PIC16C73A-20I/SO - 8-Bit 20MHz OTP MCU, 7KB, 28-SOIC | Microchip
MPN: PIC16C73A-20I/SO β End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $14.5 | $14.50 |
| 10 | $12.95 | $129.50 |
| 100 | $11.4 | $1,140.00 |
| 500 | $10.2 | $5,100.00 |
| 1,000 | $9.3 | $9,300.00 |
PIC16C73A-20I/SO Overview
A microcontroller (MCU) is a single-chip computer containing a processor core, program memory (ROM/Flash/OTP), data memory (RAM), and configurable peripheral blocks such as timers, A/D converters, and communication interfaces. MCUs form the lowest tier of the embedded computing hierarchy - beneath microprocessors and SoCs - and are the workhorse of embedded control. PIC mid-range MCUs specifically target cost-sensitive 8-bit applications where deterministic instruction timing and low power are priorities.
Key features of the PIC16C73A include 35 single-word instructions (all single-cycle except program branches which are two cycles), an integrated 8-channel 8-bit A/D converter, two 8-bit timers plus one 16-bit timer, a Capture/Compare/PWM (CCP) module, a synchronous serial port (SSP) supporting SPI and I2C, and a USART for asynchronous serial communication. The high sink/source current of 25/25 mA per I/O allows direct drive of LEDs and small relays, reducing external component count. The 5V, 4 MHz typical supply current of 15 uA and 3V, 32 kHz standby current of 1 uA support battery-backed designs.
The device is fabricated in CMOS technology for fully-static operation, meaning the clock can be stopped and the internal state preserved - a feature useful for low-power sleep modes. The architecture uses a 14-bit wide instruction word with separate program and data buses (Harvard architecture), enabling simultaneous instruction fetch and data access. This separation is the key architectural advantage of the PIC family and is why PIC mid-range devices outperform many 8-bit competitors on raw MIPS-per-MHz.
Typical applications include industrial control panels, sensor signal conditioning front-ends, appliance controllers, automotive body electronics (non-safety), HVAC thermostats, and consumer product logic replacement. The integrated A/D converter and USART make it particularly well-suited for bridge-sensor data acquisition nodes that must communicate back to a host controller. The PIC16C73A-20I/SO is OTP-based and intended for production-volume designs rather than prototyping - for field programming consider the PIC16F73 Flash-based successor.
A key design consideration: OTP means the program memory is programmed once and cannot be erased. Engineers should validate firmware on a Flash equivalent (such as the PIC16F73) before committing to the OTP PIC16C73A for production. Ensure the brown-out reset voltage threshold is correctly configured for the 4.0-5.5V supply range.
This page synthesizes distributor pricing, drop-in pin-compatible alternatives, and practical design notes not found in a single manufacturer datasheet, giving procurement and design engineers a single decision-ready reference.
