PIC16C73A-04I/SO - 8-bit OTP MCU, 4MHz, 7KB, 28-SOIC | Microchip
MPN: PIC16C73A-04I/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.36 | $8.36 |
| 10 | $7.55 | $75.50 |
| 100 | $6.41 | $641.00 |
| 500 | $5.62 | $2,810.00 |
| 1,000 | $4.78 | $4,780.00 |
PIC16C73A-04I/SO Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, non-volatile program memory (here OTP EPROM), volatile data memory (RAM), peripherals, and I/O on one die. The PIC16C7X mid-range family was designed as low-cost, high-performance, fully-static CMOS MCUs for embedded control, and the PIC16C73A-04I/SO sits between the smaller PIC16C72 (28-pin) and the larger PIC16C74A/76/77 (40-pin) variants, sharing the same peripheral set so code can scale across packages.
Key features of the PIC16C73A-04I/SO include 7KB of one-time-programmable (OTP) EPROM, 192 bytes of data RAM, 22 general-purpose I/O pins with 25 mA source/sink capability, an 8-channel 8-bit A/D converter, a USART for asynchronous/synchronous serial, an SSP module supporting SPI and I2C, and a 25 mA sink/source current suitable for driving LEDs and small relays directly. It also supports industrial temperature range (-40C to +85C) and a low-power standby current of approximately 1 uA typical at 3V/32 kHz.
The PIC16C73A-04I/SO is built on a fully-static CMOS process, which means the clock can be stopped and the device held in its current state without losing register contents - useful for power-saving designs. The 4 MHz "-04" speed grade delivers 4 million instructions per second (Fosc/4) with a 1 us instruction cycle, and the wide operating voltage range (2.5V to 6.0V for the broader family, 4V to 5.5V for this industrial-temperature grade) makes it suitable for 5V industrial buses.
Typical applications include industrial control panels, sensor interface boards, motor-control front-ends (with the CCP module for PWM), low-cost consumer appliances, and embedded instrumentation. The integrated 8-bit ADC simplifies analog front-ends, while the USART enables RS-232/RS-485 communication without an external transceiver IC for short-distance links.
When designing with this part, note that OTP (one-time-programmable) memory cannot be erased or rewritten - use the PIC16F73 (Flash) or PIC16C73B (improved revision) for development or any application requiring firmware updates in the field. The "I" suffix denotes the industrial temperature range (-40C to +85C); the "SO" suffix indicates 28-pin SOIC packaging.
This page synthesizes distributor stock and pricing, same-package drop-in alternatives including newer revision and Flash-based variants, and practical design notes not collected in any single source.
Drop-in alternatives for PIC16C73A-04I/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 PIC16C73A-04I/SO (same form factor and footprint) — differing in Package, Program Memory Type, ADC, Core Architecture, Program Memory Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C73B-04I/SO
✅ Drop-In✓ In Stock
$7.1 / Unit
View Datasheet →PIC16C73A-04I/SP
✅ Drop-In✓ In Stock
$4.55 / Unit
View Datasheet →PIC16C73A-10I/SO
✅ Drop-In✓ In Stock
$3.55 / Unit
View Datasheet →PIC16F73-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C73A-04E/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C73A-04I/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC16CXX mid-range, 8-bit RISC |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 7KB (4K x 14 words) |
| Data RAM | 192 bytes |
| Data EEPROM | Not present |
| Maximum CPU Speed | 4 MHz (1 us instruction cycle) |
| Operating Voltage | 4 V to 5.5 V |
| I/O Pins | 22 |
| A/D Converter | 8 channels, 8-bit resolution |
| Timers | Two 8-bit + one 16-bit with CCP |
| Communication Peripherals | USART (AUSART), SSP (SPI / I2C) |
| I/O Sink/Source Current | 25 mA / 25 mA |
| Standby Current | 1 uA typical at 3 V / 32 kHz |
| Operating Temperature | -40 C to +85 C (Industrial, "I" suffix) |
| Package | 28-pin SOIC (SO), 7.50 mm body width |
| Mounting Type | Surface Mount |
| Instruction Set | 35 single-word instructions, all single-cycle except branches |
