HCS361-I/P - KEELOQ Code Hopping Encoder, 8-PDIP | Microchip
MPN: HCS361-I/P ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.45 | $2.45 |
| 10 | $2.18 | $21.80 |
| 100 | $1.85 | $185.00 |
| 500 | $1.62 | $810.00 |
| 1,000 | $1.45 | $1,450.00 |
HCS361-I/P Overview
A code hopping encoder is a security-focused transmitter IC that transmits a different encrypted code on every button press, defeating simple replay attacks. It belongs to the broader category of encoders/decoders/multiplexers (logic ICs), and within Microchip's portfolio it is a member of the KEELOQ family — a hierarchy that runs encoder -> KEELOQ hopping encoder -> security transmitter IC -> logic IC -> integrated circuit. The HCS361 sits between the lower-cost HCS300/HCS301 and newer HCS362/HCS365 devices, balancing small package outline, low BOM cost, and patented hopping-code security.
Key features include 28/32-bit serial number programming, 64-bit encryption key storage in EEPROM, unique 67-bit transmission per button event, three button inputs (S0/S1/S2), a 4-word (S0..S3 with PWM) option (per family datasheet), low standby current for battery-powered fobs, automatic code-word synchronization, and Microchip's patented KEELOQ learning algorithm so a paired receiver only needs to remember the last transmitted code. HCS361-I/P is the industrial temperature (-40 °C to +85 °C) variant in the through-hole PDIP-8 footprint.
The device uses Microchip's KEELOQ nonlinear block-cipher algorithm with a 64-bit manufacturer key and a 16/20-bit discriminator. On every button press the encoder generates a fresh 32-bit hopping code by combining the counter value, the button bitmap, and the encrypted discriminator; the receiver validates the rolling counter and decrypts the discriminator before accepting the transmission, providing strong replay-attack immunity for garage-door openers, gate controls, alarm panels, and automotive RKE.
Typical applications include garage-door and gate openers, automotive Remote Keyless Entry transmitters, wireless doorbells, alarm and security system keypads, asset-tracking fobs, and industrial access-control handheld remotes. Pair it with a Microchip HCS compatible receiver decoder (e.g., the receiver side of the HCS family) to complete a one-way secure link.
When designing with the HCS361-I/P, observe the VDD decoupling guidance from the datasheet (a 0.1 µF ceramic cap close to the VDD pin), the RF section layout for the companion transmitter PCB, and the four-button debounce pattern in Microchip application notes. The industrial -40 °C to +85 °C range makes this part suitable for outdoor fobs and unheated enclosures, while the through-hole PDIP-8 package simplifies hand-soldering and prototype builds.
This page synthesizes distributor pricing, drop-in package alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for HCS361-I/P — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
HCS361/P
✅ Drop-In📋 Reference alternative (not in catalog)
HCS361T-I/P
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
HCS361-I/P Maximum Ratings & Electrical Characteristics
| Function | KEELOQ code hopping encoder |
| Serial Number Length | 28 / 32 bit (programmable) |
| Encryption Key Length | 64 bit (programmable, EEPROM) |
| Transmission Code Length | 67 bit (32-bit hopping + 35-bit fixed) |
| Hopping Code Length | 32 bit |
| Fixed Code Length | 35 bit |
| Number of Button Inputs | 3 (S0, S1, S2) |
| Supply Voltage Range (datasheet) | 2.0 V to 6.6 V |
| Supply Voltage Range (distributor listing) | 3.0 V to 6.9 V |
| Operating Temperature Range | -40 °C to +85 °C (industrial, -I suffix) |
| Package / Case | 8-PDIP (0.300 inch / 7.62 mm body) |
| Mounting Type | Through Hole |
| Packaging | Tube |
| Lead Free Status | Lead Free |
| RoHS Status | RoHS compliant |
| Category | Encoders, Decoders, Multiplexers & Demultiplexers |
HCS361-I/P Pin Configuration
| Pin 1 | S0 — Button input 0 (also LED drive / PWM in some configurations) |
| Pin 2 | S1 — Button input 1 |
| Pin 3 | S2 — Button input 2 |
| Pin 4 | VSS — Ground |
| Pin 5 | DATA — Serialized transmission output to RF stage |
| Pin 6 | VDD — Positive supply (2.0 V to 6.6 V) |
| Pin 7 | OSC1 — Oscillator input (RC or external clock) |
| Pin 8 | OSC2 — Oscillator output |
Typical Applications
HCS361-I/P is suitable for 6 applications: Garage Door Opener Remote, Automotive Remote Keyless Entry (RKE), Wireless Doorbell / Access Control, Alarm System Keypad / Panic Button, Industrial Wireless Remote Control, Asset Tracking / Wireless Sensor Tag.