Drop-in alternatives for PIC16C73A-20I/SO 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 PIC16C73A-20I/SO (same form factor and footprint) β differing in Package, Timers, Mounting Type, Program Memory Size, RAM Size.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
PIC16C73B-20I/SO
β Drop-Inπ Reference alternative (not in catalog)
PIC16F73-I/SO
β Drop-Inπ Reference alternative (not in catalog)
PIC16C73A-20/SO
β Drop-Inπ Reference alternative (not in catalog)
PIC16C73A-10E/SO
β Drop-Inβ In Stock
$6.55 / Unit
View Datasheet βPIC16C73A-20/SP
β Drop-Inβ In Stock
$7.2 / Unit
View Datasheet βPIC16C73A-20I/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC16CXX mid-range 8-bit RISC |
| Program Memory Type | OTP (One-Time-Programmable) |
| Program Memory Size | 7 KB (4K x 14 words) |
| RAM Size | 192 bytes |
| Maximum Clock Frequency | 20 MHz |
| Instruction Cycle Time | 200 ns (single-cycle, 4 clock periods) |
| Supply Voltage (VDD) | 4.0 V to 5.5 V |
| I/O Pins | 22 |
| A/D Converter | 8-bit, 8 channels |
| Timers | 2 x 8-bit Timer0/Timer2 + 1 x 16-bit Timer1 |
| CCP Modules | 1 (Capture/Compare/PWM) |
| Serial Interfaces | SSP (SPI/I2C) + USART |
| I/O Sink/Source Current | 25 mA / 25 mA |
| Typical Supply Current (5V, 4 MHz) | 15 uA |
| Standby Current (3V, 32 kHz) | 1 uA typical |
| Operating Temperature Range | -40 C to +85 C (Industrial) |
| Package | 28-SOIC (SO) |
| Mounting Type | Surface Mount |
PIC16C73A-20I/SO Pin Configuration
| Pin 1 | /MCLR β Master Clear (reset) input, active low |
| Pin 2 | RA0/AN0 β Port A bit 0 / analog input 0 |
| Pin 3 | RA1/AN1 β Port A bit 1 / analog input 1 |
| Pin 4 | RA2/AN2 β Port A bit 2 / analog input 2 |
| Pin 5 | RA3/AN3/VREF β Port A bit 3 / analog input 3 / VREF+ |
| Pin 6 | RA4/T0CKI β Port A bit 4 / Timer0 clock input |
| Pin 7 | RA5/AN4/SS β Port A bit 5 / analog input 4 / SPI slave select |
| Pin 8 | OSC1/CLKIN β Oscillator input / external clock in |
| Pin 9 | OSC2/CLKOUT β Oscillator output / clock out |
| Pin 10 | RC0/T1OSO/T1CKI β Port C bit 0 / Timer1 oscillator output / clock in |
| Pin 11 | RC1/T1OSI/CCP2 β Port C bit 1 / Timer1 oscillator input / CCP2 |
| Pin 12 | RC2/CCP1 β Port C bit 2 / Capture/Compare/PWM 1 |
| Pin 13 | RC3/SCK/SCL β Port C bit 3 / SPI clock / I2C clock |
| Pin 14 | RC4/SDI/SDA β Port C bit 4 / SPI data in / I2C data |
| Pin 15 | RC5/SDO β Port C bit 5 / SPI data out |
| Pin 16 | RC6/TX/CK β Port C bit 6 / USART TX / clock |
| Pin 17 | RC7/RX/DT β Port C bit 7 / USART RX / data |
| Pin 18 | VSS β Ground |
| Pin 19 | VDD β Positive supply voltage |
| Pin 20 | RB0/INT β Port B bit 0 / external interrupt |
| Pin 21 | RB1 β Port B bit 1 |
| Pin 22 | RB2 β Port B bit 2 |
| Pin 23 | RB3 β Port B bit 3 |
| Pin 24 | RB4 β Port B bit 4 |
| Pin 25 | RB5 β Port B bit 5 |
| Pin 26 | RB6/PGC β Port B bit 6 / ICSP clock |
| Pin 27 | RB7/PGD β Port B bit 7 / ICSP data |
| Pin 28 | VSS β Ground (second VSS for noise isolation) |
Typical Applications
PIC16C73A-20I/SO is suitable for 6 applications: Industrial Sensor Interface Node, HVAC Thermostat Controller, Appliance Control Board, Automotive Body Electronics (Non-Safety), Consumer Product Logic Replacement, Battery-Backed Sensor Logger.
Industrial Sensor Interface Node
The PIC16C73A-20I/SO is well matched to industrial sensor interface nodes where 22 digital I/O pins, an integrated 8-channel 8-bit A/D converter, and a USART are needed to bridge 4-20 mA or 0-10 V sensor signals back to a host PLC or HMI. Its 20 MHz clock provides 5 MIPS throughput, sufficient to execute averaging and linearization routines on multiple analog channels at 100 Hz update rates. Placed on a 28-SOIC carrier with an RS-485 transceiver on the USART pins, it forms a polled slave node on a Modbus RTU network. The OTP program memory suits high-volume industrial deployments where firmware is final. Designers should add external ESD protection on the analog inputs because the integrated A/D lacks robust TVS clamps.
