PIC16F631-I/SS - 8-Bit MCU, 20MHz, 1.75KB Flash, SSOP-20 | Microchip
MPN: PIC16F631-I/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.84 | $2.84 |
| 10 | $2.55 | $25.50 |
| 100 | $2.1 | $210.00 |
| 500 | $1.78 | $890.00 |
| 1,000 | $1.45 | $1,450.00 |
PIC16F631-I/SS Overview
A microcontroller (MCU) is a single-chip computer containing a CPU core, program memory (Flash/ROM), data memory (RAM), peripheral set (timers, ADC, communication interfaces), and I/O pins on one integrated circuit. PIC microcontrollers use Microchip's enhanced mid-range 8-bit RISC architecture with only 35 single-cycle instructions (excluding branches), making them easy to program and debug. PIC MCUs belong to the broader category of embedded controllers within the semiconductor device hierarchy: microcontroller -> embedded processor -> integrated circuit -> semiconductor.
Key features include 11 I/O pins, an internal oscillator, a comparator module, an Enhanced Universal Synchronous Asynchronous Receiver Transmitter (EUSART), and nanoWatt power-saving modes. The integrated Flash program memory supports in-circuit serial programming (ICSP), enabling firmware updates after PCB assembly. The device includes a 10-bit ADC (on related family members), though the PIC16F631 variant omits the ADC to optimize cost for applications needing only digital I/O and timing.
The PIC16F631-I/SS uses a Harvard bus architecture with separate program and data memory buses, plus a 14-bit instruction word optimized for compact code density. The wide 2.0V-5.5V supply range allows direct operation from a single Li-Ion cell, two AA cells, or a regulated 3.3V/5V rail, eliminating the need for multiple voltage rails in cost-sensitive designs. The 'I' suffix indicates the industrial temperature range of -40C to +85C.
Typical applications include consumer appliance controls, sensor interface modules, low-cost motor controllers, LED lighting drivers, battery-powered instruments, and white goods user interfaces. The device's combination of small SSOP package, low power consumption, and integrated peripherals makes it especially suitable for space-constrained designs where BOM cost is critical.
When designing with the PIC16F631-I/SS, ensure the ICSP clock and data lines (RB6/RB7) are accessible for in-circuit programming. Decouple VDD with a 0.1uF ceramic capacitor placed close to the pin. Use the internal oscillator when crystal accuracy is not required; otherwise provide an external resonator on OSC1/OSC2.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, providing an information-gain summary that goes beyond a single source.
Drop-in alternatives for PIC16F631-I/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 PIC16F631-I/SS (same form factor and footprint) — differing in I/O Pins, Package, Core Architecture, Supply Voltage (VDD), RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16F631-E/SS
✅ Drop-In✓ In Stock
$1.18 / Unit
View Datasheet →PIC16F631T-I/SS
✅ Drop-In✓ In Stock
$0.92 / Unit
View Datasheet →PIC16F630-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F630T-E/SL
✅ Drop-In✓ In Stock
$1.12 / Unit
View Datasheet →PIC16F628A-I/SS
✅ Drop-In✓ In Stock
$1.41 / Unit
View Datasheet →PIC16F631-I/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC16 enhanced mid-range RISC |
| Program Memory Type | Flash |
| Program Memory Size | 1.75 KB (1K x 14 words) |
| RAM Size | 64 bytes |
| EEPROM Size | 128 bytes |
| Maximum CPU Frequency | 20 MHz |
| Instruction Set | 35 instructions (all single-cycle except branches) |
| Supply Voltage Range | 2.0 V to 5.5 V |
| I/O Pins | 18 (11 general-purpose I/O multiplexed with peripherals) |
| Operating Temperature Range | -40 C to +85 C (Industrial) |
| Package Type | 20-pin SSOP (Shrink Small Outline Package) |
| Mounting Type | Surface Mount |
| Oscillator | Internal 8 MHz + external oscillator support |
| Power-Saving Modes | nanoWatt technology (Sleep, Watchdog timer) |
| Peripherals | Enhanced USART, Comparators, Timer0/1/2, PWM, ICSP |
| MSL Level | MSL1 (unlimited floor life at <30C / 85% RH) |
| RoHS Status | Compliant |
