PIC16C66T-20E/SO - 8-Bit 20MHz OTP MCU 14KB | Microchip
MPN: PIC16C66T-20E/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.2 | $8.20 |
| 10 | $7.55 | $75.50 |
| 100 | $6.78 | $678.00 |
| 500 | $5.92 | $2,960.00 |
| 1,000 | $5.1 | $5,100.00 |
PIC16C66T-20E/SO Overview
What is a PIC16C microcontroller? PIC16C is Microchip's legacy 8-bit OTP/EPROM MCU family using a RISC-style Harvard architecture with 35 single-cycle instructions, a hardware multiplier on select variants, and a separate 14-bit program bus from the 8-bit data bus. The PIC16C6x sub-family adds enhanced peripherals (USART, capture/compare/PWM, 8-bit ADC on some members) versus the simpler PIC16C5x baseline. Within the broader taxonomy this places PIC16C66 as: 8-bit MCU -> RISC microcontroller -> PIC microcontroller -> embedded controller -> semiconductor IC.
Key features include 14 KB (8K x 14 word) OTP program memory, 368 bytes of data RAM, 20 MHz maximum clock, a wide 4.0 V to 6.0 V supply range for the extended (-40C to +125C) industrial/automotive temperature grade, USART serial port, capture/compare/PWM modules, 8-bit A/D converter channels, and 22 I/O pins. The '20E' suffix indicates a 20 MHz maximum clock with the extended temperature grade, while 'SO' specifies the 28-pin SOIC package.
The PIC16C66 architecture uses a 14-bit instruction word and a two-stage instruction pipeline, providing deterministic single-cycle instruction execution at the oscillator clock rate (except for program branches which take two cycles). The 'E' extended temperature grade and the part's mature CMOS process make it suitable for automotive and industrial environments where higher-temperature operation and proven long-term reliability are required.
Typical applications include industrial control nodes, automotive body and chassis subsystems, appliance controllers, and embedded sensor interfaces. It is well matched to designs that need more code space and more peripheral channels than the PIC16C6x baseline while staying within an OTP-programmable cost structure.
Design consideration: OTP memory cannot be re-programmed in-circuit, so plan code development on a windowed (JW) or Flash-equivalent part, then commit the final code image to the PIC16C66T-20E/SO for production. The 4.0-6.0V supply range excludes direct 3.3V system use.
This page synthesizes distributor pricing from DigiKey and Octopart, real-time stock signals, drop-in PIC16C66 family alternatives (same 28-SOIC footprint, same 20 MHz clock, same 14 KB OTP memory map), and practical OTP programming notes not aggregated on any single distributor page.
Drop-in alternatives for PIC16C66T-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 PIC16C66T-20E/SO (same form factor and footprint) — differing in Core Architecture, Package, Timers, Data RAM, Maximum Clock Frequency.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C66T-20/SO
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$8.2 / Unit
View Datasheet →PIC16C66-20/SO
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$5.45 / Unit
View Datasheet →PIC16C66T-10E/SO
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$5.8 / Unit
View Datasheet →PIC16C66-10/SO
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$6.93 / Unit
View Datasheet →PIC16F877A-I/SO
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
PIC16C66T-20E/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC (Harvard) |
| Program Memory Type | OTP (One-Time Programmable), 14-bit words |
| Program Memory Size | 14 KB (8K x 14 words) |
| Data RAM | 368 x 8 bytes |
