PIC16C74B-04/L - 8-Bit OTP MCU 7KB 4MHz 33 I/O PLCC-44 | Microchip
MPN: PIC16C74B-04/L ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.81 | $4.81 |
| 10 | $4.42 | $44.20 |
| 100 | $3.94 | $394.00 |
| 500 | $3.59 | $1,795.00 |
| 1,000 | $3.32 | $3,320.00 |
PIC16C74B-04/L Overview
An OTP microcontroller is a type of non-volatile programmable logic device whose program memory can be written exactly once after manufacture, retaining its code without power and offering lower per-unit cost than ceramic-windowed UV erasable parts for production runs. The PIC16C74B-04/L sits in the broader taxonomy: microcontroller -> 8-bit MCU -> mid-range RISC MCU -> CMOS embedded controller -> semiconductor, where it bridges simple 8-pin PIC10/12 devices and the 16-bit PIC24/dsPIC families. This positioning explains its adoption in industrial control, automotive body electronics and legacy embedded designs.
Key features include 192 bytes of data RAM, two 8-bit timers plus one 16-bit timer, a 5-channel 8-bit A/D converter with brown-out reset and a watchdog timer. The synchronous serial port can be configured as either a 3-wire SPI or 2-wire I2C interface, and a separate USART provides asynchronous serial communication. An 8-level deep hardware stack and 35 single-word RISC instructions reduce code density and ease firmware development for legacy C and assembly projects.
The architecture implements a Harvard-style memory map with separate code and data buses, allowing instruction fetch and operand read to occur in a single clock cycle for most instructions. Program branches are two cycles; everything else executes in one cycle. The OTP program memory is implemented as EPROM cells, giving deterministic in-system programming via the standard Microchip ICSP protocol. Brown-out reset, power-on reset and the watchdog timer provide three independent reset sources that harden the device against brown-out and software-stall conditions in unattended equipment.
Typical applications include industrial control logic, automotive body and chassis subsystems (pre-CAN era platforms), appliance controllers, security and access-control panels, and legacy communication peripherals requiring USART plus SPI or I2C on the same silicon. The wide 4V-5.5V operating range tolerates unregulated 5V supplies common in industrial cabinets.
When designing with this device, plan the OTP programming flow early because the part cannot be reprogrammed in-circuit after the UV window is sealed. Place a 100 nF decoupling capacitor close to VDD and VSS, and reserve the MCLR pin for the standard Microchip ICSP header so production programming and field firmware recovery remain practical.
This page synthesizes distributor pricing, drop-in alternatives and practical design notes not found in the standalone PIC16C74B datasheet.
Drop-in alternatives for PIC16C74B-04/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 PIC16C74B-04/L (same form factor and footprint) — differing in Package, Mounting Type, Timers, Core Architecture, Operating Temperature.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C74B-04I/L
✅ Drop-In✓ In Stock
$2.61 / Unit
View Datasheet →PIC16C74B-20/L
✅ Drop-In✓ In Stock
$8.2 / Unit
View Datasheet →PIC16C74B-20I/L
✅ Drop-In✓ In Stock
$8.92 / 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 →PIC16C74AT-10I/L
✅ Drop-In✓ In Stock
$5.64 / Unit
View Datasheet →PIC16F74-I/L
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C74B-04/L Maximum Ratings & Electrical Characteristics
| Product Family | PIC16CXX mid-range 8-bit MCU |
| CPU Core | 8-bit RISC (Harvard architecture) |
| Instruction Set | 35 single-word instructions |
| Maximum Clock Frequency | 20 MHz |
| Speed Grade (this part) | 04 = 4 MHz clock input |
