Packaging information
| Package | Pins DSBGA (YZ) | 30 |
| Operating temperature range (°C) -20 to 70 |
| Package qty | Carrier 3,000 | LARGE T&R |
Features for the AFE4900
- Synchronized PPG, ECG signal acquisition at data rates up to 1 kHz
- ECG signal chain:
- Standalone ECG acquisition up to 4 kHz
- Input bias: 1-lead ECG with RLD bias
- Programmable INA gain: 2.15 to 12.92
- Input noise (1 Hz to 150 Hz): 2.5 µVrms at 1 kHz, 1.25 µVrms at 4-kHz data rate
- AC, DC lead-off detect: 12.5-nA to 100-nA
- IEC 60601 Test report available on request
- PPG receiver:
- Supports three time-multiplexed PD inputs
- 24-Bit representation of current from PD
- DC offset subtraction DAC (Up to ±126-µA) at TIA input for each LED, ambient
- Digital ambient subtraction at ADC output
- Noise filtering with programmable bandwidth
- Transimpedance gain: 10 kΩ to 2 MΩ
- Dynamic range up to 100 dB
- Receiver operates in PPG-only mode at approximately 1-µA/Hz sampling rate
- Power-down mode: approximately 0 µA
- PPG transmitter:
- Four LEDs in common anode configuration
- 8-Bit LED current up to 200 mA
- Mode to fire two LEDs in parallel
- Programmable LED on-time
- Simultaneous support of three LEDs for SpO2, or multiwavelength HRM
- Average current of 30 µA adequate for
a
typical heart-rate monitoring scenario:- 20-mA Setting, 60-µs pulse duration,
25-Hz sampling rate
- 20-mA Setting, 60-µs pulse duration,
- Clocking using an external or internal clock
- FIFO with 128-sample depth for ECG and PPG
- I2C, SPI interfaces: selectable by pin
- 2.6-mm × 2.1-mm, 0.4-mm Pitch DSBGA package
- Supplies:
- Rx: 1.8 V to 1.9 V (LDO bypass),
2.0 V to 3.6 V (LDO enabled) - Tx: 3 V to 5.25 V
- IO: 1.7 V to Rx_SUP
- Rx: 1.8 V to 1.9 V (LDO bypass),
Description for the AFE4900
The AFE4900 device is an analog front-end (AFE) for synchronized electrocardiogram (ECG), photoplethysmogram (PPG) signal acquisition. The device can also be used for optical bio-sensing applications, such as heart-rate monitoring (HRM) and saturation of peripheral capillary oxygen (SpO2). The PPG signal chain supports up to four switching light-emitting diodes (LEDs) and up to three photodiodes (PDs). The LEDs can be switched on using a fully integrated LED driver. The current from the photodiode is converted into voltage by the transimpedance amplifier (TIA) and digitized using an analog-to-digital converter (ADC). The ECG signal chain has an instrumentation amplifier (INA) with a programmable gain that interfaces to the same ADC. A right-leg drive (RLD) amplifier set can be used to the bias for the ECG input pins. AC and dc lead-off detect schemes are supported. The ADC codes from the PPG and ECG phases can be stored in a 128-sample first in, first out (FIFO) block and read out using either an I2C or a serial programming interface (SPI) interface.