PIC16LF84AT-04I/SO - 4MHz 8-Bit Flash MCU, 18-SOIC | Microchip
MPN: PIC16LF84AT-04I/SO ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.71 | $2.71 |
| 10 | $2.55 | $25.50 |
| 100 | $2.32 | $232.00 |
| 500 | $2.1 | $1,050.00 |
| 1,000 | $1.95 | $1,950.00 |
PIC16LF84AT-04I/SO Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program and data memory, peripherals, and I/O on one die. Within the broader taxonomy, the PIC16F84A belongs to the 8-bit PIC16 mid-range architecture family, sitting under the Microchip PIC microcontrollers product line, and ultimately under the semiconductor / embedded computing category. The "LF" prefix denotes the low-voltage (2.0 V-5.5 V) variant, while the "T" suffix indicates tape-and-reel packaging for high-volume SMT assembly.
Key features of this part include 4 MHz maximum operating frequency, 14-bit wide instruction word, 35 single-word instructions (most single-cycle), 8-level deep hardware stack, four interrupt sources, a Watchdog Timer with its own on-chip RC oscillator, and an ICD-friendly in-circuit serial programming (ICSP) interface. The Flash memory supports 10,000 erase/write cycles typical, while the EEPROM supports 1,000,000 cycles typical, with data retention specified by Microchip.
From an architectural standpoint, the PIC16F84A uses a Harvard architecture with separate program and data buses, enabling simultaneous instruction fetch and data access. The device also features Power-on Reset, Brown-out Detect, Power-up Timer, and an integrated 10-bit timer/counter, plus a second 8-bit timer from the Timer0 module, providing robust embedded control primitives.
Typical applications include low-power battery-operated sensor nodes, consumer appliance control panels, automotive body and interior modules, industrial control logic, learning and hobbyist circuits, and educational microcontroller training kits. The wide 2.0 V-5.5 V supply range also makes it suitable for 3.3 V and 5 V mixed-voltage systems.
Designers should note that this part is supplied in tape-and-reel packaging for SMT pick-and-place, with 13 usable I/O pins and 1 input-only pin (RA4), and that all programming is performed via ICSP. For new designs, the modern PIC16F84A successor families (PIC16F1xxx) are recommended, but the LF84A remains a drop-in option for legacy maintenance.
This page combines verified distributor pricing, parameter-level comparisons against same-family and cross-brand Microchip alternatives, and practical design notes not present in the manufacturer datasheet.
Drop-in alternatives for PIC16LF84AT-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 PIC16LF84AT-04I/SO (same form factor and footprint) — differing in Package, Timers, Operating Temperature, Core Architecture, Watchdog Timer.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16LF84A-04I/SO
✅ Drop-In✓ In Stock
$2.21 / Unit
View Datasheet →PIC16LF84AT-04/SO
✅ Drop-In✓ In Stock
$2.55 / Unit
View Datasheet →PIC16LF84A-04I/P
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$2.18 / Unit
View Datasheet →PIC16LF84A-04I/SS
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$1.45 / Unit
View Datasheet →PIC16LF83T-04/SO
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$2.85 / Unit
View Datasheet →PIC16LF84AT-04I/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC16 8-bit RISC (Harvard) |
| Program Memory Type | Flash (self-programmable) |
| Program Memory Size | 1.75 KB (1K x 14 words) |
| SRAM Data Memory | 68 bytes |
| EEPROM Data Memory | 64 bytes |
| Maximum CPU Frequency | 4 MHz |
| Instruction Word Width | 14 bits |
| Supply Voltage Range | 2.0 V to 5.5 V |
| I/O Pins | 13 |
| Timers | Timer0 (8-bit) + Timer1 (16-bit) |
| Interrupt Sources | 4 |
| Hardware Stack | 8 levels |
| Operating Temperature Range | -40 C to +85 C (Industrial) |
| Package Type | 18-pin SOIC (SO), 0.300 inch body width |
| Mounting Type | Surface Mount |
| Packaging | Tape and Reel (T suffix) |
| RoHS Status | Compliant |
PIC16LF84AT-04I/SO Pin Configuration
| Pin 1 | RA2/AN2 — PORTA bit 2, analog input 2 |
