PIC12F635T-I/SN - 8-bit 20MHz MCU 1.75KB Flash 8-SOIC | Microchip
MPN: PIC12F635T-I/SN ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.88 | $1.88 |
| 10 | $1.69 | $16.90 |
| 100 | $1.46 | $146.00 |
| 500 | $1.28 | $640.00 |
| 1,000 | $1.12 | $1,120.00 |
PIC12F635T-I/SN Overview
A microcontroller (MCU) is a single-chip computer that contains a processor core, non-volatile program memory, volatile data memory, and peripherals such as timers, communication interfaces, and analog blocks. In the component taxonomy, the PIC12F635 belongs to the PIC12 mid-range family -> 8-bit PIC microcontrollers -> microcontrollers (MCU) -> embedded processors -> integrated circuits (ICs). The mid-range core implements a 14-bit instruction set optimized for compact code density in low-pin-count applications.
Key features of the PIC12F635T-I/SN include: 1.75 KB self-programmable FLASH (100K erase/write cycles typical), 64 bytes SRAM, 128 bytes EEPROM, an internal 4 MHz / 8 MHz oscillator configurable to 31 kHz LF, hardware EUSART for RS-232/RS-485 links, two analog comparators with programmable reference, an extended instruction set for C-compiler efficiency, and nanoWatt power management with multiple sleep modes. The device operates from 2.0 V to 5.5 V across the -40 C to +85 C industrial temperature range.
The PIC12F635 uses Microchip's enhanced mid-range 8-bit core with a hardware multiply, indirect/relative addressing, and a single-cycle instruction pipeline at 20 MHz (200 ns instruction cycle). On-chip in-circuit debug (ICD) and In-Circuit Serial Programming (ICSP) eliminate the need for an external programmer for development and field firmware updates, lowering total BOM cost.
Typical applications include low-cost sensor interface nodes, PIR motion detectors, LED dimming controllers, battery chargers, automotive body controllers, small appliance controls, and remote RF transmitter companion logic. The internal oscillator plus nanoWatt modes make the part especially attractive for battery-powered designs where 8 pins are sufficient.
When designing with the PIC12F635T-I/SN, observe the absolute-maximum VDD of 7.5 V and place a 0.1 uF decoupling capacitor within 3 mm of the VDD pin. For analog comparator or ADC-like voltage references, add a 10 uF bulk capacitor to reduce switching noise. Always run Microchip's MPASM or XC8 toolchain with the --ROM option below 1.75 KB to preserve ICD space.
This page synthesizes distributor pricing, drop-in same-package alternatives from the PIC12F family, and practical design notes not consolidated in the Microchip datasheet.
Drop-in alternatives for PIC12F635T-I/SN — 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 PIC12F635T-I/SN (same form factor and footprint) — differing in Package, MSL Level, Internal Oscillator, Operating Temperature, Program Memory (Flash).
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC12F635-I/SN
✅ Drop-In📋 Reference alternative (not in catalog)
PIC12F635T-I/MD
✅ Drop-In✓ In Stock
$0.3 / Unit
View Datasheet →PIC12F635-I/MF
✅ Drop-In✓ In Stock
$0.88 / Unit
View Datasheet →PIC12F635-E/SN
✅ Drop-In✓ In Stock
$0.62 / Unit
View Datasheet →PIC12F683-I/SN
✅ Drop-In📋 Reference alternative (not in catalog)
PIC12F675-I/SN
✅ Drop-In✓ In Stock
$0.74 / Unit
View Datasheet →ATtiny13A-SU
✅ Drop-In📋 Reference alternative (not in catalog)
PIC12F635T-I/SN Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit enhanced mid-range |
| Program Memory (Flash) | 1.75 KB (1K x 14) |
| Data RAM | 64 bytes |
| Data EEPROM | 128 bytes |
| Maximum CPU Clock | 20 MHz |
| Instruction Cycle | 200 ns at 20 MHz |
| Supply Voltage (VDD) | 2.0 V to 5.5 V |
| I/O Pins | 6 |
| Timers | Timer0 (8-bit), Timer1 (16-bit) |
| Communication | EUSART (RS-232/RS-485) |
| Analog Peripherals | 2 comparators with programmable reference |
| Special Features | Watchdog Timer, Brown-Out Detect, Power-On Reset, ICD, ICSP |
| Operating Temperature | -40 C to +85 C (Industrial) |
| Package | 8-SOIC (3.90 mm body) |
| Mounting Type | Surface Mount |
| MSL Level | 1 |
| RoHS Status | Compliant |
| Lead-Free | Yes |
PIC12F635T-I/SN Pin Configuration
| Pin 1 | VDD — Positive supply voltage (2.0 V to 5.5 V) |
