HCS201-I/SN

Specialized ICS Overview

The HCS201-I/SN is a code hopping encoder utilizing KEELOQ® technology for secure remote keyless entry systems. It generates unique 66-bit transmission codes by combining a 32-bit encrypted hopping code with a 28-bit serial number and button status information. The device operates on a supply voltage of 3.5V to 13V, or as low as 2.0V when using the integrated step-up regulator. It features three button inputs supporting seven functions, selectable baud rates, and an internal oscillator. Security is ensured through read-protected programmable encryption keys and non-volatile synchronization data stored in on-chip EEPROM.

Specialized ICS Feature Summary

• KEELOQ® Code Hopping: Generates unique 66-bit codes (32-bit encrypted + 34-bit fixed) to prevent code scanning and replay attacks.
• Integrated Step-Up Regulator: Allows operation from battery voltages as low as 2.0V via VDDB pin, maintaining stable VDD.
• Secure Memory: Contains 192 bits of EEPROM storing a 64-bit read-protected crypt key, 28-bit serial number, and sync counter.
• Flexible Input/Output: Supports three switch inputs for up to seven functions and provides PWM data output for RF transmission.

Specialized ICS Applications

• Automotive Remote Keyless Entry (RKE) systems
• Automotive alarm and immobilizer systems
• Gate and garage door openers
• Identity tokens and access control systems

Specialized ICS Procurement Notes

Verify that the ordering suffix 'I' confirms industrial temperature range qualification (-40°C to +85°C) and 'SN' denotes the 8-SOIC surface-mount package. Confirm RoHS compliance status directly with Microchip Technology documentation prior to procurement. Ensure programming equipment supports the specific serial interface requirements for loading the crypt key and serial number into the device's EEPROM.

Specialized ICS Selection Notes

Select the HCS201-I/SN for unidirectional security applications requiring high resistance to code grabbing. Choose this model if the design necessitates an integrated step-up regulator to support low-voltage battery sources (down to 2.0V). Verify that the system decoder supports the KEELOQ algorithm and compatible learning strategies. Consider the 8-SOIC package constraints for PCB layout and thermal management within the specified operating temperature range.

Specialized ICS Part Context

The HCS201 belongs to the Microchip HCS (High-Security Crypto) series, specifically designed for cost-effective, high-security remote access solutions. It complements decoder counterparts such as the HCS200 and HCS300 families. The I/SN variant specifies the industrial grade performance and surface-mount packaging, distinguishing it from PDIP through-hole versions like the HCS201-I/P.

Specialized ICS Replacement Considerations

Direct functional replacements within the same family include other HCS201 variants with different packages, such as HCS201-I/P for through-hole mounting. Cross-family substitution requires verifying decoder compatibility with the KEELOQ algorithm and ensuring equivalent voltage ranges and pin configurations are maintained.

Specialized ICS FAQ

How does the HCS201 prevent code scanning attacks?

It uses KEELOQ® code hopping technology to generate a unique 66-bit transmission code for every button press. The 32-bit encrypted portion changes unpredictably with each transmission, making static code scanning ineffective.

What is the minimum operating voltage for the HCS201?

The standard operating voltage range is 3.5V to 13V. However, when the built-in step-up regulator is utilized, the device can operate with a battery input (VDDB) as low as 2.0V.

Can the encryption key be read from the device after programming?

No. The 64-bit encryption key stored in the on-chip EEPROM is read-protected. It cannot be accessed via external connections once programmed, preventing unauthorized extraction of security credentials.