Recommended
HVAC Thermostat Controller
The PIC16C73A-20I/SO drives HVAC thermostat controllers requiring reliable fan, compressor, and valve actuation plus temperature sensing. Its 25 mA sink/source capability directly drives small relays and triac opto-isolators without external buffers, reducing BOM cost. The industrial -40 to +85 C temperature rating suits unconditioned equipment rooms and rooftop units. The integrated A/D reads thermistor or RTD bridges, while the CCP module generates PWM for variable-speed blower control. At 20 MHz, the firmware can simultaneously service the user interface (seven-segment display scan), the A/D averaging loop, and the safety watchdog. The PIC16F73-I/SO is recommended for prototype work; the OTP PIC16C73A is preferred for the final production thermostat.
Recommended
Appliance Control Board
The PIC16C73A-20I/SO is a proven choice for appliance control boards in washing machines, dishwashers, and microwave ovens where cost dominates and the firmware is stable. Its 35 single-word instruction set executes motor control loops (via the CCP PWM output), reads keypad inputs on Port B (with internal weak pull-ups), and drives seven-segment or LCD displays on Port C. The 192-byte RAM accommodates state-machine variables for multi-step wash cycles, while the 7 KB OTP holds the full appliance program. Industrial temperature grade ensures reliability in hot equipment compartments. Engineers should add a hardware watchdog timer (e.g., TPL5010 reset supervisor) because OTP firmware cannot be patched in the field.
Recommended
Automotive Body Electronics (Non-Safety)
The PIC16C73A-20I/SO serves non-safety automotive body electronics such as seat-position controllers, mirror-adjust modules, and interior lighting controllers where 5V supply is available and CAN is not required. The 8-bit A/D reads potentiometer wiper voltages for position feedback, and the USART interfaces to a body control module for diagnostics. Industrial temperature grade covers most cabin environments; for under-hood or extreme climates, the extended-temperature variants are required. Note that this part is not AEC-Q100 qualified - safety-critical ECUs must use automotive-qualified PIC18 or dsPIC alternatives. Designers targeting automotive should validate against ISO 7637-2 transient immunity at the system level.
Consumer Product Logic Replacement
The PIC16C73A-20I/SO frequently replaces legacy 4-bit or discrete-logic controllers in consumer products where added features (timer, A/D, USART) provide competitive differentiation. Its 20 MHz performance runs user-interface state machines, PWM-driven motor/solenoid control, and low-speed communication protocols concurrently. OTP memory locks the production firmware to prevent unauthorized cloning - a feature valued in branded consumer appliances. The 22 I/O pins comfortably accommodate keypad scan, LED matrix drive, and buzzer/enable lines. At sub-10 USD unit pricing in volume, it competes favorably against CPLD-based solutions that require additional configuration memory and programming infrastructure.
Battery-Backed Sensor Logger
The PIC16C73A-20I/SO's low standby current (1 uA typical at 3V, 32 kHz) makes it suitable for battery-backed sensor loggers that spend most of their life in sleep and wake periodically to sample. The integrated 8-bit A/D digitizes temperature or humidity sensor outputs directly, and the SSP can interface to an external serial EEPROM for non-volatile log storage. The 4.0-5.5V supply range can be met by a single lithium-thionyl-chloride primary cell with a boost regulator or a 2x AA alkaline stack. Engineers should use Timer1 in real-time-clock mode with a 32.768 kHz crystal to maintain time-of-day across long sleep intervals, and use the /MCLR pin for wake-from-reset to minimize active current.
