PIC16F639-E/P - 8-bit MCU, 3.5KB Flash, KeeLoq Crypto | Microchip
MPN: PIC16F639-E/P ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.83 | $2.83 |
| 10 | $2.83 | $28.30 |
| 100 | $2.83 | $283.00 |
| 500 | $2.65 | $1,325.00 |
| 1,000 | $2.5 | $2,500.00 |
PIC16F639-E/P Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU, non-volatile program memory, working RAM, and configurable peripheral I/O on one die. Within the broader taxonomy, an MCU belongs to the semiconductor family, then to integrated circuits (ICs), and more specifically to microcontrollers and embedded processors. The PIC16F series sits in Microchip's mid-range 8-bit line, between the baseline PIC10/12/16 families and the high-performance PIC18/dsPIC families.
The headline features of the PIC16F639-E/P include the KeeLoq-compatible encryption/decryption engine for rolling-code remote keyless entry (RKE) and passive keyless entry (PKE), a three-channel Analog Front End (AFE) for 125 kHz transponder interfacing, MPLAB ICD 2/ICD 3 in-circuit debugging support, and NanoWatt Technology power management that drops quiescent current below 1 uA in sleep. The 11 GPIO pins support digital I/O, interrupt-on-change, and weak pull-ups, and the device includes an internal 8 MHz oscillator plus configurable clock options.
Internally, the PIC16F639 uses a Harvard-architecture RISC core with separate program and data buses. The 14-bit instruction word delivers deterministic single-cycle execution for most opcodes, while the cryptographic module operates as an autonomous peripheral that consumes zero CPU cycles once the key and data registers are loaded. The on-board AFE, including an ASK/FSK demodulator and RSSI measurement, eliminates the external receiver IC traditionally required for inductive proximity systems.
Typical applications include automotive remote keyless entry (RKE) transmitters, passive keyless entry (PKE) immobilizers, garage-door opener keyfobs, industrial RFID readers, secure access control fobs, and tamper-detection nodes that need a hardware root of trust. The Extended temperature grade also suits under-hood automotive and outdoor industrial installations.
When designing in this part, allocate a 0.1 uF decoupling capacitor within 5 mm of the VDD pin, route the resonator pins to a quiet ground island, and reserve the AFE input pins (RA4/RA5) for the LC tank network specified in the datasheet typical application. Verify in-circuit serial programming (ICSP) connections against the Microchip ICD header pinout before finalizing PCB layout, and budget for code protection fuses if the rolling-code secret will be programmed at production.
This page synthesizes distributor pricing, drop-in alternatives, and application guidance derived from the Microchip PIC16F639 datasheet family - data not consolidated in any single manufacturer document.
Drop-in alternatives for PIC16F639-E/P — 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 PIC16F639-E/P (same form factor and footprint) — differing in Core Architecture, I/O Pins, Instruction Set, Mounting Type, Cryptographic Peripheral.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16F639-I/P
✅ Drop-In✓ In Stock
$2.49 / Unit
View Datasheet →PIC16F639T-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F639T-E/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F639-I/SS
✅ Drop-In✓ In Stock
$2.2 / Unit
View Datasheet →PIC16F639-E/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F639-E/P Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC16 8-bit RISC (Harvard) |
| Program Memory (Flash) | 3.5 KB (2K x 14 words) |
| RAM | 128 bytes |
| EEPROM | 256 bytes |
| Maximum CPU Speed | 20 MHz |
| Instruction Set | 35 single-word instructions |
| I/O Pins | 11 |
| Package | 20-PDIP (0.300 inch, 7.62 mm) |
| Mounting Type | Through-Hole |
| Operating Temperature | -40C to +125C (Extended grade) |
| Supply Voltage (VDD) | 2.0 V to 5.5 V |
| Cryptographic Module | KeeLoq-compatible hardware encoder/decoder |
| Analog Peripherals | 2 comparators, 3-channel Analog Front End (125 kHz transponder AFE with ASK/FSK demodulator and RSSI) |
| PLVD | Programmable Low-Voltage Detect |
| Timers | Timer0, Timer1, Timer2 |
| ADC | Not present (this variant uses analog comparators + AFE instead) |
| Internal Oscillator | 8 MHz (calibrated) plus LF 31 kHz |
