLDC schemes, eliminating Hall-effect sensors and reducing total system cost. At 5 MIPS instruction throughput, the MCU executes PI control loops with adequate phase margin for 12V/24V motor rails. The industrial temperature grade supports under-hood automotive and outdoor equipment deployments.
Recommended
Consumer Remote Control and IR Transmitter
Battery-powered remote controls for TVs, set-top boxes, and consumer audio equipment benefit from the PIC16C621T-20I/SS's low-cost 8-bit core, low-power SLEEP mode, and integrated timer peripherals. The 20 MHz clock drives accurate 38 kHz carrier generation for NEC/RC-5 IR protocols with sub-microsecond timing precision. The 13 I/O pins connect to a key matrix scanner and IR LED driver transistors. OTP memory is acceptable for remote controls since firmware rarely changes once the protocol set is finalized. Brown-Out Reset prevents lockup when battery voltage drops below safe operating levels, an essential feature for alkaline and coin-cell powered devices.
Recommended
Automotive Body Electronics (Non-Safety)
Interior lighting controllers, mirror-adjust modules, and seat-position memories use the PIC16C621T-20I/SS for non-safety automotive body electronics where AEC-Q100 is not mandatory. The industrial -40C to +85C temperature range handles cabin-environment extremes, and BOR/WDT provide robustness against load-dump transients common in 12V automotive electrical systems. The 13 I/O pins drive LED arrays, sense switch inputs, and communicate via LIN-bus bit-banging to a body controller. The OTP architecture locks firmware to prevent unauthorized feature modification. For new safety-relevant designs, the AEC-Q100-qualified PIC16F62x family is recommended instead.
Recommended
HVAC Thermostat and Building Control
Commercial and residential HVAC thermostat designs use the PIC16C621T-20I/SS for setpoint handling, hysteresis control, and relay actuation. The integrated analog comparator directly reads thermistor temperature sensors against internal voltage references, enabling bang-bang thermostat control without ADC overhead. The 1.75 KB OTP memory holds week-day scheduling, hysteresis constants, and user-interface state machines. CCP-driven PWM modulates furnace gas valves or triac-fired heating elements. The 20-SSOP package provides low thermal resistance for thermostat enclosures, while BOR and WDT ensure reliable recovery from power-line disturbances typical in building electrical systems.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C621T-20I/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C621A-20E/SS | PIC16C621AT-20I/SS | PIC16C620A-20I/SS | PIC16F621-I/SS | PIC16F628A-I/SS |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 20-SSOP | 20-SSOP - same | 20-SSOP - same | 20-SSOP - same | 20-SSOP - same | 20-SSOP - same |
| Program Memory | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB Flash | 3.5 KB Flash |
| Memory Type | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | Flash (reprogrammable) | Flash (reprogrammable) |
| Max CPU Speed | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| RAM Size | 80 bytes | 80 bytes | 80 bytes | 80 bytes | 80 bytes | 224 bytes |
| Number of I/O Pins | 13 | 13 | 13 | 13 | 13 | 16 |
| Operating Temperature | -40C to +85C (Industrial) | -40C to +125C (Extended) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) |
| Onboard Peripherals | BOR, POR, WDT, Comparator, CCP | BOR, POR, WDT, Comparator, CCP | BOR, POR, WDT, Comparator, CCP | BOR, POR, WDT, Comparator, basic CCP | BOR, POR, WDT, Comparator, CCP | BOR, POR, WDT, Comparator, CCP, USART |
Key Differentiators
- Cost-optimized OTP program memory for stable firmware (vs PIC16F621-I/SS)
- Integrated analog comparator saves BOM cost (vs PIC16F628A-I/SS)
- Industrial temperature grade for harsh environments (vs PIC16C621-20I/P (PDIP))
Design Notes
OTP (One-Time Programmable) memory cannot be erased or rewritten - any firmware bug discovered after programming is permanent. Validate firmware on a Flash-equivalent (PIC16F621 or PIC16F628A) before committing to PIC16C621 OTP programming for production. The '20' in the part number denotes 20 MHz max clock; operating beyond this requires the PIC16C621-40 speed grade. Always check Microchip's latest errata document before OTP programming.
The 20-SSOP package has a 0.65 mm lead pitch requiring careful PCB footprint design. Follow IPC-7351 surface-mount land pattern guidelines with pad width of approximately 0.40 mm and pad length of 1.0 mm to ensure reliable solder fillets. Place a 100 nF decoupling capacitor within 3 mm of the VDD pin (pin 14) and a 10 uF bulk capacitor near the MCLR pin (pin 4) to stabilize supply during Brown-Out Reset events. Keep the OSC1/OSC2 traces short and shield them from high-current switching traces.
The PIC16C621T-20I/SS operates from a supply voltage of 2.5V to 6.0V with integrated Brown-Out Reset (BOR) to prevent code execution below the safe operating threshold. For 5V designs the device delivers full 20 MHz performance; at 3.3V operation, derate maximum clock frequency per the datasheet electrical characteristics table. Power-On Reset (POR) holds the device in reset during VDD ramp-up until the supply stabilizes. Use an external voltage supervisor (e.g. MCP100) if your application requires a tighter reset threshold than the on-chip BOR provides.
When using the ICSP (In-Circuit Serial Programming) interface via RB6/RB7, isolate these pins from capacitive loads exceeding 50 pF during programming to avoid programming failures. Add 4.7 kohm pull-up resistors on MCLR and RB7 if long cables connect these to programming headers. For noise-sensitive analog comparator applications, keep the AN0/AN1/AN2/AN3 traces short and route them away from PWM-driven switching signals, since the comparator inputs share the digital port A pins and can pick up switching transients.
Compliance Information
RoHS, REACH, lead-free and halogen-free status for PIC16C621T-20I/SS marked [DATA_NEEDED] - not confirmed in provided data; PIC16C62x family datasheet does not specify these compliance attributes. AEC-Q100 not qualified - this is an industrial-grade part, not automotive-grade.