PIC16F631-I/SS Pin Configuration
| Pin 1 | VDD — Positive supply voltage (2.0V to 5.5V) |
| Pin 2 | RA5/T1CKI/OSC1/CLKIN — Port A bit 5 / Timer1 clock input / Oscillator input / External clock input |
| Pin 3 | RA4/T1G/OSC2/CLKOUT — Port A bit 4 / Timer1 gate / Oscillator output / Clock output |
| Pin 4 | RA3/MCLR/VPP — Port A bit 3 / Master Clear reset (active low) / ICSP programming voltage |
| Pin 5 | RC5 — Port C bit 5 |
| Pin 6 | RC4 — Port C bit 4 |
| Pin 7 | RC3/AN7 — Port C bit 3 / Analog channel 7 (comparator) |
| Pin 8 | RC2/AN6 — Port C bit 2 / Analog channel 6 (comparator) |
| Pin 9 | RC1/AN5 — Port C bit 1 / Analog channel 5 (comparator) |
| Pin 10 | RC0/AN4 — Port C bit 0 / Analog channel 4 (comparator) |
| Pin 11 | RC6/AN8 — Port C bit 6 / Analog channel 8 / TX/CK |
| Pin 12 | RC7/AN9 — Port C bit 7 / Analog channel 9 / RX/DT |
| Pin 13 | RB7 — Port B bit 7 / ICSP data |
| Pin 14 | RB6 — Port B bit 6 / ICSP clock |
| Pin 15 | RB5/AN11 — Port B bit 5 / Analog channel 11 |
| Pin 16 | RB4/AN10 — Port B bit 4 / Analog channel 10 |
| Pin 17 | RB3/AN9 — Port B bit 3 / Analog channel 9 |
| Pin 18 | RB2/AN8 — Port B bit 2 / Analog channel 8 |
| Pin 19 | RB1/AN7 — Port B bit 1 / Analog channel 7 |
| Pin 20 | RB0/AN6 — Port B bit 0 / Analog channel 6 |
Typical Applications
PIC16F631-I/SS is suitable for 6 applications: Consumer Appliance Control Boards, Battery-Powered Sensor Modules, LED Lighting Drivers, Industrial Control and User Interfaces, Low-Cost Motor Control, Automotive Aftermarket Accessories.
Consumer Appliance Control Boards
The PIC16F631-I/SS fits consumer appliance control boards such as washing machines, microwave ovens, and rice cookers where cost dominates the BOM. Its 18 I/O pins directly drive 7-segment LED displays, relay coils, and keypad matrix scans without external logic. The 20 MHz CPU executes 5 MIPS, sufficient for PID temperature control loops at 100 Hz update rates. The wide 2.0V-5.5V supply lets the same PCB accept either 3.3V or 5V power bricks. Internal 8 MHz oscillator eliminates crystal cost and the 128-byte EEPROM stores user-setpoints through power cycles. The SSOP-20 package fits beneath the keypad in slim appliance front panels.
Recommended
Battery-Powered Sensor Modules
The PIC16F631-I/SS suits battery-powered sensor modules such as wireless thermostats, door/window contacts, and remote controls thanks to its nanoWatt technology and 2.0V-5.5V supply range. Sleep current below 1 uA extends CR2032 coin-cell life to 5+ years in duty-cycled applications. The 8 MHz internal oscillator eliminates the always-on crystal current draw (~1 mA typical), and the Watchdog timer wakes the MCU at programmable intervals. The 128-byte EEPROM stores calibration constants and device IDs. The SSOP-20 footprint allows compact PCB layouts in space-constrained sensor enclosures.
Recommended
LED Lighting Drivers
The PIC16F631-I/SS drives LED lighting applications such as dimmable bulbs, RGB strips, and signage controllers using its PWM module and Enhanced USART for DMX512 or WS2812 protocol generation. The 20 MHz CPU bit-bangs WS2812 NeoPixel timing within 1% accuracy using tight assembly loops, controlling up to 18 LED channels in parallel. The 2.0V-5.5V supply accepts boost-converter outputs directly, simplifying the power tree. Internal comparators implement over-temperature and over-current protection without external op-amps. The SSOP-20 package sits behind the LED PCB in slim bulb form factors.
Recommended
Industrial Control and User Interfaces
The PIC16F631-I/SS serves industrial control panels, HVAC thermostats, and security keypads where its industrial -40C to +85C temperature range and 18 I/O pins accommodate button matrices, character LCDs, and relay outputs. The Enhanced USART interfaces with industrial sensors using RS-485 transceivers or Modbus RTU protocols. The 128-byte EEPROM stores calibration tables and operator passwords through 1 million erase/write cycles per Microchip datasheet. The SSOP-20 industrial-rated package withstands factory floor vibration and thermal stress.
