PIC16C74AT-20I/L - 8-bit 20MHz PIC MCU, 7KB OTP, 44-PLCC | Microchip
MPN: PIC16C74AT-20I/L ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $13.5 | $13.50 |
| 10 | $12.15 | $121.50 |
| 100 | $10.8 | $1,080.00 |
| 500 | $9.45 | $4,725.00 |
| 1,000 | $8.1 | $8,100.00 |
PIC16C74AT-20I/L Overview
What is a PIC 16C microcontroller? PIC 16C devices are members of Microchip's classic mid-range 8-bit microcontroller family, fully static CMOS designs that integrate a RISC CPU core, program memory, data RAM, and a rich set of on-chip peripherals around a unified instruction set. They sit in the broader hierarchy of PIC microcontrollers -> 8-bit microcontrollers -> microcontrollers (MCU) -> microcontrollers and processors -> semiconductors. The "16C" prefix denotes EPROM-based (erasable windowed) program memory, while PIC16F variants use flash; PIC16C parts are typically used where traceability, in-circuit reprogrammability in a windowed package, or long-term reliability validation of the OTP silicon is required.
Key features of the PIC16C74AT-20I/L include 33 general-purpose digital I/O pins, an 8-channel 8-bit Analog-to-Digital Converter (ADC), two Capture/Compare/PWM (CCP) modules, an asynchronous/synchronous USART with address masking, a Master Synchronous Serial Port (MSSP) supporting both I2C (Master/Slave) and SPI modes, and a Parallel Slave Port. System integrity features include a Brown-Out Reset (BOR), Power-On Reset (POR), a Watchdog Timer (WDT) with its own on-chip RC oscillator, and dual oscillator options (XT/HS/RC/LP). The "-20I" suffix indicates a 20 MHz speed grade and an industrial temperature range of -40C to +85C.
The PIC16C74AT-20I/L uses a Harvard architecture with a separate 14-bit instruction word and 8-bit data path, executing most instructions in a single 200 ns cycle (at 20 MHz). The wide operating voltage range of 4.0 V to 6.0 V supports both 5 V regulated rails and battery-backed systems, while the high sink/source current of 25 mA per I/O pin enables direct LED or relay drive without external buffers.
Typical applications include industrial process control, motor control front-ends, instrumentation, automotive body electronics (non-safety), and embedded control in white goods and HVAC subsystems. The on-chip ADC, CCP/PWM and MSSP peripherals make it well suited to closed-loop control systems where deterministic instruction timing and integrated analog simplify the BOM.
When designing with this part, confirm that OTP program memory matches the production flow - OTP can be programmed only once and is unsuitable for designs that require firmware updates. Designers targeting long life-cycles should evaluate the flash-based PIC16F74A family or the migration path documented in Microchip device migration guides.
This page synthesizes distributor pricing, same-package drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for PIC16C74AT-20I/L — 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 PIC16C74AT-20I/L (same form factor and footprint) — differing in Mounting Type, Package, Core Architecture, I/O Sink/Source Current, Maximum Clock Frequency.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C74A-20I/L
✅ Drop-In✓ In Stock
$8.75 / Unit
View Datasheet →PIC16C74A-10/L
✅ Drop-In✓ In Stock
$8.4 / Unit
View Datasheet →PIC16C74A-04I/P
✅ Drop-In✓ In Stock
$7.5 / Unit
View Datasheet →PIC16F74A-I/L
