link to page 1 link to page 1 link to page 1 link to page 1 link to page 3 link to page 4 link to page 7 link to page 7 link to page 7 link to page 8 link to page 9 link to page 15 link to page 15 link to page 15 link to page 16 link to page 16 link to page 16 link to page 16 link to page 17 link to page 17 link to page 17 link to page 18 link to page 19 link to page 20 link to page 20 AD8244Data SheetTABLE OF CONTENTS Features .. 1 Guarding .. 14 Applications ... 1 Input Protection ... 15 Pin Configuration ... 1 Layout Considerations ... 15 General Description ... 1 Differential Signal Chains ... 15 Revision History ... 2 Low Output Impedance vs. Frequency.. 15 Specifications ... 3 Applications Information .. 16 Absolute Maximum Ratings .. 6 Electrocardiogram (ECG) ... 16 Thermal Resistance .. 6 Filtering .. 16 ESD Caution .. 6 Photodiode Amplifier .. 17 Pin Configuration and Function Descriptions ... 7 Low Noise, JFET Input Buffer .. 18 Typical Performance Characteristics ... 8 Outline Dimensions ... 19 Theory of Operation .. 14 Ordering Guide .. 19 Overview .. 14 REVISION HISTORY 12/14—Rev. 0 to Rev. A Added Figure 1 Caption and Changes to Figure 2 ... 1 Changes to Low Output Impedance vs. Frequency Section ... 15 Changes to Electrocardiogram (ECG) Section, Filtering Section, Figure 42, and Figure 43 .. 16 Changes to Figure 44 .. 17 Changes to Ordering Guide .. 19 10/13—Revision 0: Initial Version Rev. A | Page 2 of 20 Document Outline FEATURES APPLICATIONS PIN CONFIGURATION GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION OVERVIEW GUARDING INPUT PROTECTION LAYOUT CONSIDERATIONS DIFFERENTIAL SIGNAL CHAINS LOW OUTPUT IMPEDANCE vs. FREQUENCY APPLICATIONS INFORMATION ELECTROCARDIOGRAM (ECG) FILTERING Sallen-Key Low-Pass Filter Sallen-Key High-Pass Filter Twin-T Notch Filter PHOTODIODE AMPLIFIER LOW NOISE, JFET INPUT BUFFER OUTLINE DIMENSIONS ORDERING GUIDE