PIC16C621-20/P - 1.75KB OTP 8-Bit MCU 20MHz | Microchip 18-DIP
MPN: PIC16C621-20/P ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.95 | $2.95 |
| 10 | $2.55 | $25.50 |
| 100 | $2.15 | $215.00 |
| 500 | $1.85 | $925.00 |
| 1,000 | $1.55 | $1,550.00 |
PIC16C621-20/P Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, program memory, working RAM, and peripheral I/O on one die, optimized for deterministic embedded control. PIC microcontrollers sit in the broader hierarchy of microcontrollers -> embedded processors -> semiconductors, and the PIC16C family occupies the original mid-range PIC architecture with 35 single-word instructions and a 14-bit instruction word. Compared to Flash-based successors (PIC16F), this OTP EPROM variant is one-time programmable and is typically used in low-volume or mature production designs.
Key features include a fully-static CMOS design, wide operating voltage range to 6.0V, and very low power consumption (15 uA typical at 5V/4MHz and 1 uA at 3V/32 kHz). The PIC16C621 includes an 8-bit timer/counter, a watchdog timer with its own on-chip RC oscillator for reliable reset, and a power-on reset circuit. Compared to the PIC16C620, the PIC16C621 adds a 5-bit analog comparator, while the 'C' (CMOS EPROM) suffix distinguishes it from earlier NMOS parts.
Architecturally the device uses a Harvard RISC core with separate 14-bit program and 8-bit data paths, allowing most instructions to execute in a single 200ns instruction cycle at 20MHz. The 13 I/O pins are multiplexed with peripheral functions and are bidirectional with individually programmable direction. The CMOS EPROM process technology makes the part suitable for battery-powered and industrial environments where static power dissipation must be kept in the microampere range.
Typical applications include appliance controllers, automotive subsystems, low-power sensor interfaces, and simple closed-loop control where the OTP memory provides cost-effective firmware storage. The wide 3.0V to 6.0V supply range and industrial/extended temperature options make this part popular in industrial instrument clusters, HVAC controls, and legacy embedded products.
When designing with the PIC16C621-20/P, plan for an EPROM programmer window or socketed programming during prototyping, and verify that the 20MHz oscillator grade matches system timing budgets. Note that the OTP version cannot be electrically erased, so firmware must be fully validated before production programming. For new designs, evaluate the flash-based PIC16F84A/PIC16F628A equivalents on the same 18-pin DIP footprint.
Drop-in alternatives for PIC16C621-20/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 PIC16C621-20/P (same form factor and footprint) — differing in Program Memory Type, RAM Size, Package, Timers, Program Memory Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C621A-20/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C621-04I/P
✅ Drop-In✓ In Stock
$1.38 / Unit
View Datasheet →PIC16C621-04E/P
✅ Drop-In✓ In Stock
$2.85 / Unit
View Datasheet →PIC16C620A-20I/P
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.55 / Unit
View Datasheet →PIC16F84A-20/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F628A-I/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C621-20/P Maximum Ratings & Electrical Characteristics
| Program Memory Size | 1.75 KB (1K x 14) |
| Program Memory Type | OTP EPROM |
| RAM Size | 80 x 8 (80 bytes) |
| EEPROM Data Memory | None (ROM-based) |
| Number of I/O Pins | 13 |
| CPU Core | PIC16C mid-range 8-bit RISC |
| Instruction Set Size | 35 instructions, 14-bit word |
| Maximum Clock Frequency | 20 MHz |
| Instruction Cycle Time | 200 ns at 20 MHz |
| Operating Voltage Range | 3.0 V to 6.0 V |
| Operating Temperature Range | 0C to +70C (commercial) |
| Supply Current @ 5V/4MHz | 15 uA typical |
| Supply Current @ 3V/32kHz | 1 uA typical |
| Package / Case | 18-DIP (0.300 inch, 7.62mm) |
| Mounting Type | Through-Hole |
| Oscillator Type | External |
| Timers | 1 x 8-bit Timer/Counter + WDT |
| Analog Comparator | Yes |
| Watchdog Timer | Yes, dedicated on-chip RC oscillator |
| Power-On Reset | Yes |
| Packaging | Tube |
PIC16C621-20/P Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O port A bit 2 |
| Pin 2 | RA3 — Bidirectional I/O port A bit 3 |
