Datasheet ADP1874, ADP1875 (Analog Devices) - 2

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ADP1874/ADP1875 Data Sheet TABLE OF CONTENTS
Features .. 1 Timer Operation .. 23 Applications ... 1 Pseudo-Fixed Frequency ... 24 General Description ... 1 Power Good Monitoring ... 24 Typical Applications Circuit .. 1 Voltage Tracking ... 25 Revision History ... 2 Applications Information .. 27 Specifications ... 3 Feedback Resistor Divider .. 27 Absolute Maximum Ratings .. 6 Inductor Selection .. 27 Thermal Resistance .. 6 Output Ripple Voltage (ΔVRR) .. 27 Boundary Condition .. 6 Output Capacitor Selection... 27 ESD Caution .. 6 Compensation Network .. 28 Pin Configuration and Function Descriptions ... 7 Efficiency Consideration ... 29 Typical Performance Characteristics ... 8 Input Capacitor Selection .. 30 ADP1874/ADP1875 Block Digram ... 18 Thermal Considerations .. 31 Theory of Operation .. 19 Design Example .. 32 Startup .. 19 External Component Recommendations .. 34 Soft Start .. 19 Layout Considerations ... 36 Precision Enable Circuitry .. 19 IC Section (Left Side of Evaluation Board) ... 38 Undervoltage Lockout ... 19 Power Section ... 38 On-Board Low Dropout Regulator .. 20 Differential Sensing .. 39 Thermal Shutdown ... 20 Typical Application Circuits ... 40 Programming Resistor (RES) Detect Circuit .. 20 12 A, 300 kHz High Current Application Circuit .. 40 Valley Current-Limit Setting .. 20 5.5 V Input, 600 kHz Application Circuit ... 40 Hiccup Mode During Short Circuit ... 22 300 kHz High Current Application Circuit .. 41 Synchronous Rectifier .. 22 Outline Dimensions ... 42 ADP1875 Power Saving Mode (PSM) .. 22 Ordering Guide .. 42
REVISION HISTORY 7/12—Rev. 0 to Rev. A
Changes to Table 7 .. 21
3/11—Revision 0: Initial Version
Rev. A | Page 2 of 44 Document Outline Features Applications General Description Typical Applications Circuit Table of Contents Revision History Specifications Absolute Maximum Ratings Thermal Resistance Boundary Condition ESD Caution Pin Configuration and Function Descriptions Typical Performance Characteristics ADP1874/ADP1875 Block Digram Theory of Operation Startup Soft Start Precision Enable Circuitry Undervoltage Lockout On-Board Low Dropout Regulator Thermal Shutdown Programming Resistor (RES) Detect Circuit Valley Current-Limit Setting Hiccup Mode During Short Circuit Synchronous Rectifier ADP1875 Power Saving Mode (PSM) Timer Operation Pseudo-Fixed Frequency Power Good Monitoring Voltage Tracking Applications Information Feedback Resistor Divider Inductor Selection Output Ripple Voltage (ΔVRR) Output Capacitor Selection Compensation Network Output Filter Impedance (ZFILT) Error Amplifier Output Impedance (ZCOMP) Error Amplifier Gain (Gm) Current-Sense Loop Gain (GCS) Crossover Frequency Efficiency Consideration Channel Conduction Loss MOSFET Driver Loss Switching Loss Diode Conduction Loss Inductor Loss Input Capacitor Selection Thermal Considerations Design Example Input Capacitor Inductor Current Limit Programming Output Capacitor Feedback Resistor Network Setup Compensation Network Loss Calculations External Component Recommendations Layout Considerations IC Section (Left Side of Evaluation Board) Power Section Differential Sensing Typical Application Circuits 12 A, 300 kHz High Current Application Circuit 5.5 V Input, 600 kHz Application Circuit 300 kHz High Current Application Circuit Outline Dimensions Ordering Guide