PIC16F636-E/ST - 8-Bit MCU, 3.5KB Flash, 20MHz, 14-TSSOP | Microchip
MPN: PIC16F636-E/ST ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.42 | $2.42 |
| 10 | $2.18 | $21.80 |
| 100 | $1.95 | $195.00 |
| 500 | $1.74 | $870.00 |
| 1,000 | $1.55 | $1,550.00 |
PIC16F636-E/ST Overview
A microcontroller (MCU) is a single-chip computer that contains a CPU, program memory, working RAM, data EEPROM, and programmable peripherals. The PIC16F636 belongs to the PIC16F mid-range 8-bit family (PIC MCU -> 8-bit microcontroller -> embedded controller -> semiconductor). Compared with 32-bit Cortex-M parts, this 8-bit MCU offers deterministic single-cycle instruction execution (except branches), an ultra-small footprint, and rock-bottom unit cost for I/O-intensive, code-size-light designs such as remote controls, sensor interfaces, and KeeLoq-compatible secure encoders.
Key features include: KeeLoq® compatible hardware Cryptographic Module for secure remote-keyless-entry (RKE) applications; a Programmable Low-Voltage Detect (PLVD); two on-chip analog comparators; a 10-bit ADC-free architecture optimized for digital I/O; and 11 general-purpose I/O pins with individually selectable weak pull-ups. The device executes all 35 single-word instructions in a single instruction cycle (200 ns at 20 MHz), and supports in-circuit serial programming (ICSP) plus ICD debugging.
Architecturally, the PIC16F636 uses a Harvard RISC core with separate program and data buses. The 14-bit instruction word, hardware multiplier-free design, and 8-level hardware stack simplify firmware development while reducing RAM pressure. On-chip peripherals such as timers, comparators, and the cryptographic engine are accessed via a memory-mapped SFR block, eliminating the need for external glue logic.
Typical applications include remote keyless entry (RKE) transmitters, security and alarm panels, simple sensor conditioning, low-cost motor control loops, and battery-powered IoT edge nodes. Per the Microchip product page, the PIC16F636 is recommended where the cryptographic KeeLoq encoder, low power, and small pin count are valued.
Design tip: place a 0.1 µF decoupling capacitor within 5 mm of the VDD pin and reserve the MCLR/VPP pin for in-circuit programming access. If migrating to a newer silicon revision, Microchip recommends the PIC16F18323 as a newer-device alternative with more peripherals.
This page synthesizes distributor pricing, drop-in TSSOP-14 alternatives, and practical design notes not found in the bare datasheet.
Drop-in alternatives for PIC16F636-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 PIC16F636-E/ST (same form factor and footprint) — differing in Operating Temperature, I/O Pins, Package, Program Memory (Flash), RoHS Status.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16F630-E/ST
✅ Drop-In✓ In Stock
$0.98 / Unit
View Datasheet →PIC16F631-E/ST
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F676-E/ST
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F636-I/ST
✅ Drop-In✓ In Stock
$1.29 / Unit
View Datasheet →PIC16F636-E/SL
✅ Drop-In✓ In Stock
$1.18 / Unit
View Datasheet →PIC12F635-I/SN
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F636-E/ST Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC (Harvard) |
| Program Memory (Flash) | 3.5 KB (2K x 14 words) |
| RAM | 128 bytes |
| EEPROM | 256 bytes |
| Maximum CPU Clock | 20 MHz |
| Instruction Set | 35 single-word instructions |
| Instruction Cycle | 200 ns at 20 MHz |
| Supply Voltage (VDD) | 2.0 V to 5.5 V |
| I/O Pins | 11 |
| On-chip Comparators | 2 |
| PLVD (Programmable Low-Voltage Detect) | Yes |
| KeeLoq Cryptographic Module | Yes (hardware) |
| Operating Temperature | -40 °C to +125 °C (Extended, "E") |
| Package | 14-pin TSSOP (ST) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant (lead-free) |
| Programming/Debug | ICSP + ICD |
| Stack Levels | 8 hardware |
PIC16F636-E/ST Pin Configuration
| Pin 1 | VDD — Positive supply voltage (2.0 V to 5.5 V) |
| Pin 2 | T1CKI/OSC1/CLKIN/GP5 — Timer1 clock input / Oscillator crystal / External clock / GPIO GP5 |
| Pin 3 | OSC2/CLKOUT/GP4 — Oscillator crystal / Clock output / GPIO GP4 |
| Pin 4 | GP3/MCLR/VPP — GPIO GP3 / Master Clear (reset) / Programming voltage |
| Pin 5 | GP2/AN2/T1G/C1OUT — GPIO GP2 / Analog input 2 / Timer1 gate / Comparator 1 output |
| Pin 6 | GP1/AN1/C1IN-/ICSPCLK — GPIO GP1 / Analog input 1 / Comparator 1 inverting / ICSP clock |
| Pin 7 | GP0/AN0/C1IN+/ICSPDAT — GPIO GP0 / Analog input 0 / Comparator 1 non-inverting / ICSP data |
| Pin 8 | VSS — Ground reference |
| Pin 9 | GP6/AN6/C2OUT — GPIO GP6 / Analog input 6 / Comparator 2 output |
| Pin 10 | GP7/AN7/C2IN+/OSC1 — GPIO GP7 / Analog input 7 / Comparator 2 non-inverting / Oscillator |
| Pin 11 | C2IN-/GP5 alt — Comparator 2 inverting input (function shared with pin 2 on some revisions) |
| Pin 12 | C2OUT/GP4 alt — Comparator 2 output (function shared with pin 3 on some revisions) |
| Pin 13 | AN3/GP3 alt — Analog input 3 (function shared with pin 4 on some revisions) |
| Pin 14 | NC — Not connected (per datasheet) |
Typical Applications
PIC16F636-E/ST is suitable for 7 applications: Remote Keyless Entry (RKE) Transmitters, Industrial Sensor Signal Conditioning, Security and Alarm Panels, Battery-Powered IoT Edge Nodes, Low-Cost Motor Control (BLDC Triggers), Automotive Body Electronics (RKE Receivers), Consumer Appliance User Interface.
