PIC16F84-04/SO - 4MHz 8-bit Flash MCU 1.75KB SOIC-18 | Microchip
MPN: PIC16F84-04/SO ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.99 | $4.99 |
| 10 | $4.49 | $44.90 |
| 100 | $3.99 | $399.00 |
| 500 | $3.59 | $1,795.00 |
| 1,000 | $3.19 | $3,190.00 |
PIC16F84-04/SO Overview
An 8-bit flash microcontroller is a self-contained computing element with integrated CPU, non-volatile flash program memory, working RAM, and peripheral set on a single silicon die. The 8-bit class sits at the bottom of the MCU taxonomy (8-bit -> microcontroller -> embedded processor -> semiconductor), and PIC microcontrollers specifically use a Harvard RISC architecture that separates program and data paths, giving a deterministic instruction timing useful for interrupt-driven control. The PIC16F84-04/SO is a classic member of this class, often used in introductory and legacy industrial designs.
Key features include 13 digital I/O pins across two ports (PORTA 5-bit, PORTB 8-bit), 64 bytes of EEPROM data memory, a 14-bit instruction word, and an 8-bit timer (TMR0) with an 8-bit programmable prescaler. The device supports in-circuit serial programming (ICSP) via RB6/RB7, allowing field firmware updates without removing the part. The 18-pin SOIC footprint simplifies hand-soldering and breadboard prototyping.
Technically, the part uses a Harvard RISC core with a 14-bit program word and a 200ns instruction cycle at maximum clock, plus a 15-deep hardware stack and 8-level interrupt structure. Power-on reset, power-up timer, oscillator start-up timer, and watchdog timer with on-chip RC oscillator provide robust brownout-free operation from 4.0V to 5.5V.
Typical applications include hobbyist and educational electronics, simple sensor signal conditioning, low-speed serial protocol bridging, LED driver controllers, and legacy industrial control replacement. The wide 4.0-5.5V range and 13 I/O make it well suited to 5V logic systems. Note that Microchip recommends PIC16F84A as a newer replacement; PIC16F628A can also serve as a pin-to-pin upgrade.
When designing, ensure the oscillator configuration bits match the external resonator and that ICSP header access is preserved for field firmware updates. Add decoupling of 100nF on VDD close to the pin.
This page synthesizes distributor pricing, drop-in alternatives (including the recommended PIC16F84A upgrade), practical design notes, and pinout data not consolidated on a single distributor page.
Drop-in alternatives for PIC16F84-04/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 PIC16F84-04/SO (same form factor and footprint) — differing in Package, Timers, Core Architecture, Operating Temperature, I/O Pins.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16F84A-04/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F84A-20/SO
✅ Drop-In✓ In Stock
$1.78 / Unit
View Datasheet →PIC16F84-04I/SO
✅ Drop-In✓ In Stock
$2.18 / Unit
View Datasheet →PIC16F84-10I/SO
✅ Drop-In✓ In Stock
$2.1 / Unit
View Datasheet →PIC16LF84A-04I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F628A-04/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F88-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F84-04/SO Maximum Ratings & Electrical Characteristics
| Family | PIC16F PIC16 Microcontroller IC |
| Core Architecture | 8-bit Harvard RISC |
| Program Memory | 1.75 KB (1K x 14) Flash |
| RAM | 68 bytes |
| EEPROM Data Memory | 64 bytes |
| Instruction Set Size | 35 single-word instructions |
| Instruction Word Length | 14-bit |
| Maximum Clock Frequency | 4 MHz |
| Instruction Cycle Time | 200 ns at 4 MHz |
| Supply Voltage (VDD) | 4.0 V to 5.5 V |
| I/O Pins | 13 |
| Timers | 1 x 8-bit (TMR0 with 8-bit prescaler) |
| Operating Temperature | -40 C to +70 C (industrial) |
| Package | 18-pin SOIC (SO) |
| Mounting Type | Surface Mount |
| Programming Interface | ICSP (In-Circuit Serial Programming) on RB6/CLK and RB7/DAT |
| RoHS Status | Compliant |
| Lead-Free | Yes |
PIC16F84-04/SO Pin Configuration
| Pin 1 | RA2 — PORTA bit 2, digital I/O |
| Pin 2 | RA3 — PORTA bit 3, digital I/O |
| Pin 3 | RA4/T0CKI — PORTA bit 4 / Timer0 clock input (open-drain output) |
| Pin 4 | MCLR — Master Clear (reset, active low) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — PORTB bit 0 / External interrupt input |
| Pin 7 | RB1 — PORTB bit 1, digital I/O |
| Pin 8 | RB2 — PORTB bit 2, digital I/O |
| Pin 9 | RB3 — PORTB bit 3, digital I/O |
| Pin 10 | RB4 — PORTB bit 4, digital I/O |
| Pin 11 | RB5 — PORTB bit 5, digital I/O |
| Pin 12 | RB6/PGC — PORTB bit 6 / ICSP clock (ICSP test pin) |
| Pin 13 | RB7/PGD — PORTB bit 7 / ICSP data (ICSP test pin) |
| Pin 14 | VSS — Ground (secondary) |
| Pin 15 | VDD — Positive supply voltage |
| Pin 16 | OSC2/CLKOUT — Oscillator output / Clock out |
| Pin 17 | OSC1/CLKIN — Oscillator input / Clock in |
| Pin 18 | RA0 — PORTA bit 0, digital I/O |
Typical Applications
PIC16F84-04/SO is suitable for 6 applications: Hobbyist and Educational Electronics, Legacy Industrial Control Replacement, Simple Sensor Signal Conditioning, Low-Speed Serial Protocol Bridging, LED Display and Indicator Controllers, Consumer Appliance Control Boards.
