PIC16C66/JW - 8-Bit 20MHz 14KB EPROM MCU | Microchip | 28-CDIP
MPN: PIC16C66/JW ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $38.5 | $38.50 |
| 10 | $35.2 | $352.00 |
| 25 | $32.8 | $820.00 |
| 100 | $29.4 | $2,940.00 |
PIC16C66/JW Overview
A microcontroller (MCU) is a single-chip computer containing a CPU, memory (program + data), and peripherals. The PIC16C66 belongs to the PIC16C family of OTP/EPROM-based 8-bit MCUs from Microchip Technology, positioned in the broader hierarchy: PIC16C66 -> PIC16C mid-range family -> PIC16 8-bit MCU family -> PIC microcontroller -> microcontroller -> embedded IC -> semiconductor. EPROM-based MCUs like the PIC16C66 were the dominant in-system programmable solution before flash memory became standard in mid-range microcontrollers.
Key features of the PIC16C66 include fully static operation, wide operating voltage from 2.5V (low-power) to 6.0V, low power consumption of 15 uA typical at 5V/4MHz and 1 uA at 3V/32kHz, three timers (Timer0, Timer1, Timer2), a USART for serial communication, a Capture/Compare/PWM (CCP) module, an 8-bit ADC with multiple channels, and a watchdog timer for reliable operation. It supports commercial, industrial, and extended temperature ranges and offers programmable code protection.
The PIC16C66 uses a Harvard architecture with separate program and data buses, allowing instruction fetch and data access to occur in the same clock cycle. Most instructions execute in a single cycle except program branches which take two, giving an effective throughput close to 200ns per instruction at 20MHz. The EPROM windowed ceramic package allows the program memory to be erased and reprogrammed multiple times during development.
Typical applications include industrial control systems, automotive subsystems (pre-CAN era), appliance controllers, instrumentation, and legacy embedded products designed in the 1990s. The windowed CDIP-28 form factor makes it convenient for breadboard and engineering prototype use, where UV erasure is feasible.
When designing with this device, note that the EPROM-based PIC16C66 has been superseded by flash-based equivalents such as the PIC16F76 in the same 28-pin SPDIP footprint. Modern designs should migrate to flash-based parts unless EPROM windowed erasure is specifically required.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone, including pin-compatibility guidance for migration to PIC16F and PIC16C6x flash variants.
Drop-in alternatives for PIC16C66/JW — 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 PIC16C66/JW (same form factor and footprint) — differing in Package, Program Memory Type, Program Memory Size, Timers, Core Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C66-20I/SP
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$6.3 / Unit
View Datasheet →PIC16C66-20/SP
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$4.61 / Unit
View Datasheet →PIC16F76-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C65B-20I/P
✅ Drop-In✓ In Stock
$5.42 / Unit
View Datasheet →PIC16C63A-20I/SP
✅ Drop-In✓ In Stock
$5.38 / Unit
View Datasheet →PIC16C66/JW Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC16C 8-bit RISC |
| Program Memory Type | UV-EPROM (windowed, erasable) |
| Program Memory Size | 14 KB (8K x 14 words) |
| RAM | 368 bytes |
| EEPROM Data Memory | None |
| Maximum Clock Speed | 20 MHz |
| Instruction Cycle Time | 200 ns (single-cycle, except branches) |
| Number of Instructions | 35 single-word |
| I/O Pins | 22 |
| Supply Voltage Range | 2.5 V to 6.0 V |
| Typical Supply Current (5V, 4MHz) | 15 uA |
| Typical Supply Current (3V, 32kHz) | 1 uA |
| Timers | Timer0, Timer1, Timer2 (3 x 8/16-bit) |
| Communication Interfaces | USART (SCI), SSP (SPI/I2C) |
| ADC | 8-bit, 5 to 8 channels |
| CCP Module | Capture/Compare/PWM |
| Watchdog Timer | Yes |
| Package | 28-pin CDIP (Ceramic DIP) with UV window |
| Operating Temperature Range | Commercial / Industrial / Extended (per datasheet) |
PIC16C66/JW Pin Configuration
| Pin 1 | RA2/AN2 — PORTA bit 2 / Analog input channel 2 |
| Pin 2 | RA3/AN3/VREF+ — PORTA bit 3 / Analog input 3 / ADC voltage reference positive |
| Pin 3 | RA4/T0CKI — PORTA bit 4 / Timer0 clock input |
| Pin 4 | RA5/AN4/SS — PORTA bit 5 / Analog input 4 / SPI slave select |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — PORTB bit 0 / External interrupt input |
| Pin 7 | RB1 — PORTB bit 1 |
| Pin 8 | RB2 — PORTB bit 2 |
| Pin 9 | RB3/PGM — PORTB bit 3 / Low-voltage programming input |
| Pin 10 | RB4 — PORTB bit 4 |
| Pin 11 | RB5 — PORTB bit 5 |
| Pin 12 | RB6/PGC — PORTB bit 6 / In-circuit debugger clock |
