Texas Instruments AFE4490RHAR

Description
The AFE4490 is a fully integrated analog front-end (AFE) designed for pulse oximeter applications. It comprises 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 AFE4490 offers flexible timing control, allowing users to customize device timing characteristics. An integrated oscillator, driven by an external crystal, provides a low-jitter clock. The device communicates with external microcontrollers or host processors via an SPI interface. Packaged in a compact QFN-40 (6 mm x 6 mm), the AFE4490 operates over a temperature range of -40°C to 85°C.

Features
Transmit Section:
Integrated LED driver (H-bridge or push/pull)
110-dB dynamic range across full range
Programmable LED current ranges (50 mA, 75 mA, 100 mA, 150 mA, 200 mA) with 8-bit resolution
Low power consumption (100 μA average LED current)
LED on-time programmability from (50 μs settle time) to 4 ms
Independent LED2 and LED1 current reference
Receive Channel:
High dynamic range
Input-referred noise: 50 PARMS (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 consumption (<2.3 mA at 3.0-V supply)
Rx sample time: 50 μs to 250 μs
I-V amplifier with seven separate LED2 and LED1 programmable feedback R and C settings
Integrated Functions:
Digital ambient estimation and subtraction
Fault diagnostics (photodiode and LED open and short detection, cable on/off detection)

Applications
Medical pulse oximeter applications
Industrial photometry applications