PIC16C66-20E/SO - 8-Bit 20MHz OTP MCU 14KB | Microchip
MPN: PIC16C66-20E/SO ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.95 | $8.95 |
| 10 | $8.06 | $80.60 |
| 100 | $7.17 | $717.00 |
| 500 | $6.45 | $3,225.00 |
| 1,000 | $5.74 | $5,740.00 |
PIC16C66-20E/SO Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, program memory (ROM/EPROM/OTP/Flash), data RAM, timers, serial communication peripherals, and I/O on one die. MCUs sit at the lowest tier of the embedded computing hierarchy below microprocessors (MPUs), digital signal controllers (DSCs), and application processors. The PIC16C6X architecture in particular is a Harvard RISC design with 35 single-word instructions, single-cycle execution (except program branches which take two), and DC-to-20 MHz clock input capability, giving it a deterministic instruction throughput that is well suited to real-time control loops.
Key features of the PIC16C66-20E/SO include three timers (Timer0, Timer1, Timer2), a USART for asynchronous and synchronous serial communication, an MSSP module supporting SPI and I2C, an 8-bit ADC with 5 input channels on some variants of the family, and a capture/compare/PWM (CCP) module. The OTP program memory is field-programmable using a standard device programmer such as the MPLAB PM3, and the device is fabricated in CMOS technology for low power consumption.
Typical applications include industrial control subsystems, automotive body and chassis electronics, sensor signal conditioning front-ends, low-cost consumer appliances, and legacy embedded products that require a stable 5V 8-bit MCU with proven PIC16 architecture compatibility. The extended temperature grade makes this part especially attractive where commercial-grade parts would fail thermally.
When designing with the PIC16C66-20E/SO, ensure that the supply rail is regulated within 4V to 5.5V and that decoupling is placed close to VDD/VSS pins. Note that OTP memory cannot be erased - for development cycles consider the PIC16F66 or PIC16C66-JW (windowed EPROM) variant, both sharing the same 28-pin footprint. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for PIC16C66-20E/SO — 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 PIC16C66-20E/SO (same form factor and footprint) — differing in Package, Timers, Program Memory Size, Program Memory Type, Core Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C66-20/SO
✅ Drop-In✓ In Stock
$5.45 / Unit
View Datasheet →PIC16C66-20I/SO
✅ Drop-In✓ In Stock
$6.42 / Unit
View Datasheet →PIC16C66T-20E/SO
✅ Drop-In✓ In Stock
$5.1 / Unit
View Datasheet →PIC16C66-04I/SO
✅ Drop-In✓ In Stock
$5.1 / Unit
View Datasheet →PIC16C66-20/SP
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$4.61 / Unit
View Datasheet →PIC16C66-20E/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC16C 8-bit RISC (Harvard) |
| Program Memory Type | OTP (One-Time Programmable) EPROM |
| Program Memory Size | 14 KB (8K x 14 words) |
| Data RAM | 368 bytes |
| Maximum Clock Frequency | 20 MHz |
| Instruction Set | 35 single-word instructions |
| Execution Time | 200 ns per instruction (1 cycle, except branches = 2 cycles) |
| Supply Voltage (VDD) | 4.0 V to 5.5 V |
| I/O Pins | 22 |
| Package | 28-pin SOIC (SO) - 300 mil wide |
| Temperature Grade | Extended (Automotive) -40C to +125C (per E suffix) |
| Timers | 3 (Timer0, Timer1, Timer2) |
| Serial Peripherals | USART, MSSP (SPI/I2C) |
| CCP Module | Yes (Capture/Compare/PWM) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
PIC16C66-20E/SO Pin Configuration
| Pin 1 | RA2/AN2/VREF- — Port A bit 2 / analog input 2 / negative voltage reference |
| Pin 2 | RA3/AN3/VREF+ — Port A bit 3 / analog input 3 / positive voltage reference |
| Pin 3 | RA4/T0CKI — Port A bit 4 / Timer0 clock input |
| Pin 4 | RA5/SS/AN4 — Port A bit 5 / SPI slave select / analog input 4 |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — Port B bit 0 / external interrupt input |
