The AFE4490RHAT is a fully-integrated Analog Front End 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 complete 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 communicates to an external microcontroller or host processor using an SPI™ interface.
● Flexible pulse sequencing and timing control
● Transmit - Integrated LED driver (H-Bridge, Push or Pull)
● Transmit - 110dB Dynamic range across full range (Enables low noise at low LED current)
● Transmit - Programmable ranges of 50mA, 75mA 100mA, 150mA and 200mA, with 8-bit current resolution
● Transmit - LED on-time programmability from (50µs + Settle Time) to 4ms
● Transmit - Independent LED2, LED1 current reference
● Receive channel with high dynamic range
● Receive - 50pARMS (at 5µA PD Current) Input-referred noise
● Receive - 13.5 Noise-free bits (at 5µA PD Current)
● Receive - Analog ambient cancellation scheme with selectable 1 to 10µA Ambient current
● Receive - 50µs to 4ms Rx Sample time
● Receive - I-V Amplifier with seven separate LED2 and LED1 programmable feedback R and C settings
● Receive - Integrated digital ambient estimation and subtraction
● Integrated fault diagnostics - Photodiode and LED Open/Short detection, Cable ON or OFF detection