| Instruction Cycle Time | 200 ns at 20 MHz |
| Program Memory Type | OTP (One-Time Programmable) EPROM |
| Program Memory Size | 7 KB (4K x 14 words) |
| Data RAM | 192 bytes |
| Data EEPROM | Not present on C-series; use F-series for Flash |
| Supply Voltage (VDD) | 4.0 V to 5.5 V |
| Digital I/O Pins | 33 |
| A/D Converter | 8 channels, 8-bit resolution |
| Timers | 2 x 8-bit + 1 x 16-bit (3 total) |
| Capture/Compare/PWM | 2 modules (CCP) |
| Serial Interfaces | 1 x SPI/I2C (SSP) + 1 x USART |
| Parallel Slave Port (PSP) | Yes |
| Watchdog Timer | Yes (on-chip WDT with dedicated RC oscillator) |
| Brown-out Reset | Yes |
| Power-on Reset | Yes |
| Hardware Stack | 8 levels x 13-bit |
| Package | 44-pin PLCC (16.59 x 16.59 mm), windowed CERDIP variant uses 28-pin CERDIP |
| Operating Temperature Range | 0C to +70C (commercial, /L suffix not specified as extended) |
| Mounting Type | Surface Mount (PLCC socket) |
| RoHS Status | Compliant (lead-free PLCC package per Microchip product page) |
PIC16C74B-04/L Pin Configuration
| Pin 1 | MCLR/VPP — Master Clear (reset) input / ICSP programming voltage |
| 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 / Voltage reference |
| Pin 6 | RA4/T0CKI — PORTA bit 4 / Timer 0 clock input |
| Pin 7 | RA5/AN4/SS — PORTA bit 5 / Analog input 4 / SPI slave select |
| Pin 8 | RE0/RD/AN5 — PORTE bit 0 / Parallel Slave Port read / Analog input 5 |
| Pin 9 | RE1/WR/AN6 — PORTE bit 1 / Parallel Slave Port write / Analog input 6 |
| Pin 10 | RE2/CS/AN7 — PORTE bit 2 / Parallel Slave Port chip select / Analog input 7 |
| Pin 11 | VDD — Positive supply voltage (4.0 V to 5.5 V) |
| Pin 12 | VSS — Ground reference |
| Pin 13 | OSC1/CLKIN — Oscillator input / external clock input |
| Pin 14 | OSC2/CLKOUT — Oscillator output / clock output (Fosc/4) |
| Pin 15 | RC0/T1OSO/T1CKI — PORTC bit 0 / Timer 1 oscillator / Timer 1 clock input |
| Pin 16 | RC1/T1OSI/CCP2 — PORTC bit 1 / Timer 1 oscillator input / CCP2 |
| Pin 17 | RC2/CCP1 — PORTC bit 2 / Capture-Compare-PWM 1 |
| Pin 18 | RC3/SCK/SCL — PORTC bit 3 / SPI clock / I2C clock |
| Pin 19 | RC4/SDI/SDA — PORTC bit 4 / SPI data in / I2C data |
| Pin 20 | RC5/SDO — PORTC bit 5 / SPI data out |
| Pin 21 | RC6/TX/CK — PORTC bit 6 / USART TX / USART clock |
| Pin 22 | RC7/RX/DT — PORTC bit 7 / USART RX / USART data |
| Pin 23 | RD0/PSP0 — PORTD bit 0 / Parallel Slave Port bit 0 |
| Pin 24 | RD1/PSP1 — PORTD bit 1 / Parallel Slave Port bit 1 |
| Pin 25 | RD2/PSP2 — PORTD bit 2 / Parallel Slave Port bit 2 |
| Pin 26 | RD3/PSP3 — PORTD bit 3 / Parallel Slave Port bit 3 |
| Pin 27 | RD4/PSP4 — PORTD bit 4 / Parallel Slave Port bit 4 |
| Pin 28 | RD5/PSP5 — PORTD bit 5 / Parallel Slave Port bit 5 |
| Pin 29 | RD6/PSP6 — PORTD bit 6 / Parallel Slave Port bit 6 |
| Pin 30 | RD7/PSP7 — PORTD bit 7 / Parallel Slave Port bit 7 |
| Pin 31 | VSS — Ground reference |
| Pin 32 | VDD — Positive supply voltage (4.0 V to 5.5 V) |
| Pin 33 | RB0/INT — PORTB bit 0 / External interrupt input |
| Pin 34 | RB1 — PORTB bit 1 |
| Pin 35 | RB2 — PORTB bit 2 |
| Pin 36 | RB3 — PORTB bit 3 (also PGМ low-voltage programming) |
| Pin 37 | RB4 — PORTB bit 4 |
| Pin 38 | RB5 — PORTB bit 5 |
| Pin 39 | RB6/PGC — PORTB bit 6 / ICSP clock |
| Pin 40 | RB7/PGD — PORTB bit 7 / ICSP data |
| Pin 41 | VSS — Ground reference |
| Pin 42 | VDD — Positive supply voltage (4.0 V to 5.5 V) |
| Pin 43 | NC — Not connected (per datasheet) |
| Pin 44 | NC — Not connected (per datasheet) |
Typical Applications
PIC16C74B-04/L is suitable for 6 applications: Industrial Control Logic, Automotive Body Electronics, Appliance Controllers, Security and Access-Control Panels, Legacy Communication Peripherals, Data Acquisition Front-Ends.