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C74AT-20I/L Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 16C, 8-bit RISC, Harvard |
| Maximum CPU Frequency | 20 MHz |
| Instruction Cycle Time | 200 ns (at 20 MHz) |
| Program Memory Type | OTP (One-Time-Programmable) EPROM |
| Program Memory Size | 7 KB (4K x 14) |
| Data RAM | 192 bytes |
| General-Purpose I/O Pins | 33 |
| ADC | 8 channels, 8-bit |
| CCP/PWM Modules | 2 |
| Communication Interfaces | I2C (MSSP), SPI (MSSP), USART (SCI) |
| Operating Voltage Range | 4.0 V to 6.0 V |
| Operating Temperature Range | -40 C to +85 C (Industrial, "I" grade) |
| I/O Sink/Source Current | 25 mA per pin |
| Package | 44-PLCC (16.59 x 16.59 mm) |
| Mounting Type | Surface Mount (PLCC socket or direct) |
| Watchdog Timer | Yes, dedicated on-chip RC oscillator |
| Brown-Out Reset / Power-On Reset | Yes (BOR and POR) |
PIC16C74AT-20I/L 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 — PORTA bit 2 / Analog input 2 |
| Pin 5 | RA3/AN3/VREF+ — PORTA bit 3 / Analog input 3 / ADC VREF+ |
| Pin 6 | RA4/T0CKI — PORTA bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4/SS — PORTA bit 5 / Analog input 4 / SPI Slave Select |
| Pin 8 | OSC1/CLKIN — Oscillator input / external clock |
| Pin 9 | OSC2/CLKOUT — Oscillator output / clock out |
| Pin 10 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator output / Timer1 clock |
| Pin 11 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator input / CCP2 |
| Pin 12 | RC2/CCP1 — PORTC bit 2 / CCP1 |
| Pin 13 | RC3/SCK/SCL — PORTC bit 3 / MSSP SPI clock / I2C clock |
| Pin 14 | RD0/PSP0 — PORTD bit 0 / Parallel Slave Port bit 0 |
| Pin 15 | RD1/PSP1 — PORTD bit 1 / Parallel Slave Port bit 1 |
| Pin 16 | RD2/PSP2 — PORTD bit 2 / Parallel Slave Port bit 2 |
| Pin 17 | RD3/PSP3 — PORTD bit 3 / Parallel Slave Port bit 3 |
| Pin 18 | RC4/SDI/SDA — PORTC bit 4 / MSSP SPI data in / I2C data |
| Pin 19 | RC5/SDO — PORTC bit 5 / MSSP SPI data out |
| Pin 20 | RC6/TX/CK — PORTC bit 6 / USART TX / USART clock |
| Pin 21 | RC7/RX/DT — PORTC bit 7 / USART RX / USART data |
| Pin 22 | RD4/PSP4 — PORTD bit 4 / Parallel Slave Port bit 4 |
| Pin 23 | RD5/PSP5 — PORTD bit 5 / Parallel Slave Port bit 5 |
| Pin 24 | RD6/PSP6 — PORTD bit 6 / Parallel Slave Port bit 6 |
| Pin 25 | RD7/PSP7 — PORTD bit 7 / Parallel Slave Port bit 7 |
| Pin 26 | VSS — Ground reference |
| Pin 27 | VDD — Positive supply voltage |
| Pin 28 | RB0/INT — PORTB bit 0 / External interrupt |
| Pin 29 | RB1 — PORTB bit 1 |
| Pin 30 | RB2 — PORTB bit 2 |
| Pin 31 | RB3 — PORTB bit 3 |
| Pin 32 | RB4 — PORTB bit 4 |
| Pin 33 | RB5 — PORTB bit 5 |
| Pin 34 | RB6/PGC — PORTB bit 6 / ICSP clock |
| Pin 35 | RB7/PGD — PORTB bit 7 / ICSP data |
| Pin 36 | RE0/RD — PORTE bit 0 / Parallel Slave Port read control |
| Pin 37 | RE1/WR — PORTE bit 1 / Parallel Slave Port write control |
| Pin 38 | RE2/CS — PORTE bit 2 / Parallel Slave Port chip select |
| Pin 39 | VDD — Positive supply voltage |
| Pin 40 | VSS — Ground reference |
| Pin 41 | RA6/OSC2 — PORTA bit 6 / alternate oscillator output |
| Pin 42 | RA7/OSC1 — PORTA bit 7 / alternate oscillator input |
| Pin 43 | RC0 — PORTC bit 0 (alt) |
| Pin 44 | NC — Not connected (per datasheet PLCC pin map) |
Typical Applications
PIC16C74AT-20I/L is suitable for 6 applications: Industrial Process Control, Motor Control Front-End, HVAC Subsystem Controller, Instrumentation and Data Acquisition, Automotive Body Electronics (Non-Safety), White Goods and Appliance Control.
