PIC16F636-I/ST - 8-bit MCU, 3.5KB Flash, 20MHz | Microchip
MPN: PIC16F636-I/ST ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.09 | $2.09 |
| 10 | $1.88 | $18.80 |
| 100 | $1.66 | $166.00 |
| 500 | $1.47 | $735.00 |
| 1,000 | $1.29 | $1,290.00 |
PIC16F636-I/ST Overview
An 8-bit microcontroller (MCU) is a small, self-contained computer-on-a-chip that integrates a CPU, program memory, RAM, peripherals and I/O in a single package. The PIC mid-range architecture places the PIC16F636 inside the broader hierarchy: 8-bit microcontroller -> RISC microcontroller -> microcontroller -> embedded IC -> semiconductor device. Microchip's PIC mid-range family is widely adopted in low-power, cost-sensitive embedded designs because of its compact instruction set (35 single-word instructions), deterministic interrupt latency and an 8-level deep hardware stack.
Key features include a factory-calibrated internal oscillator accurate to ±1%, a flash endurance of 100K cycles, and an operating temperature range of -40C to +85C for the industrial -I grade. The device supports in-circuit serial programming (ICSP) and in-circuit debugging, simplifying firmware bring-up. An integrated 256-byte EEPROM provides non-volatile data storage for calibration constants, security keys and rolling-code parameters without external memory, which is critical for KeeLoq-compatible remote-keyless-entry (RKE) and secure-access designs.
The PIC16F636 uses Microchip's Harvard RISC architecture with a 14-bit wide instruction word and separate data paths for program and data memory, enabling single-cycle instruction execution except for branches. Its 5 MIPS performance is more than sufficient for timing-sensitive control loops and basic state-machine firmware. Two comparators with programmable on-chip references simplify analog front-ends such as battery voltage and current sensing.
Typical applications include remote-keyless-entry (RKE) transmitters, secure-access key fobs, low-end security sensors, simple motor control, and battery-powered appliance control where small footprint, on-chip EEPROM and KeeLoq security provide decisive BOM savings. Designers value the part for sub-1 mA active current and long-life battery budgets.
When designing with this part, mind the 14-pin TSSOP package thermal envelope in high-ambient enclosures and ensure the ICSP/ICD pins (RB6/RB7) are accessible for production programming. Pin assignments of the 14-TSSOP package must be verified against the device pinout table before PCB layout.
Drop-in alternatives for PIC16F636-I/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 PIC16F636-I/ST (same form factor and footprint) — differing in Operating Temperature, Package, Core Architecture, Data EEPROM, I/O Pins.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16F636-E/ST
✅ Drop-In✓ In Stock
$1.55 / Unit
View Datasheet →PIC16F636T-I/ST
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F630-I/ST
✅ Drop-In✓ In Stock
$1.05 / Unit
View Datasheet →PIC16F616-I/ML
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.18 / Unit
View Datasheet →PIC16F631-I/SO
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.28 / Unit
View Datasheet →PIC16F636-I/ST Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC mid-range 8-bit RISC |
| Program Memory (Flash) | 3.5 KB (2K x 14 words) |
| Data RAM | 128 bytes |
| Data EEPROM | 256 bytes |
| Maximum Clock Speed | 20 MHz |
| Instruction Throughput | 5 MIPS |
| Instruction Set Size | 35 single-word instructions |
| Hardware Stack | 8 levels |
| I/O Pins | 12 |
| Supply Voltage | 4.5 V to 5.5 V |
| On-chip Oscillator | Factory-calibrated internal RC, ±1% accuracy |
| Operating Temperature | -40 C to +85 C (industrial -I grade) |
| Package | 14-TSSOP (4.40 mm body width, ST suffix) |
| Mounting Type | Surface Mount |
| Peripherals | KeeLoq crypto module, PLVD, 2 comparators |
| Programming/Debug | ICSP and in-circuit debugger on RB6/RB7 |
| Flash Endurance | 100K erase/write cycles (typical) |