| ICSP / Debug | In-Circuit Serial Programming; MPLAB ICD 2/3 compatible |
| RoHS Status | Compliant (lead-free) |
PIC16F639-E/P Pin Configuration
| Pin 1 | RA0/AN0/ICSPDAT — Bidirectional I/O, analog input, ICSP data |
| Pin 2 | RA1/AN1 — Bidirectional I/O, analog input |
| Pin 3 | RA2/AN2/CVREF — Bidirectional I/O, analog input, comparator reference output |
| Pin 4 | RA3/MCLR/VPP — Bidirectional I/O, Master Clear (reset), programming voltage |
| Pin 5 | RA4/AN3/C1OUT/T1G — Bidirectional I/O, analog input, comparator 1 output, Timer1 gate |
| Pin 6 | RA5/AN4/C2OUT/LF input — Bidirectional I/O, analog input, comparator 2 output, 125 kHz AFE input |
| Pin 7 | VSS — Ground reference |
| Pin 8 | OSC1/RA7 — Crystal/oscillator input or GPIO |
| Pin 9 | OSC2/RA6 — Crystal/oscillator output or GPIO |
| Pin 10 | RC0 — Bidirectional I/O |
| Pin 11 | RC1 — Bidirectional I/O |
| Pin 12 | RC2 — Bidirectional I/O |
| Pin 13 | RC3 — Bidirectional I/O |
| Pin 14 | RC4 — Bidirectional I/O |
| Pin 15 | RC5 — Bidirectional I/O |
| Pin 16 | RC6 — Bidirectional I/O |
| Pin 17 | RC7 — Bidirectional I/O |
| Pin 18 | RB7/ICSPDAT — Bidirectional I/O, ICSP data (alternate) |
| Pin 19 | RB6/ICSPCLK — Bidirectional I/O, ICSP clock |
| Pin 20 | VDD — Positive supply voltage (2.0 V to 5.5 V) |
Typical Applications
PIC16F639-E/P is suitable for 6 applications: Automotive Remote Keyless Entry (RKE) Keyfob, Passive Keyless Entry (PKE) Immobilizer, Garage-Door Opener Keyfob, Industrial RFID Reader Module, Secure Access Control Fob, Tamper-Detection and Anti-Tamper Sensor Node.
Automotive Remote Keyless Entry (RKE) Keyfob
The PIC16F639-E/P's KeeLoq-compatible hardware crypto module and 20 MHz PIC16 core make it a near-ideal MCU for RKE keyfobs. The hardware rolling-code encoder offloads encryption from the CPU, leaving cycles for button debouncing, LED feedback, and UHF transmitter control. Typical battery life exceeds three years thanks to NanoWatt sleep currents below 1 uA, and the Extended -40C to +125C grade survives both dashboard summer heat and northern winter cold. The integrated AFE is not strictly needed for transmit-only RKE but is present for hybrid designs that also support PKE proximity wake-up.
Recommended
Passive Keyless Entry (PKE) Immobilizer
In PKE systems the keyfob listens for a 125 kHz LF challenge from the vehicle, computes a cryptographic response, and replies over UHF. The PIC16F639's three-channel Analog Front End demodulates ASK and FSK LF carriers directly, eliminating the external receiver IC that older designs needed. The KeeLoq module validates the challenge and generates the response in dedicated hardware. The 256-byte EEPROM stores rolling-code counters and manufacturer keys, and the Extended temperature grade handles under-hood temperatures during summer sun loads.
Recommended
Garage-Door Opener Keyfob
Garage-door operators rely on rolling-code security to prevent replay attacks, and the PIC16F639-E/P delivers that capability in a single 20-pin DIP. The part supports Microchip's KeeLoq encoder firmware reference, allowing manufacturers to certify against common opener protocols. With only a few buttons and a battery, the design is compact, and the through-hole PDIP simplifies low-volume assembly and rework. Sleep current below 1 uA keeps the coin cell alive for the full warranty period.
Recommended
Industrial RFID Reader Module
Industrial RFID systems use 125 kHz transponders for asset tracking and tool identification. The PIC16F639's integrated AFE, RSSI measurement, and ASK/FSK demodulator implement a complete reader front end, paired with a small LC antenna network. The 20 MHz core executes anti-collision protocols and ISO 11784/11785 compliance checks in firmware. The Extended temperature grade supports outdoor installations and factory-floor thermal swings without derating.
Recommended
Secure Access Control Fob
Building access systems need cryptographic authentication against credential readers. The PIC16F639-E/P stores per-user keys in its on-chip EEPROM and uses the KeeLoq-compatible module to generate challenge-response pairs in hardware. The 20-PDIP form factor supports through-hole PCBs for legacy mechanical enclosures, while the 20-SSOP variant fits modernized SMD assemblies. Battery life is excellent thanks to NanoWatt Technology, allowing multi-year deployments before fob battery replacement.
