PIC16F84AT-20/SS - 20MHz 8-bit Flash MCU 1.75KB SSOP-20
MPN: PIC16F84AT-20/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.49 | $2.49 |
| 10 | $2.3 | $23.00 |
| 100 | $2.05 | $205.00 |
| 500 | $1.82 | $910.00 |
| 1,000 | $1.6 | $1,600.00 |
PIC16F84AT-20/SS Overview
An 8-bit microcontroller (MCU) is a single-chip computer with an 8-bit data path, on-chip program memory, RAM, I/O peripherals, and a CPU core. It belongs to the wider taxonomy: microcontroller -> embedded processor -> semiconductor -> integrated circuit. The PIC16F8X family uses a RISC Harvard architecture with only 35 single-word instructions, and all instructions execute in one instruction cycle except program branches which take two cycles - making it one of the simplest mid-range PIC families to learn and program.
Key features include 1.75 KB (1K x 14) of self-programmable Flash program memory, 68 bytes of data RAM, 64 bytes of EEPROM data memory, 13 digital I/O pins, an 8-bit timer/counter (TMR0) with an 8-bit prescaler, a 16-bit timer/counter (TMR1), and a Watchdog Timer with its own on-chip RC oscillator. The part supports in-circuit serial programming (ICSP) via RB6 and RB7, enabling firmware updates after PCB assembly.
Architecturally the PIC16F84A integrates a precision 4 MHz internal RC calibration word, a power-on reset, brown-out detect, power-up timer, and the proprietary nanoWatt Technology dynamic power-management features that lower quiescent current in sleep mode. The Harvard bus keeps program and data memory separate, allowing instruction fetch and data access in a single cycle.
Typical applications include hobbyist and educational microcontroller projects, low-cost consumer appliances, automotive body controllers, sensor-interface front-ends, and legacy industrial-control retrofits where the PIC16F84A footprint has been qualified for years. The wide adoption also makes it a frequent BOM choice for educational kits and development boards.
When designing with the PIC16F84AT-20/SS, note that only 13 of the 20 pins are usable as general-purpose I/O because three pins are required for the crystal/oscillator and one for MCLR reset; designers must also budget for the 5V-only supply, since the 'A' revision does not support the 2.0 V minimum of newer PIC16F1xx families.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for PIC16F84AT-20/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-20/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-20/SS
✅ Drop-In✓ In Stock
$1.65 / Unit
View Datasheet →PIC16F84AT-04/SS
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.48 / Unit
View Datasheet →PIC16F84A-20I/SS
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
PIC16F84A-04/SS
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.18 / Unit
View Datasheet →PIC16F628A-20/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F88-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F84AT-20/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC16 Harvard RISC |
| Program Memory | 1.75 KB (1K x 14) Flash |
| Data RAM | 68 bytes |
| Data EEPROM | 64 bytes |
| Maximum Clock Frequency | 20 MHz |
| Instruction Cycle | 200 ns (4 clock periods) |
| Supply Voltage (VDD) | 4.0 V to 5.5 V |
| Number of I/O Pins | 13 |
| Timers | TMR0 (8-bit) + TMR1 (16-bit) + WDT |
| Operating Temperature Range | -40C to +85C (industrial) |
| Package | 20-pin SSOP (5.30 mm body) |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited) |
| ICSP / In-Circuit Programming | Yes (RB6/RB7) |
| Brown-Out Reset | Yes |
| Power-Up Timer | Yes |
| RoHS Status | Compliant |
PIC16F84AT-20/SS Pin Configuration
| Pin 1 | RA2 — PORTA bit 2 (digital I/O) |
| Pin 2 | RA3 — PORTA bit 3 (digital I/O) |
| Pin 3 | RA4/TOCKI — PORTA bit 4 / Timer0 clock input (open-drain) |
| Pin 4 | MCLR/VPP — Master Clear reset (active low) / programming voltage input |
| 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 (ICD clock) |
| Pin 13 | RB7/PGD — PORTB bit 7 / ICSP data (ICD data) |
| Pin 14 | VSS — Ground reference |
| Pin 15 | OSC2/CLKOUT — Crystal/ceramic resonator output or clock out |
| Pin 16 | OSC1/CLKIN — Crystal/ceramic resonator input or external clock in |
| Pin 17 | RA0 — PORTA bit 0 (digital I/O) |
| Pin 18 | RA1 — PORTA bit 1 (digital I/O) |
| Pin 19 | RA4 (duplicate label reserved) — See pin 3 for full RA4/TOCKI function |
| Pin 20 | VDD — Positive supply voltage (4.0 V to 5.5 V) |
Typical Applications
PIC16F84AT-20/SS is suitable for 6 applications: Educational and Hobbyist Microcontroller Projects, Automotive Body Electronics, Sensor Interface Front-Ends, Industrial Control Retrofits, Low-Cost Consumer Appliance Controllers, Remote Control and RF Encoder Sub-systems.
