Microchip Technology AT97SC3205T-U3A14-20

Overview

AT97SC3205T-U3A14-20 from Microchip Technology (formerly Atmel) is a TCG-compliant Trusted Platform Module (TPM) 1.2 security IC integrating an AVR® RISC microprocessor, hardware asymmetric crypto engine, 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 400 kHz and targets secure boot, platform authentication, and key management in embedded computing systems.

For engineers reviewing the AT97SC3205T-U3A14-20 datasheet, AT97SC3205T-U3A14-20 pinout, AT97SC3205T-U3A14-20 application, or AT97SC3205T-U3A14-20 equivalent, this page delivers verified electrical specs, validated I²C timing constraints, confirmed GPIO mapping for TPM_NV_INDEX_GPIO_00 and PP/GPIO, thermal range validation (-40°C to +85°C), and package-specific pinout for the 32-pad QFN variant.

Technical Context

The AT97SC3205T-U3A14-20 implements the full TCG TPM 1.2 specification using on-die AVR CPU, dedicated crypto accelerators, and internal EEPROM for RSA key storage. Its I²C interface supports both Standard (100 kHz) and Fast Mode (400 kHz) with strict pull-up resistor requirements: 800 Ω on SM_DAT and 1.5 kΩ on SM_CLK for stable high-speed operation.

Security architecture includes physical tamper detection via XTAMPER (TestBI/GPIO/XTAMPER pin), low-power deep-sleep recovery via TWI_Wakeup# dual-pin activation, and hardware-enforced RNG certified to FIPS-140-2. The device uses dynamic internal memory management for RSA key caching without host intervention beyond standard TCG commands.

Key Specifications

Pinout & Package

AT97SC3205T-U3A14-20 is packaged in a 32-pad Very Thin QFN (32M3) with 0.40 mm pitch and exposed GND center pad. Pin assignments are validated per Atmel-8883AS-TPM-AT97SC3205T-Datasheet-Summary_022014, Table 1-2 and Figure 1-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar TPM 1.2 security applications.

Compared with AT97SC3205T-U3A14-20, the SLB9665 offers broader industry adoption but omits tamper sensing, while the NPCT750 adds LPC flexibility at the cost of pinout and interface compatibility - making AT97SC3205T-U3A14-20 optimal for compact, I²C-based industrial systems needing physical security enforcement.

Availability

AT97SC3205T-U3A14-20 is available at Aetrix Electronics and suitable for secure boot authentication, platform integrity attestation, and hardware-based key management requiring stable component supply across industrial design cycles.

Supply support for AT97SC3205T-U3A14-20 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 product support, documentation, and qualification for legacy Atmel security ICs including the AT97SC3205T series.

The AT97SC3205T belongs to Atmel's Trusted Platform Module family, designed specifically to deliver certified, single-chip TPM 1.2 functionality for embedded systems requiring hardware-rooted trust and cryptographic acceleration.

FAQ

What is the operating voltage range for AT97SC3205T-U3A14-20?

The AT97SC3205T-U3A14-20 operates at a nominal supply voltage of 3.3 V with ±5% tolerance. Stable operation requires strict decoupling: 2200–4700 pF capacitors placed within 5 mm of each VCC pin and adjacent GND, plus a 0.1 µF capacitor located within 10 mm of the VCC node. Exceeding voltage limits risks permanent damage to the internal EEPROM and crypto engines.

Does AT97SC3205T-U3A14-20 support both Standard and Fast Mode I²C?

Yes, AT97SC3205T-U3A14-20 supports I²C Standard Mode (100 kHz) and Fast Mode (400 kHz). For reliable 400 kHz operation, the datasheet specifies 800 Ω pull-up on SM_DAT and 1.5 kΩ on SM_CLK. Clock duty cycle should approach 50% to maximize noise immunity - deviations degrade timing margin and increase CRC error rates during command transmission.

How is physical presence enforced on AT97SC3205T-U3A14-20?

AT97SC3205T-U3A14-20 enforces physical presence via the PP/GPIO pin, which defaults to active-high input with internal pull-down. When asserted, it signals hardware-level authorization for privileged operations like BIOS updates or key deletion. The pin must be driven high externally (e.g., via pushbutton) - leaving it floating results in default low state and rejection of protected commands.

What is the purpose of the TestBI/GPIO/XTAMPER pin on AT97SC3205T-U3A14-20?

The TestBI/GPIO/XTAMPER pin on AT97SC3205T-U3A14-20 serves three roles: as an optional GPIO, as the XTAMPER tamper detection input (active high), or as a manufacturing test signal. In production, it is commonly configured as XTAMPER to detect enclosure breaches. If unused, it must be tied to GND via a 4.7 kΩ resistor to prevent floating inputs that could trigger false tamper events or I/O contention.

Is AT97SC3205T-U3A14-20 certified to FIPS-140-2?

Yes, AT97SC3205T-U3A14-20 is FIPS-140-2 Level 2 certified, covering its hardware random number generator (RNG), HMAC, AES, SHA, and RSA cryptographic engines. This certification validates compliance with NIST SP 800-22 statistical randomness tests and physical security requirements including resistance to environmental attacks - essential for government and regulated-industry deployments.