| Pin 3 | RA4/T0CKI — I/O port A bit 4 / Timer0 clock input |
| Pin 4 | MCLR — Master clear reset input (active low) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — I/O port B bit 0 / external interrupt |
| Pin 7 | RB1 — Bidirectional I/O port B bit 1 |
| Pin 8 | RB2 — Bidirectional I/O port B bit 2 |
| Pin 9 | RB3 — Bidirectional I/O port B bit 3 |
| Pin 10 | RB4 — Bidirectional I/O port B bit 4 |
| Pin 11 | RB5 — Bidirectional I/O port B bit 5 |
| Pin 12 | VSS — Ground reference (secondary) |
| Pin 13 | RB6 — Bidirectional I/O port B bit 6 |
| Pin 14 | RB7 — Bidirectional I/O port B bit 7 |
| Pin 15 | VDD — Positive supply voltage |
| Pin 16 | OSC2/CLKOUT — Oscillator output / clock out |
| Pin 17 | OSC1/CLKIN — Oscillator input / clock in |
| Pin 18 | RA1 — Bidirectional I/O port A bit 1 |
Typical Applications
PIC16C621-20/P is suitable for 7 applications: Appliance Control Boards, Industrial Instrumentation, Automotive Body Electronics, Battery-Powered Sensor Nodes, HVAC Thermostat Controllers, Remote Control Transmitters, Security Keypads and Access Panels.
Appliance Control Boards
The PIC16C621-20/P suits appliance controllers such as washing-machine timers, microwave user-interface panels, and dishwasher cycle controllers, where its 1.75KB OTP program memory holds fixed control firmware, 13 digital I/O drive 7-segment displays and keypads, and the analog comparator reads water-level sensors. The 3.0V to 6.0V supply range directly accepts the regulated 5V rail common on appliance power boards. With 15 uA typical current at 5V/4MHz, standby power is minimal, helping meet energy-star regulations on white goods.
Recommended
Industrial Instrumentation
In industrial panel meters and process-control transmitters, the PIC16C621-20/P reads analog sensor inputs through its on-chip 5-bit analog comparator and multiplexes data onto a 4-digit LED display using the 13 digital I/O pins. The 20MHz instruction rate provides sufficient headroom for 100ms update intervals while leaving CPU bandwidth for keypad scanning and serial I/O. Industrial temperature grade variants (PIC16C621-20I/P) extend operation to -40C to +85C, suitable for factory-floor environments.
Recommended
Automotive Body Electronics
Legacy automotive body-control modules - including seat controllers, mirror adjusters, and lighting sequencers - use the PIC16C621-20/P for its low quiescent current (1 uA at 3V/32kHz) and rugged CMOS design that tolerates 12V battery transients after external regulation. The 13 I/O drive relays and LEDs directly through transistors, while the watchdog timer with dedicated RC oscillator protects against code lockup in EMI-rich underhood environments. Engineers migrating newer designs should evaluate PIC16F628A-I/P for Flash flexibility.
Recommended
Battery-Powered Sensor Nodes
Battery-powered sensor nodes for HVAC and building automation benefit from the PIC16C621-20/P's 1 uA supply current at 3V/32kHz, which lets a single coin cell operate the device for years between replacements. The analog comparator wakes the MCU when a sensor threshold is crossed, and the 13 I/O drive a low-power radio or wired interface. The 3.0V minimum supply matches 2xAA alkaline cell voltage after a low-drop regulator. Use sleep mode extensively to maximize battery life.
Recommended
HVAC Thermostat Controllers
The PIC16C621-20/P runs the control loop in wall-mount thermostats, where the analog comparator interfaces directly with a thermistor bridge and the 13 I/O drive triacs for the HVAC contactor, fan relay, and LCD segments. The wide 3.0V to 6.0V supply operates from 24VAC rectified supply with simple zener regulation. The 20MHz clock provides fast PI loop computation, while the 1.75KB OTP holds the scheduling and setpoint logic.
Recommended
Remote Control Transmitters
Garage-door openers, ceiling-fan remotes, and simple RF keyfobs use the PIC16C621-20/P to encode button presses and modulate a low-power ASK or OOK transmitter. The PIC16C mid-range core's deterministic 200ns instruction cycle at 20MHz generates precise timing for the RF bit stream, while the 1.75KB program memory holds multiple device codes. Sleep current around 1 uA extends battery life on a CR2032 coin cell, and the 18-DIP package simplifies hand-soldered prototyping.