Garage Door Opener Remote
The HCS361-I/P is a strong fit for single-button or multi-button garage-door opener remotes because it produces a unique 67-bit hopping code on every press, defeating the simple replay attacks that earlier fixed-code garage systems were vulnerable to. Its 2.0 V to 6.6 V supply range accepts either a CR2032 coin cell plus booster or two AAA cells, and the industrial -40 °C to +85 °C range tolerates uninsulated metal garages in winter and hot attics in summer. The 8-pin PDIP package simplifies hand-soldering on the transmitter PCB during prototype builds, while Microchip's KEELOQ learning algorithm lets the receiver side accept a new remote in seconds.
Recommended
Automotive Remote Keyless Entry (RKE)
For automotive Remote Keyless Entry fobs, the HCS361-I/P's three button inputs (S0, S1, S2) cleanly map to lock, unlock, and trunk release, with the encrypted discriminator ensuring only the paired vehicle's receiver can act on the command. The 32-bit hopping counter rolls forward on each press so a code-grabber replaying an old transmission is rejected by the receiver's rolling-counter window check. The industrial temperature grade is sufficient for cabin and door-pocket environments; for under-hood or outdoor-mirror applications, prefer Microchip's higher-grade KEELOQ family members. Pair with a UHF transmitter stage (315 MHz or 433.92 MHz SAW-based) for a complete unidirectional RKE link.
Recommended
Wireless Doorbell / Access Control
The HCS361-I/P serves as the secure transmitter IC in wireless doorbells and small access-control panels, where it generates a different code on every button press to prevent neighbours from triggering the chime or gate by replay. Its 2.0 V minimum supply and low standby current extend battery life in wall-mounted transmitters that may sit idle for months. The 67-bit frame length and 64-bit encryption key provide sufficient entropy for residential and light-commercial deployments, and Microchip's KEELOQ family includes reference firmware so the receiver MCU can be brought up quickly. Designers should still follow Microchip AN642 for the learning sequence.
Recommended
Alarm System Keypad / Panic Button
For alarm panels and panic-button fobs, the HCS361-I/P's hopping-code security prevents the simple 'capture-and-replay' attacks that defeated earlier fixed-code alarm remotes, while its three buttons can encode arm, disarm, and panic functions in a single fob. The 64-bit manufacturer key and per-device serial number mean each fob must be individually learned by the alarm panel, supporting multi-user installations. The 8-PDIP through-hole package eases field-replacement servicing. The industrial -40 °C to +85 °C range supports outdoor sheds and unheated warehouses where alarms are commonly installed.
Recommended
Industrial Wireless Remote Control
The HCS361-I/P fits industrial crane, hoist, and conveyor remote controls where safety depends on preventing accidental or malicious actuation. Its rolling 32-bit hopping counter plus 64-bit encryption key exceed the security threshold for unidirectional industrial control links, and the industrial -40 °C to +85 °C temperature range tolerates plant-floor and outdoor tower-crane environments. Designers should add a manual 'enable' or 'confirm' button (S2) to require deliberate two-step actuation on hazardous equipment, and pair with a Microchip receiver MCU running the standard KEELOQ decode routine. The PDIP-8 package is convenient for ruggedized hand-held enclosures.
