PIC16C74BT-04I/PT - 8-Bit 4MHz OTP MCU 7KB | TQFP-44 | Microchip
MPN: PIC16C74BT-04I/PT β End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $12.5 | $12.50 |
| 10 | $11.2 | $112.00 |
| 100 | $9.85 | $985.00 |
| 500 | $8.4 | $4,200.00 |
| 1,000 | $7.1 | $7,100.00 |
PIC16C74BT-04I/PT Overview
What is an 8-bit OTP microcontroller? An 8-bit MCU is a microprocessor unit that processes data 8 bits at a time; OTP (One-Time-Programmable) memory can be written exactly once, making these parts economical for mature, high-volume products where firmware is finalized before production. The PIC16CXX family sits in Microchip's mid-range hierarchy (PIC10/12/16/18 base architecture family -> 8-bit MCU -> microcontroller -> embedded processor) and is widely used in industrial control, automotive subsystems, and consumer appliances.
Key features of the PIC16C74BT-04I/PT include 33 digital I/O lines, an external oscillator interface, integrated peripherals suited for embedded control, and CMOS fully-static design that minimizes power consumption. The 35-instruction RISC instruction set simplifies code generation, and the Harvard architecture separates program and data buses for deterministic instruction throughput.
Technically, the device operates from a 5 V supply, supports in-circuit serial programming via Microchip's ICSP protocol, and includes brown-out and watchdog features typical of mid-range PIC controllers. The OTP EPROM cell array is well-suited for legacy designs that have moved past prototyping but still demand the reliability and toolchain maturity of the PIC16C architecture.
Typical applications include industrial automation controllers, automotive body and chassis subsystems, consumer appliance control boards, and embedded sensor interfaces. The wide operating temperature range and CMOS static design also fit unattended remote data-acquisition nodes.
When designing in this part, note that OTP cannot be reprogrammed - any firmware update requires physical replacement. For new designs requiring flash memory, consider the pin-compatible PIC16F74 or PIC16F877A families that share the same 44-pin TQFP footprint. Always confirm timer, ADC, and peripheral parity when migrating firmware from older PIC16C7x designs.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone, helping engineers evaluate long-term availability and supply-chain risk for legacy OTP PIC16 designs.
Drop-in alternatives for PIC16C74BT-04I/PT β 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 PIC16C74BT-04I/PT (same form factor and footprint) β differing in Core Architecture, Program Memory Size, Program Memory Type, Temperature Grade.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
PIC16C74B-04I/PT
β Drop-Inπ Reference alternative (not in catalog)
PIC16C74BT-04E/PT
β Drop-Inβ In Stock
$6.08 / Unit
View Datasheet βPIC16C74BT-20I/PT
β Drop-Inβ In Stock
$3.02 / Unit
View Datasheet βPIC16C74BT-04I/PQ
β Drop-Inβ In Stock
$6.1 / Unit
View Datasheet βPIC16F74-I/PT
β Drop-Inπ Reference alternative (not in catalog)
PIC16F747-I/PT
β Drop-Inπ Reference alternative (not in catalog)
PIC16C74BT-04I/PT Maximum Ratings & Electrical Characteristics