Hobbyist and Educational Electronics
The PIC16F84-04/SO is a classic choice for learning embedded development because of its 35-instruction set, deterministic 200ns instruction cycle, and 13 digital I/O lines. Its 4 MHz maximum speed is fast enough for LED blinking, button debouncing, and simple serial bit-banging at 9600 baud without timing issues. The 1.75 KB flash comfortably holds introductory projects such as a stopwatch, dice roller, or 7-segment display driver. Because Microchip publishes the datasheet, instruction set reference, and MPASM assembler for free, students can move from schematic to working firmware in a single lab session. The 18-pin SOIC package is also breadboard-friendly with a SOIC-to-DIP adapter.
Recommended
Legacy Industrial Control Replacement
The PIC16F84-04/SO is widely deployed in legacy industrial controllers, particularly in 5V logic control gates for conveyor sequencing, machine-tool interlocks, and small pump drivers. Its 4.0-5.5V supply range and 25 mA per-pin drive capability allow direct interfacing to 5V relays, optocouplers, and triac drivers without level shifters. The 64-byte EEPROM is sufficient for storing calibration constants, run-hour counters, and configuration parameters that survive power cycles. ICSP via RB6/RB7 enables in-field firmware updates without removing the part from the PCB, which is essential in factories where downtime is expensive. New designs should consider PIC16F628A or PIC16F88 for more headroom.
Recommended
Simple Sensor Signal Conditioning
With 13 digital I/O pins and an 8-bit timer, the PIC16F84-04/SO can handle simple sensor front-end tasks such as pulse-width measurement, frequency-to-digital conversion for low-speed anemometers, or contact-debouncing for mechanical limit switches. The Harvard architecture guarantees deterministic interrupt latency of about 5 instruction cycles, which is critical when sampling quadrature encoders or capturing fast edges from Hall-effect sensors. Adding an external RC network or comparator extends the part into the analog domain. The 4 MHz clock supports sampling rates up to 200 kHz in tight loops, suitable for slow industrial sensors.
Recommended
Low-Speed Serial Protocol Bridging
The PIC16F84-04/SO can bit-bang UART, SPI master, or 1-Wire protocols from its 13 I/O pins at 4 MHz, achieving 9600 baud UART cleanly with 1% timing error or better when using the hardware timer. This makes it useful for bridging between legacy equipment that uses RS-232, I2C, or custom serial protocols in factory automation. The 1.75 KB flash is enough to hold protocol state machines plus a small command parser. Add a MAX232 for RS-232 level translation or an HC05 for Bluetooth bridging. Note that for any design requiring more than one hardware UART, PIC16F628A is a better fit.
Recommended
LED Display and Indicator Controllers
With 25 mA sink/source capability per pin, the PIC16F84-04/SO can directly drive small LEDs, 7-segment displays, and Charlieplexed indicator arrays without driver transistors. The 4 MHz clock supports multiplexed display refresh rates above 100 Hz, well above the flicker threshold. The 1.75 KB flash holds lookup tables for hex-to-7-segment decoding, custom character fonts, and PWM generation via the 8-bit timer. Adding external current-limiting resistors and BCD decoders extends the design to multi-digit numeric readouts common in test equipment and consumer appliances.
