Gehäuseinformationen
| Gehäuse | Pins DSBGA (YZ) | 30 |
| Betriebstemperaturbereich (°C) -40 to 85 |
| Gehäusemenge | Träger 250 | SMALL T&R |
Merkmale von AFE4420
- Supports signal acquisition of up to 16 phases
- Flexible allocation of LEDs and PDs in each phase
- Accurate, continuous heart-rate monitoring:
- Up to 100-dB dynamic range
- Low current for continuous operation on a wearable device with a typical
value
- 15 µA for an LED, 20 µA for the receiver
- Transmitter:
- Supports common anode LED configuration
- 8-Bit programmable LED current with range adjustable from 50 mA to 200 mA
- Mode to fire two LEDs in parallel
- Programmable LED on-time
- Simultaneous support of 4 LEDs for optimized SpO2, HRM, or multi-wavelength HRM
- Programmable control signals to extend operation to 8 LEDs using external SPDT switches
- Receiver:
- Supports 4 time-multiplexed photodiode inputs
- Individual DC offset subtraction DAC at TIA input for each LED, ambient with 7-bit control and range up to ±254 µA
- Transimpedance gain: 10 kΩ to 2 MΩ
- Digital ambient subtraction at ADC output to suppress ambient tones
- Noise filtering with programmable bandwidth
- Supports external clock and internal oscillator modes
- Automatic ambient cancellation mode (AACM) to increase receiver dynamic range
- Two programmable GPIO pins with flexible interrupt generation
- FIFO with 128-sample depth
- I2C, SPI interfaces: selectable by pin
- Operating temperature range: –40°C to +85°C
- 2.6-mm × 2.1-mm DSBGA, 0.4-mm pitch
- Supplies:
- Rx:
- 1.7 V to 1.9 V (LDO bypass)
- 1.9 V to 3.6 V (LDO enabled)
- Tx: 3 V to 5.5 V
- IO: 1.7 V to RX_SUP
- Rx:
Beschreibung von AFE4420
The AFE4420 is an analog front-end for optical bio-sensing applications, such as heart-rate monitoring (HRM) and saturation of peripheral capillary oxygen (SpO2). The device supports up to four switching light-emitting diodes (LEDs) and up to four photodiodes. Up to 16 signal phases can be defined and the signal can be acquired from each phase in a synchronized manner and stored in a 128-sample First in, First out (FIFO) block. The FIFO can be read out using either an I2C or a SPI interface. The AFE also has a fully integrated LED driver with an 8-bit current control. The device has a high dynamic range transmit-and-receive circuitry that helps with the sensing of very small signal levels.