PIC16C74BT-20E/L - 8-Bit 20MHz OTP MCU 7KB PLCC-44 | Microchip
MPN: PIC16C74BT-20E/L ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.85 | $6.85 |
| 10 | $6.2 | $62.00 |
| 100 | $5.45 | $545.00 |
| 500 | $4.78 | $2,390.00 |
| 1,000 | $4.15 | $4,150.00 |
PIC16C74BT-20E/L Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU, memory (program + RAM), and programmable I/O peripherals onto one silicon die. The PIC16CXX mid-range family uses a Harvard architecture with separate program and data buses, a 14-bit instruction word, and a RISC instruction set, executing one instruction per instruction cycle (4 clock cycles) for predictable deterministic timing. Within the broader semiconductor hierarchy, an MCU belongs to the logic IC family -> microprocessor -> embedded controller -> mixed-signal SoC.
Key features include 33 digital I/O pins, two 8-bit and three 16-bit timer/counter modules, a 5-channel 8-bit ADC, two analog comparators, a Universal Synchronous/Asynchronous Receiver/Transmitter (USART/SCI), a Serial Peripheral Interface (SPI), and an Inter-Integrated Circuit (I2C) bus. The OTP program memory allows one-time programming by the developer, distinguishing this part from UV-erasable EPROM variants. Operating voltage ranges from 4.0V to 6.0V, suiting 5V industrial and automotive designs.
The PIC16C74B architecture employs a 14-bit instruction pipeline with an 8-level hardware stack, supporting interrupt-driven designs with prioritized vectored interrupts. Brown-out Reset (BOR) and Power-on Reset (POR) circuitry protect against unstable supply conditions, while the Watchdog Timer (WDT) with its own on-chip RC oscillator provides system recovery from software lockups - critical for automotive and industrial environments where firmware reliability is non-negotiable.
Typical applications include automotive body electronics, industrial control subsystems, sensor interface modules, HVAC controllers, and legacy embedded systems requiring field-programmable OTP at production volume. The 20MHz instruction throughput and 5-channel ADC make it well-suited for closed-loop motor control and PID-based process regulation.
When designing with the PIC16C74B, ensure the operating supply stays within 4.0V to 6.0V and that decoupling capacitors (typically 0.1uF ceramic) are placed within 5mm of VDD/SS pins. The PLCC-44 socket allows field replacement and in-circuit programming, but OTP memory means firmware must be fully verified before production programming.
Drop-in alternatives for PIC16C74BT-20E/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 PIC16C74BT-20E/L (same form factor and footprint) — differing in Core Architecture, Program Memory Size, RAM Size, Maximum Clock Frequency, Mounting Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C74BT-20/L
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C74BT-20I/L
✅ Drop-In✓ In Stock
$3.25 / Unit
View Datasheet →PIC16C74B-20/L
✅ Drop-In✓ In Stock
$8.2 / Unit
View Datasheet →PIC16C74B-04E/L
✅ Drop-In✓ In Stock
$9.3 / Unit
View Datasheet →PIC16F74-I/L
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C74BT-20E/L Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC16CXX mid-range 8-bit RISC |
| Program Memory Size | 7 KB (4K x 14) OTP |
| RAM Size | 192 x 8 bytes |
| Maximum Clock Frequency | 20 MHz |
| Instruction Cycle Time | 200 ns (at 20 MHz) |
| Operating Voltage (VDD) | 4.0 V to 6.0 V |