Recommended
Security Keypads and Access Panels
Door-entry keypads and alarm-system arming stations use the PIC16C621-20/P to scan a 4x4 matrix keypad, compare entered codes against OTP-stored PINs, and trigger a relay output. The 13 I/O drive up to 16 keys with diode isolation plus LED status and buzzer, and the watchdog timer resets the device on keypad-scan lockup. Low 15 uA active current at 5V keeps standby power minimal for always-on security installations.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C621-20/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C621A-20/P | PIC16C621-04I/P | PIC16C621-04E/P | PIC16C620A-20I/P | PIC16F84A-20/P | PIC16F628A-I/P |
|---|---|---|---|---|---|---|---|
| Package | 18-DIP (0.300 inch) | 18-DIP (0.300 inch) - same | 18-DIP (0.300 inch) - same | 18-DIP (0.300 inch) - same | 18-DIP (0.300 inch) - same | 18-DIP (0.300 inch) - same | 18-DIP (0.300 inch) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory Type | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | Flash | Flash |
| Program Memory Size | 1.75 KB | 1.75 KB | 1.75 KB | 1.75 KB | 1.75 KB | 1.75 KB | 3.5 KB |
| RAM Size | 80 bytes | 80 bytes | 80 bytes | 80 bytes | 80 bytes | 68 bytes | 224 bytes |
| Number of I/O | 13 | 13 | 13 | 13 | 13 | 13 | 16 |
| Maximum Clock Frequency | 20 MHz | 20 MHz | 4 MHz | 4 MHz | 20 MHz | 20 MHz | 20 MHz |
| Analog Comparator | Yes (2 inputs, 1 output) | Yes | Yes | Yes | No | No | Yes (2 inputs) |
| Lifecycle Status | NRND | NRND | NRND | NRND | NRND | Active | Active |
Key Differentiators
- Lower standby current than PIC16F84A (vs PIC16F84A-20/P)
- Integrated analog comparator not present on PIC16C620 (vs PIC16C620-20/P)
- Same 18-DIP footprint across Flash and OTP families (vs PIC16F628A-I/P)
Design Notes
The PIC16C621-20/P supply range is 3.0V to 6.0V per Microchip datasheet 30402D. Place a 100 nF decoupling capacitor as close as possible to VDD (pin 14) with a 10 uF bulk capacitor at the board input. For battery applications, the LP oscillator mode at 32.768 kHz draws approximately 1 uA; combined with sleep mode this enables multi-year coin-cell operation. Verify brown-out reset threshold if VDD can dip below 4.5V during motor inrush events.
The 18-pin PDIP footprint accepts standard 0.300 inch through-hole sockets for production programming. Route the MCLR line with a 10 kohm pull-up to VDD and add a 100 nF cap to ground for noise immunity. The OSC1/OSC2 traces should be kept short (<10mm) and shielded from switching nodes to prevent clock jitter; for crystal mode, add 15-33 pF load caps selected for the specific crystal CL specification.
Because the PIC16C621-20/P uses OTP EPROM, it cannot be re-programmed or in-circuit debugged after the blank device is programmed once. Always prototype with a windowed CERDIP PIC16C621/JW or a Flash-based PIC16F84A-20/P first, then migrate the validated hex file to the OTP part for production. Also note that the PIC16C621 has a 5-bit analog comparator multiplexed onto RA0-RA3; disabling this peripheral in code frees those pins for digital I/O.
The CMOS PIC16C621 dissipates minimal quiescent power (15 uA typical at 5V/4MHz = 75 uW), so no thermal management is required for the 18-DIP package. In high-I/O switching applications where all 13 outputs drive 20mA loads simultaneously, the total dissipation can approach 1.3W at 5V but the thermal resistance of the PDIP (approximately 100 C/W) keeps the junction well below 125C. Avoid sustained operation above 4 MHz at 6V in sealed enclosures without airflow.
Compliance Information
PIC16C621-20/P in plastic DIP is pre-RoHS and uses lead-bearing solder finish. RoHS-compliant versions exist under /PREL suffix or in PIC16C621A die revision. Not AEC-Q100 qualified - use PIC16F628A-I/P for new automotive designs. REACH compliance per Microchip product statement.
