Datasheet ADP2442 (Analog Devices)

36 V,1 A, Synchronous, Step-Down, DC-to-DC Regulator with External Clock Synchronization Data Sheet ADP2442 FEATURES TYPICAL CIRCUIT CONFIGURATION Wide input voltage range from 4.5 V to 36 V C2 Low minimum on time of 50 ns typical C1 Maximum load current of 1 A VOUT CBOOST High efficiency of up to 94% D C T Adjustable output down to 0.6 V RTOP N VC BS VIN FB AG VIN ±1% output voltage accuracy RBOTTOM ADP2442 VOUT Adjustable switching frequency from 300 kHz to 1 MHz COMP SW External synchronization from 300 kHz to 1 MHz R C COUT COMP D / IN O Q C E Pulse skip mode or forced fixed frequency mode O E D PGND N EN CCOMP PG FR SY MO Precision enable input pin (EN) Open-drain power good RFREQ
01 0
Internal soft start
10667-
Overcurrent-limit protection
Figure 1.
Shutdown current of less than 15 μA UVLO and thermal shutdown
The ADP2442 offers the flexibility of external clock
12-lead, 3 mm × 3 mm LFCSP package
synchronization. The switching frequency can be synchronized to
Supported by the ADIsimPower™ tool set
an external clock, applied to the SYNC/MODE pin. The ADP2442
Reference similar product ADP2441 with pr ogrammable soft
can also be configured to operate in the forced fixed frequency
start and tracking
mode for low EMI or power saving mode to reduce the switching losses at light load.
APPLICATIONS
The ADP2442 uses hiccup mode to protect the IC from short
Point of load applications
circuits or from overcurrent conditions on the output. The internal
Distributed power systems
soft start limits inrush current during startup for a wide variety of
Industrial control supplies
load capacitances. Other key features include input undervoltage
Standard rail conversion to 24 V/12 V/5 V/3.3 V
lockout (UVLO), thermal shutdown (TSD), and precision enable
GENERAL DESCRIPTION
(EN), which can also be used as a logic level shutdown input. The ADP2442 is a constant frequency, current mode control, The ADP2442 is available in a 3 mm × 3 mm, 12-lead LFCSP synchronous, step-down, dc-to-dc regulator that is capable of package and is rated for a junction temperature range from driving loads of up to 1 A with excellent line and load regulation −40°C to +125°C. characteristics. The ADP2442 operates with a wide input voltage
100
range from 4.5 V to 36 V, which makes it ideal for regulating
90 VOUT = 12V
power from a wide variety of sources. In addition, the ADP2442
80
has very low minimum on time (50 ns) and is, therefore, suitable
V
for applications requiring a very high step-down ratio.
70 OUT = 5V ) % ( 60
The output voltage can be adjusted from 0.6 V to 0.9 × V
Y
IN. High
C N
efficiency is obtained with integrated low resistance N-channel
50 IE C VOUT = 3.3V
MOSFETs for both high-side and low-side devices.
40 FFI E
The switching frequency is adjustable from 300 kHz to 1 MHz with
30
an external resistor. The ADP2442 also has an accurate power-good
20
(PGOOD) open-drain output signal.
V 10 IN = 24V PWM = 300kHz 0
02
0.01 0.1 1
0
LOAD (A)
0667- 1 Figure 2. Efficiency vs. Load Current, VIN = 24 V
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Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION TYPICAL CIRCUIT CONFIGURATION REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS EFFICIENCY IN FORCED FIXED FREQUENCY MODE EFFICIENCY IN PULSE SKIP MODE INTERNAL BLOCK DIAGRAM THEORY OF OPERATION CONTROL ARCHITECURE Fixed Frequency Mode Pulse Skip Mode ADJUSTABLE FREQUENCY POWER GOOD MODE OF OPERATION EXTERNAL SYNCHRONIZATION SOFT START UNDERVOLTAGE LOCKOUT PRECISION ENABLE/SHUTDOWN CURRENT-LIMIT AND SHORT-CIRCUIT PROTECTION THERMAL SHUTDOWN APPLICATIONS INFORMATION ADIsimPOWER DESIGN TOOL SELECTING THE OUTPUT VOLTAGE SETTING THE SWITCHING FREQUENCY EXTERNAL COMPONENT 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 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