Industrial Control Logic
The PIC16C74B-04/L fits industrial control cabinets because its 4V-5.5V supply tolerates unregulated 5V rails and its 8-channel 8-bit ADC reads multiple sensor inputs (temperature, pressure, level) without external ADCs. The PIC16 mid-range RISC core runs one instruction per 200 ns cycle, enabling deterministic 1 ms control loops for valve sequencing, motor start/stop interlocks and conveyor coordination. Brown-out reset, watchdog timer and the wide commercial temperature range harden the design against brown-out, software stall and ambient temperature swings in factory-floor enclosures.
Recommended
Automotive Body Electronics
The PIC16C74B-04/L is widely deployed in pre-CAN automotive body controllers (window lifts, mirror adjusters, seat controllers, lighting modules) where its 33 digital I/O pins drive relays, switches and lamps while the 8-channel ADC reads potentiometers for position feedback. The PIC16CXX mid-range architecture provides 35 single-word RISC instructions so seat-position algorithms fit within 7 KB of OTP code. While not AEC-Q100 qualified, the part's robustness in automotive aftermarket and pre-OBD-II platforms is well established. Designers needing automotive-grade qualification today should evaluate the PIC16F family with extended temperature grades.
Recommended
Appliance Controllers
The PIC16C74B-04/L is suited to white-goods appliance controllers (washing machines, dishwashers, microwave ovens) because its 33 I/O pins drive segment displays, keypads, triac-trigger optos and buzzer drivers, while the 8-channel ADC monitors motor current, water level and temperature sensors. The 4V-5.5V supply rails accept rectified-transformer 5V outputs common in appliance SMPS designs, and the watchdog timer plus brown-out reset prevent runaway firmware in unattended kitchen or laundry environments. The OTP memory locks the final firmware to deter unauthorized feature tampering.
Recommended
Security and Access-Control Panels
The PIC16C74B-04/L fits security alarm panels and access-control terminals because its USART links to modems or central monitoring receivers, while the SSP port (SPI or I2C) connects to keypad scanners, RFID readers or real-time clocks. The PIC16CXX core's deterministic interrupt response handles multiple zone inputs in <200 ns, ensuring no missed alarm events during scanning. OTP memory locks the security firmware to prevent code extraction that could compromise alarm logic. 192 bytes of RAM buffer event logs and the 8-channel ADC monitors backup-battery voltage and tamper switches.
Recommended
Legacy Communication Peripherals
The PIC16C74B-04/L's dual serial interfaces (SSP for SPI/I2C plus USART) make it ideal for legacy communication peripherals such as RS-232 to SPI bridges, modem front-ends and protocol converters used in industrial telemetry. The 35-instruction RISC core executes state-machine code for framing, CRC and flow control within the 7 KB OTP budget. The 4V-5.5V supply accepts telecom 5V rails and the 44-pin PLCC package delivers all I/O including the PSP for parallel-host attachment. Brown-out reset ensures clean recovery from telecom-bay power glitches.
