AFE4410 Datasheet, PDF (1/7 Pages) Texas Instruments – Ultra-Small, Integrated AFE With FIFO for Wearable, Continuous Optical Heart-Rate Monitoring and Biosensing

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AFE4410
SBAS832 – MAY 2017
AFE4410 Ultra-Small, Integrated AFE With FIFO for
Wearable, Continuous Optical Heart-Rate Monitoring and Biosensing
1 Features
•1 Accurate, Continuous Heart-Rate Monitoring:
– Up to 100-dB Dynamic Range for Accurate
Heart-Rate Detection
– Low Current for Continuous Operation on a
Wearable Device With a Typical Value:
– 30 µA for an LED, 25 µA for the Receiver
• Transmitter:
– 4 LEDs in Common Anode Configurations
– 8-Bit Programmable LED Current to 200 mA
– Mode to Fire Two LEDs in Parallel
– Programmable LED On-Time
– Simultaneous Support of 3 LEDs for Optimized
SpO₂, HRM, 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
• Receiver:
– Supports 3 Time-Multiplexed PD Inputs
– 24-Bit Representation of Current Input From
PD in Twos Complement Format
– Individual DC Offset Subtraction DAC
(Up to ±126-µA Range) at TIA Input for Each
LED, Ambient
– Digital Ambient Subtraction at ADC Output
– Transimpedance Gain: 10 kΩ to 2 MΩ
– Noise Filtering With Programmable Bandwidth
– Receiver Operates at Approximately 1-µA/Hz
Sampling Rate (Example, 25 µA at 25 Hz)
– Hardware Power-Down Mode: Approximately
0-µA Current
• Flexible Pulse Sequencing and Timing Control
• Clocking Via External Clock or Internal Oscillator
• FIFO With 128-Sample Depth:
– Programmable Partitioning Across Phases
• Pin-Selectable I²C, SPI Interface
• Operating Temperature Range: –20°C to +70°C
• 2.6-mm × 2.1-mm, 0.4-mm Pitch DSBGA Package
• Supplies:
– Tx: 3 V to 5.25 V
– Rx: 1.8 V to 1.9 V (LDO Bypass),
2.0 V to 3.6 V (LDO Enabled)
– IO: 1.7 V to Rx_SUP
1
2 Applications
• Optical Heart-Rate Monitoring (HRM) for
Wearables, Hearables
• Heart-Rate Variability (HRV)
• Pulse Oximetry (SpO₂) Measurements
• Maximum Oxygen Consumption (VO₂ Max)
3 Description
The AFE4410 is an analog front-end for optical
biosensing applications, such as heart-rate
monitoring (HRM). The device supports up to four
switching light-emitting diodes (LEDs) and up to three
photodiodes (PDs). The current from the photodiode
is converted into voltage by the transimpedance
amplifier (TIA) and digitized using an analog-to-digital
converter (ADC). The ADC code is stored in a 128-
sample first in, first-out block (FIFO) with
programmable depth. The FIFO can be read out
using either an I²C interface or a serial peripheral
interface (SPI). The AFE also has a fully integrated
LED driver with 8-bit current control. The device has
high dynamic range transmit-and-receive circuitry
offering a dynamic range of up to 100 dB that
enables accurate heart-rate sensing. The AFE
achieves extremely low current levels by operating an
ultralow power (ULP) mode set by using the
ENABLE_ULP register bit.
Device Information⁽¹⁾
PART NUMBER PACKAGE
BODY SIZE (NOM)
AFE4410
DSBGA (30)
2.60 mm × 2.10 mm
(1) For all available packages, see the package option addendum
at the end of the datasheet.
PD1
PD2
PD3
Simplified Block Diagram
INP1
INM1
INP2
INM2
INP3
INM3
TX_SUP
RX_SUP
1.8 V LDOs
CONTROL1
TX_SUP
ALDO_1V8, DLDO_1V8
LED1
TX1
LED2 LED3 LED4
TX2
TX3 TX4
IO_SUP
Offset
DAC
CF
RF
Noise
TIA
reduction
RF
filter (x4)
ILED
ADC
Decimation
Threshold
Detection
FIFO
SPI/
I2C Interface
CF
4 MHz
Oscillator
Timing Engine
128 kHz
Oscillator
CLK
THR_DET_RDY
I2C_SPI_SEL
SPI
I2C
RESETZ
ADC_RDY
PROG_OUT1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.