| I/O Pins | 33 |
| Timers | 2 x 8-bit, 3 x 16-bit |
| ADC | 5-channel, 8-bit |
| Analog Comparators | 2 |
| Communication Interfaces | USART/SCI, SPI, I2C |
| Operating Temperature Range | -40 C to +125 C (automotive grade E) |
| Package | 44-pin PLCC (16.59 x 16.59 mm), J-bend leads |
| Mounting Type | Surface Mount (PLCC socket compatible) |
| Lead Form | J-Bend (PLCC) |
| Brown-out Reset | Yes |
| Watchdog Timer | Yes (independent on-chip RC oscillator) |
| Program Memory Type | OTP (One-Time Programmable) |
PIC16C74BT-20E/L Pin Configuration
| Pin 1 | RA2/AN2/VREF- — PORTA bit 2 / Analog input 2 / ADC VREF- |
| Pin 2 | RA3/AN3/VREF+ — PORTA bit 3 / Analog input 3 / ADC VREF+ |
| 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 | RE0/RD/AN5 — PORTE bit 0 / Read signal for PSP / Analog input 5 |
| Pin 6 | RE1/WR/AN6 — PORTE bit 1 / Write signal for PSP / Analog input 6 |
| Pin 7 | RE2/CS/AN7 — PORTE bit 2 / Chip select for PSP / Analog input 7 |
| Pin 8 | VDD — Positive supply (4.0V to 6.0V) |
| Pin 9 | VSS — Ground reference |
| Pin 10 | OSC1/CLKIN — Crystal oscillator input / external clock input |
| Pin 11 | OSC2/CLKOUT — Crystal oscillator output / clock output (Fosc/4) |
| Pin 12 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer1 oscillator output / Timer1 clock input |
| Pin 13 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer1 oscillator input / Capture-Compare-PWM 2 |
| Pin 14 | RC2/CCP1 — PORTC bit 2 / Capture-Compare-PWM 1 |
| Pin 15 | RC3/SCK/SCL — PORTC bit 3 / SPI clock / I2C clock |
| Pin 16 | RC4/SDI/SDA — PORTC bit 4 / SPI data in / I2C data |
| Pin 17 | RC5/SDO — PORTC bit 5 / SPI data out |
| Pin 18 | RC6/TX/CK — PORTC bit 6 / USART transmit / USART clock |
| Pin 19 | RC7/RX/DT — PORTC bit 7 / USART receive / USART data |
| Pin 20 | VSS — Ground reference |
| Pin 21 | RD0/PSP0 — PORTD bit 0 / Parallel Slave Port bit 0 |
| Pin 22 | RD1/PSP1 — PORTD bit 1 / Parallel Slave Port bit 1 |
| Pin 23 | RD2/PSP2 — PORTD bit 2 / Parallel Slave Port bit 2 |
| Pin 24 | RD3/PSP3 — PORTD bit 3 / Parallel Slave Port bit 3 |
| Pin 25 | RD4/PSP4 — PORTD bit 4 / Parallel Slave Port bit 4 |
| Pin 26 | RD5/PSP5 — PORTD bit 5 / Parallel Slave Port bit 5 |
| Pin 27 | RD6/PSP6 — PORTD bit 6 / Parallel Slave Port bit 6 |
| Pin 28 | RD7/PSP7 — PORTD bit 7 / Parallel Slave Port bit 7 |
| Pin 29 | VSS — Ground reference |
| Pin 30 | VDD — Positive supply (4.0V to 6.0V) |
| Pin 31 | RB0/INT — PORTB bit 0 / External interrupt |
| Pin 32 | RB1 — PORTB bit 1 |
| Pin 33 | RB2 — PORTB bit 2 |
| Pin 34 | RB3 — PORTB bit 3 |
| Pin 35 | RB4 — PORTB bit 4 (interrupt-on-change) |
| Pin 36 | RB5 — PORTB bit 5 (interrupt-on-change) |
| Pin 37 | RB6/PGC — PORTB bit 6 / In-circuit debugger clock |
| Pin 38 | RB7/PGD — PORTB bit 7 / In-circuit debugger data |
| Pin 39 | RA0/AN0 — PORTA bit 0 / Analog input 0 |
| Pin 40 | RA1/AN1 — PORTA bit 1 / Analog input 1 |
| Pin 41 | MCLR/VPP — Master clear reset / Programming voltage input |
| Pin 42 | NC — Not connected (per datasheet) |
| Pin 43 | NC — Not connected (per datasheet) |
| Pin 44 | NC — Not connected (per datasheet) |
Typical Applications
PIC16C74BT-20E/L is suitable for 6 applications: Automotive Body Control Modules, Industrial HVAC Control, Sensor Interface Front-Ends, Motor Speed Controllers, Vending Machine Controllers, Legacy Industrial PLC I/O Modules.