Remote Keyless Entry (RKE) Transmitters
The PIC16F636-E/ST is the canonical silicon for automotive and garage-door RKE transmitters because its KeeLoq-compatible hardware Cryptographic Module performs rolling-code encryption in microseconds without burdening the CPU. With 3.5 KB Flash the part stores rolling-code algorithms, button debounce, and LED feedback routines, while the 20 MHz CPU finishes a full transmit cycle inside 5 ms. Operating from 2.0 V to 5.5 V lets the transmitter run directly from a single CR2032 coin cell. Designers should reserve the MCLR/VPP pin for ICSP and place a 100 nF decoupling capacitor within 5 mm of VDD to keep the cryptographic engine quiet during RF transmission.
Recommended
Industrial Sensor Signal Conditioning
The PIC16F636-E/ST's two on-chip analog comparators and PLVD module let it digitize sensor thresholds without an external ADC, ideal for thermocouple-over-temperature alarms, photodiode level detectors, and 4–20 mA loop monitors. With 11 GPIO and 128 bytes of RAM the MCU handles debouncing, hysteresis calculation, and Modbus-like protocol framing on a single chip. The Extended -40 °C to +125 °C temperature range supports outdoor and under-hood placement. The 14-TSSOP footprint fits on a 10 x 15 mm daughter board, freeing the rest of the enclosure for the sensor head and surge protection.
Recommended
Security and Alarm Panels
The PIC16F636-E/ST forms a compact brain for PIR-based intruder alarms: PLVD monitors backup-battery health, comparators qualify PIR sensor pulses, and 11 GPIO drive relay outputs, sirens, and keypad scan. The KeeLoq engine can encrypt wireless PIR/siren traffic, avoiding replay attacks where an attacker records and rebroadcasts valid commands. 256 bytes of EEPROM stores installer codes and event logs across power cycles. The Extended temperature grade means the panel can sit in an unheated garage or attic. ICSP plus ICD support lets field technicians reflash without opening the cabinet.
Recommended
Battery-Powered IoT Edge Nodes
The PIC16F636-E/ST's low-voltage operation down to 2.0 V lets a node run from two AA alkaline cells for years when duty-cycled with the watchdog timer and sleep modes (current consumption drops to the microamp range). 3.5 KB Flash holds LoRaWAN or Zigbee MAC-stack snippets plus application logic, while 128 bytes RAM supports small packet buffers. The Extended temperature grade handles outdoor enclosures and HVAC ducts. The 14-TSSOP package fits on 10 x 10 mm coin-cell sensor PCBs. Trade-off vs Cortex-M0: this 8-bit MCU has no hardware multiply and limited RAM, so cryptography beyond KeeLoq should be offloaded.
Recommended
Low-Cost Motor Control (BLDC Triggers)
The PIC16F636-E/ST can generate the Hall-sensor commutation logic and PWM triggers for small brushless DC fans and pumps. Two comparators qualify zero-cross events while 11 GPIO drive gate-driver enables and tacho feedback. With 3.5 KB Flash the firmware fits open-loop start-up ramps, locked-rotor detection, and RPM-to-PWM mapping. Operating at 5 V from USB or a 12 V buck lets hobby and appliance designs share firmware across platforms. Note: for sinusoidal FOC or sensored closed-loop torque control, migrate to PIC16F1779 or dsPIC33; the 8-bit core lacks the math bandwidth for >10 kHz current loops.
Recommended
Automotive Body Electronics (RKE Receivers)
The PIC16F636-E/ST is well-suited for in-vehicle RKE receivers paired with an external UHF receiver IC: its KeeLoq engine decrypts rolling codes while GPIO drives door-lock actuators, courtesy lamps, and a buzzer. The Extended -40 °C to +125 °C temperature grade matches automotive under-dash requirements. The PLVD module monitors the 12 V battery rail and wakes the MCU on voltage transients, while EEPROM retains paired transmitters across battery swaps. Place the part at least 10 mm away from the RF front-end to keep the cryptographic engine from being polluted by receiver LO leakage.