| Pin 2 | GP5/T1CKI/OSC1/CLKIN — GPIO / Timer1 clock input / crystal oscillator input / external clock input |
| Pin 3 | GP4/T1G/OSC2/CLKOUT — GPIO / Timer1 gate / crystal oscillator output / clock out (Fosc/4) |
| Pin 4 | GP3/MCLR/VPP — GPIO / Master Clear reset (active low) / ICSP programming voltage input |
| Pin 5 | GP2/T0CKI/INT/COUT/AN3 — GPIO / Timer0 clock input / external interrupt / comparator output / analog channel 3 |
| Pin 6 | GP1/CIN-/ICSPCLK — GPIO / comparator negative input / ICSP clock |
| Pin 7 | GP0/CIN+/ICSPDAT — GPIO / comparator positive input / ICSP data |
| Pin 8 | VSS — Ground reference |
Typical Applications
PIC12F635T-I/SN is suitable for 6 applications: PIR Motion Sensor Controller, Battery Charger Controller, LED Dimmer and Lighting Controller, Automotive Body Electronics Module, Remote RF Transmitter Companion Logic, Small Appliance Control Board.
PIR Motion Sensor Controller
The PIC12F635T-I/SN is well suited for PIR motion-sensor controller nodes because its two on-chip analog comparators can directly interface to the PIR element preamplifier output without an external op-amp, while the nanoWatt sleep mode keeps idle current below 1 uA for battery-powered detectors. At 20 MHz the core can run the motion-detection state machine, debounce the analog comparator output, and drive a relay or TRIAC within microseconds. The 6 GPIO are sufficient for PIR input, LED indicator, relay driver, and ICSP programming without external mux. Designers should connect the PIR element to GP1/CIN+ and GP0/CIN+ inputs and use the internal comparator reference for threshold detection, saving a comparator IC and several passive components versus discrete designs.
Recommended
Battery Charger Controller
For single-cell Li-ion or NiMH charger designs, the PIC12F635T-I/SN provides a CC/CV control loop running from the on-chip 8-bit Timer0 and one analog comparator, with the 128-byte EEPROM storing calibration constants and charge-termination parameters. The 2.0 V minimum supply enables direct operation from a single Li-ion cell during the low-voltage pre-charge phase, while the 5.5 V maximum accommodates USB-derived rails. The EUSART allows SMBus or UART communication with a host BMS for state-of-charge reporting. Programming via ICSP through the GP0/GP1 pins leaves all six GPIO free for charger hardware, eliminating an external programmer connector in production.
Recommended
LED Dimmer and Lighting Controller
The PIC12F635T-I/SN drives LED dimmers and small lighting controllers using its 16-bit Timer1 for PWM generation and the internal 8 MHz oscillator for timing accuracy without external crystals. In a trailing-edge TRIAC dimmer, the comparator detects zero-cross events and Timer1 schedules the TRIAC firing pulse; in a DC LED dimmer, Timer0 generates the PWM at 1-2 kHz to avoid flicker. The 6 GPIO easily support a TRIAC gate, zero-cross sense, dimming pot ADC input, and status LED, while nanoWatt sleep modes keep standby consumption under 1 uA for Energy Star compliance.
Recommended
Automotive Body Electronics Module
Automotive body controllers such as door lock modules, mirror adjusters, and rain-sensor interfaces use the PIC12F635T-I/SN for its small 8-SOIC footprint, 2.0-5.5 V supply tolerance to 12 V battery transients (with external TVS clamp), and industrial -40 C to +85 C operating range. The EUSART interfaces to a LIN or RS-485 bus for body-network communication, while the two comparators handle current sensing for short-circuit protection. For underhood applications above +85 C, designers should migrate to PIC12F635-E/SN which extends to +125 C. The 1.75 KB FLASH fits typical body-control state machines comfortably.
Recommended
Remote RF Transmitter Companion Logic
As a companion controller to a 315/433/868 MHz SAW-based RF transmitter, the PIC12F635T-I/SN handles button-matrix scanning, encoding, and security-code generation in 8-pin SOIC form. The 1.75 KB FLASH accommodates fixed-code or learning-code protocols like PT2262 or EV1527 emulation, while the internal oscillator eliminates the external resonator that would otherwise consume 2 GPIO pins. The Watchdog Timer and BOD keep the device locked during brownout events in battery-transmitter designs, extending battery life to multi-year levels.
