AD8233 Datasheet, PDF (1/30 Pages) Analog Devices – Fitness and activity heart rate monitors

Data Sheet
50 μA, 2 mm × 1.7 mm WLCSP, Low Noise,
Heart Rate Monitor for Wearable Products
AD8233
FEATURES
Fully integrated, single-lead electrocardiogram (ECG) front end
Low quiescent supply current: 50 μA (typical)
Leads on/off detection while in shutdown (<1 μA)
Common-mode rejection ratio: 80 dB (dc to 60 Hz)
2 or 3 electrode configurations
High signal gain (G = 100) with dc blocking capabilities
2-pole adjustable high-pass filter
Accepts up to ±300 mV of half cell potential
Fast restore feature improves filter settling
Uncommitted op amp
3-pole adjustable low-pass filter with adjustable gain
Integrated right leg drive (RLD) amplifier with shutdown
Single-supply operation: 1.7 V to 3.5 V
Integrated reference buffer generates virtual ground
Rail-to-rail output
Internal RFI filter
8 kV human body model (HBM) ESD rating
Shutdown pin
2 mm × 1.7 mm WLCSP
APPLICATIONS
Fitness and activity heart rate monitors
Portable ECG
Wearable and remote health monitors
Gaming peripherals
Biopotential signal acquisition, such as EMG
GENERAL DESCRIPTION
The AD8233 is an integrated signal conditioning block for ECG
and other biopotential measurement applications. It is designed
to extract, amplify, and filter small biopotential signals in the
presence of noisy conditions, such as those created by motion or
remote electrode placement. This design allows an ultralow
power analog-to-digital converter (ADC) or an embedded
microcontroller to easily acquire the output signal.
The AD8233 implements a two-pole high-pass filter for
eliminating motion artifacts and the electrode half cell potential.
This filter is tightly coupled with the instrumentation architec-
ture of the amplifier to allow both large gain and high-pass
filtering in a single stage, thereby saving space and cost.
An uncommitted operational amplifier enables the AD8233 to
create a three-pole, low-pass filter to remove additional noise.
The user can select the frequency cutoff of all filters to suit
different types of applications.
To improve the common-mode rejection of the line frequencies
in the system and other undesired interferences, the AD8233
Rev. 0
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FUNCTIONAL BLOCK DIAGRAM
A4
B4
HPSENSE IAOUT
HPDRIVE
A5
S1 10kΩ
+IN
B5
–IN ^IA
C5
A3
A2
REFIN +V_S
A3
A1
GND
FR B3
AC/DC B2
150kΩ
C4
RLDFB
D5
A2
RLD
10kΩ
AD8233
S2
SDN B1
RLD SDN C2
LEADS OFF
DETECTION
LOD
C
C1
A1
SW OPAMP+ REFOUT OPAMP–
D4
D3
C3
D2
OUT
D1
Figure 1.
includes an amplifier for driven lead applications, RLD.
The AD8233 includes a fast restore function that reduces the
duration of the otherwise long settling tails of the high-pass
filters. After an abrupt signal change that rails the amplifier
(such as a leads off condition), the AD8233 automatically
adjusts to a higher filter cutoff. This feature allows the AD8233
to recover quickly, and therefore, to take valid measurements
soon after connecting the electrodes to the subject.
The AD8233 is available in a 2 mm × 1.7 mm, 20-ball WLCSP
package. Performance is specified from 0°C to 70°C and is
operational from −40°C to +85°C.
Table 1. AD8232 vs. AD8233 Comparison
Parameter
AD8232
AD8233
Supply Current
170 μA
50 μA
Peak-to-Peak Voltage Noise
(f = 0.5 Hz to 40 Hz)
14 μV p-p
8.5 μV
Leads On/Off Detection in
Shutdown
Not included
Included
Right Leg Drive Shutdown
Not included
Included
Package Size
4 mm × 4 mm ×
0.75 mm
2 mm × 1.7 mm ×
0.5 mm
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