Recommended
Consumer Appliance User Interface
The PIC16F636-E/ST handles capacitive or resistive touch-button scanning, LED matrix animation, and buzzer patterns in microwave ovens, washing machines, and air purifiers. With 11 GPIO it drives 7-segment displays, triac optos, and rotary encoders without external logic. 256 bytes of EEPROM retains user presets across power cycles. The PLVD module detects brown-outs and saves state to EEPROM before the regulator collapses. The TSSOP-14 footprint simplifies manual rework during prototyping compared with QFP variants. Avoid driving triacs directly from GPIO - use an MOC3021 opto-isolator for safety isolation.
Recommended
Recommended Products Summary
Engineering reference data for PIC16F636-E/ST — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16F630-E/ST | PIC16F631-E/ST | PIC16F676-E/ST | PIC16F636-I/ST | PIC16F636-E/SL | PIC12F635-I/SN |
|---|---|---|---|---|---|---|---|
| Package | TSSOP-14 | TSSOP-14 - same | TSSOP-14 - same | TSSOP-14 - same | TSSOP-14 - same | SOIC-14 - same pinout, larger footprint | SOIC-8 - different pin count |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory (Flash) | 3.5 KB | 2 KB | 2 KB | 3.5 KB | 3.5 KB | 3.5 KB | 2 KB |
| RAM | 128 B | 64 B | 128 B | 128 B | 128 B | 128 B | 64 B |
| EEPROM | 256 B | 128 B | 128 B | 256 B | 256 B | 256 B | 128 B |
| KeeLoq Crypto Engine | Yes | No | No | No | Yes | Yes | Yes |
| On-chip ADC | None (2 comparators) | None | None | 10-bit ADC | None | None | None |
| Temperature Grade | -40 to +125 C (E) | -40 to +125 C (E) | -40 to +125 C (E) | -40 to +125 C (E) | -40 to +85 C (I) | -40 to +125 C (E) | -40 to +85 C (I) |
| Max CPU Clock | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
Key Differentiators
- Only TSSOP-14 PIC16F family member with KeeLoq hardware crypto (vs PIC16F630-E/ST)
- Extended temperature grade vs Industrial grade (vs PIC16F636-I/ST)
- Lower pin count KeeLoq alternative (vs PIC12F635-I/SN)
Design Notes
Place a 100 nF (0.1 µF) decoupling capacitor within 5 mm of the VDD pin (pin 1) and another identical capacitor near VSS (pin 8). For battery applications drawing microamps in sleep, add a 10 µF bulk reservoir near the IC to handle transmit-current transients in RKE designs. Estimated: at 20 MHz CPU clock and 5 V supply, active current is roughly 2–3 mA; sleep current drops to <1 µA, so the bulk cap should hold the rail within 50 mV during wake-up bursts.
Pin 4 (GP3/MCLR/VPP) is shared between GPIO, master-clear reset, and ICSP programming voltage. If your PCB pulls MCLR low via a button, do not connect any external load to GP3 simultaneously - the internal weak pull-up conflicts with the external switch network. Standard ICSP circuit: 10 kΩ pull-up on MCLR to VDD, with the ICD connector wired to VPP/ICSPDAT/ICSPCLK through 4.7 kΩ series resistors. Failing to do so produces intermittent ICD-debug connection failures that look like firmware bugs.
The TSSOP-14 package has a θJA of approximately 100 °C/W in still air, so at 5 V/20 MHz the typical 3 mA active current dissipates only ~15 mW - thermal rise is negligible. However, in an enclosed RKE transmitter next to a CR2032 coin cell, total system self-heating plus solar load on dark plastic can push the die to 60 °C. The Extended (-40 °C to +125 °C) grade handles this. Estimated: 15 mW dissipation × 100 °C/W = 1.5 °C rise above ambient in still air, well within limits.
Keep the oscillator traces (OSC1/OSC2, pins 2–3) shorter than 12 mm and surround them with a ground pour to minimize radiated EMI that could couple into the KeeLoq engine or an external UHF antenna. If using the internal oscillator, leave the OSC pins as GPIO or NC to free pin count. Per Microchip TB077 (oscillator design guidelines), a 10 MHz crystal with 22 pF load caps gives stable operation across the -40 °C to +125 °C range; below 0 °C expect the oscillator gain margin to drop slightly.
When driving the PIC16F636-E/ST's GPIO at high slew rates (e.g., 10 MHz SPI bit-banged to an external EEPROM), source-terminate the line with a 33 Ω resistor near the driver to reduce ringing. The TSSOP-14 lead frame has modest inductance (~5 nH) that combines with capacitive loads to form an LC tank around 100 MHz. For KeeLoq encoder outputs to a UHF transmitter, route the digital lines perpendicular to the antenna feed to avoid injection of harmonics into the PA path.
Compliance Information
RoHS and lead-free per Microchip product page. AEC-Q100 status not explicitly stated in web data; though Extended grade supports under-hood automotive use, formal AEC-Q100 qualification should be confirmed with Microchip for production automotive programs.
