Datasheet ADP2441 (Analog Devices)

36 V,1 A, Synchronous, Step-Down DC-to-DC Regulator Data Sheet ADP2441 FEATURES TYPICAL CIRCUIT CONFIGURATION Wide input voltage range of 4.5 V to 36 V C3 Low minimum on time of 50 ns Maximum load current of 1 A C4 CBST High efficiency of up to 94% VOUT Adjustable output down to 0.6 V RTOP T ND CC VIN ±1% output voltage accuracy FB V BS VIN AG Adjustable switching frequency of 300 kHz to 1 MHz RBOTTOM ADP2441 VOUT COMP SW Pulse skip mode at light load for power saving K VIN Q R CIN COUT Precision enable input pin EN T RCOMP GOOD RE PGND P F SS/ Open-drain power good C External soft start with tracking COMP Overcurrent-limit protection RFREQ
001
Shutdown current of less than 15 µA
10581-
UVLO and thermal shutdown
Figure 1.
12-lead, 3 mm × 3 mm LFCSP package 100 V Reference similar product ADP2442 w ith synchronization OUT = 5V VOUT = 12V 90 capability 80 APPLICATIONS 70 VOUT = 3.3V Point of load applications %) ( 60 Y Distributed power systems C N 50 IE Industrial control supplies 40 FFIC Standard rail conversion to 24 V/12 V/5 V/3.3 V E VIN = 24V 30 f GENERAL DESCRIPTION SW = 300kHz 20
The ADP2441 is a constant frequency, current mode control,
10
synchronous, step-down dc-to-dc regulator that is capable of
0
driving loads up to 1 A with excel ent line and load regulation
0.02 0.2 1
002 characteristics. The ADP2441 operates with a wide input voltage
LOAD (A)
10581- range of 4.5 V to 36 V, which makes it ideal for regulating power Figure 2. Efficiency vs. Load Current, VIN = 24 V from a wide variety of sources. In addition, the ADP2441 has The ADP2441 uses hiccup mode to protect the IC from short very low minimum on time (50 ns) and is, therefore, suitable for circuits or from overcurrent conditions on the output. The external applications requiring a very high step-down ratio. programmable soft start limits inrush current during startup for The output voltage can be adjusted from 0.6 V to 0.9 V × V a wide variety of load capacitances. Other key features include IN. High efficiency is obtained with integrated low resistance N- tracking, input undervoltage lockout (UVLO), thermal shutdown channel MOSFETs for both high-side and low-side devices. (TSD), and precision enable (EN), which can also be used as a logic level shutdown input. The switching frequency is adjustable from 300 kHz to 1 MHz with an external resistor. The ADP2441 also has an accurate power-good The ADP2441 is available in a 3 mm × 3 mm, 12-lead LFCSP (PGOOD) open-drain output signal. package and is rated for a junction temperature range of −40°C to +125°C. At light load conditions, the regulator operates in pulse skip mode by skipping pulses and reducing switching losses to improve energy efficiency. In addition, at medium to heavy load conditions, the regulator operates in fixed frequency pulse-width modulation (PWM) mode to reduce electromagnetic interference (EMI).
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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