| RoHS Status | Compliant |
PIC16F636-I/ST Pin Configuration
| Pin 1 | VDD — Positive supply voltage (4.5V to 5.5V) |
| Pin 2 | RA5/OSC1/CLKIN — General I/O / oscillator input / external clock input |
| Pin 3 | RA4/OSC2/CLKOUT — General I/O / oscillator output / clock output |
| Pin 4 | RA3/MCLR/VPP — General I/O / Master Clear (active-low reset) / programming voltage |
| Pin 5 | RC5 — General I/O port C bit 5 |
| Pin 6 | RC4 — General I/O port C bit 4 |
| Pin 7 | RC3 — General I/O port C bit 3 |
| Pin 8 | RC2 — General I/O port C bit 2 |
| Pin 9 | RC1 — General I/O port C bit 1 |
| Pin 10 | RC0 — General I/O port C bit 0 |
| Pin 11 | RA2/AN2/CVREF — General I/O / analog input 2 / comparator voltage reference output |
| Pin 12 | RA1/AN1/C1IN- — General I/O / analog input 1 / comparator 1 inverting input |
| Pin 13 | RA0/AN0/C1IN+ — General I/O / analog input 0 / comparator 1 non-inverting input |
| Pin 14 | VSS — Ground reference (0 V) |
Typical Applications
PIC16F636-I/ST is suitable for 6 applications: KeeLoq Remote Keyless Entry (RKE) Transmitters, Garage Door Openers and Gate Controls, Battery-Powered Security Sensors, Industrial Remote Control Handsets, Small Appliance and Consumer Electronics Control, Automotive Aftermarket Alarm Systems.
KeeLoq Remote Keyless Entry (RKE) Transmitters
The PIC16F636-I/ST is purpose-built for KeeLoq-compatible secure RKE key fobs where 256-byte on-chip EEPROM stores rolling-code keys and 12 I/O lines drive push-buttons, LED indicators and SAW-resonator-based RF transmitters. The on-chip KeeLoq hardware engine handles encryption and decryption of 32-bit hopping-code transmissions at the 5 MIPS throughput the device delivers, enabling under-20 ms code-response latency with low MCU load. Battery life benefits from the part's low active current and ability to wake from interrupt on button-press, making it ideal for coin-cell-powered key fobs where standby drain directly determines service interval.
Recommended
Garage Door Openers and Gate Controls
Garage door openers and gate controllers benefit from the PIC16F636-I/ST's KeeLoq crypto module and 256-byte EEPROM for storing secure rolling codes shared with the receiver module. The 20 MHz instruction rate supports sub-100 ms button-to-RF transmission cycles while the 14-TSSOP package simplifies integration into hand-held transmitter housings. Two on-chip comparators can monitor battery voltage through an external resistor divider, triggering low-battery warning transmissions before the cell becomes unreliable, an important safety consideration for residential and commercial access-control deployments.
Recommended
Battery-Powered Security Sensors
Wireless PIR motion, door/window contact, and glass-break sensors pair well with the PIC16F636-I/ST in 5V coin-cell or AA-powered designs. The factory-calibrated ±1% internal RC oscillator eliminates crystal cost and reduces PCB area, while the 256-byte EEPROM stores calibration coefficients and zone identifiers. The on-chip PLVD (Programmable Low-Voltage Detect) module generates an interrupt below a user-set Vdd threshold, allowing the firmware to send a 'low-battery' event over RF before cell voltage collapses. With 12 I/O pins the MCU directly drives PIR analog, reed-switch inputs, status LEDs and a low-power RF transmitter.
Recommended
Industrial Remote Control Handsets
Crane, hoist and industrial equipment remote-control handsets leverage the PIC16F636-I/ST's KeeLoq hardware module for secure command authentication, reducing the risk of replay or spoofed-control events. The 12 I/O pins support multi-button joysticks, deadman switches and emergency-stop wiring with hardware interrupts, while the 5V industrial supply rail is directly compatible with the 4.5 V to 5.5 V Vdd range. The industrial -I temperature grade (-40 C to +85 C) covers outdoor and factory-ambient operation, and the 14-TSSOP package withstands vibration typical of heavy-machinery cabs.
