AFE4490 Datasheet | Texas Instruments

Features - 1 Fully-Integrated Analog Front-End for Pulse Oximeter Applications: - Flexible Pulse Sequencing and Timing Control - Transmit: - Integrated LED Driver (H-Bridge, Push, or Pull) - 110-d B Dynamic Range Across Full Range (Enables Low Noise at Low LED Current) - LED Current: - Programmable Ranges of 50 m A, 75 m A, 100 m A, 150 m A, and 200 m A, Each with 8-Bit Current Resolution - Low Power: - 100 µA + Average LED Current - LED On-Time Programmability from (50 µs + Settle Time) to 4 ms - Independent LED2, LED1 Current Reference - Receive Channel with High Dynamic Range: - Input-Referred Noise: 50 p ARMS (at 5-µA PD Current) - 13.5 Noise-Free Bits (at 5-µA PD Current) - Analog Ambient Cancellation Scheme with Selectable 1-µA to 10-µA Ambient Current - Low Power: < 2.3 m W at 3.0-V Supply - Rx Sample Time: 50 µs to 4 ms - I-V Amplifier with Seven Separate LED2 and LED1 Programmable Feedback R and C Settings - Integrated Digital Ambient Estimation and Subtraction - Integrated Fault Diagnostics: - Photodiode and LED Open and Short Detection - Cable On or Off Detection - Supplies: - Rx = 2.0 V to 3.6 V - Tx = 3.0 V or 5.25 V - Package: pact VQFN-40 (6 mm × 6 mm) - Specified Temperature Range: - 40°C to 85°C 2 Applications - Medical Pulse Oximeter Applications - Industrial Photometry Applications 3 Description The AFE4490 is a fully-integrated analog front-end (AFE) that is ideally suited for pulse-oximeter applications. The device consists of a low-noise receiver channel with a 22-bit analog-to-digital converter (ADC), an LED transmit section, and diagnostics for sensor and LED fault detection. The device is a very configurable timing controller. This flexibility enables the user to have plete control of the device timing characteristics. To ease clocking requirements and provide a low-jitter clock to the device, an oscillator is also integrated that functions from an external crystal. The device municates to an external microcontroller or host processor using an SPI™...