| Maximum Clock Frequency | 20 MHz |
| Instruction Cycle | 1 cycle (200 ns @ 20 MHz); 2 cycles for branches |
| Supply Voltage (Vdd) | 4.0 V to 6.0 V |
| Operating Temperature Grade | Extended (-40C to +125C), 'E' suffix |
| I/O Pins | 22 |
| Package | 28-pin SOIC (SO, 0.295 inch / 7.50 mm body width) |
| Mounting Type | Surface Mount |
| A/D Converter | 8-bit, multi-channel (channel count per datasheet) |
| Serial Interface | USART / SCI |
| Timers | Timer0, Timer1, Timer2 + CCP modules (per family datasheet) |
| Shipping Packaging | Tape & Reel (TR), 'T' suffix |
PIC16C66T-20E/SO Pin Configuration
| Pin 1 | MCLR/Vpp — Master Clear (reset) input / ICSP programming voltage |
| Pin 2 | RA0/AN0 — Port A bit 0 / analog input 0 |
| Pin 3 | RA1/AN1 — Port A bit 1 / analog input 1 |
| Pin 4 | RA2/AN2 — Port A bit 2 / analog input 2 |
| Pin 5 | RA3/AN3/Vref — Port A bit 3 / analog input 3 / ADC Vref |
| Pin 6 | RA4/T0CKI — Port A bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4/SS — Port A bit 5 / analog input 4 / SPI slave select |
| Pin 8 | RE0/RD/AN5 — Port E bit 0 / read control / analog input 5 |
| Pin 9 | RE1/WR/AN6 — Port E bit 1 / write control / analog input 6 |
| Pin 10 | RE2/CS/AN7 — Port E bit 2 / chip select / analog input 7 |
| Pin 11 | VDD — Positive supply (4.0 V to 6.0 V) |
| Pin 12 | VSS — Ground |
| Pin 13 | OSC1/CLKIN — Oscillator crystal input / external clock in |
| Pin 14 | OSC2/CLKOUT — Oscillator crystal output / clock out (Fosc/4) |
| Pin 15 | RC0/T1OSO/T1CKI — Port C bit 0 / Timer1 oscillator out / Timer1 clock in |
| Pin 16 | RC1/T1OSI/CCP2 — Port C bit 1 / Timer1 oscillator in / CCP2 I/O |
| Pin 17 | RC2/CCP1 — Port C bit 2 / CCP1 I/O |
| Pin 18 | RC3/SCK/SCL — Port C bit 3 / SPI clock / I2C clock |
| Pin 19 | RD0/PSP0 — Port D bit 0 / Parallel Slave Port bit 0 |
| Pin 20 | RD1/PSP1 — Port D bit 1 / Parallel Slave Port bit 1 |
| Pin 21 | RD2/PSP2 — Port D bit 2 / Parallel Slave Port bit 2 |
| Pin 22 | RD3/PSP3 — Port D bit 3 / Parallel Slave Port bit 3 |
| Pin 23 | RC4/SDI/SDA — Port C bit 4 / SPI data in / I2C data |
| Pin 24 | RC5/SDO — Port C bit 5 / SPI data out |
| Pin 25 | RC6/TX/CK — Port C bit 6 / USART TX / USART clock |
| Pin 26 | RC7/RX/DT — Port C bit 7 / USART RX / USART data |
| Pin 27 | RD4/PSP4 — Port D bit 4 / Parallel Slave Port bit 4 |
| Pin 28 | RD5/PSP5 — Port D bit 5 / Parallel Slave Port bit 5 |
Typical Applications
PIC16C66T-20E/SO is suitable for 6 applications: Automotive Body Control Module, Industrial Sensor Interface Node, Appliance Control Board, Remote Sensor / Wireless Data Logger, Legacy Industrial PLC I/O Module, Consumer Electronics User Interface Controller.
Automotive Body Control Module
The PIC16C66T-20E/SO's extended -40C to +125C temperature grade and mature OTP architecture fit automotive body and chassis subsystems such as seat controllers, mirror modules, HVAC flap drivers, and lighting node ECUs. Its 22 I/O pins handle multiple switch inputs, low-side driver outputs, and LIN/SCI communication; the USART supports the 19200 baud LIN slave protocol used in body networks. The 14 KB OTP program space accommodates state-machine code for multiplexing wiper timing, courtesy lamp dimming, and climate-mode logic. Versus an automotive Flash MCU the OTP part is preferred for fully frozen, end-of-life production where no field updates are planned, saving incremental die cost. Design tip: place a 100 nF ceramic decoupling cap within 5 mm of the Vdd/Vss pins and keep the MCLR/Vpp pull-up within 10 mm of pin 1 to avoid spurious resets during cranking transients.
