AD8232ACPZ Datasheet, PDF (1/28 Pages) Analog Devices – Single-Lead, Heart Rate Monitor Front End

Data Sheet
Single-Lead, Heart Rate Monitor Front End
AD8232
FEATURES
Fully integrated single-lead ECG front end
Low supply current: 170 µA (typical)
Common-mode rejection ratio: 80 dB (dc to 60 Hz)
Two or three 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
Leads off detection: ac or dc options
Integrated right leg drive (RLD) amplifier
Single-supply operation: 2.0 V to 3.5 V
Integrated reference buffer generates virtual ground
Rail-to-rail output
Internal RFI filter
8 kV HBM ESD rating
Shutdown pin
20-lead 4 mm × 4 mm LFCSP package
APPLICATIONS
Fitness and activity heart rate monitors
Portable ECG
Remote health monitors
Gaming peripherals
Biopotential signal acquisition
GENERAL DESCRIPTION
The AD8232 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 for an ultralow
power analog-to-digital converter (ADC) or an embedded
microcontroller to acquire the output signal easily.
The AD8232 can implement 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 AD8232 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.
FUNCTIONAL BLOCK DIAGRAM
20
19
HPSENSE IAOUT
HPDRIVE
1
S1 10kΩ
+IN
2
–IN ^IA
3
18
17
REFIN +V_S
A3
16
GND
FR 15
AC/DC 14
150kΩ
4
RLDFB
5
A2
RLD
10kΩ
AD8232
S2
LEADS-OFF
DETECTION
SDN 13
LOD+
C1
12
LOD–
C2
11
A1
SW OPAMP+ REFOUT OPAMP–
6
7
8
9
OUT
10
Figure 1.
To improve common-mode rejection of the line frequencies
in the system and other undesired interferences, the AD8232
includes an amplifier for driven lead applications, such as right
leg drive (RLD).
The AD8232 includes a fast restore function that reduces the
duration of 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 AD8232 automatically adjusts to a
higher filter cutoff. This feature allows the AD8232 to recover
quickly, and therefore, to take valid measurements soon after
connecting the electrodes to the subject.
The AD8232 is available in a 4 mm × 4 mm, 20-lead LFCSP
package. Performance is specified from 0°C to 70°C and is
operational from −40°C to +85°C.
Rev. A
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