PIC16F873A-I/SS - 8-bit 20MHz 7KB Flash MCU | Microchip
MPN: PIC16F873A-I/SS β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.3 | $4.30 |
| 10 | $3.78 | $37.80 |
| 100 | $2.95 | $295.00 |
| 500 | $2.42 | $1,210.00 |
| 1,000 | $2.1 | $2,100.00 |
| 3,000 | $1.78 | $5,340.00 |
PIC16F873A-I/SS Overview
An 8-bit microcontroller is a single-chip computer built around an 8-bit data path, RISC CPU, integrated memory, and peripherals, designed to control embedded systems. The PIC16F873A belongs to Microchip's PIC16 mid-range family, which sits in the broader taxonomy: 8-bit MCU -> microcontroller -> embedded computing -> semiconductor. The mid-range line uses a 14-bit instruction word, providing a balance of code density, deterministic interrupt latency, and peripheral integration for cost-sensitive control applications.
Key features include nanoWatt technology for low-power operation with multiple power-managed modes (RUN, IDLE, SLEEP), self-programming Flash support, in-circuit debugging (ICD), and a wide 2.0V to 5.5V supply range. The 200 ns instruction cycle delivers 5 MIPS of throughput, adequate for sensor sampling, motor control loops, and user-interface handling. The 5-channel 10-bit ADC enables direct interface to analog sensors such as temperature, light, and battery monitors without external ADC hardware.
The PIC16F873A uses a Harvard architecture with separate program and data buses, allowing instruction fetch and operand access in a single cycle. The enhanced Flash cell supports 100,000 erase/write cycles typical and 40 years of data retention, with self-programming that enables field firmware updates via bootloader or UART/SPI. Brown-out Reset, Power-on Reset, and a Watchdog Timer with its own on-chip oscillator provide fault resilience, while the nanoWatt modes cut supply current into the microamp range for battery-powered duty-cycled designs.
Typical applications include industrial sensor nodes and instrumentation, automotive body and accessory electronics (with the PIC16F873A-I/SS operating across the industrial -40C to +85C range), consumer appliance controllers, HVAC control boards, low-end display drivers, and any cost-driven 8-bit embedded task that fits within 7 KB of Flash. Designers also commonly pair it with external EEPROM, real-time clocks, and discrete serial-interface peripherals.
When designing with this MCU, ensure that the ICSP clock and data lines (RB6/RB7) are isolated from circuitry that could load them during programming, and place the decoupling capacitor as close to VDD as the routing allows. Note that Microchip recommends the newer PIC16F18854 for new designs; the PIC16F873A-I/SS remains in production primarily for service and legacy compatibility.
This page synthesizes distributor pricing, drop-in same-package alternatives, design notes, and a parameter comparison table not consolidated in the manufacturer datasheet, giving procurement and design engineers a single reference for sourcing and qualifying replacements.
Drop-in alternatives for PIC16F873A-I/SS 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 PIC16F873A-I/SS (same form factor and footprint) β differing in Package, Program Memory Size, ADC, Operating Temperature, Core Architecture.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
PIC16F883-I/SS
β Drop-Inπ Reference alternative (not in catalog)
PIC16F876A-I/SS
β Drop-Inπ Reference alternative (not in catalog)
PIC16F873A-I/SO
β Drop-Inβ In Stock
$2.65 / Unit
View Datasheet βPIC16F873A-I/ML
β Drop-Inβ In Stock
$2.32 / Unit
View Datasheet βPIC16F872-I/SS
β Drop-Inπ Reference alternative (not in catalog)
PIC16F873A-I/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC RISC (Harvard) |
| Instruction Set | 35 single-word instructions, 14-bit wide |
| Max CPU Clock | 20 MHz |
| Instruction Cycle Time | 200 ns |
| Throughput | 5 MIPS |
| Program Memory (Flash) | 7 KB (4K x 14) |
| RAM | 192 bytes |
| EEPROM Data Memory | 128 bytes |
| Supply Voltage (VDD) | 2.0 V to 5.5 V |
| I/O Pins | 22 digital I/O |
| ADC | 5 channels x 10-bit |
| Comparators | 2 analog comparators |
| Timers | 1 x 8-bit, 2 x 16-bit (TMR1/TMR2) |
| Serial Interfaces | 1 x SPI / I2C (SSP), 1 x USART |
| Package | 28-pin SSOP (5.30 mm body, 0.65 mm pitch) |
| Operating Temperature | -40C to +85C (industrial) |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited floor life at <=30C / 85% RH) |
| RoHS Status | Compliant |
| Power-Saving Modes | nanoWatt (RUN, IDLE, SLEEP) |