Industrial Process Control
The PIC16C74AT-20I/L fits industrial process control loops because its 20 MHz RISC core, 8-channel 8-bit ADC and two CCP/PWM modules implement PID control of valves, heaters and motor drives within a single chip. Its 4.0 V to 6.0 V supply tolerates 5 V industrial backplanes and 24 V-derived rails after regulation, while -40 C to +85 C operation survives factory-floor temperatures. The integrated I2C/SPI MSSP and USART simplify the connection to sensor front-ends, HMI displays and supervisory PLCs over RS-485 or I2C. Compared with discrete analog loops, the PIC16C74A reduces BOM, PCB area and mean time to repair in long-life machinery.
Recommended
Motor Control Front-End
The PIC16C74AT-20I/L's two CCP/PWM modules and 33 GPIO pins (25 mA sink/source) make it a compact motor control front-end for brushed DC, unipolar stepper and small BLDC drive stages. The 200 ns instruction cycle at 20 MHz provides the deterministic loop time needed for sinusoidal commutation at moderate RPM, while the 8-bit ADC samples back-EMF or current shunt signals. Brown-Out Reset and Watchdog Timer preserve safe state on brown-outs in noisy motor environments, and the USART feeds debug telemetry or accepts trajectory commands from a higher-level controller. Use this PIC16C7X part when design traceability and OTP locking outweigh flash reprogrammability.
Recommended
HVAC Subsystem Controller
The PIC16C74AT-20I/L is well suited to HVAC subsystem controllers for fan speed, damper and thermostat loops thanks to its 7 KB OTP program memory, which comfortably fits typical HVAC state machines with sensor linearization tables. The 8-channel ADC reads thermistor, humidity and pressure transducers, while the CCP/PWM outputs drive TRIAC phase-angle control of AC loads or PWM to brushless fan drivers. I2C/SPI links to an external display or keypad controller, and the USART exposes a maintenance/diagnostic port. The 44-PLCC package is socket-friendly for serviceability in field-replaceable control boards, an asset for white-goods and HVAC integrators managing long service windows.
Recommended
Instrumentation and Data Acquisition
For instrumentation and slow-channel data acquisition, the PIC16C74AT-20I/L integrates an 8-bit ADC, USART and I2C/SPI in a single chip, enabling compact 8-channel voltmeters, panel meters and laboratory instruments. The Harvard architecture and 14-bit instruction word produce predictable loop timing critical for accurate ADC sampling windows, while 192 bytes of RAM buffer small acquisition bursts before USART upload to a host. OTP memory locks calibration coefficients and firmware for regulatory traceability in medical or test equipment. When paired with an external 12-/16-bit ADC via SPI, the PIC16C74A can act as a deterministic acquisition and display controller.
Recommended
Automotive Body Electronics (Non-Safety)
Although not AEC-Q100 qualified, the PIC16C74AT-20I/L appears in legacy automotive body-electronics designs (interior lighting, seat controllers, accessory multiplexers) where the -40 C to +85 C industrial temperature range covers cabin conditions. The 33 GPIO pins drive relays, LEDs and small solenoids directly at 25 mA per pin, while the MSSP implements LIN-style or I2C body networks. For safety-critical ADAS or powertrain, Microchip directs designers to dsPIC33 and PIC18 AEC-Q100 parts. The 44-PLCC socketed package supports service-friendly module replacement across long vehicle service windows.