Recommended
Data Acquisition Front-Ends
The PIC16C74B-04/L is well suited to multi-channel data-acquisition front-ends that require simultaneous sensor sampling because its 8-channel 8-bit ADC provides 8 single-ended inputs with selectable reference and conversion speed. The PIC16CXX RISC core can buffer ADC results to the 192-byte RAM and forward packets over the USART at up to several hundred kbaud without CPU stall. The 33 digital I/O pins trigger sample timing from external events, and the 8-level hardware stack supports nested interrupt service routines for burst-mode acquisition. OTP memory locks the calibration coefficients for production runs.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C74B-04/L — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C74B-04I/L | PIC16C74B-20/L | PIC16F74-I/L | PIC16C74A-10/L |
|---|---|---|---|---|---|
| Package | 44-pin PLCC (16.59x16.59 mm) | 44-pin PLCC - same | 44-pin PLCC - same | 44-pin PLCC - same | 44-pin PLCC - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 7 KB OTP | 7 KB OTP | 7 KB OTP | 7 KB Flash | 7 KB OTP |
| Speed Grade (clock input) | 04 = 4 MHz (20 MHz max) | 04 = 4 MHz (20 MHz max) | 20 = 20 MHz max | 20 MHz max | 10 = 10 MHz |
| Temperature Grade | 0C to +70C (commercial) | -40C to +85C (industrial) | 0C to +70C (commercial) | -40C to +85C (industrial) | 0C to +70C (commercial) |
| ADC Channels | 8 x 8-bit | 8 x 8-bit | 8 x 8-bit | 8 x 8-bit | 8 x 8-bit |
| Program Memory Type | OTP (one-time write) | OTP | OTP | Flash (in-circuit reprogrammable) | OTP |
| Pin Count | 44 | 44 | 44 | 44 | 44 |
Key Differentiators
- 44-pin PLCC with 8-channel 8-bit ADC and Parallel Slave Port (PSP) (vs PIC16C73B-04I/SP (28-pin SOIC, 5-channel ADC, no PSP))
- Flash-based in-circuit reprogrammability on the same 44-pin PLCC footprint (vs PIC16C74B-04/L (OTP, no field reprogrammability))
- Dual serial interfaces (SSP for SPI/I2C + separate USART) (vs PIC16C73B-04I/SO (same peripherals))
Design Notes
Place a 100 nF decoupling capacitor within 5 mm of each VDD pin (pins 11, 32, 42) and a single 10 uF bulk capacitor at the board's power-entry point. The PIC16C74B-04/L has three VDD pins distributed across the 44-pin PLCC perimeter; failure to decouple all three can produce code-fetch glitches during SPI or USART bursts because the high-speed serial I/O switching creates local supply droop. Also route VSS (pins 12, 31, 41) to a low-impedance ground plane rather than a thin trace.
Because the PIC16C74B-04/L uses OTP program memory, plan the final firmware build before programming and verify it in a windowed CERDIP sample (PIC16C74B-04/JW) first. The OTP cell cannot be erased after the package window is sealed, so every locked production unit with bad firmware is scrap. Reserve RB6 (PGC) and RB7 (PGD) for the ICSP header and ensure MCLR is pulled to VDD through a resistor so ICSP can drive it during programming. Configuration bits (oscillator, watchdog, brown-out, code protect) must be set in the source before the final OTP write.
Route the 20 MHz oscillator traces (OSC1/OSC2, pins 13/14) as short, symmetrical loops guarded by ground and keep them away from the USART pins (RC6/RC7, pins 21/22) and SPI lines (RC3/RC4/RC5, pins 18-20) to avoid coupling oscillator harmonics into the serial data. Place the analog inputs AN0-AN7 (PORTA and PORTE alternate pins) on the opposite side of the package from the digital PORTD/PSP bus, and provide a separate analog ground island if mixed-signal accuracy matters.
Compliance Information
RoHS and REACH compliance per Microchip product page. Part is not AEC-Q100 qualified; for automotive applications requiring AEC-Q100, evaluate the PIC16F or dsPIC families instead. Lead-free PLCC package is standard.