Recommended
Low-Cost Motor Control
The PIC16F631-I/SS implements low-cost brushed DC motor and small stepper motor control in fans, pumps, valves, and small appliances using its PWM module and Enhanced USART. The 20 MHz CPU generates complementary PWM signals with adjustable dead-time at 20 kHz switching frequency, sufficient for sub-100W motor drives. Comparators detect back-EMF for sensorless commutation in BLDC applications when paired with external signal conditioning. The 2.0V-5.5V supply accepts rectified 5V or 12V wall adapters after regulation. The SSOP-20 fits motor-driver PCBs alongside H-bridge ICs.
Recommended
Automotive Aftermarket Accessories
The PIC16F631-I/SS fits automotive aftermarket accessories such as alarm remotes, gauge drivers, and interior lighting controllers where its industrial temperature range covers cabin environments. The Enhanced USART interfaces with OBD-II diagnostic readers using LIN or K-Line protocols. Internal comparators monitor battery voltage for low-voltage cutoff in always-on accessories. The 2.0V-5.5V supply accepts 12V battery after a simple LDO regulator. The SSOP-20 package meets the size and weight constraints of handheld remote controls and dashboard-mounted modules.
Recommended
Recommended Products Summary
Engineering reference data for PIC16F631-I/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16F631-E/SS | PIC16F631T-I/SS | PIC16F630-I/SS | PIC16F628A-I/SS |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 20-pin SSOP | 20-pin SSOP - same | 20-pin SSOP - same | 20-pin SSOP - same | 20-pin SSOP - same |
| Flash Memory | 1.75 KB | 1.75 KB | 1.75 KB | 0.875 KB (-50%) | 3.5 KB (+100%) |
| RAM Size | 64 bytes | 64 bytes | 64 bytes | 64 bytes | 224 bytes (+250%) |
| Maximum CPU Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| I/O Pins | 18 | 18 | 18 | 12 (-33%) | 16 (-11%) |
| Supply Voltage Range | 2.0V to 5.5V | 2.0V to 5.5V | 2.0V to 5.5V | 2.0V to 5.5V | 3.0V to 5.5V |
| Operating Temperature Range | -40C to +85C | -40C to +125C | -40C to +85C | -40C to +85C | -40C to +85C |
| Enhanced USART | Yes | Yes | Yes | No | Yes |
| Unit Price (qty 1) | $2.84 | ~$3.10 | ~$2.84 | ~$2.20 | ~$3.50 |
Key Differentiators
- Cost-optimized variant of PIC16F family without ADC peripheral (vs PIC16F677-I/SS)
- Lower Flash and I/O count vs enhanced family members (vs PIC16F628A-I/SS)
- nanoWatt technology for battery-powered designs (vs PIC16F630-I/SS)
Design Notes
Estimated: At 20 MHz active mode with all peripherals on, the PIC16F631-I/SS draws approximately 5-8 mA from VDD. Place a 0.1 uF ceramic decoupling capacitor within 5 mm of the VDD pin (pin 1) with a short, wide trace. Add a bulk 10 uF tantalum or ceramic capacitor near the MCU for stable operation during high-current I/O transitions. For battery applications, use Sleep mode (<1 uA) and configure the Watchdog timer to wake at programmable intervals.
The SSOP-20 package has 0.65 mm pitch leads that require careful PCB layout for reliable hand-soldering. Use a land pattern with pad width of 0.40 mm and pad length of 1.50 mm per IPC-7351 nominal-density SSOP-20 guidelines. Apply no-clean solder paste via stencil and reflow in a convection oven with a peak temperature of 245C for lead-free SAC305 alloy. For ICSP programming access, route RB6 (ICSP clock) and RB7 (ICSP data) to a 2x3 or 1x6 header on the PCB edge.
Do not leave the MCLR pin (pin 4) floating - it must be tied to VDD through a 10 kohm resistor for normal operation, or pulled low for external reset. Floating MCLR causes random resets and unreliable startup. Configure CONFIG words (using __CONFIG directive in C or configuration bits in assembly) to select the internal oscillator, disable Watchdog timer if not needed, and enable the Brown-out Reset at appropriate voltage threshold. Failure to set CONFIG bits correctly results in a device that appears bricked until the configuration is corrected via ICSP.
Compliance Information
RoHS and REACH compliant per Microchip product page. Not AEC-Q100 qualified - for automotive applications choose AEC-Q100 qualified variants from PIC16F1xxx family.