| Product Family | PIC16CXX mid-range 8-bit MCU |
| Core Architecture | 8-bit RISC, Harvard |
| Maximum Clock Speed | 4 MHz |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 7 KB (4K x 14) |
| RAM Size | 192 x 8 bytes |
| Number of I/O Lines | 33 |
| Supply Voltage | 5 V (typical) |
| Oscillator Type | External |
| Operating Temperature Range | -40C to +85C (industrial grade, 'I' suffix) |
| Package / Case | 44-TQFP (10x10 mm) |
| Mounting Type | Surface Mount |
| Terminal Form | Gull Wing |
| Package Code | TQFP |
| Packaging | Tape & Reel (TR) |
| Instruction Set | 35 instructions (mid-range) |
| Technology | CMOS, fully-static |
PIC16C74BT-04I/PT Pin Configuration
| Pin 1 | MCLR/VPP β Master clear reset (active low) / ICSP programming voltage |
| Pin 2 | RA0/AN0 β PORTA bit 0 / analog input 0 |
| Pin 3 | RA1/AN1 β PORTA bit 1 / analog input 1 |
| Pin 4 | RA2/AN2 β PORTA bit 2 / analog input 2 |
| Pin 5 | RA3/AN3/VREF β PORTA bit 3 / analog input 3 / ADC reference |
| Pin 6 | RA4/T0CKI β PORTA bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4/SS β PORTA bit 5 / analog input 4 / SPI slave select |
| Pin 8 | RE0/RD/AN5 β PORTE bit 0 / read control / analog input 5 |
| Pin 9 | RE1/WR/AN6 β PORTE bit 1 / write control / analog input 6 |
| Pin 10 | RE2/CS/AN7 β PORTE bit 2 / chip select / analog input 7 |
| Pin 11 | VDD β Positive supply (5V) |
| Pin 12 | VSS β Ground |
| Pin 13 | OSC1/CLKIN β Oscillator input / external clock input |
| Pin 14 | OSC2/CLKOUT β Oscillator output / clock output |
| Pin 15 | RC0/T1OSO/T1CKI β PORTC bit 0 / Timer1 oscillator output / clock input |
| Pin 16 | RC1/T1OSI/CCP2 β PORTC bit 1 / Timer1 oscillator input / CCP2 |
| Pin 17 | RC2/CCP1 β PORTC bit 2 / CCP1 PWM/capture |
| Pin 18 | RC3/SCK/SCL β PORTC bit 3 / SPI clock / I2C clock |
| Pin 19 | RD0 β PORTD bit 0 |
| Pin 20 | RD1 β PORTD bit 1 |
| Pin 21 | RD2 β PORTD bit 2 |
| Pin 22 | RD3 β PORTD bit 3 |
| Pin 23 | RC4/SDI/SDA β PORTC bit 4 / SPI data in / I2C data |
| Pin 24 | RC5/SDO β PORTC bit 5 / SPI data out |
| Pin 25 | RC6/TX/CK β PORTC bit 6 / UART TX / clock |
| Pin 26 | RC7/RX/DT β PORTC bit 7 / UART RX / data |
| Pin 27 | RD4 β PORTD bit 4 |
| Pin 28 | RD5 β PORTD bit 5 |
| Pin 29 | RD6 β PORTD bit 6 |
| Pin 30 | RD7 β PORTD bit 7 |
| Pin 31 | VSS β Ground |
| Pin 32 | VDD β Positive supply (5V) |
| Pin 33 | RB0/INT β PORTB bit 0 / external interrupt |
| Pin 34 | RB1 β PORTB bit 1 |
| Pin 35 | RB2 β PORTB bit 2 |
| Pin 36 | RB3 β PORTB bit 3 |
| Pin 37 | RB4 β PORTB bit 4 |
| Pin 38 | RB5 β PORTB bit 5 |
| Pin 39 | RB6/PGC β PORTB bit 6 / ICSP clock |
| Pin 40 | RB7/PGD β PORTB bit 7 / ICSP data |
| Pin 41 | VSS β Ground (optional pad) |
| Pin 42 | VSS β Ground (optional pad) |
| Pin 43 | VSS β Ground (optional pad) |
| Pin 44 | VSS β Ground (optional pad) |
Typical Applications
PIC16C74BT-04I/PT is suitable for 6 applications: Industrial Automation Controllers, Automotive Body and Chassis Subsystems, Consumer Appliance Control Boards, Embedded Sensor Interface Hubs, Power Supply and UPS Monitoring, Educational and Hobbyist Embedded Projects.