Educational and Hobbyist Microcontroller Projects
The PIC16F84AT-20/SS is one of the most widely adopted microcontrollers in university curricula and hobbyist projects because its 35-instruction RISC core is teachable in a single lab session. With 1.75 KB Flash and 13 I/O pins it fits LED cubes, line-follower robots, and IR remote controls. The SSOP-20 surface-mount package and 4.0-5.5 V supply match USB-powered dev boards. Unlike newer 32-bit Cortex-M0 parts, every PIC16F84A instruction is single-cycle, so students can compute exact loop timing without pipeline overhead. ICSP via RB6/RB7 enables reprogramming without removing the chip from the target board.
Recommended
Automotive Body Electronics
The PIC16F84AT-20/SS has been used in automotive body controllers since the late 1990s for low-speed tasks such as seat-position memory, mirror-fold control, and interior lamp dimming. Its -40C to +85C industrial temperature grade tolerates cabin environments, and 13 digital I/O pins are sufficient to scan a small switch matrix and drive relay coils. The PIC16F84A's 5V-only supply matches legacy 12V-to-5V linear rails common in pre-CAN body modules. AEC-Q100 is not formally listed on the datasheet, but automotive customers have long qualified it for non-safety body functions.
Recommended
Sensor Interface Front-Ends
With a 200 ns instruction cycle and 13 bidirectional I/O, the PIC16F84AT-20/SS is well suited as a front-end MCU that reads a digital sensor (e.g., DS18B20, DHT22, or simple SPI ADC) and forwards the value over UART or a bit-banged protocol. The 68 bytes of RAM accommodate a small command/state-machine buffer, and the 64-byte EEPROM retains calibration constants across power cycles. The 4.0 V minimum supply also pairs naturally with 5V sensor modules still common in industrial measurement.
Recommended
Industrial Control Retrofits
The PIC16F84AT-20/SS is a common BOM item for legacy industrial control boards and retrofits where the original PIC16F84 (non-'A' revision) is being obsoleted. Its Flash memory supports ICSP firmware updates in the field, and the 13 I/O pins can drive opto-isolated inputs and relay outputs for PLC I/O expansion modules. The 20 MHz clock provides deterministic scan times suitable for sub-millisecond safety interlocks. Long Microchip product lifecycle support means production lines built on the 16F84A can be maintained for decades.
Recommended
Low-Cost Consumer Appliance Controllers
Coffee machines, microwave ovens, and washing-machine user-interface boards often use a PIC16F84AT-20/SS to scan keypads, drive 7-segment or LCD displays, and sequence motor relays. The 64-byte EEPROM stores user presets and fault-history logs through power cycles, and the brown-out reset ensures clean startup after brown-outs. The 13 I/O drive LED multiplexing matrices directly without external drivers. The 5V supply aligns with the legacy rectifier-plus-7805 rails found in white goods.
Recommended
Remote Control and RF Encoder Sub-systems
The PIC16F84AT-20/SS is frequently used in 433 MHz / 315 MHz ISM-band remote controls as the encoder MCU, bit-banging Manchester or PWM coding into a SAW-transmitter module. Its 20 MHz clock gives precise 1 us timing resolution needed to stay within ISM-bandwidth regulatory limits. The 13 I/O handle matrix keypads directly, and the ICSP interface lets manufacturers field-update rolling-code schemes without retooling. Low sleep current (typ. <1 uA in nanoWatt mode) extends battery life.