Recommended
Small Appliance and Consumer Electronics Control
Coffee makers, rice cookers, blenders and similar small appliances use the PIC16F636-I/ST for cost-sensitive user-interface and timing control. The 5 MIPS throughput drives PWM outputs for motor-speed or heater control loops while 256 bytes of EEPROM store user-preset cooking profiles. Two comparators monitor temperature thermistor voltages with on-chip programmable voltage reference, eliminating the need for external analog comparators. The 14-TSSOP package keeps board cost low in high-volume SKUs while the 35-instruction RISC core enables short firmware cycles for time-to-market advantage.
Recommended
Automotive Aftermarket Alarm Systems
Aftermarket automotive alarm and anti-theft modules employ the PIC16F636-I/ST for key-fob authentication via KeeLoq rolling code and for in-vehicle sensor monitoring. The PIC's two comparators interface directly with shock, tilt and glass-break sensors, while 12 I/O lines drive sirens, indicator LEDs and starter-kill relays. Although the -I industrial grade covers most climate conditions, automotive deployments at extreme temperatures can substitute the PIC16F636-E/ST (extended -40 C to +125 C grade) without firmware change. Designers should add external ESD protection on automotive connector pins.
Recommended
Recommended Products Summary
Engineering reference data for PIC16F636-I/ST — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16F636-E/ST | PIC16F636T-I/ST | PIC16F630-I/ST | PIC16F631-I/SO |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 14-TSSOP (ST) | 14-TSSOP (ST) - same | 14-TSSOP (ST) - same | 14-TSSOP (ST) - same | SOIC-14 (cross-package, but pin-compatible) |
| Program Memory (Flash) | 3.5 KB | 3.5 KB | 3.5 KB | 1 KB | 1.75 KB |
| Data RAM | 128 bytes | 128 bytes | 128 bytes | 64 bytes | 128 bytes |
| Data EEPROM | 256 bytes | 256 bytes | 256 bytes | None | 256 bytes |
| KeeLoq Crypto Module | Yes (on-chip) | Yes (on-chip) | Yes (on-chip) | No | No |
| Operating Temperature | -40 C to +85 C (industrial -I) | -40 C to +125 C (extended -E) | -40 C to +85 C (industrial -I) | -40 C to +85 C (industrial -I) | -40 C to +85 C (industrial -I) |
| Supply Voltage | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V |
Key Differentiators
- On-chip KeeLoq-compatible cryptographic hardware (vs PIC16F630-I/ST)
- 256 bytes of on-chip data EEPROM (vs PIC16F630-I/ST)
- Extended temperature grade option in same footprint (vs PIC16F636-E/ST (companion))
Design Notes
Estimated: For an RKE key fob running at 4 MHz internal oscillator, the PIC16F636-I/ST active current is below 1 mA typical at 5V. Sleep current drops to sub-1 µA when the CPU is halted and only the watchdog timer or interrupt-on-change wakes the part. Place a 100 nF decoupling capacitor within 5 mm of Vdd (pin 1) and a bulk 10 µF tantalum or ceramic on the battery terminal to handle the RF transmitter load transients.
Estimated: The 14-TSSOP package occupies roughly 5 mm x 4.4 mm with 0.65 mm pitch. Allow at least 0.20 mm trace-and-space rules on a 1 oz copper, two-layer FR-4 board to maintain manufacturability. Keep the Vdd trace short and wide (≥0.3 mm) and route the MCLR pull-up (typically 10 kOhm) directly to Vdd with no series inductance to ensure reliable in-circuit serial programming during production.
Do not omit the 10 kOhm MCLR pull-up on pin 4 (RA3/MCLR/VPP) - leaving MCLR floating makes the part vulnerable to brown-out reset and prevents ICSP entry. Configure CONFIG bits correctly in the hex file before programming to avoid locking out the part. When using the on-chip KeeLoq engine, follow Microchip's TB078 application note for EEPROM endurance and key-storage best practices to protect against side-channel attacks.
Compliance Information
RoHS and lead-free confirmed on DigiKey and Mouser product pages. AEC-Q100 not qualified - for automotive safety-critical applications consider PIC16F636-E/ST with extended temperature grade or an AEC-Q100 qualified PIC16 family member. Halogen-free per Microchip's material declaration.