Recommended
Small Appliance Control Board
Small consumer appliances such as coffee makers, blenders, and humidifiers use the PIC12F635T-I/SN as the single-chip controller for push-button input, motor TRIAC drive, temperature-sensor interface via comparator, and status LED. The 8-SOIC package fits easily on compact appliance PCBs, while ICSP programming allows firmware updates through test pads without a header connector. The nanoWatt sleep modes extend battery life in cordless appliances, and the industrial -40 C to +85 C range covers kitchen and laundry environments. EEPROM storage of user preferences survives power cycles without external NVRAM.
Recommended
Recommended Products Summary
Engineering reference data for PIC12F635T-I/SN — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC12F635-I/SN | PIC12F635T-I/MD | PIC12F635-I/MF | PIC12F635-E/SN | PIC12F683-I/SN |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 8-SOIC | 8-SOIC | 8-DFN | 8-DFN | 8-SOIC | 8-SOIC |
| Program Memory (FLASH) | 1.75 KB | 1.75 KB | 1.75 KB | 1.75 KB | 1.75 KB | 3.5 KB |
| Data RAM | 64 bytes | 64 bytes | 64 bytes | 64 bytes | 64 bytes | 128 bytes |
| Data EEPROM | 128 bytes | 128 bytes | 128 bytes | 128 bytes | 128 bytes | 256 bytes |
| Maximum Clock | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| ADC | None | None | None | None | None | 10-bit |
| EUSART | Yes | Yes | Yes | Yes | Yes | Yes |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +125 C | -40 C to +85 C |
| Approx. 1000-piece Price (USD) | $1.12 | $1.12 | $1.20 | $1.20 | $1.35 | $1.65 |
Key Differentiators
- Internal oscillator and EUSART in 8 pins (vs PIC12F629-I/SN)
- Enhanced mid-range core with hardware multiply (vs PIC12F675-I/SN)
- Industrial temperature range with extended variant available (vs ATtiny13A-SU)
Design Notes
Place a 0.1 uF ceramic decoupling capacitor within 3 mm of the VDD pin (pin 1) and a 10 uF bulk capacitor on the same node for switching-noise suppression. For battery-powered designs, the nanoWatt Sleep mode draws typically < 1 uA at 2 V; use the Watchdog Timer to wake the core periodically and keep cumulative active time below 0.1 percent of the duty cycle to maximize battery life. Always respect the absolute maximum VDD of 7.5 V; add a TVS diode if the supply is derived from an inductive or automotive 12 V rail.
Pin 4 (GP3/MCLR/VPP) is input-only - configuring it as output is not permitted and will fail verification. The MCLR function is enabled by configuration bit MCLRE; if left enabled, ensure the pin is pulled high via a 10 kohm resistor to VDD, never tied directly, to avoid programming-voltage contention during ICSP. When using the internal oscillator, clear the FOSC configuration bits to select INTOSC; failure to do this is a common factory-returns cause.
Route the ICSP signals (ICSPCLK on GP1 and ICSPDAT on GP0) with short, parallel traces to a 6-pin header or test-pad cluster for in-circuit programming access. Keep analog comparator input traces (GP0, GP1) away from switching nodes such as the TRIAC gate or PWM drive; add a 10 kohm series resistor at the comparator input for ESD protection. For designs using the external oscillator, place the crystal within 5 mm of pins 2 and 3 with grounded guard traces to reduce EMI pickup.
Estimated: at 20 MHz Fosc the EUSART can sustain reliable communication up to 115200 baud with a 0.5 percent clock-accuracy budget. If the internal 4 MHz or 8 MHz oscillator is used without calibration, expect +/- 2 percent frequency error across temperature, which limits RS-485 bus length to approximately 100 m at 9600 baud. For longer buses or higher baud rates, switch to a crystal oscillator or use the PIC12F683-I/SN which provides a calibrated 1 percent internal oscillator option. Always add a 100 ohm termination resistor at each end of the RS-485 bus.
Compliance Information
RoHS and REACH compliant per Microchip product page. Not AEC-Q100 qualified; for AEC-Q100 automotive applications, contact Microchip regarding PIC12F635 automotive-grade variants or use PIC16F series with explicit Q-1 suffix.