| Pin 2 | RA3/AN3/VREF — PORTA bit 3, analog input 3, voltage reference |
| Pin 3 | RA4/T0CKI — PORTA bit 4 (open-drain), Timer0 clock input |
| Pin 4 | RA5/AN4/SS — PORTA bit 5, analog input 4, slave select |
| Pin 5 | VSS — Ground reference |
| Pin 6 | OSC1/CLKIN — Crystal oscillator input / external clock input |
| Pin 7 | OSC2/CLKOUT — Crystal oscillator output / clock output |
| Pin 8 | RC0 — PORTC bit 0 |
| Pin 9 | RC1 — PORTC bit 1 |
| Pin 10 | RC2 — PORTC bit 2 |
| Pin 11 | RC3 — PORTC bit 3 |
| Pin 12 | RC4 — PORTC bit 4 |
| Pin 13 | RC5 — PORTC bit 5 |
| Pin 14 | RC6 — PORTC bit 6 |
| Pin 15 | RC7 — PORTC bit 7 |
| Pin 16 | VSS — Ground (some packages place VDD on pin 16) |
| Pin 17 | RA0/AN0 — PORTA bit 0, analog input 0 |
| Pin 18 | RA1/AN1 — PORTA bit 1, analog input 1 |
Typical Applications
PIC16LF84AT-04I/SO is suitable for 6 applications: Battery-Powered Sensor Node, Consumer Appliance Control, Hobbyist and Educational Projects, Automotive Body and Interior Modules, Industrial Control Logic, Retro / Legacy Replacement Design.
Battery-Powered Sensor Node
The PIC16LF84AT-04I/SO fits battery-powered sensor nodes thanks to its 2.0 V-5.5 V supply range, allowing operation from a single 3 V coin cell or 2x AA cells down to 2 V. The 4 MHz maximum clock limits MIPS to 1, but this is sufficient for periodic sensor reads and slow UART/I2C reporting at low duty cycle. The integrated Sleep mode draws typically <1 uA, and the Watchdog Timer can wake the MCU every few seconds using its internal RC oscillator. The 1.75 KB Flash holds small sensor-firmware images and the 68-byte SRAM buffers sensor data between transmission intervals.
Recommended
Consumer Appliance Control
The PIC16LF84AT-04I/SO is widely deployed in consumer appliance control panels (washing machines, microwave ovens, dishwashers, coffee machines) where its 13 I/O pins drive LED indicators, scan keypads, and control relays or triacs. The 4 MHz CPU executes most instruction cycles in 250 ns, ample for slow human-interface tasks. The 64-byte EEPROM stores user preferences (timers, settings) that survive power loss, and the integrated Brown-out Reset prevents corrupted EEPROM writes during AC brown-outs. The -40 C to +85 C industrial temperature grade suits appliance environments near heat-generating motors.
Recommended
Hobbyist and Educational Projects
The PIC16LF84AT-04I/SO (and its PDIP cousin PIC16F84A-04I/P) remains a textbook example in microcontroller education, featured in classic microcontroller textbooks and university courses. The 18-SOIC is suitable for compact SMT student projects, while the through-hole PDIP version is easier to breadboard. The 35-instruction RISC core is small enough to teach assembly language fundamentals in one semester, and the ICSP programming interface allows step-debugging with a PICkit 3/4. Many open-source projects on GitHub target this part, providing ready-made firmware examples.
Recommended
Automotive Body and Interior Modules
In automotive body and interior ECUs (door modules, mirror controllers, climate panel displays), the PIC16LF84AT-04I/SO handles simple logic tasks such as button scanning, LED driving, and LIN-bus slave communication (with external transceiver). The 2.0 V-5.5 V supply range tolerates automotive cranking transients down to 6 V on a 12 V system when paired with a regulator, and the 4 MHz speed is sufficient for 19.2 kbps LIN slaves. The 1.75 KB Flash holds state-machine code for button handling and blink patterns, while the EEPROM stores per-unit trim values.
Recommended
Industrial Control Logic
For industrial control panels, simple PLC I/O slices, and equipment status indicators, the PIC16LF84AT-04I/SO provides deterministic logic control at low cost. The 13 I/O pins can directly drive 5 V logic or small SSRs. The integrated Watchdog Timer prevents lockup in noisy industrial EMI environments, and the Brown-out Reset at VDD below ~4 V (configurable) protects against partial-supply glitches. With a 4 MHz maximum clock the device handles slow Modbus RTU polling or simple state machines without timing jitter.
