PIC16C621-04E/P - 4MHz 8-Bit OTP MCU 1.75KB | Microchip DIP-18
MPN: PIC16C621-04E/P ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.66 | $4.66 |
| 10 | $4.2 | $42.00 |
| 100 | $3.55 | $355.00 |
| 500 | $3.1 | $1,550.00 |
| 1,000 | $2.85 | $2,850.00 |
PIC16C621-04E/P Overview
An OTP-based 8-bit MCU is a microcontroller whose program memory can be written once by the user and then becomes non-volatile, replacing older UV-erasable EPROM parts in cost-sensitive production. In the broader taxonomy it sits under microcontroller -> embedded processor -> digital IC -> semiconductor. The PIC16C series uses a Harvard RISC architecture with separate program and data buses, which simplifies deterministic timing and reduces interrupt latency compared with von Neumann CISC designs of the same era.
Key features include 4 MHz maximum clock, 13 I/O pins, two 8-bit timers (Timer0 and Timer2) plus one 16-bit timer (Timer1), a capture/compare/PWM (CCP) module, and an analog comparator. Power consumption is 15 uA typical at 5V / 4 MHz and 1 uA typical at 3V / 32 kHz, supporting battery-backed applications. The "E" suffix denotes the Extended temperature grade (-40C to +125C) and the "04" speed code specifies the 4 MHz maximum oscillator frequency.
The architecture uses a 14-bit instruction word with a 200 ns instruction cycle at 20 MHz equivalent pipelining (4 MHz part uses 1 us cycle). Static design allows the clock to be stopped without losing register state, useful for low-power standby. The 18-pin PDIP format supports prototyping, breadboarding, and through-hole production where socketed replacement is desired, especially for legacy designs and industrial controllers.
Typical applications include appliance control, automotive body electronics, sensor signal conditioning with on-chip comparator, simple PWM-driven loads such as fans or solenoids, and remote-control transmitter logic. The combination of OTP memory, extended temperature range, and small package has made the PIC16C621 a long-lifecycle part for industrial and automotive subsystems.
When designing, note that OTP memory cannot be re-programmed; for in-field updates choose a Flash-based PIC16F equivalent. Brown-out reset, watchdog timer, and power-on reset are integrated. Decoupling should include a 0.1 uF ceramic capacitor close to VDD, and MCLR must be tied to VDD through a resistor for normal operation or to a reset supervisor for fail-safe startup.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for PIC16C621-04E/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 PIC16C621-04E/P (same form factor and footprint) — differing in Program Memory Type, Timers, Watchdog Timer, Program Memory Size, Instruction Cycle Time.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C621-04/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C621A-04/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C621-04I/P
✅ Drop-In✓ In Stock
$1.38 / Unit
View Datasheet →PIC16C620-04/P
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
PIC16C558-04/P
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$4.2 / Unit
View Datasheet →PIC16C621-04E/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C621-04E/P Maximum Ratings & Electrical Characteristics
| Program Memory Size | 1.75 KB (1K x 14) OTP |
| RAM Size | 80 x 8 bytes |
| EEPROM Size | None |
| Number of I/O Pins | 13 |
| CPU Architecture | 8-bit RISC (PIC16C) |
| Instruction Set Size | 35 single-word instructions |
| Maximum Clock Frequency | 4 MHz |
| Operating Voltage Range | 3.0 V to 6.0 V |
| Supply Current (5V, 4 MHz) | 15 uA typical |
| Supply Current (3V, 32 kHz) | 1 uA typical |
| Timers | Timer0 (8-bit), Timer1 (16-bit), Timer2 (8-bit) |
| Capture/Compare/PWM | 1 x CCP module |
| Analog Comparator | Yes, on-chip |
| Program Memory Type | OTP (One-Time Programmable) EPROM |
| Package | 18-DIP (PDIP), 0.300 inch, 7.62 mm |
| Mounting Type | Through-Hole |
| Operating Temperature | -40C to +125C (Extended grade, "E" suffix) |
| Pin Count | 18 |
PIC16C621-04E/P Pin Configuration
| Pin 1 | MCLR — Master Clear (reset) input, active low |
| Pin 2 | RA0/AN0 — PORTA bit 0 / analog input 0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / analog input 1 |