| Pin 7 | RB1 — Port B bit 1 |
| Pin 8 | RB2 — Port B bit 2 |
| Pin 9 | RB3/CCP1 — Port B bit 3 / Capture/Compare/PWM channel 1 |
| Pin 10 | RB4 — Port B bit 4 |
| Pin 11 | RB5 — Port B bit 5 |
| Pin 12 | RB6 — Port B bit 6 |
| Pin 13 | RB7 — Port B bit 7 |
| Pin 14 | VDD — Positive supply voltage (4.0 V to 5.5 V) |
| Pin 15 | OSC2/CLKOUT — Oscillator output / clock output |
| Pin 16 | OSC1/CLKIN — Oscillator input / external clock input |
| Pin 17 | RC0/T1OSO/T1CKI — Port C bit 0 / Timer1 oscillator output / Timer1 clock input |
| Pin 18 | RC1/T1OSI/CCP2 — Port C bit 1 / Timer1 oscillator input / CCP2 |
| Pin 19 | RC2/CCP1 — Port C bit 2 / Capture/Compare/PWM channel 1 |
| Pin 20 | RC3/SCK/SCL — Port C bit 3 / SPI clock / I2C clock |
| Pin 21 | RC4/SDI/SDA — Port C bit 4 / SPI data in / I2C data |
| Pin 22 | RC5/SDO — Port C bit 5 / SPI data out |
| Pin 23 | RC6/TX/CK — Port C bit 6 / USART transmit / USART clock |
| Pin 24 | RC7/RX/DT — Port C bit 7 / USART receive / USART data |
| Pin 25 | VSS — Ground reference |
| Pin 26 | MCLR/VPP — Master clear (reset) input / programming voltage |
| Pin 27 | RA0/AN0 — Port A bit 0 / analog input 0 |
| Pin 28 | RA1/AN1 — Port A bit 1 / analog input 1 |
Typical Applications
PIC16C66-20E/SO is suitable for 6 applications: Automotive Body Electronics, Industrial Sensor Interface Module, Legacy Consumer Appliance Control, HVAC Control Board, Point-of-Sale (POS) Terminal Peripherals, Security and Access Control Panels.
Automotive Body Electronics
The PIC16C66-20E/SO's extended -40C to +125C automotive temperature grade and 20 MHz throughput make it a fit for under-hood and body-control modules. The 22 I/O pins handle switch scanning for door/window/liftgate controls, while the USART and MSSP bridge to LIN or CAN transceivers via a sidecar IC. Per Microchip datasheet 30211D, the OTP program memory locks firmware against field tampering - desirable in automotive ECUs - and the 14 KB code space comfortably fits state-machine plus diagnostic routines. Designers pair this MCU with the MCP2515 CAN controller and a 5V LDO such as the LM7805.
Recommended
Industrial Sensor Interface Module
The PIC16C66-20E/SO's 22 I/O and 8-bit ADC front end suit it to 4-20 mA loop signal conditioning and multi-channel thermocouple/bridge sensor reading. Per Microchip datasheet 30211D, the 20 MHz core delivers 5 MIPS which is sufficient for 10 Hz update rates on 4 channels with linearization and digital filtering. The MSSP I2C master mode simplifies interfacing to EEPROM calibration tables and digital temperature sensors. Industrial DIN-rail modules built around this MCU typically pair it with a 24V-to-5V isolated DC-DC and a Modbus RTU over RS-485 transceiver like the MAX485.
Recommended
Legacy Consumer Appliance Control
The PIC16C66-20E/SO drops into appliance mainboards for washing machines, dishwashers, and small kitchen appliances where cost-sensitive 8-bit control replaces mechanical timers. The three timers drive motor PWM via the CCP module, the USART interfaces to inverter display boards, and the OTP program memory prevents end-user firmware reverse-engineering. Per Microchip datasheet 30211D, the 35-instruction RISC core is well documented in legacy code repositories, shortening time-to-market for refresh designs. The E temperature grade also tolerates the heat of motor-driver proximity.
Recommended
HVAC Control Board
The PIC16C66-20E/SO is well suited to HVAC fan/blower and damper control boards thanks to its 20 MHz throughput, CCP/PWM channels, and extended temperature tolerance for plenum-mounted enclosures. Per Microchip datasheet 30211D, the 14 KB OTP stores lookup tables for PWM-versus-RPM curves and proportional control algorithms. The MSSP I2C bus connects to wall thermostats and digital temperature/humidity sensors like the HDC1080, while the USART enables service-port diagnostics.