Recommended
Retro / Legacy Replacement Design
The PIC16LF84AT-04I/SO is the go-to drop-in for legacy 5 V and 3.3 V PIC16F84A designs that need a like-for-like replacement without firmware rewrite. The 18-SOIC footprint matches legacy PCB layouts, the 14-bit instruction set is byte-compatible with PIC16F84A binaries, and the EEPROM and Flash erase/write timings are unchanged. Engineers maintaining long-lifecycle industrial products (medical instruments, scientific equipment) keep this part on the BOM precisely because the firmware is stable and validated, and a drop-in replacement avoids costly V&V re-qualification.
Recommended
Recommended Products Summary
Engineering reference data for PIC16LF84AT-04I/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16LF84A-04I/SO | PIC16LF84AT-04/SO | PIC16LF83T-04/SO |
|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 18-SOIC (SO) | 18-SOIC (SO) - same | 18-SOIC (SO) - same | 18-SOIC (SO) - same |
| Maximum CPU Frequency | 4 MHz | 4 MHz | 4 MHz | 4 MHz |
| Program Flash Memory | 1.75 KB | 1.75 KB | 1.75 KB | 0.875 KB (-50%) |
| SRAM Data Memory | 68 bytes | 68 bytes | 68 bytes | 36 bytes (-47%) |
| EEPROM Data Memory | 64 bytes | 64 bytes | 64 bytes | 64 bytes |
| Operating Voltage Range | 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 | 13 | 13 | 13 | 13 |
| Operating Temperature Range | -40 C to +85 C (Industrial, I grade) | -40 C to +85 C (Industrial) | 0 C to +70 C (Commercial) | -40 C to +85 C (Industrial) |
Key Differentiators
- Low-voltage 2.0 V-5.5 V operation with same silicon as standard PIC16F84A (vs PIC16F84A-04I/SO (non-LF version))
- Tape-and-reel packaging for high-volume SMT lines (vs PIC16LF84A-04I/SO (tray packaging))
- Higher memory density versus the older PIC16F83 predecessor (vs PIC16LF83T-04/SO)
Design Notes
The PIC16LF84AT-04I/SO supports an internal Brown-out Reset (BOR) that can be enabled in the configuration word to hold the device in Reset when VDD drops below ~4.0 V (configurable to lower thresholds). For 3.3 V designs, disable BOR or use the lower BOR voltage setting to avoid spurious resets. Always place a 100 nF decoupling capacitor as close as possible to the VDD pin, and a 10 uF bulk capacitor on the board for transient load support. Sleep mode current is typically <1 uA at 3 V with the Watchdog Timer disabled.
When designing the PCB for an 18-SOIC footprint, use a land pattern with pad width 0.51 mm and pitch 1.27 mm. The exposed thermal pad (if any) on the 18-SOIC is electrically floating and should be soldered to a small copper pour for thermal relief, but it is NOT a ground pad on this part. Route the ICSP lines RB6 (PGC) and RB7 (PGD) away from switching power or clock traces to avoid programming glitches, and keep the trace length to the MCLR pull-up under 50 mm to avoid programming-entry noise.
The RA4 pin on PIC16LF84AT-04I/SO is open-drain and requires an external pull-up resistor when used as a digital output. It is often miswired as a totem-pole output, which will not source current. The MCLR pin must be tied to VDD through a 10 kohm pull-up for normal operation; do not leave it floating. When programming in-circuit, ensure no load on PGC/PGD exceeds 50 pF or programming will fail. Finally, the configuration word must be set explicitly for the oscillator mode (HS, XT, LP, RC); a missing CONFIG line will leave the oscillator disabled.
The PIC16LF84AT-04I/SO has no internal slew-rate limiting on its digital I/O pins, so long PCB traces (>50 mm) on RB ports can ring and cause EMI issues in noisy environments. For switching rates above 1 MHz on the I/O, place a 33 ohm series-termination resistor at the driver pin. The analog inputs (RA0-RA5) have a recommended source impedance below 10 kohm to avoid ADC sampling errors; add an external buffer op-amp if driving the analog inputs from a higher-impedance source.
Compliance Information
RoHS compliance per Microchip product page; PIC16LF84A family is not AEC-Q100 qualified but is widely used in industrial and consumer applications. Halogen-free status not explicitly confirmed in the provided data.