| Pin 13 | RB7/PGD — PORTB bit 7 / In-circuit debugger data |
| Pin 14 | VSS — Ground reference (second VSS pin) |
| Pin 15 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator output / Timer1 clock input |
| Pin 16 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator input / CCP2 module |
| Pin 17 | RC2/CCP1 — PORTC bit 2 / CCP1 module (PWM output) |
| Pin 18 | RC3/SCK/SCL — PORTC bit 3 / SPI clock / I2C clock |
| Pin 19 | RC4/SDI/SDA — PORTC bit 4 / SPI data in / I2C data |
| Pin 20 | RC5/SDO — PORTC bit 5 / SPI data out |
| Pin 21 | RC6/TX/CK — PORTC bit 6 / USART transmit / USART clock |
| Pin 22 | RC7/RX/DT — PORTC bit 7 / USART receive / USART data |
| Pin 23 | VSS — Ground reference (third VSS pin) |
| Pin 24 | VDD — Positive supply voltage |
| Pin 25 | VDD — Positive supply voltage (second VDD pin) |
| Pin 26 | OSC2/CLKOUT — Oscillator output / Clock output |
| Pin 27 | OSC1/CLKIN — Oscillator input / External clock input |
| Pin 28 | MCLR/VPP — Master clear reset / Programming voltage input |
Typical Applications
PIC16C66/JW is suitable for 7 applications: Industrial Control Systems, Legacy Embedded Products, Appliance Controllers, Educational and Development Boards, Automotive Subsystems (Pre-CAN Era), Instrumentation and Data Acquisition, Prototype Development and Firmware Validation.
Industrial Control Systems
The PIC16C66/JW's 14KB EPROM, 22 I/O pins, USART, and 8-bit ADC make it well-suited for industrial control applications such as motor control, sensor interfacing, and PLC I/O expansion. The wide 2.5V to 6.0V supply range tolerates unregulated 24V-derived rails after regulation, while 368 bytes of RAM support small RTOS-like state machines. The CCP module generates PWM for valve and actuator control at frequencies up to 20MHz instruction rate. Engineers value the windowed ceramic package during prototype validation cycles because firmware bugs can be erased with UV exposure in minutes, accelerating iterative development.
Recommended
Legacy Embedded Products
Many 1990s-era products still ship with PIC16C66/JW controllers and require maintenance replacements. The windowed CDIP-28 package allows field re-programming for firmware updates via UV erasure and EPROM burner, supporting legacy systems where redesign is not economically justified. The 20MHz clock and 35-instruction RISC core deliver deterministic interrupt response suitable for real-time control loops. For legacy field replacements, the PIC16C66-20I/SP (plastic SPDIP variant) provides the same die in a non-windowed package at lower cost when in-circuit programming is not required.
Recommended
Appliance Controllers
White goods and appliance controllers (washing machines, dishwashers, HVAC thermostats) historically used PIC16C66/JW for its mix of ADC channels, PWM outputs, and timer/counter resources. The 22 I/O pins are sufficient to drive 7-segment displays, relay coils, and triac interfaces while reading temperature sensors and keypad inputs. The low 1 uA sleep current at 3V/32kHz supports battery-backed RTC operation. The industrial temperature range meets appliance environmental requirements.
Recommended
Educational and Development Boards
Universities and training labs use PIC16C66/JW on development boards to teach 8-bit embedded programming because the UV-windowed ceramic package allows students to erase and reprogram the device repeatedly without part replacement. The 35-instruction RISC core is approachable for beginners, while peripherals (USART, ADC, CCP, timers) provide enough complexity for advanced labs. The 28-pin DIP form factor is breadboard-friendly and supports through-hole soldering exercises.
Recommended
Automotive Subsystems (Pre-CAN Era)
Before CAN bus adoption, PIC16C66/JW was used in body control modules, instrument clusters, and lighting controllers in 1990s vehicles. Its 22 I/O, USART, and ADC channels support dashboard gauge driving, switch matrix scanning, and PWM dimming. The extended temperature range meets under-hood and cabin automotive requirements. For modern automotive designs, migrate to PIC16F or dsPIC33 families with CAN-FD and AEC-Q100 qualification.
Recommended
Instrumentation and Data Acquisition
The PIC16C66/JW's 8-bit ADC with multiple channels, combined with USART for PC communication and 368 bytes RAM for sample buffering, suits portable instrumentation like multimeters, thermometers, and environmental monitors. The 20MHz instruction rate supports sampling rates up to ~500kSps when the ADC and UART are coordinated. Low-power modes extend battery life in field-portable instruments. The windowed package supports calibration firmware updates via UV erasure during manufacturing.
