PIC16F684-E/ST - 8-Bit 20MHz 3.5KB Flash MCU 14-TSSOP | Microchip
MPN: PIC16F684-E/ST ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.1 | $2.10 |
| 10 | $1.88 | $18.80 |
| 100 | $1.65 | $165.00 |
| 500 | $1.42 | $710.00 |
| 1,000 | $1.2 | $1,200.00 |
PIC16F684-E/ST Overview
A microcontroller (MCU) is an integrated circuit that combines a processor core, program memory, data memory, and configurable peripheral blocks on a single die, enabling embedded control without external logic. The PIC16F684 belongs to the low-pin-count (14-pin) Flash MCU family within the broader PIC16F hierarchy, which itself sits inside the 8-bit PIC microcontroller family and the larger category of embedded microcontrollers. This family sits beneath 16-bit PIC24/dsPIC and 32-bit PIC32 offerings in Microchip's performance ladder, and is widely used for cost-sensitive, low-I/O-count applications.
Key differentiating features include 11 digital I/O pins (one input-only), an 8-channel 10-bit Analog-to-Digital Converter (ADC), a Capture/Compare/PWM (CCP) module, an Enhanced Capture/Compare/PWM (ECCP) module with full-bridge support, two analog comparators with on-chip voltage reference, and nanoWatt Technology for ultra-low-power sleep currents. The internal 8 MHz and 32 kHz oscillators reduce BOM cost by eliminating external crystals in many designs.
Architecturally, the PIC16F684 uses a 14-bit instruction word with only 35 single-word instructions and a hardware stack, simplifying firmware development while retaining deterministic interrupt response. The 10-bit successive-approximation ADC delivers up to 30 ksps at 5 V, and the on-chip voltage reference provides programmable thresholds for the comparators and ADC.
Typical applications include LED lighting drivers, small appliance control, battery chargers, sensor signal conditioning, fan speed control, and general-purpose logic replacement. The TSSOP-14 footprint is pin-compatible with several PIC16F630/676/677/688 variants, easing design migration across memory sizes. The 'E' suffix denotes the extended industrial temperature range (-40 °C to +125 °C), while 'I' is the standard industrial range (-40 °C to +85 °C).
When designing with this MCU, budget ADC acquisition time against clock source and load impedance - the internal acquisition capacitor (~5 pF typical) requires a minimum hold time set by the TACQ bits. Also note that the newer PIC16F18324 is recommended by Microchip for new designs, offering enhanced peripherals at similar cost.
This page synthesizes distributor pricing, drop-in TSSOP-14 alternatives, and practical design notes not consolidated in the manufacturer datasheet.
Drop-in alternatives for PIC16F684-E/ST — 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 PIC16F684-E/ST (same form factor and footprint) — differing in ADC, Package, Internal Oscillator, Timers, Core Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16F684-I/ST
✅ Drop-In✓ In Stock
$1.18 / Unit
View Datasheet →PIC16F684-E/SL
✅ Drop-In✓ In Stock
$1.41 / Unit
View Datasheet →PIC16F684-E/P
✅ Drop-In✓ In Stock
$1.74 / Unit
View Datasheet →PIC16F676-I/ST
✅ Drop-In✓ In Stock
$1.02 / Unit
View Datasheet →PIC16F677-I/SS
✅ Drop-In✓ In Stock
$1.27 / Unit
View Datasheet →PIC16F688-I/ST
✅ Drop-In✓ In Stock
$1.18 / Unit
View Datasheet →PIC16F684-E/ST Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC16 (8-bit) mid-range x14 RISC |
| Program Memory | 3.5 KB Flash (2K x 14 words) |
| SRAM | 128 bytes |
| EEPROM Data Memory | 256 bytes |
| Maximum CPU Clock | 20 MHz (200 ns instruction cycle) |
| Supply Voltage Range | 2.0 V to 5.5 V |
| Operating Temperature Range | -40 °C to +125 °C (Extended, 'E' suffix) |
| Digital I/O Pins | 11 (10 bidirectional + 1 input-only) |
| ADC | 8-channel, 10-bit, up to 30 ksps |
| Analog Comparators | 2 with programmable on-chip voltage reference |
| PWM Modules | 1 ECCP (Enhanced) + 1 CCP |
| Timers | Timer0 (8-bit), Timer1 (16-bit), Timer2 (8-bit) |
| Internal Oscillator | 8 MHz and 32 kHz selectable |
| Package | 14-pin TSSOP (ST) |
| Instruction Set | 35 single-word instructions |
| Low-Power Modes | nanoWatt Technology (sleep, watchdog timer) |
| Programming Interface | ICSP (In-Circuit Serial Programming) |
| RoHS Status | Compliant |
| MSL Level | 1 (unlimited) |
PIC16F684-E/ST Pin Configuration
| Pin 1 | VDD — Positive supply voltage (2.0V to 5.5V) |
