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Analog Devices’ ADP2441 is a 36V/1A synchronous step-down DC/DC power regulator with load current up to 1A, input voltage 4.5V-36V, output voltage from 0.6V to 0.9VxVIN, accuracy ±1%, switching frequency from 300 kHz To 1 MHz, the efficiency is as high as 94%, and the shutdown current is less than 15uA. It is mainly used in POL, distributed power system, industrial control power supply and DC converter. This article introduces the main features of ADP2441, block diagram, various typical application circuits and evaluation of ADP2441 Main board features, Circuit diagrams, bill of materials and layout of PCB components.

The ADP2441 is a constant frequency, current mode control, synchronous, step-down dc-to-dc regulator that is capable of driving loads up to 1 A with excellent line and load regulation characteristics. The ADP2441 operates with a wide input voltage range of 4.5 V to 36 V, which makes it ideal for regulating power from a wide variety of sources. In addition, the ADP2441 has very low minimum on time (50 ns) and is, therefore, suitable for applications requiring a very high step-down ratio.

The output voltage can be adjusted from 0.6 V to 0.9 V × VIN. High efficiency is obtained with integrated low resistance N-channel MOSFETs for both high-side and low-side devices.

The switching frequency is adjustable from 300 kHz to 1 MHz with an external resistor. The ADP2441 also has an accurate power-good (PGOOD) open-drain output signal.

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).

The ADP2441 uses hiccup mode to protect the IC from short circuits or from overcurrent conditions on the output. The external programmable soft start limits inrush current during startup for a wide variety of load capacitances. Other key features include tracking, input undervoltage lockout (UVLO) , thermal shutdown (TSD), and precision enable (EN), which can also be used as a logic level shutdown input.

The ADP2441 is available in a 3 mm × 3 mm, 12-lead LFCSP package and is rated for a junction temperature range of −0℃ to +125℃.

ADP2441 main features:

Wide input voltage range of 4.5 V to 36 V

Low minimum on time of 50 ns

Maximum load current of 1 A

High efficiency of up to 94%

Adjustable output down to 0.6 V

±1% output voltage accuracy

Adjustable switching frequency of 300 kHz to 1 MHz

Pulse skip mode at light load for power saving

Precision enable input pin

Open-drain power good

External soft start with tracking

Overcurrent-limit protection

Shutdown current of less than 15 μA

UVLO and thermal shutdown

12-lead, 3 mm × 3 mm LFCSP package

ADP2441 application:

Point of load applications

Distributed power systems

Industrial control supplies

Standard rail conversion to 24 V/12 V/5 V/3.3 V

Figure 1. ADP2441 block diagram

Figure 2. ADP2441 Typical Application Circuit Diagram (1): VIN = 24 V ± 10%, VOUT = 5 V, fSW = 700 kHz

Figure 3. ADP2441 Typical Application Circuit Diagram (2): VIN = 24 V ± 10%, VOUT = 12 V, fSW = 600 kHz

Figure 4. ADP2441 Typical Application Circuit Diagram (3): VIN = 12 V ± 10%, VOUT = 5 V, fSW = 500 kHz

Figure 5. ADP2441 Typical Application Circuit Diagram (4): VIN = 36 V ± 10%, VOUT = 3.3 V, fSW = 300 kHz

ADP2441 Evaluation Board

The ADP2441 evaluation board is a complete, dc-to-dc switch-ing regulator design based on the ADP2441, a configurable, 1 A, synchronous step-down, dc-to-dc regulator.

The ADP2441 is a synchronous, step-down dc-to-dc switching regulator that uses a current mode pulse-width modulation (PWM) control scheme at medium-to-heavy load currents for high efficiency and smoothly transitions to a pulse skip mode at light loads to conserve power. The power switch and synchronous rectifier are integrated for minimal external part count and high efficiency. The ADP2441 is optimized for operation with small ferrite core inductors and ceramic capacitors to deliver the maximum output power per square millimeter of the PCB board area.

The ADP2441-EVALZ is available with 5 V at 1 A output, switching frequency set to 500 kHz. If needed, the ADP2441 evaluation board configuration can be modified by changing the values of the appropriate passive components.

Complete specifications for the ADP2441 device can be found in the ADP2441 data sheet, which is available from Analog Devices, Inc., and should be consulted in conjunction with this user guide when using the evaluation board.

ADP2441 Evaluation Board Key Features:

Full-featured evaluation board for the ADP2441

Configurable synchronous step down dc-dc switching regulator

Operating voltage range of board: VIN = 6 V to 36 V

Output voltage is set to 5 V or can be adjusted

Maximum load 1 A

Switching frequency set to 500 kHz or adjustable switching frequency of 300 kHz to 1 MHz

Power saving mode at light load

Precision enable input pin

Current limit protection

Power good output

External soft start set to 6 ms or external tracking available

Board size: 53 mm × 53 mm

Figure 6. ADP2441 Evaluation Board Outline Drawing

Figure 7. ADP2441 Evaluation Board Circuit Diagram

ADP2441 Evaluation Board Bill of Materials:

Figure 7. ADP2441 Evaluation Board PCB Component Layout

For details, see:

http://www.analog.com/static/imported-files/data_sheets/ADP2441.pdf

and

http://www.analog.com/static/imported-files/user_guides/UG-407.pdf