Datasheet AD8233 (Analog Devices) - 29

Data Sheet AD8233 USING AD5940, AD8232, AND AD8233 FOR
AD5940 GPIOx pin) and the AD5940 switch matrix
BIOIMPEDANCE AND ELECTROCARDIOGRAM (ECG)
disconnects the AD8232 and the AD8233 from the electrodes.
MEASUREMENTS
When an ECG measurement is required, the AD5940 switch The AD5940 can be used in conjunction with the AD8232 and matrix disconnects the AD5940 AFE from the electrodes and the AD8233 to perform bioimpedance and ECG measurements. connects the AD8233 front end. The AD8233 analog output is The same electrodes can be used to facilitate both measurements. connected to the high performance, 16-bit ADC on the When a bioimpedance measurement (for example, body AD5940 through an AINx pin. The measurement data is stored composition, hydration, and electrodermal activity (EDA)) is in the AD5940 data FIFO to be read by the host control er. required, the AD8232 and AD8233 are put into shutdown (the For more information, refer to the AN-1557 Application Note. SDN pin on the AD8232 and the AD8233 is control ed by the
VBIAS0 VZERO0 AIN1 EXCITATION VREF2V5 C BUFFER ISO RLIMIT CE0 HSDAC E1 LP DUAL CE0 OUTPUT AIN0 R DAC LIMITECG RE0 LP RF = 0Ω AMP LPTIA AIN4 R = INFΩ HPDRIVE HPSENSE TIA AFE2 RLIMIT +IN IAOUT ECG DE0 AFE3 +VS SE0 +V SW2_1 –IN AD8233 S E1 E2 REFIN SW CISO GND AIN2 OPAMP+ E3 E2 AIN6 FR REFOUT 10MΩ AC/DC OPAMP– RLD SDN +V E4 S OUT AIN4 TO RLDFB SDN HOST/ RLD LOD AD5940 C UX ISO 10MΩ BIA M AIN3 E3 RLIMITECG AIN1 ADC AIN0 AAF COARSE C V OFFSET ISO R BIAS LIMIT HSTIA CORRECTION AIN1 E4 RTIABIA AD5940 CTIABIA
079
RLIMITECG
13737- Figure 79. Body Composition and ECG System Solution Using the AD5940 with the AD8232 and AD8233 Rev. D | Page 29 of 32 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS INSTRUMENTATION AMPLIFIER PERFORMANCE CHARACTERISTICS OPERATIONAL AMPLIFIER PERFORMANCE CHARACTERISTICS RLD AMPLIFIER PERFORMANCE CHARACTERISTICS REFERENCE BUFFER PERFORMANCE CHARACTERISTICS SYSTEM PERFORMANCE CHARACTERISTICS THEORY OF OPERATION ARCHITECTURE OVERVIEW INSTRUMENTATION AMPLIFIER OPERATIONAL AMPLIFIER RLD AMPLIFIER REFERENCE BUFFER FAST RESTORE CIRCUIT LEADS ON OR OFF DETECTION DC Leads On or Off Detection AC Leads On or Off Detection STANDBY OPERATION INPUT PROTECTION RADIO FREQUENCY INTERFERENCE POWER SUPPLY REGULATION AND BYPASSING INPUT REFERRED OFFSETS LAYOUT RECOMMENDATIONS APPLICATION INFORMATION ELIMINATING ELECTRODE OFFSETS HIGH-PASS FILTERING Two-Pole High-Pass Filter Additional High-Pass Filtering Options LOW-PASS FILTERING AND GAIN Driving ADCs DRIVEN ELECTRODE MEASURING SURFACE ELECTROMYOGRAPHY (EMG) OR ELECTROENCEPHALOGRAPHY (EEG) APPLICATION CIRCUITS Heart Rate Measurement (HRM) Next to the Heart Exercise Application, HRM at the Hands Holter Monitor Configuration Portable Heart Rate and Activity Monitor System Synchronous ECG and Photoplethysmography (PPG) Measurement Using Transimpedance Amplifier (TIA) ADC Mode Using the ADPD1080 USING AD5940, AD8232, AND AD8233 FOR BIOIMPEDANCE AND ELECTROCARDIOGRAM (ECG) MEASUREMENTS DIE INFORMATION OUTLINE DIMENSIONS ORDERING GUIDE