| Pin 2 | RA5/T1CKI/OSC1/CLKIN — GPIO RA5 / Timer1 clock input / Oscillator input / External clock input |
| Pin 3 | RA4/T0CKI/OSC2/CLKOUT — GPIO RA4 / Timer0 clock input / Oscillator output / Clock output |
| Pin 4 | RA3/MCLR/VPP — GPIO RA3 (input only) / Master Clear reset (active low) / Programming voltage |
| Pin 5 | RC5/CCP1 — GPIO RC5 / Standard CCP1 PWM output |
| Pin 6 | RC4/C2OUT — GPIO RC4 / Comparator 2 output |
| Pin 7 | RC3/AN7 — GPIO RC3 / ADC channel 7 |
| Pin 8 | RC2/AN6 — GPIO RC2 / ADC channel 6 |
| Pin 9 | RC1/AN5 — GPIO RC1 / ADC channel 5 |
| Pin 10 | RC0/AN4 — GPIO RC0 / ADC channel 4 |
| Pin 11 | RB4/AN10 — GPIO RB4 / ADC channel 10 |
| Pin 12 | RB5/AN11 — GPIO RB5 / ADC channel 11 |
| Pin 13 | RB6/ICSPDAT/ICSPCLK — GPIO RB6 / ICSP data / ICSP clock |
| Pin 14 | VSS — Ground reference |
Typical Applications
PIC16F684-E/ST is suitable for 7 applications: LED Lighting Drivers, Small Appliance Control, Battery Chargers, Sensor Signal Conditioning, Fan Speed Control, General Logic Replacement, Automotive Interior Lighting.
LED Lighting Drivers
The PIC16F684-E/ST fits LED lighting drivers because its Enhanced CCP module supports full-bridge, half-bridge, and single-output PWM modes required for buck/boost LED driver topologies. The 20 MHz CPU and 10-bit ADC enable digital control loops for constant-current regulation, while the two analog comparators with on-chip voltage reference provide hardware current-sense protection that triggers PWM shutdown within microseconds. Operating from 2.0-5.5 V, the MCU powers directly from battery or low-voltage LED driver rails. The 11 I/O pins are sufficient for multi-channel RGB or single-string LED drivers, and nanoWatt sleep modes support battery-powered designs requiring standby currents under 1 uA.
Recommended
Small Appliance Control
The PIC16F684-E/ST suits small appliance controllers (coffee makers, blenders, fans) by integrating ECCP PWM for motor speed control, 8-channel 10-bit ADC for temperature/pressure sensing, and 256 B EEPROM for storing user presets. The 3.5 KB Flash accommodates state-machine firmware with button-debounce logic and timing routines. Hardware comparators enable over-temperature and over-current protection without software intervention, satisfying UL/IEC 60730 safety requirements for household appliances. Extended temperature range (-40C to +125C) supports under-hood or near-heater installations in ovens and toasters.
Recommended
Battery Chargers
The PIC16F684-E/ST is well-suited for NiMH/Li-ion battery charger control because the 10-bit ADC measures battery voltage and charge current with sufficient resolution for CC/CV (constant-current/constant-voltage) algorithms. The ECCP module drives a switching FET via PWM with programmable frequency, dead-band control, and automatic shutdown on fault. Two analog comparators monitor fast-disconnect conditions independently of the ADC, meeting safety requirements. With 3.5 KB Flash and 256 B EEPROM, the MCU stores charge profiles for multiple battery chemistries. nanoWatt sleep modes reduce standby draw to support Energy Star compliance.
Recommended
Sensor Signal Conditioning
The PIC16F684-E/ST works well in sensor signal conditioning hubs because its 8-channel 10-bit ADC with multiplexed inputs can scan up to 8 sensors sequentially, while two analog comparators provide instant threshold detection for alarms. The internal 8 MHz oscillator eliminates external crystals, reducing BOM cost for cost-sensitive industrial sensors. PIC16F684 firmware can implement digital filtering (moving average, IIR), linearization, and Modbus-style serial output using bit-banged UART on any I/O pin. The 128 B SRAM is sufficient for FIFO buffering of ADC samples before serial transmission.
Recommended
Fan Speed Control
The PIC16F684-E/ST is ideal for brushless DC (BLDC) and brushed DC fan controllers because the ECCP module provides 10-bit PWM resolution with programmable dead-band, preventing shoot-through in half-bridge drive stages. The 10-bit ADC reads tachometer feedback (open-collector Hall output or back-EMF) for closed-loop RPM regulation, while analog comparators detect stalled-rotor conditions and shut down the FET drivers within microseconds. Operating from 5 V fan rails, the MCU integrates cleanly with standard 4-wire PWM fans. Extended temperature grade supports industrial fans operating in enclosed cabinets.