PIC16C73A-04I/SO Pin Configuration
| Pin 1 | MCLR/VPP — Master Clear (Reset) input / Programming voltage input |
| Pin 2 | RA0/AN0 — PORTA bit 0 / Analog input channel 0 |
| Pin 3 | RA1/AN1 — PORTA bit 1 / Analog input channel 1 |
| Pin 4 | RA2/AN2/VREF- — PORTA bit 2 / Analog input channel 2 / ADC negative reference |
| Pin 5 | RA3/AN3/VREF+ — PORTA bit 3 / Analog input channel 3 / ADC positive reference |
| Pin 6 | RA4/T0CKI — PORTA bit 4 (open-drain) / Timer0 clock input |
| Pin 7 | RA5/AN4/SS — PORTA bit 5 / Analog input channel 4 / SPI Slave Select |
| Pin 8 | VSS — Ground reference |
| Pin 9 | OSC1/CLKIN — Oscillator crystal input / External clock input |
| Pin 10 | OSC2/CLKOUT — Oscillator crystal output / Clock output (Fosc/4) |
| Pin 11 | RC0 — PORTC bit 0 |
| Pin 12 | RC1 — PORTC bit 1 |
| Pin 13 | RC2 — PORTC bit 2 |
| Pin 14 | RC3 — PORTC bit 3 |
| Pin 15 | RC4 — PORTC bit 4 |
| Pin 16 | RC5 — PORTC bit 5 |
| Pin 17 | RC6 — PORTC bit 6 / USART TX |
| Pin 18 | RC7 — PORTC bit 7 / USART RX |
| Pin 19 | VSS — Ground reference |
| Pin 20 | VDD — Positive supply voltage (4V to 5.5V) |
| Pin 21 | RB0/INT — PORTB bit 0 / External interrupt input |
| Pin 22 | RB1 — PORTB bit 1 |
| Pin 23 | RB2 — PORTB bit 2 |
| Pin 24 | RB3 — PORTB bit 3 |
| Pin 25 | RB4 — PORTB bit 4 |
| Pin 26 | RB5 — PORTB bit 5 |
| Pin 27 | RB6 — PORTB bit 6 |
| Pin 28 | RB7 — PORTB bit 7 |
Typical Applications
PIC16C73A-04I/SO is suitable for 6 applications: Industrial Sensor Interface Board, Low-Cost Consumer Appliance Controller, Motor Control PWM Front-End, Embedded Data Acquisition Module, Automotive Body Electronics (Legacy), Educational Microcontroller Trainer.
Industrial Sensor Interface Board
The PIC16C73A-04I/SO fits industrial sensor interface boards because its 8-channel 8-bit A/D converter directly digitizes up to eight analog sensor channels (temperature, pressure, level) without an external ADC, and its 22 I/O lines handle discrete inputs, relay outputs, and indicator LEDs. The integrated USART connects to RS-485 transceivers for industrial fieldbus, and the 4 MHz instruction cycle provides 1 us deterministic response for time-critical control loops. Its 4V-5.5V supply matches 5V industrial rails, and the -40C to +85C industrial temperature grade handles factory-floor environments.
Recommended
Low-Cost Consumer Appliance Controller
The PIC16C73A-04I/SO is well-suited to consumer appliance controllers (coffee machines, washing machine control boards, microwave user interfaces) because its 25 mA I/O sink/source current drives triac optocouplers, LED indicators, and 7-segment displays directly, eliminating driver transistors. The 7KB OTP memory holds state-machine control firmware, the USART links to an inverter panel display module, and the SSP/I2C bus connects to EEPROM for user presets. Fully-static CMOS design with 1 uA standby supports battery-backed clock and timer functions across power cycles.
Recommended
Motor Control PWM Front-End
The PIC16C73A-04I/SO serves as a motor-control PWM front-end by leveraging its 16-bit timer with Capture/Compare/PWM (CCP) module to generate PWM signals up to 10-bit resolution at the 4 MHz instruction rate. The 8-bit ADC samples motor current through a shunt amplifier for closed-loop current control, while the USART feeds back telemetry to a master controller. Industrial temperature rating and 5V tolerance match automotive and industrial 12V/24V bus environments when paired with appropriate TVS protection.
Recommended
Embedded Data Acquisition Module
The PIC16C73A-04I/SO is used in embedded data-acquisition modules where its 8-channel 8-bit ADC scans analog inputs at the 4 MHz instruction rate, storing samples in the 192-byte RAM buffer before burst transmission via USART to a host. The 35 single-word instruction set keeps the C/assembly firmware compact (well under 7KB), and the wide operating voltage (4V-5.5V) lets the module share power with the host 5V rail. Low 1 uA standby enables sleep-mode operation between scheduled acquisitions, useful for battery-powered field loggers.