Recommended
Consumer Appliance Control Boards
The PIC16F84-04/SO has been historically used in small consumer appliances such as coffee makers, washing-machine front panels, microwave oven timers, and air-conditioner remote receivers. Its 5V operation aligns with legacy appliance power rails, and 13 I/O is enough for a 4x4 keypad matrix plus a 2-digit LED display. The 64-byte EEPROM stores user preferences, and the watchdog timer protects against code lockup in unattended appliances. AEC-Q100 is not applicable (consumer, not automotive). Migration to PIC16F818 or PIC16F819 is recommended for new consumer appliance designs.
Recommended
Recommended Products Summary
Engineering reference data for PIC16F84-04/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16F84A-04/SO | PIC16F84A-20/SO | PIC16F84-04I/SO | PIC16F84-10I/SO | PIC16LF84A-04I/SO | PIC16F628A-04/SO | PIC16F88-I/SO |
|---|---|---|---|---|---|---|---|---|
| Package | 18-pin SOIC (SO) | 18-pin SOIC (SO) - same | 18-pin SOIC (SO) - same | 18-pin SOIC (SO) - same | 18-pin SOIC (SO) - same | 18-pin SOIC (SO) - same | 18-pin SOIC (SO) - same | 18-pin SOIC (SO) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | |||
| Maximum Clock | 4 MHz | 4 MHz | 20 MHz | 10 MHz | 4 MHz | 4 MHz (20 MHz with -20 speed grade) | 20 MHz | |
| Program Flash | 1.75 KB | 1.75 KB | 1.75 KB | 1.75 KB | 2 KB | 7 KB | ||
| RAM | 68 bytes | 68 bytes | 68 bytes | 128 bytes | 256 bytes | |||
| EEPROM | 64 bytes | 64 bytes | 128 bytes | 256 bytes | ||||
| Supply Voltage | 4.0 V to 5.5 V | 4.0 V to 5.5 V | 2.0 V to 5.5 V | 4.0 V to 5.5 V | 2.0 V to 5.5 V | |||
| I/O Pins | 13 | 13 | 16 | 16 | ||||
| Internal Oscillator | No (external required) | No (external required) | Yes, 4 MHz internal | Yes, 8 MHz internal with PLL | ||||
| USART | No | No | Yes (hardware) | Yes (AUSART) |
Key Differentiators
- Recommended modern replacement with identical memory map (vs PIC16F84A-04/SO)
- Extended temperature range for industrial deployment (vs PIC16F84-04I/SO)
- Wider supply voltage range for battery-powered designs (vs PIC16LF84A-04I/SO)
- Pin-compatible upgrade with USART and internal oscillator (vs PIC16F628A-04/SO)
Design Notes
The PIC16F84-04/SO operates from a single 4.0-5.5V rail. Place a 100nF decoupling capacitor as close as physically possible to the VDD pin (pin 14 on SOIC-18), with a 10uF bulk capacitor at the board's power-entry point. Power-on reset, power-up timer, and oscillator start-up timer are handled internally, so an external reset supervisor is not required for normal operation. If your design operates in electrically noisy industrial environments, add a 10k pull-up to MCLR and a small RC filter (10k + 100nF) for additional ESD immunity. Estimated supply current at 4 MHz is approximately 2-6 mA depending on I/O loading.
Route the oscillator traces (OSC1/OSC2) as short as possible and keep them away from high-current switching traces to reduce EMI coupling. Provide a ground pour under the oscillator area and keep digital signal traces at least 3 mm away from the crystal traces. If using a ceramic resonator with built-in capacitors, the resonator's ground pin should connect directly to the ground pour with a via. The ICSP header should be a 5-pin 0.1-inch header with VDD, VSS, MCLR, RB6/PGC, RB7/PGD, so field firmware updates remain possible after board assembly.
Common pitfalls with PIC16F84-04/SO designs: (1) forgetting that RA4 is an open-drain output and cannot source current directly - add a pull-up if driving an LED or logic high; (2) using the wrong oscillator configuration bits in the __CONFIG directive; (3) omitting the MCLR pull-up resistor which can cause spurious resets; (4) confusing pin 1 numbering between SOIC (pin 1 at RA2 with notch/dot at top-left) and DIP packages; (5) exceeding 25 mA per pin or 200 mA total package dissipation - the absolute maximum ratings per the datasheet. Always cross-check configuration fuses against the latest Microchip datasheet revision before finalizing the design.
Compliance Information
RoHS and REACH compliant per Microchip product page. Not AEC-Q100 qualified (consumer/industrial grade, not automotive). Lead-free and matte-tin finish. Conflict-minerals statement available from Microchip corporate responsibility page.