ADM7155Data SheetPIN CONFIGURATIONS AND FUNCTION DESCRIPTIONSVREG 18 VINVREG 18 VINVOUT 2ADM7155 7 ENVOUT 27 ENADM7155TOP VIEWBYP 3 (Not to Scale) 6 REFBYP 3TOP VIEW6 REF(Not to Scale)GND 45 REF_SENSEGND 45 REF_SENSENOTESNOTES1. THE EXPOSED PAD IS LOCATED ON THE BOTTOM OF1. THE EXPOSED PAD IS LOCATED ON THE BOTTOM OFTHE PACKAGE. THE EXPOSED PAD ENHANCESTHE PACKAGE. THE EXPOSED PAD ENHANCESTHERMAL PERFORMANCE, AND IT IS ELECTRICALLYTHERMAL PERFORMANCE, AND IT IS ELECTRICALLYCONNECTED TO GND INSIDE THE PACKAGE. CONNECT 04 -0 CONNECTED TO GND INSIDE THE PACKAGE. CONNECTTHE EP TO THE GROUND PLANE ON THE BOARD TO 003 THE EP TO THE GROUND PLANE ON THE BOARD TOENSURE PROPER OPERATION. 12325 ENSURE PROPER OPERATION. 12325- Figure 3. 8-Lead LFCSP Pin Configuration Figure 4. 8-Lead SOIC Pin Configuration Table 6. Pin Function Descriptions Pin No.MnemonicDescription 1 VREG Regulated Input Supply Voltage to LDO Amplifier. Bypass VREG to GND with a 10 μF or greater capacitor. 2 VOUT Regulated Output Voltage. Bypass VOUT to GND with a 10 μF or greater capacitor. 3 BYP Low Noise Bypass Capacitor. Connect a 1 μF capacitor from the BYP pin to GND to reduce noise. Do not connect a load to ground. 4 GND Ground Connection. 5 REF_SENSE Reference Sense. Connect Pin 5 to the REF pin. Do not connect Pin 5 to VOUT or GND. 6 REF Low Noise Reference Voltage Output. Bypass REF to GND with a 1 μF capacitor. Short REF_SENSE to REF for fixed output voltages. Do not connect a load to ground. 7 EN Enable. Drive EN high to turn on the regulator; drive EN low to turn off the regulator. For automatic startup, connect EN to VIN. 8 VIN Regulator Input Supply Voltage. Bypass VIN to GND with a 10 μF or greater capacitor. EP Exposed Pad. The exposed pad is located on the bottom of the package. The exposed pad enhances thermal performance, and it is electrically connected to GND inside the package. Connect the EP to the ground plane on the board to ensure proper operation. Rev. C | Page 6 of 24 Document Outline FEATURES APPLICATIONS TYPICAL APPLICATION CIRCUIT GENERAL DESCRIPTION REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS THERMAL DATA THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION APPLICATIONS INFORMATION ADIsimPOWER DESIGN TOOL CAPACITOR SELECTION Output Capacitor Input and VREG Capacitor REF Capacitor BYP Capacitor Capacitor Properties UNDERVOLTAGE LOCKOUT (UVLO) PROGRAMMABLE PRECISION ENABLE START-UP TIME REF, BYP, AND VREG PINS CURRENT-LIMIT AND THERMAL OVERLOAD PROTECTION THERMAL CONSIDERATIONS Thermal Characterization Parameter (ΨJB) PSRR PERFORMANCE PCB LAYOUT CONSIDERATIONS OUTLINE DIMENSIONS ORDERING GUIDE