Recommended
Asset Tracking / Wireless Sensor Tag
The HCS361-I/P can serve as the authentication transmitter in disposable or reusable asset-tracking tags where each tag emits a unique, encrypted identifier that the receiver uses to log presence or movement. While it was originally designed for button-driven RKE, designers can wire S0 to a periodic wake-up circuit to produce scheduled beacon transmissions. The 64-bit encryption key ensures cloned tags cannot impersonate legitimate ones, and the industrial temperature grade supports cold-chain and outdoor logistics tags. For pure beaconing, newer KEELOQ parts with lower standby current may be preferable, but the HCS361-I/P remains a cost-effective option for short-lifecycle tags.
Recommended
Recommended Products Summary
Engineering reference data for HCS361-I/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | HCS361/P | HCS361T-I/P |
|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 8-PDIP | 8-PDIP (same) | 8-PDIP (same) |
| Function | KEELOQ code hopping encoder | KEELOQ code hopping encoder | KEELOQ code hopping encoder |
| Transmission Code Length | 67 bit | 67 bit | 67 bit |
| Encryption Key Length | 64 bit (programmable) | 64 bit (programmable) | 64 bit (programmable) |
| Button Inputs | 3 (S0, S1, S2) | 3 (S0, S1, S2) | 3 (S0, S1, S2) |
| Supply Voltage | 2.0 V to 6.6 V | 2.0 V to 6.6 V | 2.0 V to 6.6 V |
| Operating Temperature | -40 C to +85 C (industrial) | 0 C to +70 C (commercial) | -40 C to +85 C (industrial) |
| RoHS / Lead Free | Yes / Yes | Yes / Yes | Yes / Yes |
| Unit Price (1 pc, as of 2026-10-15) | $2.45 | $2.30 (approx, distributor-dependent) | $2.50 (approx, distributor-dependent) |
Key Differentiators
- Industrial -40 °C to +85 °C operating range in PDIP-8 (vs HCS361/P)
- Same die, package and pinout as the commercial-temperature variant (vs HCS361/P)
- Through-hole PDIP-8 simplifies prototype and field service (vs HCS361-I/SN)
Design Notes
Place a 0.1 µF ceramic decoupling capacitor as close as possible to the HCS361-I/P VDD pin (pin 6) with the ground return to pin 4. The encoder draws brief pulses of current during transmission; without local decoupling the supply can sag enough to corrupt the transmission. For battery-powered fobs with CR2032 cells, add a 10 µF bulk capacitor in parallel to handle the RF-stage inrush.
Do not confuse the HCS361-I/P with the HCS300 or HCS301 — although all are KEELOQ encoders, their transmission frame lengths and button encodings differ (HCS361 = 67 bits / 3 buttons, HCS300/HCS301 = 66 bits / 4 buttons). A receiver trained for HCS361 will reject HCS300 transmissions and vice versa. Match the encoder family to the receiver's trained algorithm before laying out the PCB.
For the companion UHF transmitter stage, keep the HCS361-I/P DATA output (pin 5) trace short and route it away from the antenna feed. A 50 Ω controlled-impedance line from DATA to the SAW-based transmitter modulator input minimizes ringing. Place the oscillator components (typically a resistor from OSC1 to VDD and a trim capacitor on OSC2) within a few millimetres of pins 7 and 8 to avoid frequency drift and EMI.
The HCS361-I/P relies on a stable internal timebase to derive its hopping-code timing. Use the resistor-and-capacator values recommended in the Microchip datasheet for your target transmission rate (typically 100 µs per TE) and avoid ceramic capacitors with high voltage coefficients (e.g., Y5V) on the oscillator pin — use X7R or C0G/NP0 instead to keep the carrier frequency on-wool stability across temperature.
Compliance Information
RoHS compliant and lead free per Microchip product page and DigiKey listing (sku 286306). REACH and conflict-mineral declarations available from Microchip on request. Not AEC-Q100 qualified — automotive RKE applications should confirm system-level qualification at the receiver and RF stages.
