Datasheet ADP2441 (Analog Devices) - 6

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ADP2441 Data Sheet PIN CONFIGURATION AND FUNCTION DESCRIPTIONS ND T CC AG V BS 1 12 1 10 FB 1 9 VIN ADP2441 COMP 2 TOP 8 SW VIEW EN 3 7 PGND 4 5 6 Q K R RE T GOOD F P SS/ NOTES
003
1. THE EXPOSED PAD SHOULD BE CONNECTED TO THE SYSTEM AGND PLANE AND PGND PLANE.
10581- Figure 3. Pin Configuration, Top View
Table 4. Pin Function Descriptions Pin No. Mnemonic Description
1 FB Feedback Regulation Voltage is 0.6 V. Connect this pin to a resistor divider from the output of the dc-to-dc regulator. 2 COMP Error Amplifier Compensation. Connect a resistor and capacitor in series to ground. 3 EN Precision Enable. This features offers ±5% accuracy when using a 1.25 V reference voltage. Pull this pin high to enable the regulator and low to disable the regulator. Do not leave the EN pin floating. 4 PGOOD Active High Power-Good Output. This pin is pulled low when the output is out of regulation. 5 FREQ Switching Frequency. A resistor to AGND sets the switching frequency (see the Setting the Switching Frequency section). Do not leave the FREQ pin floating. 6 SS/TRK Soft Start/Tracking Input. A capacitor to ground is required to program the soft start time, which gradually ramps up the output. A resistive divider to an external reference is required on this pin to track an external voltage. 7 PGND Power Ground. Connect a decoupling ceramic capacitor as close as possible between the VIN pin and this pin. Connect this pin directly to the exposed pad. 8 SW Switch. The midpoint for the drain of the low-side N-channel power MOSFET switch and the source for the high-side N-channel power MOSFET switch. 9 VIN Power Supply Input. Connect this pin to the input power source, and connect a bypass ceramic capacitor directly from this pin to PGND, as close as possible to the IC. The operation voltage is 4.5 V to 36 V. 10 BST Boost. Connect a 10 nF ceramic capacitor between the BST and SW pins as close to the IC as possible to form a floating supply for the high-side N-Channel power MOSFET driver. This capacitor is needed to drive the gate of the N-channel power MOSFET above the supply voltage. 11 VCC Output of the Internal Low Dropout Regulator. This pin supplies power for the internal controller and driver circuitry. Connect a 1 µF ceramic capacitor between VCC and AGND and a 1 µF ceramic capacitor between VCC and PGND. The VCC output is active when the EN pin voltage is more than 0.7 V. 12 AGND Analog Ground. This pin is the internal ground for the control functions. Connect this pin directly to the exposed pad. EP Exposed Thermal Pad. The exposed pad should be connected to AGND and PGND. Rev. C | Page 6 of 32 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION TYPICAL CIRCUIT CONFIGURATION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS INTERNAL BLOCK DIAGRAM THEORY OF OPERATION CONTROL ARCHITECURE Fixed Frequency Mode Pulse Skip Mode ADJUSTABLE FREQUENCY POWER GOOD SOFT START TRACKING Coincident Tracking Ratiometric Tracking UNDERVOLTAGE LOCKOUT (UVLO) PRECISION ENABLE/SHUTDOWN CURRENT-LIMIT AND SHORT-CIRCUIT PROTECTION THERMAL SHUTDOWN APPLICATIONS INFORMATION SELECTING THE OUTPUT VOLTAGE SETTING THE SWITCHING FREQUENCY SOFT START EXTERNAL COMPONENTS SELECTION Input Capacitor Selection Inductor Selection Output Capacitor Selection BOOST CAPACITOR VCC CAPACITOR LOOP COMPENSATION LARGE SIGNAL ANALYSIS OF THE LOOP COMPENSATION DESIGN EXAMPLE CONFIGURATION AND COMPONENTS SELECTION Resistor Divider Switching Frequency Soft Start Capacitor Inductor Selection Input Capacitor Selection Output Capacitor Selection Compensation Selection SYSTEM CONFIGURATION TYPICAL APPLICATION CIRCUITS DESIGN EXAMPLE OTHER TYPICAL CIRCUIT CONFIGURATIONS POWER DISSIPATION AND THERMAL CONSIDERATIONS POWER DISSIPATION Inductor Losses Power Switch Conduction Losses Switching Losses Transition Losses THERMAL CONSIDERATIONS EVALUATION BOARD THERMAL PERFORMANCE CIRCUIT BOARD LAYOUT RECOMMENDATIONS OUTLINE DIMENSIONS ORDERING GUIDE