HCS300T/SN

Specialized ICS Overview

The HCS300T/SN is a KEELOQ code hopping encoder manufactured by Microchip Technology, designed for secure remote keyless entry systems. It operates within a voltage range of 2.0V to 6.3V and features four button inputs with internal pull-down resistors. The device generates a unique 66-bit transmission code word comprising a 32-bit encrypted portion and a 34-bit fixed portion. Key security parameters include a programmable 64-bit encryption key and a 28-bit serial number stored in on-chip EEPROM. The component is housed in an 8-SOIC package (0.154-inch width) and utilizes surface mount technology.

Specialized ICS Feature Summary

• Generates a 66-bit unique transmission code using KEELOQ code hopping technology to prevent code scanning and replay attacks.
• Features a programmable 64-bit encryption key and a 28-bit serial number stored in read-protected on-chip EEPROM.
• Operates on a supply voltage between 2.0V and 6.3V with four selectable button inputs supporting up to 15 functions.
• Includes automatic low battery signal transmission and configurable baud rates for flexible system integration.

Specialized ICS Applications

• Automotive Remote Keyless Entry (RKE) systems
• Automotive alarm and immobilizer systems
• Gate and garage door openers
• Burglar alarm systems and identity tokens

Specialized ICS Procurement Notes

Verify the specific ordering suffix against the manufacturer's datasheet to confirm package type and tape/reel specifications. Ensure that the procurement channel provides valid documentation confirming the component grade and manufacturing origin. Cross-reference the part number with official Microchip databases to validate current production status and availability constraints.

Specialized ICS Selection Notes

Select this encoder for unidirectional security applications requiring high resistance to code grabbing. Ensure the paired decoder supports the KEELOQ algorithm and compatible baud rate settings. Verify that the system design accommodates the 2.0V to 6.3V operating range and integrates appropriate RF circuitry for the PWM output pin.

Specialized ICS Part Context

This component belongs to the HCS300 series of KEELOQ encoders. The 'T' suffix typically indicates tape and reel packaging, while 'SN' denotes the SOIC-8 surface mount package variant. This family is widely used in legacy and modern access control systems due to its cost-effectiveness and established security protocol.

Specialized ICS Replacement Considerations

Direct replacements must support the same KEELOQ encryption algorithm and 66-bit code word structure. Verify compatibility with existing decoders regarding baud rate selection and synchronization counter handling. Consult Microchip documentation for updated models if the HCS300 series is discontinued or if enhanced security features are required.

Specialized ICS FAQ

How does the HCS300 prevent code replay attacks?

It uses KEELOQ code hopping technology where a 16-bit synchronization counter increments with each transmission, ensuring every 66-bit code word is unique and unpredictable.

What is the function of the SEED value in the HCS300?

The 32-bit seed value is transmitted when all four buttons are pressed simultaneously, enabling a 'Secure Learn' process for higher security pairing with the receiver.

Can the encryption key be read externally from the chip?

No, the 64-bit encryption key is stored in on-chip EEPROM that is read-protected and inaccessible via external connections after programming.