Recommended
Prototype Development and Firmware Validation
The /JW windowed ceramic DIP package is specifically designed for engineering development workflows where firmware must be erased and reprogrammed dozens of times. UV erasure takes 20-30 minutes, after which the device can be reprogrammed with new firmware. This makes PIC16C66/JW ideal for early-stage development before transitioning to one-time-programmable (OTP) or flash variants for production. The CDIP-28 package also supports socketed programmers for high-throughput testing.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C66/JW — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C66-20I/SP | PIC16F76-I/SP | PIC16C65B-20I/P | PIC16C63A-20I/SP |
|---|---|---|---|---|---|
| Package | 28-CDIP (windowed ceramic) | SPDIP-28 (plastic, same footprint) | SPDIP-28 (plastic, same footprint) | PDIP-28 (plastic, same footprint) | SPDIP-28 (plastic, same footprint) |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 14 KB UV-EPROM | 14 KB UV-EPROM (same) | 14 KB flash | 7 KB UV-EPROM (-50%) | 4 KB UV-EPROM (-71%) |
| RAM | 368 bytes | 368 bytes | 368 bytes | 192 bytes (-48%) | 192 bytes (-48%) |
| I/O Pins | 22 | 22 | 22 | 22 | 22 |
| Max Clock Speed | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Memory Type | UV-EPROM (windowed) | UV-EPROM (non-windowed) | Flash (in-circuit reprogrammable) | UV-EPROM (non-windowed) | UV-EPROM (non-windowed) |
| USART | Yes | Yes | Yes | Yes | Yes |
| ADC | 8-bit, 5-8 channels | 8-bit, 5-8 channels | 8-bit, 5-8 channels | 8-bit, 5-8 channels | 8-bit, 5-8 channels |
| Lifecycle Status | NRND | NRND | Active | Obsolete | Obsolete |
| Pinout Compatibility | Reference (28-DIP) | Yes (drop-in) | Yes (drop-in, firmware rebuild for flash) | Yes (drop-in, smaller memory) | Yes (drop-in, smaller memory) |
Key Differentiators
- Windowed EPROM package for repeated erasure (vs PIC16C66-20/SP)
- Full 14KB program memory in 28-pin package (vs PIC16C65B-20I/P)
- Flash-based equivalent available for production (vs PIC16F76-I/SP)
Design Notes
The /JW windowed ceramic package requires UV erasure (typically 20-30 minutes under a UV lamp rated 12 mW/cm^2 at 253.7 nm) before reprogramming. Production volumes must migrate to PIC16C66-20/SP (plastic DIP, one-time-programmable EPROM) or PIC16F76-I/SP (flash). Engineers retaining /JW for development should store erased devices in opaque tubes to prevent ambient UV erasure.
Place a 0.1 uF decoupling capacitor as close as possible to each VDD pin (pins 24 and 25) with a short trace to the nearest VSS pin. For designs operating above 10MHz, add a bulk 10 uF tantalum or aluminum electrolytic capacitor near the VDD pins. The PIC16C66 has two VDD and three VSS pins to reduce ground bounce; all must be connected for reliable high-frequency operation.
For 20MHz operation, keep the oscillator traces (OSC1/OSC2, pins 27/26) short and surrounded by a ground guard ring. Use a crystal or ceramic resonator with load capacitors matched to the crystal specification (typically 15-33 pF). For clock-sensitive applications, the internal oscillator drift may exceed USB or UART timing tolerances; consider an external crystal or resonator.
The MCLR pin (pin 28) requires a 10 kOhm pull-up to VDD for normal operation. For in-circuit debugging or programming, use a 10-47 kOhm resistor instead of a direct connection to allow the debugger to drive MCLR low. Avoid long MCLR traces that can pick up noise and cause spurious resets, especially near PWM or relay-switching signals.
Separate analog and digital ground planes when using the ADC. Connect AGND (VSS pins near analog inputs) and DGND at a single point near the MCU. Place analog reference bypass capacitor (0.1 uF) directly on the VREF+ pin if used. For mixed-signal designs, allocate dedicated analog input pins (AN0-AN4) and avoid routing digital signals near them.
Compliance Information
PIC16C66/JW contains lead (Pb) in the ceramic DIP package and UV-window glass, making it non-RoHS compliant per current EU RoHS Directive 2011/65/EU exemptions for legacy through-hole ceramic packages. AEC-Q100 qualification status not documented for this automotive-era PIC16C part. Modern automotive designs should migrate to AEC-Q100-qualified flash MCUs.
