AFE4400_15 Datasheet, PDF (1/87 Pages) Texas Instruments – AFE4400 Integrated Analog Front-End for Heart Rate Monitors and Low-Cost Pulse Oximeters

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AFE4400
SBAS601H – DECEMBER 2012 – REVISED JULY 2014
AFE4400 Integrated Analog Front-End for Heart Rate Monitors and
Low-Cost Pulse Oximeters
1 Features
•1 Fully-Integrated Analog Front-End for Pulse
Oximeter Applications:
– Flexible Pulse Sequencing and
Timing Control
• Transmit:
– Integrated LED Driver
(H-Bridge, Push, or Pull)
– Dynamic Range: 95 dB
– 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
– Low Power: < 670 µA at 3.3-V Supply
– Integrated Digital Ambient Estimation and
Subtraction
– Flexible Receive Sample Time
– Flexible Transimpedance Amplifier with
Programmable LED Settings
• Integrated Fault Diagnostics:
– Photodiode and LED Open and
Short Detection
– Cable On and Off Detection
• Supplies:
– Rx = 2.0 V to 3.6 V
– Tx = 3.0 V to 5.25 V
• Package: Compact VQFN-40 (6 mm × 6 mm)
• Specified Temperature Range: 0°C to 70°C
2 Applications
• Low-Cost Medical Pulse Oximeter Applications
• Optical HRM
• Industrial Photometry Applications
3 Description
The AFE4400 is a fully-integrated analog front-end
(AFE) 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 device 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 device is a complete AFE solution packaged in a
single, compact VQFN-40 package (6 mm × 6 mm)
and is specified over the operating temperature range
of 0°C to 70°C.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
AFE4400
VQFN (40)
6.00 mm × 6.00 mm
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
AFE4400
Supply
(2.0 V to 3.6 V)
Photodiode
Rx
TIA
Diagnostic
PD Open or Short
Cable Off
LED Open or Short
ûADC
RED
Amb (RED)
IR
Amb (IR)
AFE
SPI
SPI
Interface
Timing
Controller
LED
Driver
LED
Tx
LED
Current
Control
DAC
Tx Supply
(3.0 V or 5.25 V)
OSC
AFE
8 MHz
1
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.