Recommended
Automotive Body Electronics (Legacy)
The PIC16C73A-04I/SO has been used in legacy automotive body electronics (HVAC panel controllers, lighting modules, instrument-cluster slaves) where its 5V-tolerant I/O directly drives 12V relay coils via transistors and its industrial temperature range covers cabin environments. The integrated USART daisychains multiple PIC slaves to a central body controller, and the 8-bit ADC reads switch positions and potentiometers. Note: for new automotive designs requiring AEC-Q100 qualification, migrate to PIC16F73 or modern dsPIC33/PIC18 successors with full automotive certification.
Recommended
Educational Microcontroller Trainer
The PIC16C73A-04I/SO is a popular subject for educational microcontroller trainers and university embedded-systems labs because the PIC16C7X mid-range architecture is simple enough for beginners (35 instructions, single-cycle execution) yet rich enough to teach real peripherals (ADC, USART, I2C, timers, PWM). Its 28-SOIC package is breadboard-friendly with an SOIC-to-DIP adapter, MPLAB X IDE and the XC8 compiler are free, and the PICkit 3 programmer supports in-circuit debugging of the family. The 7KB program memory is sufficient for multi-week lab assignments and capstone projects.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C73A-04I/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C73B-04I/SO | PIC16C73A-04I/SP | PIC16C73A-10I/SO | PIC16F73-I/SO | PIC16C73A-04E/SO |
|---|---|---|---|---|---|---|
| Package | 28-SOIC | 28-SOIC (same) | 28-SPDIP (through-hole) | 28-SOIC (same) | 28-SOIC (same) | 28-SOIC (same) |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 7KB OTP | 7KB OTP | 7KB OTP | 7KB OTP | 4KB Flash | 7KB OTP |
| Max CPU Speed | 4 MHz | 4 MHz | 4 MHz | 10 MHz | 20 MHz | 4 MHz |
| Temperature Range | -40C to +85C (Industrial) | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +125C (Extended) |
| I/O Pins | 22 | 22 | 22 | 22 | 22 | 22 |
| ADC | 8 ch, 8-bit | 8 ch, 8-bit | 8 ch, 8-bit | 8 ch, 8-bit | 8 ch, 8-bit | 8 ch, 8-bit |
| Memory Type | OTP (one-time programmable) | OTP | OTP | OTP | Flash (reprogrammable) | OTP |
| Peripherals | USART, SSP/SPI/I2C, CCP | USART, SSP/SPI/I2C, CCP | USART, SSP/SPI/I2C, CCP | USART, SSP/SPI/I2C, CCP | USART, SSP/SPI/I2C, CCP + ICSP | USART, SSP/SPI/I2C, CCP |
Key Differentiators
- Revised silicon with errata fixes in same package (vs PIC16C73B-04I/SO)
- Flash-based reprogrammability with same peripherals (vs PIC16F73-I/SO)
- Higher CPU speed grade available in identical package (vs PIC16C73A-10I/SO)
Design Notes
PIC16C73A-04I/SO uses OTP (one-time-programmable) EPROM - firmware cannot be erased or rewritten after programming. Plan prototypes carefully: any firmware bug requires throwing away the MCU and starting with a fresh part. For development and field-updateable designs, use the Flash-based PIC16F73 instead, which is pin-compatible in the same 28-SOIC package.
Estimated: at VDD=5V and Fosc=4 MHz, the PIC16C73A-04I/SO typically draws about 2-5 mA active and 1 uA in sleep mode. Add a 100 nF decoupling capacitor as close to the VDD pin (pin 20) as possible, plus a bulk 10 uF tantalum or aluminum polymer capacitor near the supply pins. The MCLR/VPP pin (pin 1) should be pulled up through a 10 kohm resistor to VDD, with a 100 nF cap to ground for noise filtering.
At maximum 4 MHz operation and 5V supply, the PIC16C73A-04I/SO dissipates roughly 25 mW internally (estimated from datasheet DC characteristics), well within the 28-SOIC thermal envelope of approximately 80 C/W. The industrial -40C to +85C operating range is achievable without special PCB thermal relief in most designs. For continuous high-temperature operation above 70C ambient, provide a small copper pour connected to VSS pins (8 and 19) to share heat dissipation across both ground pins.
Compliance Information
RoHS, REACH, lead-free, and halogen-free status not explicitly stated in the provided web snippets. As of 2026-09-18, Microchip's product page for PIC16C73A recommends migrating to PIC16C73B or PIC16F73 - request latest material declaration sheets from Microchip directly for compliance certificates. Part is NRND, not AEC-Q100 qualified.
