Synaptics Fs7605 Touch Fingerprint Sensor With Pureprint-tm- Top 【8K】

Technical Report: Synaptics FS7605 – PurePrint™ Anti-Spoofing & TMR Top Integration

Document ID: SYNA-FS7605-TECH-REPORT
Date: April 24, 2026
Subject: Evaluation of Synaptics FS7605 Sensor with PurePrint™ and TMR Top (Touch-embedded)

9.2 Mechanical Design

• Cover thickness: ≤ 300 µm (glass or ceramic)
• Air gap: 0 µm (direct bond via optically clear adhesive)
• Ring electrode recommended for enhanced liveness detection.

2. Industrial Handheld Terminals

Warehouse scanners and medical tablets require gloves-off security. The FS7605's ability to read low-amplitude fingerprints (common in manual laborers with worn ridges) makes it superior to optical sensors. Cover thickness: ≤ 300 µm (glass or ceramic)

How PurePrint Works

1. Neural Network Classification: The FS7605 integrates a dedicated neural processing unit (NPU) directly on the sensor die. When you place your finger, the sensor captures raw data. Simultaneously, the PurePrint engine analyzes the image for artifacts of "fake-ness"—air bubbles in silicone, unnatural reflectivity in gelatin, or pixel regularity in printed images.
2. Spoof Detection: The system has been trained on millions of fake fingerprints (printed, molded, gelatine, Play-Doh, and latex). It distinguishes between the natural electrical impedance of live skin (which has moisture and salt) vs. the uniform impedance of synthetics.
3. Local Processing (The TOP Security): Crucially, all of this analysis happens inside the sensor chip. The host processor (CPU of the phone or laptop) never sees the raw fingerprint image. The chip sends back only a "Yes/No" token via the Trusted Output Protocol. This prevents malware on the PC from intercepting your biometric data.

5.1 Enrollment Process

1. Host sends an enrollment command.
2. Sensor captures finger, runs PurePrint™, extracts minutiae (endpoints, bifurcations).
3. Template (encrypted with device-unique key) is stored in on-chip flash.
4. Host receives only enrollment success/failure – no template data leaves the sensor.

Recommendation for OEMs

• Obtain the FS7605 datasheet and integration guide from Synaptics; validate glass/display stack compatibility and max thickness.
• Plan secure storage in TEE/SE and certification path (e.g., FIDO/Android).
• Conduct field testing across temperatures, humidity, screen protectors, and real-world contamination.
• Tune PurePrint parameters for target market and threat model; consider additional liveness checks at system level.

9.3 SPI Configuration

• Mode 0 (CPOL=0, CPHA=0)
• Clock up to 48 MHz
• Payload: commands (1 byte) + length + data + CRC32

8.3 IoT and Access Control

• Smart locks with anti-spoof requirement
• POS terminals (PCI compliance via match-in-sensor)
• Automotive (ignition and driver identification)

Why "TOP" matters for Zero-Trust Architecture

In enterprise environments, PurePrint-TM- TOP allows the FS7605 to be certified for Windows Hello and FIDO2. It creates a hardware root of trust. If the sensor cannot verify that the finger is attached to a living human, it does not release the authentication key. 8.3 IoT and Access Control

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