PIC16F84AT-20E/SS - 8-bit 20MHz PIC MCU, 1.75KB Flash | Microchip
MPN: PIC16F84AT-20E/SS ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.2 | $5.20 |
| 10 | $4.65 | $46.50 |
| 100 | $3.95 | $395.00 |
| 500 | $3.4 | $1,700.00 |
| 1,000 | $2.95 | $2,950.00 |
PIC16F84AT-20E/SS Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, non-volatile program memory, working RAM, and programmable I/O on one die. PIC16 devices from Microchip are members of the larger PIC family, which sits within the 8-bit MCU hypernymy of microcontroller -> embedded processor -> semiconductor IC. The PIC16F84A in particular was a popular baseline part used to teach embedded programming and remains widely deployed in legacy industrial, hobby, and educational designs.
Key features include 13 programmable digital I/O pins, on-chip Power-On Reset (POR), a Watchdog Timer (WDT) with dedicated on-chip RC oscillator, an asynchronous serial port (USART/SCI) capability through the RB port, and In-Circuit Serial Programming (ICSP) via two pins. The 'T' suffix denotes tape-and-reel packaging, the '20' denotes 20 MHz maximum clock, the 'E' denotes the Enhanced temperature range (-40C to +125C), and '/SS' denotes the SSOP-20 (5.30 mm) package.
The PIC16F84A uses a Harvard-architecture 14-bit instruction word, RISC-style instruction set, and a 35-instruction opcode table that allows most instructions to complete in one instruction cycle (4 clock cycles). The 8-level deep hardware stack and 15 special-function hardware registers give the device a deterministic execution model suitable for real-time control tasks.
Typical applications include hobby and educational projects, simple sensor interfaces, LED controllers, low-end motor-control sequencers, replacement of legacy 8051-based designs, and In-Circuit Serial Programming (ICSP) bootloader hosts. The wide operating voltage (2.0 V to 5.5 V) and low-power CMOS process make it suited to both battery and mains-powered designs.
When designing with the PIC16F84A, note that the device has no on-chip analog peripherals (no ADC, no comparator) - all analog signal conditioning must be done externally. The Flash memory endurance is 1000 erase/write cycles typical and 100K read cycles, and EEPROM endurance is 1M erase/write cycles typical, both per the manufacturer datasheet.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes that go beyond what the bare Microchip datasheet provides, including a comparison matrix against the original PIC16F84A-20I/SS and the modern PIC16F690-I/SS baseline.
Drop-in alternatives for PIC16F84AT-20E/SS — 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 PIC16F84AT-20E/SS (same form factor and footprint) — differing in Package, Core Architecture, Maximum Clock Frequency, RoHS Status, I/O Pins.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16F84A-20I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F84A-20/SS
✅ Drop-In✓ In Stock
$1.65 / Unit
View Datasheet →PIC16F84AT-20/SS
✅ Drop-In✓ In Stock
$1.6 / Unit
View Datasheet →PIC16F84AT-04/SS
✅ Drop-In✓ In Stock
$1.48 / Unit
View Datasheet →PIC16F84A-04/SS
✅ Drop-In✓ In Stock
$2.18 / Unit
View Datasheet →PIC16F84AT-20E/SS Maximum Ratings & Electrical Characteristics
| Core Processor | PIC |
| Core Size | 8-bit |
| Core Series | PIC16 |
| Instruction Set Architecture | RISC (14-bit instruction word) |
| Maximum Clock Frequency | 20 MHz |
| Program Memory Size | 1.75 KB (1K x 14 words) Flash |
| RAM Size | 68 bytes |
| EEPROM Size | 64 bytes |
| Number of I/O Pins | 13 |
| Package | 20-SSOP (5.30 mm body width, 0.65 mm pitch) |
| Operating Voltage Range | 2.0 V to 5.5 V (extended temp E: 2.0 V to 5.5 V) |
| Operating Temperature Range | -40C to +125C (E suffix = Enhanced) |
| Peripherals | POR (Power-On Reset), WDT (Watchdog Timer) |
| Mounting Type | Surface Mount (SSOP) |
| Packaging | Tape & Reel (T suffix) |
| Data Converters | None (no on-chip ADC) |
| Connectivity | ICSP (In-Circuit Serial Programming) |
| RoHS Status | Compliant (per DigiKey listing) |
PIC16F84AT-20E/SS 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#/VPP — Master Clear (active-low reset) / ICSP VPP programming voltage |
| 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, interrupt-on-change) |
| Pin 11 | RB5 — PORTB bit 5 (digital I/O, interrupt-on-change) |
| Pin 12 | RB6/PGC — PORTB bit 6 / ICSP clock (programming) |
| Pin 13 | RB7/PGD — PORTB bit 7 / ICSP data (programming) |
| Pin 14 | VDD — Positive supply voltage (2.0 V to 5.5 V) |
| Pin 15 | OSC2/CLKOUT — Oscillator output / clock output (crystal mode) |
| Pin 16 | OSC1/CLKIN — Oscillator input / external clock input (crystal mode) |
| Pin 17 | RA0 — PORTA bit 0 (digital I/O) |
| Pin 18 | RA1 — PORTA bit 1 (digital I/O) |
| Pin 19 | RA2 — PORTA bit 2 (digital I/O, alternate function on pin 19) |
| Pin 20 | RA3 — PORTA bit 3 (digital I/O, alternate function on pin 20) |
Typical Applications
PIC16F84AT-20E/SS is suitable for 6 applications: Hobby and Educational Embedded Projects, Legacy Industrial Control and Sequencing, LED Display Drivers and Chasing Light Controllers, Simple Sensor Interfaces with External ADC, Replacement of Legacy 8051 Designs, ICSP Bootloader Hosts and Programmers.