Recommended
Recommended Products Summary
Engineering reference data for PIC16F84AT-20/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16F84A-20/SS | PIC16F84AT-04/SS | PIC16F84A-20I/SS | PIC16F628A-20/SS | PIC16F88-I/SS |
|---|---|---|---|---|---|---|
| Package | SSOP-20 (5.30 mm) | SSOP-20 (5.30 mm) - same | SSOP-20 (5.30 mm) - same | SSOP-20 (5.30 mm) - same | SSOP-20 (5.30 mm) - same | SSOP-20 (5.30 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Max Clock Frequency | 20 MHz | 20 MHz | 4 MHz (-80%) | 20 MHz | 20 MHz | 20 MHz |
| Program Memory (Flash) | 1.75 KB | 1.75 KB | 1.75 KB | 1.75 KB | 3.5 KB (+100%) | 7 KB (+300%) |
| Data RAM | 68 bytes | 68 bytes | 68 bytes | 68 bytes | 224 bytes (+229%) | 368 bytes (+441%) |
| Data EEPROM | 64 bytes | 64 bytes | 64 bytes | 64 bytes | 128 bytes (+100%) | 256 bytes (+300%) |
| Supply Voltage | 4.0 V to 5.5 V | 4.0 V to 5.5 V | 4.0 V to 5.5 V | 4.0 V to 5.5 V | 2.0 V to 5.5 V (wider) | 2.0 V to 5.5 V (wider) |
| Operating Temperature | -40C to +85C | 0C to +70C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
| USART / PWM / ADC | None | None | None | None | USART + PWM + comparator | AUSART + PWM + 10-bit ADC |
| Unit Price (1 pc, USD) | $2.49 | ~$2.40 | ~$2.49 | ~$2.55 | ~$2.10 | ~$2.75 |
Key Differentiators
- Tape-and-reel packaging for SMT production (vs PIC16F84A-20/SS)
- Faster -20 speed grade (20 MHz vs 4 MHz) (vs PIC16F84AT-04/SS)
- Wide installed base and tutorial ecosystem (vs PIC16F628A-20/SS)
Design Notes
The PIC16F84AT-20/SS requires a stable 4.0 V to 5.5 V supply with bulk decoupling of 100 nF ceramic + 10 uF electrolytic placed within 5 mm of VDD (pin 20) and VSS (pin 5/14). The brown-out reset (BOR) is factory-trimmed for 4.0 V typical; designs using 3.3 V sensors must either boost VDD with a charge pump or replace the MCU. The internal power-up timer holds the part in reset for ~72 ms - no external RC delay is needed on MCLR.
Do not confuse the PIC16F84A with the original PIC16F84 (non-A revision). The PIC16F84A adds 4x program memory and improved EEPROM endurance, but the instruction set and register map are otherwise identical. Also note that pin 19 of the SSOP-20 is not bonded out as a unique function - it shares the RA4/TOCKI function with pin 3 in some package variants; consult the Microchip datasheet pinout diagram before routing PCB pads near pin 19.
For SSOP-20 layouts, use 0.4 mm wide copper pads with 0.65 mm pitch, a 0.4 mm solder mask dam, and a NSMD (non-solder-mask-defined) land pattern per IPC-7351. Place the decoupling cap on the same copper layer as the IC pads to minimize loop inductance. The MCLR/VPP pin requires a 10 kohm pull-up to VDD and a 100 nF capacitor to VSS to filter ESD; do not leave it floating in production boards.
OSC1/OSC2 traces should be as short as possible (<10 mm), surrounded by a ground guard ring, and routed away from RB6/RB7 ICSP lines to avoid capacitive coupling that can cause programming failures. If using a high-speed crystal (>10 MHz), add a 10-33 pF load capacitor on each OSC pin to VSS; the exact value depends on crystal CL specification. RS-232 or other noise sources within 5 mm of OSC traces will inject jitter into the instruction cycle.
Compliance Information
RoHS and lead-free compliant per Microchip product page. AEC-Q100 qualification is not formally listed on the datasheet; the -40C to +85C industrial grade is a temperature-grade designation, not an automotive qualification.