Recommended
Point-of-Sale (POS) Terminal Peripherals
The PIC16C66-20E/SO powers secondary peripherals in POS systems - barcode scanners, magnetic-stripe readers, customer displays - where its 20 MHz core handles protocol decoding in real time. Per Microchip datasheet 30211D, the USART and MSSP supply simultaneous RS-232 host link and I2C keypad connection. The OTP memory ensures firmware integrity in cash-handling environments. A typical implementation uses the MCU as a slave decoder, sending parsed data to a host application processor over RS-232 or USB-CDC via a CP2102N bridge.
Recommended
Security and Access Control Panels
The PIC16C66-20E/SO's extended temperature range and 22 GPIO drive small alarm panels, keypad readers, and access controllers. Per Microchip datasheet 30211D, the 14 KB OTP holds access lists and event logs for several hundred users, while the CCP module drives a piezo buzzer for alarm tones. The MSSP I2C bus connects to a PCF8574 I/O expander to scan 4x4 keypads, and the USART links to a downstream GSM or Ethernet module for off-premise reporting. End-of-line resistor monitoring is implemented via the ADC input.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C66-20E/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C66-20/SO | PIC16C66-20I/SO | PIC16C66T-20E/SO | PIC16C66-04I/SO | PIC16C66-20/SP |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SOIC (SO) - 300 mil | 28-SOIC (SO) - same | 28-SOIC (SO) - same | 28-SOIC (SO) - same | 28-SOIC (SO) - same | 28-PDIP (SP) - through-hole, NOT footprint drop-in |
| Maximum Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 4 MHz (-80%) | 20 MHz |
| Program Memory Type | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM |
| Program Memory Size | 14 KB (8K x 14) | 14 KB | 14 KB | 14 KB | 14 KB | 14 KB |
| Data RAM | 368 bytes | 368 bytes | 368 bytes | 368 bytes | 368 bytes | 368 bytes |
| Temperature Grade | Extended -40C to +125C | Commercial 0C to +70C | Industrial -40C to +85C | Extended -40C to +125C | Industrial -40C to +85C | Commercial 0C to +70C |
| I/O Pins | 22 | 22 | 22 | 22 | 22 | 22 |
Key Differentiators
- Extended automotive temperature grade on the same 20 MHz / 14 KB OTP die (vs PIC16C66-20/SO)
- Same 28-SOIC die available in industrial temp with potentially lower pricing (vs PIC16C66-20I/SO)
- Pin-compatible 4 MHz variant available for low-EMI designs (vs PIC16C66-04I/SO)
Design Notes
The PIC16C66-20E/SO requires a regulated 4.0 V to 5.5 V supply. Place a 100 nF ceramic decoupling capacitor within 5 mm of the VDD pin (pin 14) and a bulk 10 uF tantalum or aluminum capacitor at the board input. A second 100 nF cap on AVDD/VREF if using the ADC improves analog noise rejection. For automotive 12 V bus operation, a TLE4290 or LM7805 pre-regulator is recommended, with a TVS such as SMAJ5.0CA for transient protection.
OTP program memory cannot be erased. Prototype with the JW (windowed) EPROM variant PIC16C66-20/JW or the Flash-based PIC16F66 in the same 28-SOIC footprint to avoid scrapping production parts during development. Also note that MCLR (pin 26) must NOT be left floating - tie it to VDD through a 10 kohm resistor for normal operation, or to a reset supervisor for production reliability. The E temperature grade only applies when the part is operated within the 4V to 5.5V supply spec.
Route the oscillator traces (OSC1/OSC2, pins 16/15) as short as possible and shield them from high-current switching nodes. Place the crystal or resonator within 5 mm of the IC and add a guard ground ring. The ICSP pins (RB6/RB7 for programming, MCLR/VPP for voltage) should be brought out to an in-circuit programming header for production programming convenience, even though the device itself is not reprogrammable in-circuit.
Compliance Information
RoHS compliant per Microchip product page. Automotive temperature grade (-40C to +125C) is specified but PIC16C66-20E/SO is not formally AEC-Q100 qualified - confirm with Microchip for safety-critical deployments. Lead-free per Microchip packaging marking.