Hobby and Educational Embedded Projects
The PIC16F84AT-20E/SS is a classic teaching MCU for embedded systems courses, robotics clubs, and self-learners because its 35-instruction RISC opcode table, 14-bit instruction word, and 1.75 KB Flash are simple enough for an introductory textbook yet rich enough to build real projects. Its 20 MHz core runs most beginner example programs (LED blink, button debounce, seven-segment multiplexing) without timing pressure. ICSP via PGD/PGC lets students reprogram the device without removing it from the breadboard, accelerating iteration cycles in classroom labs.
Recommended
Legacy Industrial Control and Sequencing
The PIC16F84AT-20E/SS's -40C to +125C Enhanced temperature range makes it suitable for legacy factory-floor control panels, relay sequencing boards, and machine state machines that must operate reliably in unconditioned enclosures. Its 13 digital I/O can drive opto-isolators, scan matrix keypads, and read limit switches without additional glue logic. The 64-byte EEPROM stores non-volatile setpoints that survive power cycling, while the Watchdog Timer resets the device if firmware ever locks up in the field.
Recommended
LED Display Drivers and Chasing Light Controllers
The PIC16F84AT-20E/SS drives simple LED matrix displays, chasing-light controllers, and Christmas-light animators where each of the 13 I/O pins can sink or source 25 mA directly to LEDs without external drivers. The 1.75 KB Flash holds pattern lookup tables for moderate-length animations, while the 20 MHz clock generates precise multiplexing timing for 8x8 matrices via Charlieplexing or direct multiplexing. With EEPROM-stored patterns, end users can cycle through preset sequences without firmware changes.
Recommended
Simple Sensor Interfaces with External ADC
For temperature, light, or humidity sensing, the PIC16F84AT-20E/SS pairs with an external SPI ADC such as the MCP3002 (2-channel 10-bit) or MCP3202 (2-channel 12-bit) to provide analog measurement capability that the bare MCU lacks. The MCU's USART (via RB ports in software bit-bang) streams digitized readings to a host PC or LCD. Its 2.0 V to 5.5 V supply range allows direct connection to 3.3 V sensors without level shifters, and the EEPROM records calibration constants.
Recommended
Replacement of Legacy 8051 Designs
The PIC16F84AT-20E/SS is frequently chosen as a low-risk replacement for aging 8051-based controllers because its 20 MHz clock delivers comparable or better throughput than a 12 MHz 8051, while its Flash memory supports in-system updates that mask the EPROM-only 8051's programming inconvenience. The Harvard architecture eliminates the 8051's accumulator-bottleneck, simplifying firmware migration. PIC assembly code or C code (via Hi-Tech PICC or XC8) compiles to compact PIC16 instructions that fit easily in the 1.75 KB Flash.
Recommended
ICSP Bootloader Hosts and Programmers
The PIC16F84AT-20E/SS is occasionally used as the host controller inside ICSP programming fixtures and field-upgrade tools. Its two dedicated ICSP pins (RB6/PGC clock, RB7/PGD data) and MCLR#/VPP high-voltage programming pin make it a natural fit for driving a downstream target MCU during factory programming. The 1.75 KB Flash accommodates the bootloader itself, while the EEPROM stores programming parameters and serial numbers. The Enhanced -40C to +125C temperature rating supports outdoor or industrial programming stations.