Automotive Body Control Modules
The PIC16C74BT-20E/L's automotive-grade -40C to +125C operating range and 20MHz throughput make it a strong fit for automotive body control modules managing door locks, window lifters, seat position memory, and interior lighting. The 5-channel 8-bit ADC reads potentiometric position sensors for seat and mirror adjustment, while the 33 digital I/O pins drive relay drivers and switch-matrix keypad inputs. Its 7KB OTP program memory holds fixed-function body-control firmware, and the integrated CAN-less USART/SPI/I2C stack supports communication with body domain controllers. The automotive E temperature grade handles under-hood thermal stress without derating.
Recommended
Industrial HVAC Control
In HVAC fan-coil and rooftop-unit controllers, the PIC16C74BT-20E/L provides the deterministic 200ns instruction cycle needed for closed-loop temperature regulation with PID control running at 1 kHz update rates. The 5-channel ADC samples thermistor inputs (return air, supply air, outdoor, coil, and setpoint potentiometer), while two 16-bit timers drive triac phase-angle firing for variable-speed blower motors. The 33 I/O pins interface with thermostat keypads, mode switches, and 7-segment displays. OTP memory suits fixed-firmware production runs where per-unit programming cost dominates over flexibility.
Recommended
Sensor Interface Front-Ends
The PIC16C74BT-20E/L serves as a digital front-end for legacy 4-20 mA and 0-10V industrial sensor transmitters, multiplexing multiple analog channels through its 5-input ADC, linearizing the result, and outputting a calibrated value via the USART in Modbus RTU format. The 20MHz clock sustains 9600/19200 baud Modbus traffic without CPU saturation, leaving cycles for sensor linearization math. The 192-byte RAM is adequate for Modbus packet buffers and a small coefficient table, and the 7KB OTP holds the calibration and protocol stack. The automotive E temperature grade suits outdoor or cabinet-mounted installations.
Recommended
Motor Speed Controllers
For low-voltage brushed DC and universal motor speed controllers, the PIC16C74BT-20E/L generates PWM at up to 20MHz timer resolution, enabling 10-bit PWM at 19.5 kHz for quiet BLDC commutation or 8-bit PWM at 78 kHz for ultrasonic-frequency silent drives. The three 16-bit timers handle quadrature encoder input for closed-loop velocity feedback, while the 5-channel ADC monitors motor current via shunt resistor, supply voltage, and temperature. OTP memory locks the motor control algorithm at production. The automotive temperature grade handles under-hood or unventilated enclosure environments without thermal derating.
Recommended
Vending Machine Controllers
The PIC16C74BT-20E/L's 33 I/O pins accommodate multi-currency coin acceptor interfaces, MDB peripheral bus, vend-mechanism actuator drivers, and 7-segment or character-LCD user displays. The 7KB OTP memory stores pricing tables, audit logs, and vending state machine firmware that is rarely updated in the field. The 20MHz instruction throughput handles real-time pulse counting from coin validators at 50 kHz maximum without dropped counts. Two analog comparators enable zero-cross detection for triac-driven refrigeration compressors. OTP ensures fixed production firmware, deterring field tampering and reducing EEPROM-related counterfeit risk.