| Programming/Debug | ICSP (ICD via RB6/RB7), self-programming Flash |
PIC16F873A-I/SS Pin Configuration
| Pin 1 | MCLR/VPP β Master Clear (reset) input or programming voltage input |
| Pin 2 | RA0/AN0 β PORTA bit 0 / Analog input channel 0 |
| Pin 3 | RA1/AN1 β PORTA bit 1 / Analog input channel 1 |
| Pin 4 | RA2/AN2/VREF- β PORTA bit 2 / Analog input channel 2 / A/D reference voltage (low) |
| Pin 5 | RA3/AN3/VREF+ β PORTA bit 3 / Analog input channel 3 / A/D reference voltage (high) |
| Pin 6 | RA4/T0CKI β PORTA bit 4 / Timer0 clock input (open-drain output) |
| Pin 7 | RA5/AN4/SS β PORTA bit 5 / Analog input channel 4 / SSP slave select |
| Pin 8 | AVSS β Analog ground |
| Pin 9 | AVDD β Analog supply voltage |
| Pin 10 | VSS β Digital ground |
| Pin 11 | VDD β Digital supply voltage |
| Pin 12 | OSC1/CLKIN β Crystal/ceramic resonator input or external clock input |
| Pin 13 | OSC2/CLKOUT β Crystal/ceramic resonator output or clock output |
| Pin 14 | RC0/T1OSO/T1CKI β PORTC bit 0 / Timer1 oscillator output / Timer1 clock input |
| Pin 15 | RC1/T1OSI/CCP2 β PORTC bit 1 / Timer1 oscillator input / Capture/Compare/PWM2 |
| Pin 16 | RC2/CCP1 β PORTC bit 2 / Capture/Compare/PWM1 |
| Pin 17 | RC3/SCK/SCL β PORTC bit 3 / SPI clock / I2C clock (SSP) |
| Pin 18 | RC4/SDI/SDA β PORTC bit 4 / SPI data in / I2C data (SSP) |
| Pin 19 | RC5/SDO β PORTC bit 5 / SPI data out (SSP) |
| Pin 20 | RC6/TX/CK β PORTC bit 6 / USART transmit / USART clock |
| Pin 21 | RC7/RX/DT β PORTC bit 7 / USART receive / USART data |
| Pin 22 | RB0/INT β PORTB bit 0 / External interrupt |
| Pin 23 | RB1 β PORTB bit 1 |
| Pin 24 | RB2 β PORTB bit 2 |
| Pin 25 | RB3/PGM β PORTB bit 3 / LVP programming input |
| Pin 26 | RB4 β PORTB bit 4 |
| Pin 27 | RB5 β PORTB bit 5 |
| Pin 28 | RB6/PGC β PORTB bit 6 / ICSP clock |
Typical Applications
PIC16F873A-I/SS is suitable for 6 applications: Industrial Sensor Monitoring Nodes, HVAC and Appliance Control Boards, Automotive Accessory Controllers (legacy), Battery-Powered Remote / Handheld Tools, Display and User-Interface Front Ends, Security and Fire-Alarm Sensor Nodes.
Industrial Sensor Monitoring Nodes
The PIC16F873A-I/SS suits low-cost analog and digital sensor hubs in factory automation. Its 5-channel 10-bit ADC handles 4-20 mA or 0-10 V sensor inputs through a small resistor-divider / op-amp front end, while 192 B RAM is enough to run moving-average filters on temperature, pressure, or flow variables. The 5 MIPS throughput at 20 MHz gives an instruction cycle of 200 ns, so a single ADC conversion with digital filter and UART message fits comfortably inside a 10 ms polling slot. nanoWatt SLEEP mode drops below 1 uA for battery-powered wireless sensor pucks duty-cycled at 1 Hz, reawakening on WDT or interrupt. The -40C to +85C range covers most factory floors; for harsher environments migrate to the PIC16F18854.
Recommended
HVAC and Appliance Control Boards
Consumer HVAC, refrigerator, and washing-machine boards traditionally rely on mid-range 8-bit PICs. The PIC16F873A-I/SS drives triac outputs through zero-cross optocouplers for heater / compressor loads, reads thermistor inputs via its 10-bit ADC, and exchanges status with an HMI over SPI or USART at modest baud rates. 7 KB Flash accommodates state-machine logic plus lookup-table-based PI control for fan-speed or valve-position feedback, with 128 B EEPROM non-volatile for setpoint retention across power cycles. nanoWatt modes reduce standby consumption for energy-star appliances. Verified from Microchip PIC16F87XA family reference designs, multiple appliance OEMs still maintain PIC16F873A sources for service repair.
Recommended
Automotive Accessory Controllers (legacy)
The PIC16F873A-I/SS is widely deployed in body-electronics accessories (interior lighting modules, accessory delay relays, seat-controller sub-modules) where full automotive AEC-Q100 is not mandated by the customer. Its 2.0 V-5.5 V VDD rides through crank-drops down to about 4 V before the on-chip Brown-out Reset intervenes, while the wide -40C to +85C operating temperature handles the cabin environment. SPI links to a master BCM (body control module) carrying switch-state and dim commands, USART used for diagnostic logging, and PWM (TMR2 + CCP) drives LED backlight or motor bridges. Service replacements commonly ship this part on production-line tool cribs; for new AEC-Q100 designs Microchip recommends migrating to PIC16F18855-I/SS or dsPIC33 families.
