Microchip Technology AT97SC3205T-X3A1420B

Overview

AT97SC3205T-X3A1420B from Microchip Technology (formerly Atmel) is a TCG-compliant Trusted Platform Module (TPM) 1.2 security IC implementing hardware-based asymmetric cryptography, FIPS-140-2 certified RNG/AES/SHA/RSA engines, and 2066-byte NV user storage. It operates at 3.3V with I²C interface up to 400kHz and targets embedded platform root-of-trust applications.

For engineers reviewing the AT97SC3205T-X3A1420B datasheet, AT97SC3205T-X3A1420B pinout, AT97SC3205T-X3A1420B application, or AT97SC3205T-X3A1420B equivalent, key selection criteria include TPM 1.2 compliance, I²C timing constraints (SM_DAT/SM_CLK pull-up guidance), GPIO-Express-00 mapping to TPM_NV_INDEX_GPIO_00, and dual-package support (28-pin TSSOP / 32-pin QFN) with industrial temperature range (-40°C to +85°C).

Technical Context

The AT97SC3205T-X3A1420B integrates an AVR® 8-bit RISC microprocessor with dedicated crypto hardware acceleration for RSA key generation, HMAC, and SHA hashing. Its internal EEPROM stores RSA keys and supports dynamic key cache management via TCG commands like TPM_FlushSpecific and TPM_LoadKey2.

Security architecture includes physical tamper detection (XTAMPER pin), hardware physical presence (PP/GPIO), low-power deep-sleep recovery (TWI_Wakeup#), and FIPS-140-2 certification covering RNG, AES, SHA, and RSA engines - all implemented in a single-chip turnkey solution compliant with TCG TPM 1.2 specification.

Key Specifications

Pinout & Package

AT97SC3205T-X3A1420B is available in two RoHS-compliant packages: 28-pin Thin TSSOP (4.40mm × 9.70mm body, 0.65mm pitch) and 32-pad QFN (4.00mm × 4.00mm body, 0.40mm pitch). Both support industrial temperature range and share identical pin functionality except for NC pin count and layout.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar TPM security module applications.

Compared with Infineon SLB9670 and Nuvoton NPCT750, AT97SC3205T-X3A1420B uniquely delivers TPM 1.2 compliance with FIPS-140-2 certification across RNG, AES, SHA, HMAC, and RSA - validated for industrial temperatures and optimized for I²C host integration without SPI redesign.

Availability

AT97SC3205T-X3A1420B is available at Aetrix Electronics and suitable for server boot integrity, industrial PLC security, and medical device authentication requiring stable component supply across long product lifecycles.

Supply support for AT97SC3205T-X3A1420B includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microchip Technology acquired Atmel in 2016 and maintains full support for legacy Atmel security products including the AT97SC3205T series.

The AT97SC3205T-X3A1420B belongs to Atmel's Trusted Platform Module product line, designed specifically to deliver certified hardware root-of-trust for embedded systems requiring TCG-compliant secure boot, attestation, and key management.

FAQ

What is the primary compliance standard met by the AT97SC3205T-X3A1420B?

The AT97SC3205T-X3A1420B is fully compliant with the Trusted Computing Group (TCG) Trusted Platform Module (TPM) Version 1.2 Specification. It implements all mandatory TCG 1.2 commands and interfaces, enabling interoperability with industry-standard trusted computing software stacks such as Microsoft TPM Base Services and Linux tpm-tools. This compliance is foundational to its role as a hardware root-of-trust in secure boot and attestation workflows.

Does the AT97SC3205T-X3A1420B support both TSSOP and QFN packages, and are they functionally identical?

Yes, the AT97SC3205T-X3A1420B is offered in both 28-pin Thin TSSOP and 32-pad QFN packages. Functionally, both variants share identical electrical characteristics, pin definitions, and firmware - including I²C timing, GPIO mappings, and crypto engine behavior. The only differences are mechanical: TSSOP measures 4.4×9.7mm with 0.65mm pitch, while QFN is 4.0×4.0mm with 0.40mm pitch and includes an exposed thermal pad tied to GND.

How does the AT97SC3205T-X3A1420B handle secure key storage and generation?

The AT97SC3205T-X3A1420B uses internal EEPROM to store RSA keys and leverages its FIPS-140-2 certified hardware random number generator (RNG) for cryptographically secure key generation. Keys never leave the device boundary - all RSA operations (signing, decryption) occur within the protected crypto engine. The 2066-byte NV storage allows additional user-defined keys or certificates to be written via TPM_NV_Write commands under authenticated sessions.

What are the critical I²C interface design considerations for reliable operation of the AT97SC3205T-X3A1420B?

For stable 400kHz I²C operation, the AT97SC3205T-X3A1420B requires SM_DAT pull-up ≤800Ω and SM_CLK pull-up ≤1.5kΩ. The SM_CLK signal should maintain near 50% duty cycle to minimize timing jitter. Additionally, VCC decoupling is critical: place 2200–4700pF capacitors <5mm between each VCC-GND pair and a 0.1μF capacitor <10mm at the VCC node. These values are validated in Atmel's reference designs for AT97SC3205T-X3A1420B.

Is the AT97SC3205T-X3A1420B certified to FIPS-140-2, and what modules are covered?

Yes, the AT97SC3205T-X3A1420B is FIPS-140-2 Level 2 certified. Certification explicitly covers the hardware random number generator (RNG), HMAC, AES, SHA, and RSA cryptographic engines - all implemented in silicon and validated per FIPS PUB 140-2 Annexes A–D. This certification applies to the complete AT97SC3205T-X3A1420B device, including its internal EEPROM key storage and secure boot ROM, and is documented in the official Atmel FIPS certificate #1756.