Datasheet ADP2121 (Analog Devices)

600 mA, 6 MHz, Synchronous Step-Down DC-to-DC Converter Data Sheet ADP2121 FEATURES TYPICAL APPLICATION CIRCUIT Peak efficiency: 92% INPUT VOLTAGE* ADP2121 OUTPUT VOLTAGE 2.3V TO 5.5V L 1.8V, 1.82V, 1.85V, 1.875V, 2.3V Operating frequency: 6 MHz A2 VIN SW B1 0.47µH Typical quiescent current in auto mode: 36 μA CIN 2.2µF Fixed output voltage: 1.8 V, 1.82 V, 1.85 V, 1.875 V, 2.3 V C2 GND FB C1 COUT Maximum guaranteed load current: 600 mA at V 4.7µF IN = 2.7 V to 5.5 V EN MODE Input voltage: 2.3 V to 5.5 V B2 A1 Typical shutdown supply current: 0.3 μA ON PWM OFF AUTO
001
Automatic power-saving mode
407-
*FOR OUTPUT VOLTAGE = 2.3 V, INPUT VOLTAGE = 2.9 V TO 5.5V.
07
Compatible with tiny multilayer inductors
Figure 1.
Internal synchronous rectifier 95 Internal compensation AUTO MODE VIN = 2.7 V Internal soft start (VIN = 2.9V FOR VOUT = 2.3V) Output to ground short-circuit protection 85 Cycle-by-cycle current-limit protection ) % ( Enable/shutdown logic input Y C N 75 Undervoltage lockout IE C Thermal shutdown protection FFI E Ultrasmall 6-ball, 0.4 mm pitch, 1.17 mm2 WLCSP 65 VOUT = 1.8V VOUT = 1.82V APPLICATIONS VOUT = 1.85V VOUT = 1.875V VOUT = 2.3V Mobile phones 550.1 1 10 100 1000
62 0
Digital cameras
407-
LOAD CURRENT (mA)
07
Digital audio
Figure 2. Efficiency vs. Load Current for Each Voltage Option
Portable equipment GENERAL DESCRIPTION
The ADP2121 is a high frequency, low quiescent current The ADP2121 has an input voltage range of 2.3 V to 5.5 V (2.9 V step-down dc-to-dc converter optimized for portable applications to 5.5 V for VOUT = 2.3 V), allowing the use of a single Li+/Li− in which board area and battery life are critical constraints. The polymer cell, 3-cell alkaline or Ni-MH cell, and other standard 6 MHz operating frequency enables the use of tiny ceramic induc- power sources. The converter can source up to 600 mA and is tors and capacitors. Additionally, the synchronous rectification internally compensated to minimize external components. Other improves efficiency and results in fewer external components. key features, such as cycle-by-cycle peak current limit, soft start, undervoltage lockout (UVLO), output-to-ground short-circuit At high load currents, the device uses a voltage regulating pulse- protection, and thermal shutdown, protect the internal and width modulation (PWM) mode that maintains a constant external circuit components. frequency with excellent stability and transient response. In forced PWM mode, the converter continues operating in PWM for light
Table 1. Output Voltage Options
loads. At light load conditions in auto mode, the ADP2121 can
Input Voltage Typical Start-Up Fixed Output
automatically enter a power-saving mode that uses pulse-frequency
Range (V) Time (μs) Voltage (V)
modulation (PFM) to reduce the effective switching frequency and 2.3 to 5.5 75 1.8, 1.85, 1.875 ensure the longest battery life in portable applications. During logic 2.3 to 5.5 275 1.82 controlled shutdown (EN ≤ 0.4 V), the input is disconnected 2.9 to 5.5 100 2.3 from the output and draws less than 0.3 μA current (typical) from the source.
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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