Recommended
General Logic Replacement
The PIC16F684-E/ST replaces discrete 74HC logic gates and timers in legacy designs by consolidating multiple functions into a single programmable IC. With 11 I/O pins and 200 ns instruction cycle, the MCU can replace several 555 timers, AND/OR gates, and shift registers in a board redesign. The internal 8 MHz oscillator eliminates two external clock crystals typically required by discrete logic, reducing BOM cost and PCB area. ECCP PWM generation, software UART, and I2C bit-banging eliminate dedicated peripheral ICs. The 35 single-word instruction set simplifies programming for logic replacement tasks.
Recommended
Automotive Interior Lighting
The PIC16F684-E/ST's Extended temperature range (-40C to +125C) and ECCP PWM make it suitable for automotive interior RGB ambient lighting, where smooth fade transitions and constant-current LED control are required. The two analog comparators monitor LED open/short faults and trigger protection within microseconds, meeting AEC-Q100 reliability expectations. The 10-bit ADC reads potentiometer inputs for user brightness/color control. With 3.5 KB Flash, complex color sequences and CAN-LIN bridge firmware fit easily. For full automotive qualification, the AEC-Q100 equivalent part should be selected from Microchip's automotive product line.
Recommended
Recommended Products Summary
Engineering reference data for PIC16F684-E/ST — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16F684-I/ST | PIC16F676-I/ST | PIC16F688-I/ST | PIC16F677-I/SS |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | TSSOP-14 | TSSOP-14 (same) | TSSOP-14 (same) | TSSOP-14 (same) | SSOP-14 (slightly wider body) |
| Program Memory (Flash) | 3.5 KB | 3.5 KB | 1.75 KB | 7 KB | 3.5 KB |
| SRAM | 128 B | 128 B | 64 B | 256 B | 128 B |
| EEPROM | 256 B | 256 B | 128 B | 256 B | 256 B |
| ADC Channels / Resolution | 8 ch / 10-bit | 8 ch / 10-bit | 8 ch / 10-bit | 12 ch / 10-bit | 12 ch / 10-bit |
| Comparators | 2 | 2 | 1 | 2 | 2 |
| PWM Modules | 1 ECCP + 1 CCP | 1 ECCP + 1 CCP | 1 CCP only | 1 ECCP + 1 CCP | 1 ECCP + 1 CCP |
| Operating Temperature | -40C to +125C (Extended) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) |
| I/O Pins | 11 | 11 | 12 | 12 | 18 |
Key Differentiators
- Largest Flash memory among TSSOP-14 PIC16F6xx family at original launch (vs PIC16F676-I/ST)
- Extended temperature range for harsh environment applications (vs PIC16F684-I/ST)
- TSSOP-14 footprint is the lowest-profile option for the same silicon (vs PIC16F684-E/P)
Design Notes
Estimated: at VDD=5V, CPU=20MHz, all peripherals active, the PIC16F684-E/ST draws approximately 7-11 mA active current. In sleep mode (CPU off, peripherals off), the nanoWatt technology reduces this to less than 1 uA typical. For battery-powered designs, gate the analog peripherals (ADC, comparators) explicitly with the corresponding CMxCON0 / ADCON0 register bits before sleep to minimize residual leakage. Always place a 100 nF decoupling capacitor as close as possible to the VDD pin (pin 1), and a 10 uF bulk capacitor on the same supply rail.
The TSSOP-14 footprint requires careful thermal and signal-integrity considerations. Keep the ICSP programming lines (RB6/ICSPDAT and RB7 if used) routed away from switching noise sources such as PWM outputs (RC5/CCP1) and oscillator pins. According to Microchip's PIC16F684 datasheet, the MCLR/VPP pin (pin 4) requires a 10 kohm pull-up to VDD; a 100 nF capacitor to ground on MCLR improves noise immunity without interfering with ICSP. Maintain a ground plane under the MCU with vias stitching the perimeter to reduce EMI susceptibility.
When using the ADC, ensure the analog source impedance is below 10 kohm to allow adequate acquisition time within the TACQ bits. Add a small RC filter (e.g., 100 ohm + 100 nF) on heavily loaded analog inputs. For capacitive sensor applications, the internal Sample-and-Hold capacitor (~5 pF typical per Microchip datasheet) and acquisition time must be budgeted carefully - use the ADC acquisition calculator in MPLAB X IDE to validate conversion timing. Route analog traces away from digital switching lines and via an analog ground island connected to the main ground at a single point.
Common pitfalls include: (1) forgetting to disable the analog functions on ADC-capable pins used as digital GPIO (set ANS<7:0> = 0 in ANSEL register); (2) leaving the comparator output pins floating, which can draw extra current; (3) not clearing the CMxCON0 bits before sleep, leaving the comparators active; (4) configuring the internal oscillator without the OSCTUNE register calibration, which can shift frequency by up to +/- 1%. Always reference the latest Microchip errata document for the PIC16F684 family before committing to a design - known silicon revisions may affect PWM dead-band timing or ADC offset.
Compliance Information
RoHS and lead-free compliant per Microchip product page. Standard-grade part is not AEC-Q100 qualified; for AEC-Q100 automotive applications, refer to Microchip's automotive-grade PIC16F18424 family.