Recommended
White Goods and Appliance Control
The PIC16C74AT-20I/L's combination of OTP memory (locked firmware for safety), 8-bit ADC, PWM outputs and USART supports appliance control boards such as washing machines, dishwashers and small kitchen appliances. The 200 ns instruction cycle drives timer-driven wash cycles, while the ADC reads water level, temperature and turbidity sensors. Brown-Out Reset and Watchdog Timer prevent unsafe states on line-voltage brown-outs. Designers who need last-minute firmware changes during certification should evaluate the flash-based PIC16F74A family; otherwise the PIC16C74A's OTP locking enforces final production firmware, a benefit in regulated appliances.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C74AT-20I/L — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C74A-20I/L | PIC16C74A-10/L | PIC16C74A-04I/P | PIC16F74A-I/L |
|---|---|---|---|---|---|
| Package | 44-PLCC (L), 16.59 x 16.59 mm | 44-PLCC (L) - same | 44-PLCC (L) - same | PDIP-40 (P) - different | 44-PLCC (L) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 7 KB (4K x 14) OTP | 7 KB OTP | 7 KB OTP | 7 KB OTP | 7 KB Flash (in-field reprogrammable) |
| Max CPU Frequency | 20 MHz | 20 MHz | 10 MHz | 4 MHz | 20 MHz |
| Operating 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 |
| Operating Temperature | -40 C to +85 C (Industrial) | -40 C to +85 C | 0 C to +70 C (Commercial) | -40 C to +85 C | -40 C to +85 C |
| GPIO Pins | 33 | 33 | 33 | 33 | 33 |
| ADC | 8 channels, 8-bit | 8 ch x 8-bit | 8 ch x 8-bit | 8 ch x 8-bit | 8 ch x 8-bit |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Active |
Key Differentiators
- 44-PLCC package option with industrial temperature range (vs PIC16C74AT-20I/PT (TQFP-44))
- OTP EPROM program memory for firmware locking (vs PIC16F74A-I/L (Flash))
- 20 MHz instruction rate with deterministic 200 ns cycle (vs PIC16C74A-10/L (10 MHz))
Design Notes
The PIC16C74AT-20I/L uses One-Time-Programmable EPROM that can be written only once - there is no in-field firmware update path. Confirm early in the design cycle that OTP locking is acceptable, otherwise migrate to the flash-based PIC16F74A-I/L which is pin-compatible in the 44-PLCC package. Estimated: a single production firmware change on OTP requires a new silicon lot, so design firmware freeze and qualification steps as a hard gate.
VDD must be decoupled with a 100 nF ceramic capacitor placed within 5 mm of the VDD pins (PLCC pins 27 and 39) and a bulk 10 uF tantalum or aluminum polymer capacitor. Brown-Out Reset thresholds are configured in the configuration word; setting BOREN with the appropriate BOR voltage (BORV1:BORV0) protects the MCU on 5 V industrial rails subject to dropout. Estimated: a poorly decoupled VDD will trigger spurious BOR events on motor-control PCBs.
Route the analog AVss/AVdd pair (where present in the chosen configuration) away from the switching traces of CCP/PWM outputs and the Parallel Slave Port bus. Place the 8-channel ADC reference bypass capacitor adjacent to the RA3/VREF+ pin. Estimated: a 10 mm separation between analog traces and PWM edges typically keeps coupled noise below the 1 LSB of the 8-bit ADC at full-scale.
The MSSP pins SCK/SCL (RC3) and SDI/SDA (RC4) carry the I2C/SPI bus; add 4.7 kohm pull-ups on SCL/SDA when used in I2C mode and series 22-100 ohm resistors near the MCU pin when the bus runs longer than 50 mm. The USART pins RC6/TX and RC7/RX are 5 V TTL-level; connect through a level translator (e.g. MAX3232) for RS-232. Estimated: long unbussed MSSP traces on a 4-layer PCB may exceed I2C spec rise time above 100 kHz.
The PIC16C74AT-20I/L industrial-grade part is rated -40 C to +85 C junction, and the 44-PLCC package dissipates well under 1 W in typical 20 MHz applications. Inducted environments (relay drivers, motor control) should still keep the junction below 100 C; use the PLCC socket thermal pad with copper pour if fitted, and derate ambient above 60 C. Estimated: at ICC = 20 mA and VDD = 5 V, package self-heating is well under 5 C above ambient in still air.
Compliance Information
RoHS / lead-free status for the obsolete PIC16C74AT-20I/L was not present in the Verified Web Data. The PIC16C7X family is not AEC-Q100 qualified and is not recommended for safety-critical automotive applications. Confirm compliance directly with Microchip documentation for current orders.
