AFE4400 Datasheet, PDF (1/69 Pages) Texas Instruments – Integrated Analog Front-End for Heart Rate Monitors and Low-Cost Pulse Oximeters

AFE4400
www.ti.com
SBAS601D – DECEMBER 2012 – REVISED MAY 2013
Integrated Analog Front-End for
Heart Rate Monitors and Low-Cost Pulse Oximeters
Check for Samples: AFE4400
FEATURES
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•23 Fully-Integrated Analog Front-End for
Pulse Oximeter Applications:
– Flexible Pulse Sequencing and
Timing Control
• Transmit:
– Integrated LED Driver
(H-Bridge or Push/Pull)
– 95-dB Dynamic Range
– LED Current:
– Programmable to 50 mA with 8-Bit
Current Resolution
– Low Power:
– 100 µA + Average LED Current
– Programmable LED On-Time
– Independent LED2 and LED1 Current
Reference
• Receive Channel with High Dynamic Range:
– 13 Noise-Free Bits (0.1 Hz to 5 Hz)
– Low Power: < 670 µA at 3.3-V Supply
– Flexible Receive Sample Time
– Flexible Transimpedance Amplifier with
Programmable LED Settings
– Integrated Digital Ambient Estimation and
Subtraction
• Integrated Fault Diagnostics:
– Photodiode and LED Open and
Short Detection
– Cable On/Off Detection
• Supplies:
– Rx = 2.0 V to 3.6 V
– Tx = 3.0 V to 3.6 V
• Package: Compact QFN-40 (6 mm × 6 mm)
• Specified Temperature Range: 0°C to +70°C
APPLICATIONS
• Low-Cost Medical Pulse Oximeter Applications
• Optical HRM
• Industrial Photometry Applications
DESCRIPTION
The AFE4400 is a fully-integrated analog front-end
(AFE) that is ideally suited for pulse oximeter
applications. The device consists of a low-noise
receiver channel with an integrated analog-to-digital
converter (ADC), an LED transmit section, and
diagnostics for sensor and LED fault detection. The
AFE4400 is a very configurable timing controller. This
flexibility enables the user to have complete control of
the device timing characteristics. To ease clocking
requirements and provide a low-jitter clock to the
AFE4400, an oscillator is also integrated that
functions from an external crystal. The device
communicates to an external microcontroller or host
processor using an SPI™ interface.
The AFE4400 is a complete AFE solution packaged
in a single, compact QFN-40 package (6 mm ×
6 mm) and is specified over the operating
temperature range of 0°C to +70°C.
AFE4400
Supply
(2.2 V to 3.6 V)
Photodiode
RX
TIA
Diagnostic
PD Open or Short
Cable Off
LED Open or Short
û ADC
RED
Amb (RED)
IR
Amb (IR)
AFE
SPI
SPI Interface
Timing
Controller
LED
Driver
LED
Tx
Tx Driver
Supply
LED
Current
Control
DAC
5-V Supply
OSC
AFE
32 kHz
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Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
SPI is a trademark of Motorola.
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All other trademarks are the property of their respective owners.
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PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2012–2013, Texas Instruments Incorporated