Data SheetADP2121180) A 160(mOUTPUT VOLTAGE (50mV/DIV)DPWM OPERATIONL 140O H S E 120 HR T 100NG HI C80LOAD CURRENT (100mA/DIV)ITPFM OPERATIONW60S DE O40M O20AUTVOUT = 1.82V 2 -02 0 7 2.32.73.13.53.94.34.75.15.5 14 40 0 TIME (20µs/DIV) 7- 07 INPUT VOLTAGE (V) 40 07 Figure 22. Auto Mode Switching Threshold vs. Input Voltage Figure 25. Load Transient Response, 0 mA to 150 mA (VIN = 2.5 V, Auto Mode) A) 190m (VOUT = 1.8VDVL 180OUT = 1.82VOVOUT = 1.85VOUTPUT VOLTAGE (50mV/DIV)HVOUT = 1.875V170VOUT = 2.3VHRES T G 160IN H C 150IT WLOAD CURRENT (100mA/DIV)S 140NG ISI R 130 DEPFM OPERATIONO 120M O T 3 AU 110 -02 7 2.32.73.13.53.94.34.75.15.5 4 05 40 TIME (20µs/DIV) 7- 07 INPUT VOLTAGE (V) 740 0 Figure 23. Auto Mode Rising Switching Threshold vs. Input Voltage for All Figure 26. Load Transient Response, 0 mA to 150 mA Voltage Options (VIN = 3.6 V, Auto Mode) ) A 200m D ( L 180OUTPUT VOLTAGE (50mV/DIV)HO S160HRE TPWM OPERATIONNG 140CHI IT 120WLOAD CURRENT (100mA/DIV)S100ING L AL80FVOUT = 1.8VVDEOUT = 1.82VO60VOUT = 1.85VMVOUT = 1.875VOV 4 OUT = 2.3V -02 40 7 AUT2.32.73.13.53.94.34.75.15.5 5 40 TIME (20µs/DIV) -05 07 07 INPUT VOLTAGE (V) 74 0 Figure 24. Auto Mode Falling Switching Threshold vs. Input Voltage for All Figure 27. Load Transient Response, 0 mA to 150 mA Voltage Options (VIN = 4.5 V, Auto Mode) Rev. C | Page 9 of 20 Document Outline FEATURES APPLICATIONS TYPICAL APPLICATION CIRCUIT GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS THERMAL DATA THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION OVERVIEW MODE SELECTION Pulse-Width Modulation (PWM) Mode Auto Mode (PFM and PWM Switching) Pulse Frequency Modulation (PFM) Mode Transition ENABLE/SHUTDOWN INTERNAL CONTROL FEATURES Overcurrent Protection Soft Start Synchronous Rectification Compensation Undervoltage Lockout (UVLO) Output Short-Circuit Protection Thermal Shutdown (TSD) Protection APPLICATIONS INFORMATION INDUCTOR SELECTION INPUT CAPACITOR SELECTION OUTPUT CAPACITOR SELECTION PCB LAYOUT GUIDELINES OUTLINE DIMENSIONS ORDERING GUIDE