Data SheetADP5138Pin No.MnemonicDescription 24 GND Analog Ground. Connect this pin to the ground plane. 25 SYNC Synchronization Input. Connect this pin to an external clock between 2.8 MHz and 3.5 MHz to synchronize the switching frequency to the external clock. If synchronization function is not used, connect this pin to GND. 26 AVIN Bias Voltage Input Pin. Connect AVIN to PVINx, and connect a bypass capacitor between AVIN and GND. 27 EN1 Precision Enable Pin for Channel 1. Use an external resistor divider to set the turn-on threshold. To enable Channel 1 automatically, connect the EN1 pin to PVIN1. 28 FB1 Feedback Voltage Sense Input for Channel 1. Connect this pin to a resistor divider from VOUT1 for the adjustable version. For the fixed output version, connect this pin to VOUT1 directly. EP Exposed Pad. Solder the exposed pad to an external ground plane. Rev. A | Page 9 of 23 Document Outline Features Applications Typical Application Circuit General Description Revision History Functional Block Diagram Specifications Buck Regulator Specifications LDO Regulator Specifications Absolute Maximum Ratings Thermal Resistance ESD Caution Pin Configuration and Function Descriptions Typical Performance Characteristics Theory of Operation Control Scheme Precision Enable and Shutdown Oscillator and Phase Shift Synchronization Input Overvoltage Lockout (OVLO) Input Undervoltage Monitor (UVM) Input Undervoltage Lockout (UVLO) Output Voltage Power-Good Power-On Reset (POR) Soft Start and Power-Up Sequence Current-Limit and Short-Circuit Protection Active Output Discharge Thermal Shutdown Applications Information Input Capacitor Selection Output Voltage Setting Inductor Selection Output Capacitor Selection Application Circuit Factory-Programmable Options Outline Dimensions Ordering Guide Automotive Products