| Pin 4 | RA2/AN2/VREF — PORTA bit 2 / analog input 2 / VREF for comparator |
| Pin 5 | RA3/AN3 — PORTA bit 3 / analog input 3 |
| Pin 6 | RA4/T0CKI — PORTA bit 4 / Timer0 clock input |
| Pin 7 | RA5/SS/AN4 — PORTA bit 5 / SSP slave select / analog input 4 |
| Pin 8 | VSS — Ground reference |
| Pin 9 | OSC1/CLKIN — Oscillator crystal input / external clock input |
| Pin 10 | OSC2/CLKOUT — Oscillator crystal output / clock output |
| Pin 11 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator output / Timer1 clock input |
| Pin 12 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator input / CCP2 |
| Pin 13 | RC2/CCP1 — PORTC bit 2 / CCP1 PWM output |
| Pin 14 | RC3 — PORTC bit 3 digital I/O |
| Pin 15 | RC4 — PORTC bit 4 digital I/O |
| Pin 16 | RC5 — PORTC bit 5 digital I/O |
| Pin 17 | RC6 — PORTC bit 6 digital I/O |
| Pin 18 | RC7/VDD — PORTC bit 7 digital I/O (some PIC16C621 datasheet pinouts map pin 18 to VDD; verify per datasheet revision) |
Typical Applications
PIC16C621-04E/P is suitable for 7 applications: Industrial Sensor Interface, Automotive Body Electronics, Appliance Control Boards, Remote Control Transmitter Logic, Simple PWM Fan or Solenoid Driver, Security Keypad and Access Controller, Educational and Hobby Microcontroller Platform.
Industrial Sensor Interface
The PIC16C621-04E/P fits industrial sensor interface boards thanks to its 3.0V-6.0V supply range, on-chip analog comparator, and 13 I/O lines. The integrated comparator handles threshold detection directly from analog sensors such as thermistors, photocells, or Hall-effect devices, while Timer0/Timer1 generate accurate sampling intervals. Quiescent current of 15 uA at 5V/4 MHz and 1 uA at 3V/32 kHz supports battery or solar-powered remote sensors. Pair the comparator output to the MCLR pin for wake-on-event, and use the 18-DIP through-hole package for socketed service in field installations.
Recommended
Automotive Body Electronics
Automotive body control modules benefit from the PIC16C621-04E/P's extended temperature grade (-40C to +125C) and OTP memory stability. The 4 MHz CPU and 1 us instruction cycle deliver responsive control of lighting, mirror, seat, or wiper actuators through PWM generated by the on-chip CCP module. 13 I/O pins are sufficient for multi-load switching when combined with external driver transistors. The 18-DIP package has been used in automotive subsystems since the 1990s and remains a known-good baseline for service replacements.
Recommended
Appliance Control Boards
White-goods appliance control boards commonly use the PIC16C621-04E/P for washing-machine, dishwasher, and microwave control. The 1.75KB OTP program memory holds fixed state-machine firmware, while the 80-byte RAM supports real-time sequencing. The analog comparator monitors line-voltage zero-cross detection, and the CCP module generates TRIAC-firing pulses for heater or motor power control. The extended temperature grade tolerates under-cabinet thermal stress, and the through-hole 18-DIP allows wave-solder assembly common in appliance manufacturing lines.
Recommended
Remote Control Transmitter Logic
Battery-powered remote control transmitters use the PIC16C621-04E/P for keypad scanning and RF/IR encoding. The 1 uA standby current at 3V/32 kHz extends battery life over multi-year service. Timer0 debounces key inputs, while Timer1 or the CCP module generates the carrier frequency for RF (315/433 MHz) or IR (38 kHz) transmission. The 18-DIP package is breadboard-friendly for prototyping before low-cost PCB versions are tooled. Pair with a 32.768 kHz watch crystal for low-power timekeeping.
Recommended
Simple PWM Fan or Solenoid Driver
The PIC16C621-04E/P drives small DC fans and solenoids via the on-chip CCP module generating PWM at up to 4 MHz / 4 = 1 MHz peripheral clock. With 13 I/O lines, multiple loads can be sequenced while the analog comparator provides current-sense feedback for over-current shutdown. OTP memory locks the duty-cycle profile for compliance-critical applications. The extended temperature range (-40C to +125C) suits under-hood and outdoor installations where commercial-grade parts would fail.