Industrial Automation Controllers
The PIC16C74BT-04I/PT is well suited for industrial PLC and machine-control modules because its industrial -40C to +85C temperature grade tolerates factory-floor thermal stress, and its 33 digital I/O lines plus integrated peripherals (timers, UART, PWM) drive relays, solenoids, and stepper drivers directly. The OTP memory is acceptable when firmware is locked down for production and unit cost is critical. At 4 MHz the MCU provides ~1 MIPS, sufficient for PID loops, sensor multiplexing, and Modbus RTU communication at 9600-19200 baud. The 7 KB program memory holds mid-sized state machines and lookup tables for process recipes. Designers should budget for ICSP programming and external brown-out supervision for robust factory deployment.
Recommended
Automotive Body and Chassis Subsystems
The PIC16C74BT-04I/PT has historically been used in non-safety automotive body modules such as window lift controllers, seat position memory, lighting drivers, and HVAC blend-door actuators where its 33 I/O lines and PWM peripherals drive MOSFET bridges and H-bridges directly. The 5 V CMOS architecture tolerates 12 V battery inputs when paired with TVS protection and a regulator. Although the standard part is NRND, the extended-temperature variant PIC16C74BT-04E/PT (-40C to +125C) covers under-hood environments. New automotive designs should migrate to AEC-Q100-qualified PIC16F or dsPIC families, but the existing installed base keeps this part in long-term automotive aftermarket supply.
Recommended
Consumer Appliance Control Boards
White-goods appliance controllers (washing machines, dishwashers, microwave ovens, induction cooktops) frequently use the PIC16C74BT-04I/PT because OTP memory locks firmware against field tampering and the 33 I/O lines drive seven-segment displays, keypad matrices, triac interfaces, and buzzer/relay outputs without external logic. At 4 MHz the MCU executes multi-state control algorithms, timing sequences, and user-interface animations within acceptable latency. The 192-byte RAM comfortably holds stack frames and small data buffers for temperature or motor-speed feedback. The 44-pin TQFP package provides ample I/O while fitting within the constrained PCB area of appliance mainboards.
Recommended
Embedded Sensor Interface Hubs
Remote sensor-interface boards for HVAC, agriculture, and building-automation use the PIC16C74BT-04I/PT to multiplex analog and digital sensor inputs, perform linearization, and forward data over UART or SPI to a host controller. The PIC16C74B family includes multi-channel 8-bit ADC support and ample timers for periodic sampling of temperature, humidity, and pressure sensors. The OTP memory secures calibration coefficients and prevents accidental field reprogramming. The industrial temperature range and CMOS low-power operation suit unattended, battery-backed installations. Combined with an external RTC and EEPROM, the MCU forms a low-cost sensor node.
Recommended
Power Supply and UPS Monitoring
Front-panel monitoring and supervisory logic for offline UPS systems, telecom rectifiers, and solar charge controllers use the PIC16C74BT-04I/PT to sample battery voltage and current via its ADC channels, drive LCD or LED status displays, and manage alarm thresholds. The 33 I/O lines control relay drivers, fan speed (via PWM), and serial comms to the host inverter. OTP memory ensures the supervisory firmware cannot be corrupted by brown-out events. The CMOS static design draws minimal quiescent current during standby, extending battery life in backup applications. Designers typically pair this MCU with a discrete gate driver for the main converter.
