TI AFE4490RHAR

The AFE4490 is a fully integrated AFE well suited for pulse oximetry applications. The device includes a low-noise receiver channel with a 22-bit ADC, an LED transmitter section, and diagnostic functions for sensor and LED fault detection. The device features a configurable timing controller. This flexibility gives users complete control over the device timing characteristics. To simplify timing requirements and provide a low-jitter clock to the device, an oscillator clocked by an external crystal is also integrated. The device communicates with an external microcontroller or host processor via an SPI interface. The device is a complete AFE solution in a single, compact VQFN-40 package (6mm × 6mm), rated for an operating temperature range of -40°C to 85°C.

• Integrated LED driver (H-bridge, push-pull)
• 110dB dynamic range across the entire range (low noise at low LED current)
• LED current: programmable range of 50mA, 75mA, 100mA, 150mA, and 200mA, each with 8-bit current resolution
• Low power consumption: 100μA + average LED current
• LED on-time programmable from (50μs + settling time) to 4ms
• Independent LED2, LED1 current references
• Input-referred noise: 50pARMS (measured at 5μA PD current)
• 13.5 noise-free bits (measured at 5μA PD current)
• Analog ambient cancellation with selectable ambient current from 1μA to 10μA
• Low power consumption at 3.0V supply: <2.3mW
• Rx sample time: 50μs to 4ms
• I-V amplifier with 7 individual LED2 and LED1 programmable feedback R and C settings
• Integrated digital ambient estimation and subtraction
• Photodiode and LED open/short circuit detection
• Cable connect/disconnect detection
• Rx = 2.0V to 3.6V, Tx = 3.0V or 5.25V
• Compact ultra-thin VQFN-40 (6mm × 6mm)
• Rated temperature range: -40°C to 85°C

• Medical pulse oximeter applications
• Industrial light measurement applications