Packaging information
| Package | Pins DSBGA (YBG) | 36 |
| Operating temperature range (°C) -40 to 85 |
| Package qty | Carrier 250 | SMALL T&R |
Features for the AFE4950
- Supports simultaneous and synchronized acquisition of up to 24 PPG and a single-lead ECG signal.
- Flexible allocation of 8 LED, 4 PD in each phase
- ECG signal chain:
- 1-lead ECG signal acquisition up to 2 kHz
- RLD output to drive a third electrode
- Input noise : 0.7 µV-rms
- Supports up to ±0.65 V differential DC offset and +/-0.55 V common mode range
- Programmable INA gain: 11, 21
- High-pass filter with quick saturation recovery
- Integrated 300 Hz anti-aliasing low pass filter
- AC, DC lead-off detect: 2.9 nA to 92.5 nA
- Low power continuous lead-on detection
- Impedance signal chain
- Continuous low-power monitoring of impedance between 2 electrodes
- 7 MΩ range
- 300 Ω noise on 620 kΩ
- PPG Transmitter:
- 8-Bit Programmable LED Current with range adjustable from 25 mA to 250 mA
- Mode to fire two LEDs in parallel
- Support of 8 LEDs in Common Anode configuration for SpO2, Multi-Wavelength HRM
- PPG Receiver:
- 2 parallel receivers (two sets of TIA/ filter)
- Supports 4 Time-Multiplexed Photodiode Inputs to each Receiver
- 8-bit Ambient Offset subtraction at each TIA input with 256 µA range
- 8-bit LED Offset Subtraction DAC with 64 µA range
- Automatic ambient cancellation and dynamic LED DC cancellation at TIA input
- Ambient rejection close to 100 dB up to 10 Hz
- Noise filtering with programmable bandwidth
- Trans-impedance Gain: 3.7 kΩ to 1 MΩ
- Accurate, Continuous Heart-Rate Monitoring:
- System SNR up to 109-dB at 16 µA PD current
- Low Current for Continuous Operation on a Wearable Device with a Typical Value: 15-µA for an LED, 20-µA for the Receiver
- External clock and internal oscillator modes
- Acquire data synchronized with system master clock
- FIFO with 256-sample Depth
- SPI, I2C interfaces: Selectable by pin
- 2.6-mm × 2.5-mm DSBGA, 0.4-mm Pitch
- Supplies: Rx:1.7-1.9V (LDO Bypass); 1.9-3.6V (LDO Enabled), Tx:3-5.5V, IO:1.7-RX_SUP
Description for the AFE4950
The AFE4950 device is an analog front-end (AFE) for synchronized signal acquisition of PPG and ECG signals. 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 ECG signal chain supports 2- and 3-electrode configurations and has an integrated Right leg drive (RLD) buffer. The ECG signal chain can also be used to do a continuous, low-power monitoring of the impedance between pair of electrodes.