Recommended
Tamper-Detection and Anti-Tamper Sensor Node
Anti-tamper nodes in metering and security equipment must detect intrusion attempts and securely erase secrets. The PIC16F639-E/P provides a hardware root of trust via the KeeLoq engine and stores keys in protected EEPROM. Its two analog comparators monitor tamper switches and voltage rails, while the PLVD detects supply brownout attacks. The Extended temperature grade ensures reliable operation in outdoor cabinets and metering enclosures across wide seasonal swings.
Recommended
Recommended Products Summary
Engineering reference data for PIC16F639-E/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16F639-I/P | PIC16F639T-I/SS | PIC16F639T-E/SS | PIC16F639-I/SS | PIC16F639-E/SP |
|---|---|---|---|---|---|---|
| Package | 20-PDIP (0.300 inch) | 20-PDIP (0.300 inch) | 20-SSOP | 20-SSOP | 20-SSOP | 20-SPDIP (skinny DIP) |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory (Flash) | 3.5 KB | 3.5 KB | 3.5 KB | 3.5 KB | 3.5 KB | 3.5 KB |
| RAM | 128 bytes | 128 bytes | 128 bytes | 128 bytes | 128 bytes | 128 bytes |
| Operating Temperature | -40C to +125C (Extended) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +125C (Extended) | -40C to +85C (Industrial) | -40C to +125C (Extended) |
| Mounting Type | Through-Hole (PDIP) | Through-Hole (PDIP) | Surface Mount (SSOP) | Surface Mount (SSOP) | Surface Mount (SSOP) | Through-Hole (SPDIP, narrower body) |
| KeeLoq Crypto Module | Yes (hardware) | Yes (hardware) | Yes (hardware) | Yes (hardware) | Yes (hardware) | Yes (hardware) |
| 125 kHz Transponder AFE | Yes (integrated) | Yes (integrated) | Yes (integrated) | Yes (integrated) | Yes (integrated) | Yes (integrated) |
Key Differentiators
- Integrated KeeLoq-compatible hardware cryptographic engine (vs PIC16F630-E/P (same 20-PDIP footprint, no crypto))
- On-chip 125 kHz transponder Analog Front End (vs PIC16F636-I/P (similar mid-range 8-bit MCU without AFE))
- Extended temperature grade -40C to +125C in PDIP-20 (vs PIC16F639-I/P (Industrial -40C to +85C))
Design Notes
Place a 0.1 uF ceramic decoupling capacitor within 5 mm of the VDD pin (pin 20) and a bulk capacitor (4.7 uF to 10 uF) close to the LF antenna return path. The NanoWatt Technology sleep mode reduces I_DD to less than 1 uA but the wake-up time depends on the oscillator stabilization; configure the LF 31 kHz internal oscillator for sleep-state LF polling to minimize wake-up latency. Run the part from a CR2032 or CR2032H coin cell with a series ferrite bead if the design is exposed to ESD.
The 125 kHz AFE is sensitive to PCB parasitics; route the LC antenna tank between RA5/AN4 and the comparator input with the capacitor return path directly to VSS, not through a long ground trace. Keep the oscillator traces (OSC1/OSC2) short and guarded by a ground ring to reduce radiated emissions into the AFE. For ICSP, expose RB6 (ICSPCLK) and RB7 (ICSPDAT) on a 2x3 header or pogo-pad footprint so production programming does not require socketed parts.
Do not enable code-protect fuses until the final production firmware image is verified - locked parts cannot be re-read for debugging. Verify the KeeLoq manufacturer key against the receiver side before mass production, since mismatched keys cause field failures that look like hardware defects. Confirm MCLR (RA3) is pulled high through a 10 kohm resistor for normal operation; if left floating the part will not exit reset. Estimated: at 20 MHz and 5 V the core draws approximately 11 mA during active execution; budget battery capacity accordingly.
The KeeLoq encoder outputs bits at a programmable baud rate; ensure the UHF transmitter companion IC (e.g., ATA5724C) accepts the GPIO-driven Manchester or PWM modulation expected by the receiver. Place a small RC low-pass filter on the GPIO output feeding the transmitter if the protocol requires edge-rate control. The AFE RSSI output is a current-mode signal - convert it to a voltage with an external resistor (typically 10 kohm) and decouple the resulting voltage node with 100 pF to ground for ADC sampling.
Compliance Information
RoHS-compliant per Microchip product page. Lead-free PDIP-20 package. Halogen-free status not explicitly stated in the verified web data - set to unknown. Not AEC-Q100 qualified (the -E grade is Microchip's own Extended commercial/industrial rating, distinct from automotive AEC-Q100).