Recommended
Recommended Products Summary
Engineering reference data for PIC16F84AT-20E/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16F84A-20I/SS | PIC16F84A-20/SS | PIC16F84AT-20/SS | PIC16F84AT-04/SS | PIC16F84A-04/SS |
|---|---|---|---|---|---|---|
| Package | 20-SSOP (5.30 mm) | 20-SSOP (5.30 mm) - same | 20-SSOP (5.30 mm) - same | 20-SSOP (5.30 mm) - same | 20-SSOP (5.30 mm) - same | 20-SSOP (5.30 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Max Clock Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 4 MHz | 4 MHz |
| Program Memory (Flash) | 1.75 KB (1K x 14) | 1.75 KB (1K x 14) | 1.75 KB (1K x 14) | 1.75 KB (1K x 14) | 1.75 KB (1K x 14) | 1.75 KB (1K x 14) |
| RAM Size | 68 bytes | 68 bytes | 68 bytes | 68 bytes | 68 bytes | 68 bytes |
| EEPROM Size | 64 bytes | 64 bytes | 64 bytes | 64 bytes | 64 bytes | 64 bytes |
| Operating Temperature | -40C to +125C (Enhanced) | -40C to +85C (Industrial) | 0C to +70C (Commercial) | 0C to +70C (Commercial) | -40C to +125C (Enhanced) | 0C to +70C (Commercial) |
| Number of I/O | 13 | 13 | 13 | 13 | 13 | 13 |
| ADC Channels | 0 (none) | 0 (none) | 0 (none) | 0 (none) | 0 (none) | 0 (none) |
| Supply 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 | 2.0 V to 5.5 V | 2.0 V to 5.5 V |
| ICSP Programming | Yes (RB6/RB7) | Yes (RB6/RB7) | Yes (RB6/RB7) | Yes (RB6/RB7) | Yes (RB6/RB7) | Yes (RB6/RB7) |
Key Differentiators
- Enhanced -40C to +125C temperature range for industrial and outdoor use (vs PIC16F84A-20I/SS)
- Tape-and-reel packaging for high-volume SMD assembly lines (vs PIC16F84A-20I/SS)
- True drop-in compatibility with all PIC16F84A-20I/SS firmware and PCBs (vs PIC16F88-I/SS)
Design Notes
Estimated: The PIC16F84AT-20E/SS supply current at 5 V, 20 MHz, all I/O toggling, is approximately 10 mA typical and 20 mA maximum per the Microchip PIC16F8X datasheet. Add a 100 nF decoupling capacitor within 5 mm of VDD (pin 14) and a 10 uF bulk capacitor on the supply rail. For battery-powered designs operating below 4 MHz, the nanoWatt Sleep mode draws <1 uA, but the legacy PIC16F84A does not implement nanoWatt Sleep - use the PIC16F88 or PIC16F690 instead if deep sleep matters.
The SSOP-20 package has a 0.65 mm pin pitch and a thermal pad-less bottom. Route traces directly away from pins with at least 0.2 mm clearance. For ICSP, place a 6-pin header (or test pads) on the PCB connected to MCLR#/VPP, VDD, VSS, RB6/PGC, and RB7/PGD to allow in-system programming after assembly. Reserve a 4-pin footprint for a crystal or resonator at OSC1/OSC2 (pins 15 and 16) - or skip the footprint entirely if you use the internal RC oscillator (configure FOSC configuration bit).
Three common pitfalls when designing with PIC16F84AT-20E/SS: (1) The RA4 pin is open-drain and CANNOT source current - if you need a high output, add a pull-up resistor. (2) The configuration word (0x2007) must be set correctly for oscillator mode, WDT enable, and code protection - a wrong config bit can brick the part. (3) Flash endurance is only 1,000 erase/write cycles typical, so do not use Flash as a non-volatile data store - use the 64-byte EEPROM for that instead. EEPROM endurance is 1,000,000 cycles typical, sufficient for field parameter updates.
Estimated: For a 20 MHz system clock, the internal instruction cycle is 5 MHz (4 clocks per instruction). Output pin rise/fall times are approximately 25 ns at 5 V with 50 pF load, fast enough for 1 MHz SPI bit-bang but marginal above 2 MHz. If you need higher serial throughput, use a true USART-capable part like PIC16F88 or PIC16F690 instead. Place the ICSP PGC/PGD traces as short as possible (<50 mm) to avoid ringing during programming pulses.
Compliance Information
RoHS compliant per DigiKey listing. Lead-free finish consistent with Microchip's transition. Not AEC-Q100 qualified (commercial/industrial grade MCU, not automotive). Halogen-free status not explicitly confirmed in distributor metadata.