Recommended Products Summary
Engineering reference data for PIC16C73A-20I/SO β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C73B-20I/SO | PIC16F73-I/SO | PIC16C73A-20/SO | PIC16C73A-10E/SO |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SOIC | 28-SOIC - same | 28-SOIC - same | 28-SOIC - same | 28-SOIC - same |
| Program Memory | 7 KB OTP | 7 KB OTP | 7 KB Flash (re-programmable) | 7 KB OTP | 7 KB OTP |
| Maximum Clock | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 10 MHz (-50%) |
| RAM Size | 192 bytes | 192 bytes | 192 bytes | 192 bytes | 192 bytes |
| Operating Temperature | -40 to +85 C (Industrial) | -40 to +85 C (Industrial) | -40 to +85 C (Industrial) | 0 to +70 C (Commercial) | -40 to +125 C (Extended) |
| A/D Converter | 8-bit, 8 channels | 8-bit, 8 channels (improved linearity) | 8-bit, 8 channels | 8-bit, 8 channels | 8-bit, 8 channels |
| I/O Pins | 22 | 22 | 22 | 22 | 22 |
| Lifecycle Status | NRND | Active (recommended) | Active | NRND | NRND |
| Suggested Use | Production volume, firmware final | Production volume, firmware final, errata-fixed | Prototyping and small/medium volume (Flash) | Commercial-temp production volume | Lower-speed extended-temperature production |
Key Differentiators
- Industrial temperature grade with proven long-term supply (vs PIC16C73A-20/SO (commercial temp))
- Pin- and code-compatible successor available (vs PIC16C73B-20I/SO)
- Higher clock speed at same price point (vs PIC16C73A-10E/SO)
Design Notes
Do not use PIC16C73A-20I/SO for new designs. Microchip marks the A revision as Not Recommended for New Designs (NRND) and recommends migrating to PIC16C73B (pin-compatible) or PIC16F73 (Flash, same pinout) for new programs. OTP firmware on the A revision cannot be field-updated, so a silicon erratum discovered after launch cannot be patched. Reserve the A revision only for cost-down last-time-buy scenarios where existing tooling and firmware are fixed.
Brown-out reset (BOR) must be enabled in the configuration word for any production design. Without BOR, the PIC16C73A can operate below its 4.0V minimum and corrupt program execution. If BOR is disabled, add an external voltage supervisor (e.g., MCP100 or TPL5010) tied to /MCLR. Decouple VDD with a 100 nF ceramic placed within 5 mm of pin 11 and pin 19; add a 10 uF tantalum or aluminum bulk capacitor at the board power entry.
Route the crystal or resonator traces (OSC1/OSC2, pins 8 and 9) as short as possible and guard them with a ground ring to minimize EMI pickup. Keep the A/D converter analog inputs (RA0-RA5, pins 2-7) physically separated from the digital Port C lines and the USART RX/TX traces to reduce digital-to-analog crosstalk. The second VSS pin (pin 28) and the second VDD pin (pin 19) are present on 28-pin SOIC variants specifically to provide a low-impedance return path - both must be connected on the PCB.
Configure the A/D converter with an acquisition time of at least 19.72 us per the datasheet specification when using a 10 kHz or higher source impedance. Add an external op-amp buffer (e.g., MCP6002) between the sensor and the A/D pin if the source impedance exceeds 10 kohm. The internal A/D hold capacitor is only 120 pF; the RC time constant error at higher source impedances will appear as gain and linearity errors in the digitized result.
The 28-SOIC PIC16C73A package uses an industry-standard pinout shared with PIC16C73B, PIC16F73, and PIC16C76. Do not assume the pinout of unrelated 28-pin SOIC microcontrollers (PIC16F876, PIC18F252) is identical - the port assignments and power pin locations differ between mid-range and PIC18 enhanced devices. Always re-verify the pinout against the specific datasheet before laying out the PCB footprint or hand-wiring a prototype.
Compliance Information
PIC16C73A-20I/SO is lead-free and RoHS compliant per Microchip product documentation. Not AEC-Q100 qualified - this part is not recommended for automotive safety-critical ECUs. Refer to Microchip's automotive PIC product line (PIC16/18 AEC-Q100 variants) for safety-critical applications.