Recommended
Industrial Sensor Interface Node
The PIC16C66T-20E/SO provides 22 I/O pins, an 8-bit A/D converter, and a USART well suited to industrial 4-20 mA loop transmitters, thermocouple conditioning front-ends, and remote sensor multiplexer nodes. The 20 MHz clock supports 50 ksps A/D conversions with software oversampling to push effective resolution beyond the native 8 bits. The 14 KB OTP memory holds Modbus-RTU slave stacks, calibration tables, and linearization routines for RTD and thermocouple sensors. The 4.0-6.0 V supply rails integrate directly with 5 V industrial backplanes without additional level translation. OTP architecture is advantageous here because the calibration coefficients are baked in at programming time and cannot drift via accidental reprogramming in the field.
Recommended
Appliance Control Board
White-goods appliance controllers (washing machines, dishwashers, microwave ovens, refrigerators) commonly use PIC16C66T-20E/SO in their human-machine interface and motor-control logic boards. The 22 I/O pins drive 7-segment displays, keypads, buzzer PWM, triac-fire optos, and relay coils; the three timers + CCP modules generate the 50/60 Hz zero-crossing delays for triac phase-angle dimming. The 14 KB OTP holds state-machine firmware for wash cycles, lid-lock interlocks, and door-bell detection. The extended temperature rating handles under-cabinet oven environments where ambient can exceed 70C. Cost sensitivity in this market favors the mature PIC16C66 over newer Flash MCUs when the firmware is fully locked.
Recommended
Remote Sensor / Wireless Data Logger
Battery-powered wireless sensor nodes benefit from the PIC16C66T-20E/SO's low-cost OTP architecture and 20 MHz throughput. A typical implementation pairs the MCU with a 433/868 MHz ISM-band transmitter; the USART drives the radio's serial interface, the 8-bit ADC samples environmental parameters (temperature, humidity, soil moisture), and the 14 KB OTP holds packet formatting, sensor linearization, and a simple sleeping/wake scheduler. The 4.0-6.0 V Vdd lets designers pick between 4 AA cells or a single lithium-thionyl chloride primary cell with a boost regulator. OTP memory is acceptable here because the node firmware is fully fixed at deployment and avoids the erase/write power spikes of Flash MCUs.
Recommended
Legacy Industrial PLC I/O Module
Existing industrial PLC rack systems built around the PIC16C6x family use the PIC16C66T-20E/SO as a digital I/O slave controller for rack-mounted backplanes. The MCU scans 16-22 optocoupled inputs, drives 16 LED indicators, and exposes the rack state via USART or SPI to the PLC's central CPU. The 14 KB OTP handles debouncing, watchdog refresh, and the rack-specific Modbus map; OTP architecture locks the I/O map so field technicians cannot accidentally re-flash a module with incompatible firmware. Extended temperature grade lets the same module serve machine-tool cells and outdoor cabinet installations without re-qualification. Modernization tip: design a dual-footprint PCB that accepts either PIC16C66T-20E/SO (legacy support) or PIC16F877A-I/SO (new deployments) to ease inventory transitions.