Recommended
Educational and Hobbyist Embedded Projects
The PIC16C74BT-04I/PT remains popular in university embedded-systems courses and hobbyist projects because of Microchip's mature MPLAB IDE, free MPASM assembler, and abundant example code. The 33 I/O lines allow students to experiment with seven-segment multiplexing, keypad scanning, UART comms, and PWM motor control using a single TQFP-44 breakout board. While new designs typically prefer the flash-based PIC16F74 or PIC18F family, the OTP PIC16C74B is valuable for teaching mask-ROM/ROM firmware economics and for legacy course material that references the original PIC16C architecture. PICkit programmers support both OTP and flash variants on the same ICSP header.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C74BT-04I/PT β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C74B-04I/PT | PIC16C74BT-04E/PT | PIC16C74BT-20I/PT | PIC16F74-I/PT | PIC16F747-I/PT |
|---|---|---|---|---|---|---|
| Package | TQFP-44 (10x10 mm) | TQFP-44 (10x10 mm) - same | TQFP-44 (10x10 mm) - same | TQFP-44 (10x10 mm) - same | TQFP-44 (10x10 mm) - same | TQFP-44 (10x10 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Max Clock Frequency | 4 MHz | 4 MHz | 4 MHz | 20 MHz | 20 MHz | 20 MHz |
| Program Memory Type | OTP EPROM (7 KB) | OTP EPROM (7 KB) | OTP EPROM (7 KB) | OTP EPROM (7 KB) | Flash (7 KB) | Flash (7 KB) |
| RAM Size | 192 x 8 bytes | 192 x 8 bytes | 192 x 8 bytes | 192 x 8 bytes | 192 x 8 bytes | 192 x 8 bytes |
| Number of I/O | 33 | 33 | 33 | 33 | 33 | 36 |
| Operating Temperature | -40C to +85C (Industrial) | -40C to +85C | -40C to +125C (Extended) | -40C to +85C | -40C to +85C | -40C to +85C |
| Reprogrammability | None (OTP - one-time) | None (OTP) | None (OTP) | None (OTP) | Yes (Flash, ICSP) | Yes (Flash, ICSP) |
| Lifecycle Status | NRND | NRND | NRND | NRND | Active | Active |
Key Differentiators
- Tape-and-reel packaging for high-volume pick-and-place assembly (vs PIC16C74B-04I/PT (tray))
- Industrial temperature grade (-40C to +85C) (vs PIC16C74BT-04E/PT (extended grade))
- Direct PIC16C74B family compatibility (vs PIC16C74A-04I/PT)
Design Notes
The PIC16C74BT-04I/PT operates from a single 5 V supply on pins 11 and 32 (both VDD must be connected; both VSS pins 12 and 31 must be grounded). Estimated: at 4 MHz clock with all 33 I/O pins switching, the core draws approximately 5-10 mA; add 20-25 mA budget for I/O sink/source current. Place a 100 nF decoupling capacitor as close as possible to each VDD pin, plus a 10 uF bulk capacitor near the regulator output to suppress voltage transients during high-current I/O switching.
Route the external crystal (or ceramic resonator) traces from OSC1 (pin 13) and OSC2 (pin 14) directly to the crystal package with traces as short as possible and surrounded by a ground guard ring. Keep these traces away from high-frequency switching nodes such as PWM outputs (CCP1/RC2) or relay drivers. Place the MCLR/VPP pull-up resistor (typically 10 kohm) close to pin 1 and route the ICSP PGC/PGD lines on pins 39/40 to a dedicated programming header. Estimated: crystal trace capacitance should remain below 5 pF to avoid oscillator startup failure.
OTP EPROM memory cannot be erased or rewritten - any firmware bug requires physical chip replacement. Always validate firmware on a flash-equivalent PIC16F74 or PIC16F877A first, then commit to OTP programming only after full qualification. The ICSP programming voltage on MCLR/VPP (pin 1) is typically 13 V for OTP devices; verify your PICkit firmware supports this VPP level. Brown-out detection must be enabled in the configuration word to ensure predictable startup below 4 V VDD. Watchdog timer should also be enabled for unattended industrial deployments.
The TQFP-44 package has a thermal resistance (theta_JA) of approximately 50-60 C/W on a standard 4-layer JEDEC test board. Estimated: at 5 V supply, 4 MHz clock, and 33 I/O pins sourcing 20 mA total, the chip dissipates roughly 250-400 mW, producing a junction temperature rise of only 12-25 C above ambient - well within the 85 C industrial limit. No heatsink is required, but provide a small copper pour beneath the exposed die pad (if present) on pins 41-44 to aid thermal spreading and improve long-term reliability.
Compliance Information
RoHS and REACH compliant per Microchip product page; lead-free TQFP-44 package. Not AEC-Q100 qualified - not recommended for new automotive safety designs; choose PIC16F or dsPIC AEC-Q100 variants for new automotive programs.