Recommended
Legacy Industrial PLC I/O Modules
In distributed I/O blocks that interface with older PLCs over RS-232 or RS-485, the PIC16C74BT-20E/L acts as a slave protocol converter, digitizing 4-20 mA inputs through the 5-channel ADC and latching output states through the 33 digital I/O pins. The USART peripheral supports 9-bit multiprocessor communication used by some legacy PLC protocols, while the SPI peripheral interfaces with shift-register-based digital I/O expansion. The OTP memory holds the fixed protocol translator firmware. The automotive E temperature grade is suitable for factory-floor cabinets with elevated ambient temperatures from adjacent motor drives.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C74BT-20E/L — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C74BT-20/L | PIC16C74BT-20I/L | PIC16C74B-20/L | PIC16C74B-04E/L | PIC16F74-I/L |
|---|---|---|---|---|---|---|
| Package | 44-PLCC | 44-PLCC - same | 44-PLCC - same | 44-PLCC - same | 44-PLCC - same | 44-PLCC - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Core | PIC16 8-bit RISC | PIC16 8-bit RISC - same | PIC16 8-bit RISC - same | PIC16 8-bit RISC - same | PIC16 8-bit RISC - same | PIC16 8-bit RISC - same |
| Max Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 4 MHz (-80%) | 20 MHz |
| Program Memory | 7 KB OTP | 7 KB OTP | 7 KB OTP | 7 KB OTP | 7 KB OTP | 7 KB Flash (reprogrammable) |
| Operating Temperature | -40C to +125C (E grade) | 0C to +70C (commercial) | -40C to +85C (industrial) | 0C to +70C (commercial) | -40C to +125C (E grade) | -40C to +85C (industrial) |
| ADC Channels | 5 x 8-bit | 5 x 8-bit | 5 x 8-bit | 5 x 8-bit | 5 x 8-bit | 5 x 8-bit |
| I/O Pins | 33 | 33 | 33 | 33 | 33 | 33 |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete | Active |
Key Differentiators
- Automotive E temperature grade support (-40C to +125C) (vs PIC16C74B-20/L)
- OTP memory for fixed-function production firmware (vs PIC16F74-I/L)
- Higher clock speed headroom than the -04 variant (vs PIC16C74B-04E/L)
Design Notes
The PIC16C74BT-20E/L requires a regulated 4.0V to 6.0V supply; typical designs use a 7805 linear regulator or equivalent. Place a 0.1uF ceramic decoupling capacitor within 5mm of the VDD pin (pin 8) and VSS pin (pin 9), and add a bulk 10uF electrolytic at the regulator output to suppress load-transient dips. The Brown-out Reset (BOR) circuit holds the MCU in reset when VDD falls below ~4.0V, preventing code execution from corrupt memory states during power-down. Avoid noise on the MCLR/VPP pin (pin 41) by tying it to VDD through a 10kohm resistor with a 0.1uF decoupling cap directly at the pin - any noise here can spuriously trigger resets or interrupt programming mode.
The PLCC-44 package can be socketed for field upgradeability (use a 44-pin PLCC through-hole socket such as Aries 44-6518-10), or soldered directly to SMT pads with J-bend leads. When using a socket, route high-frequency signals away from the socket body to minimize parasitic inductance. Crystal traces on pins 10 (OSC1) and 11 (OSC2) should be kept short (<10mm) and guarded with a ground pour to reduce EMI susceptibility. For RS-232 driver chips, keep the charge-pump capacitors within 2mm of the driver IC pins, and route the driver outputs perpendicular to the MCU's RX/TX traces to minimize coupling.
OTP program memory cannot be erased or rewritten - verify all firmware on a flash-based PIC16F74 prototype before committing to OTP production programming. LVP (Low-Voltage Programming) mode via the PGM pin and standard ICSP mode via RB6/RB7 (PGC/PGD) are mutually exclusive configurations; the CONFIG word LVP bit determines which mode is active, and a wrong choice can lock out programming access. The Watchdog Timer (WDT) is enabled by default in the configuration word - explicitly clear the WDTE bit if WDT is not needed, or service the CLRWDT instruction in all long-timeout loops to prevent unintended resets. Do not exceed 20 MHz at VDD below 4.5V; refer to the datasheet's VDD-vs-Frequency graph.
Compliance Information
RoHS and REACH compliance status not explicitly stated in verified distributor data; the 44-pin PLCC package with J-bend leads typically uses tin-lead plating. Not AEC-Q100 qualified (automotive E temperature grade is industrial specification, not AEC-Q100). Lead-free and RoHS-compliant variants are not generally available for this obsolete OTP device.
