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See Technical Specifications

AFE4900YZT

Ultra-low-power integrated AFE for wearable optical, electrical biosensing

Manufacturer:

Texas Instruments, Inc
Mfr.Part #:

AFE4900YZT
Datasheet:

AFE4900YZT Datasheet (PDF)
Number of Bits:

24
Number of Channels:

3
Mounting Type:

Surface Mount
Base Product Number:

AFE4900
EDA/CAD Models:

Request Free CAD Models for AFE4900YZT

Email: [email protected]

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AFE4900YZT General Description

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.

Key Features

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
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

Specifications

Category	Integrated Circuits (ICs)Data AcquisitionAnalog Front End (AFE)	Series	-
Number of Bits	24	Number of Channels	3
Voltage - Supply, Analog	-	Voltage - Supply, Digital	-
Mounting Type	Surface Mount	Base Product Number	AFE4900