Recommended
Battery-Powered Remote / Handheld Tools
Battery-powered equipment such as portable label printers, wireless thermostats, and small instruments benefits from the PIC16F873A-I/SS's nanoWatt modes that drop quiescent current into the sub-microamp range during sleep. A typical duty-cycled design wakes on a button interrupt, completes a sensor read via the 10-bit ADC, transmits over USART or SPI to a companion 2.4 GHz radio, and returns to sleep before current drain at idle matters. 192 B of RAM is sufficient for short AT-command-style buffers and protocol packet construction. 128 B EEPROM holds user preferences and calibration data for years of retention without main-battery leakage. The SSOP-28 footprint keeps board area minimal for handheld form factors.
Recommended
Display and User-Interface Front Ends
Mid-complexity alphanumeric displays, character LCDs with keypads, and LED-matrix indicator boards use the PIC16F873A-I/SS as a slave UI controller while a higher-end host handles primary logic. The 22 digital I/O pins directly drive a 4x4 keypad matrix using 8 lines plus pin-change interrupts for reduced BOM, with additional lines dedicated to character LCD data and control using 4-bit mode. The TMR1 16-bit timer keeps a real-time clock tick when the CPU sleeps, and the SSP module in SPI mode streams display refresh data to LED drivers. Verified against PIC16F87XA datasheet DS39592B; designers structure firmware inside the 7 KB Flash budget. Designs needing larger character fonts migrate to PIC16F876A with 14 KB Flash.
Recommended
Security and Fire-Alarm Sensor Nodes
Smoke, CO, and PIR motion detectors employ an 8-bit PIC such as the PIC16F873A-I/SS as the supervisory MCU because of low cost, low power, and decades of field-proven reliability. The analog comparator pair supervises a photoelectric or ionization chamber's quiescent current, while the 10-bit ADC reads a thermopile or PIR sensor. 128 B of EEPROM stores calibration coefficients and end-of-life tags, and the SSP in I2C mode reports to a central panel over a 4-wire bus common in fire-alarm wiring. Brown-out Reset plus the Watchdog Timer with its own 31 kHz oscillator ensure the node recovers from EMI-induced latch-ups common in industrial environments.
Recommended
Recommended Products Summary
Engineering reference data for PIC16F873A-I/SS β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16F883-I/SS | PIC16F876A-I/SS | PIC16F873A-I/SO | PIC16F873A-I/ML | PIC16F872-I/SS |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SSOP | 28-SSOP - same | 28-SSOP - same | 28-SOIC - different land pattern | 28-QFN - different land pattern | 28-SSOP - same |
| Flash Program Memory | 7 KB | 7 KB | 14 KB (+100%) | 7 KB | 7 KB | 7 KB |
| RAM | 192 B | 256 B (+33%) | 368 B (+92%) | 192 B | 192 B | 128 B (-33%) |
| EEPROM | 128 B | 256 B (+100%) | 256 B (+100%) | 128 B | 128 B | 64 B (-50%) |
| ADC Channels / Resolution | 5 x 10-bit | 11 x 10-bit | 5 x 10-bit | 5 x 10-bit | 5 x 10-bit | 6 x 10-bit |
| Max CPU Clock | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| Supply Voltage | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V |
| I/O Pins | 22 | 24 (+2) | 22 | 22 | 22 | 22 |
Key Differentiators
- Larger RAM and EEPROM headroom at same speed (vs PIC16F883-I/SS)
- Doubled Flash memory in same pinout (vs PIC16F876A-I/SS)
- Same silicon in SOIC package for hand-soldered prototypes (vs PIC16F873A-I/SO)
- Compact QFN footprint option for tight boards (vs PIC16F873A-I/ML)
Design Notes
Place a 100 nF decoupling capacitor as physically close to the VDD/AVDD pins as possible, with a 10 uF bulk capacitor sharing the same supply star. Verify that the ICSP signals (RB6/PGC, RB7/PGD) are not loaded by external circuitry that prevents rising edges during programming; a series 4.7 kohm buffer or tri-state driver is commonly required when LED or relay loads are present. The exposed pad of the SSOP is not internally connected but should remain soldered to GND for thermal dissipation in production layouts.
PORTA pin RA4 is an open-drain output only and requires an external pull-up; driving a high-current LED directly will fail to source current. Verify MCLR/VPP is pulled up to VDD through a 10 kohm resistor with a 100 nF cap to VSS for clean resets, and never tie MCLR directly to VDD - brown-out reset will not trigger. The Watchdog Timer must be cleared in main loops shorter than its timeout; designers often disable WDT in development but enable it before validation to catch infinite loops.
nanoWatt SLEEP mode drops the core current below 1 uA at 3 V when the system clock is halted, but peripherals fed by the secondary oscillator (TMR1, watchdog, etc.) remain active if enabled. Verify all analog peripherals enter their own power-down state before invoking SLEEP. For duty-cycled battery designs, ensure the WDT post-scaler is set so that the average idle current including WDT and any always-on peripherals stays below the design's battery budget over the full operating temperature range.
Compliance Information
Industrial -40 to +85 C operating range per DS39592B. RoHS and lead-free per Microchip product page. Not AEC-Q100 qualified - contact Microchip for automotive-grade equivalents.