Recommended
Consumer Electronics User Interface Controller
Mid-volume consumer devices (set-top boxes, audio amplifiers, DVD players, hobbyist robotics) use the PIC16C66T-20E/SO as a front-panel user interface controller that offloads button scanning, IR remote decoding, and 7-segment/LED matrix display refresh from the main CPU. The USART relays decoded user actions to the host processor; the 22 I/O pins drive the display multiplex and rotary encoder inputs. The 14 KB OTP holds NEC/RC5 IR protocol decoders, button debouncing, and display character maps. Compared to a discrete logic implementation this saves PCB area and BOM cost. Per-market cost-down programs often end-of-life the PIC16C66 in favor of the PIC16F88 or PIC16F877A, so design for migration.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C66T-20E/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C66T-20/SO | PIC16C66-20/SO | PIC16C66T-10E/SO | PIC16F877A-I/SO |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SOIC (0.295 inch) | 28-SOIC (0.295 inch) - same | 28-SOIC (0.295 inch) - same | 28-SOIC (0.295 inch) - same | 28-SOIC (0.295 inch) - same |
| Core Architecture | PIC 8-bit RISC | PIC 8-bit RISC | PIC 8-bit RISC | PIC 8-bit RISC | PIC 8-bit RISC (Flash) |
| Program Memory Type | OTP, 14-bit words | OTP, 14-bit words | OTP, 14-bit words | OTP, 14-bit words | Flash (re-programmable) |
| Program Memory Size | 14 KB (8K x 14) | 14 KB (8K x 14) | 14 KB (8K x 14) | 14 KB (8K x 14) | 14 KB (8K x 14) |
| Data RAM | 368 bytes | 368 bytes | 368 bytes | 368 bytes | 368 bytes |
| Maximum Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 10 MHz (-50%) | 20 MHz |
| Supply Voltage | 4.0 V to 6.0 V | 4.0 V to 6.0 V | 4.0 V to 6.0 V | 4.0 V to 6.0 V | 2.0 V to 5.5 V (wider) |
| Temperature Grade | Extended (-40C to +125C) | Commercial (0C to +70C) | Commercial (0C to +70C) | Extended (-40C to +125C) | Industrial (-40C to +85C) |
| Shipping Packaging | Tape & Reel ('T') | Tape & Reel | Tube | Tape & Reel | Tube (or TR for 'T' variant) |
Key Differentiators
- Extended -40C to +125C temperature grade ('E' suffix) (vs PIC16C66T-20/SO)
- Tape & Reel packaging ('T' suffix) (vs PIC16C66-20/SO)
- 20 MHz clock versus 10 MHz downgrade parts (vs PIC16C66T-10E/SO)
Design Notes
The 'OTP' (One-Time Programmable) suffix means the program memory cannot be re-written after the initial programming step. Develop and debug firmware on a JW (windowed) ceramic or a PIC16F-series Flash equivalent first, then commit the final image to PIC16C66T-20E/SO for production. Attempting to re-program the part via ICSP after the first write will fail and lock the device. Always verify the configuration word bits (oscillator mode, watchdog, code protection, brown-out) before the final ICSP write - they cannot be changed later.
Place a 100 nF (0.1 uF) ceramic decoupling capacitor within 5 mm of the Vdd pin (pin 11) and a second 100 nF cap within 5 mm of the Vss pin (pin 12), with traces short and direct to the package. For designs with high-current switching loads on the board, add a 10 uF bulk tantalum or aluminum polymer cap near the MCU Vdd pin. The 4.0-6.0 V supply range excludes 3.3 V operation; if the system rail is 3.3 V use a 5 V boost regulator or migrate to a PIC16F-series part.
Keep the MCLR/Vpp pull-up resistor within 10 mm of pin 1 to avoid spurious resets from EMI; use a 10 kohm to 47 kohm pull-up to Vdd. Route the OSC1/OSC2 crystal traces short and symmetric, surrounded by a ground guard ring, to minimize clock jitter at 20 MHz. Place the crystal within 5 mm of pins 13-14. If the ICSP header is included for in-circuit programming, keep the PGD/PGC traces short and isolated from switching signals to ensure reliable programming.
Compliance Information
RoHS status not confirmed in verified web data; PIC16C6x OTP family is a legacy product line - request the latest RoHS letter from Microchip before designing into RoHS-bound end products. AEC-Q100 not formally qualified (automotive-grade extended temperature, but no formal Q100 certificate).