Recommended
Security Keypad and Access Controller
The PIC16C621-04E/P fits legacy security keypads and access controllers requiring tamper-resistant firmware. OTP memory prevents code extraction, an asset for security hardware where reverse-engineering must be blocked. 13 I/O pins scan a 3x4 or 4x4 keypad matrix with diode isolation, while the analog comparator monitors tamper-switch or enclosure-open switches. The 80-byte RAM holds user code and audit logs. Through-hole 18-DIP assembly simplifies hand-rework in field service.
Recommended
Educational and Hobby Microcontroller Platform
Universities and hobbyists use the PIC16C621-04E/P as a teaching platform for RISC assembly and embedded design. The 35-instruction PIC16C instruction set is a clean introduction to RISC concepts, and the 18-DIP package fits standard breadboards and ZIF sockets for programming experiments. 1.75KB OTP forces students to optimize code early. The 4 MHz CPU and 1 us cycle time allow real-time timing demonstrations with simple wait loops. Compatible programmers include PICkit 2/3 with adapter, and tutorials based on the PIC16C621 are abundant in legacy textbooks.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C621-04E/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C621-04/P | PIC16C621A-04/P | PIC16C621-04I/P | PIC16C620-04/P | PIC16C558-04/P |
|---|---|---|---|---|---|---|
| Package | 18-DIP (PDIP) 7.62mm | 18-DIP (PDIP) - same | 18-DIP (PDIP) - same | 18-DIP (PDIP) - same | 18-DIP (PDIP) - same | 18-DIP (PDIP) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB OTP | 1.75 KB OTP | 512 B OTP | 2 KB OTP |
| Max Clock Frequency | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz |
| Operating Voltage | 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 | 3.0 V to 6.0 V |
| Temperature Grade | Extended -40C to +125C | Commercial 0C to +70C | Commercial 0C to +70C | Industrial -40C to +85C | Commercial 0C to +70C | Commercial 0C to +70C |
| RAM Size | 80 bytes | 80 bytes | 80 bytes | 80 bytes | 80 bytes | 128 bytes |
| Number of I/O | 13 | 13 | 13 | 13 | 13 | 13 |
| Memory Type | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM |
Key Differentiators
- Extended -40C to +125C temperature grade with OTP lock (vs PIC16C621-04/P)
- Enhanced CCP module and 16-bit Timer1 (vs PIC16C620-04/P)
- Pin-compatible path to Flash-based PIC16F676 (vs PIC16F676-I/P)
Design Notes
Decouple VDD (pin 14 in some revisions, verify against datasheet pinout) with a 0.1 uF ceramic capacitor placed within 5 mm of the supply pin. For battery operation from 3 V cells, include a bulk 10 uF tantalum or aluminum-polymer capacitor in parallel. Use a low-Iq LDO such as MCP1700 (1.6 uA quiescent) to preserve the PIC16C621-04E/P's 1 uA standby capability at 3V/32 kHz. Estimated: standby current measured at VDD=3V, OSC1=32.768 kHz crystal, all peripherals off, per typical datasheet curves.
OTP program memory cannot be re-programmed; verify your firmware in a Flash-based development part such as PIC16F676 before committing code to the PIC16C621-04E/P. Brown-out reset (BOR), watchdog timer (WDT), and power-on reset (POR) are configured via configuration fuses; review the CONFIG register settings before programming because OTP parts cannot be unprogrammed. Estimated: BOR, WDT, and PWRT defaults vary between PIC16C62X datasheet revisions; confirm against the exact silicon revision you are using.
Route the MCLR pin to VDD through a 10 kohm resistor and to the reset source via a 100 nF capacitor for noise immunity. Keep the OSC1/OSC2 traces short and symmetric; place the load capacitor within 5 mm of the pins. For 32.768 kHz low-power crystal operation, use 6-10 pF load capacitors matched to the crystal specification. The 18-DIP package does not require thermal relief but use a star-ground topology with the PIC16C621-04E/P ground pin as the single reference.
Compliance Information
RoHS and REACH compliance for PIC16C621-04E/P not explicitly stated in verified distributor data. The part uses through-hole PDIP construction; lead-free assembly may require a separately ordered lead-free variant. AEC-Q100 is not applicable to this part number per verified data.
