ADI 公司的ADP1851是寬輸入電壓同步降壓控制器,輸入電壓從2.75V到20V,輸出電壓從0.6 V 到90% VIN,輸出電流大于25A,輸出電壓可跟蹤,在整個溫度范圍內(nèi)精度為±1%,可編程頻率200 kHz 到1.5 MHz,可編軟起動,主要用在通信基站和網(wǎng)絡,工業(yè)和儀表,醫(yī)療和保健.本文介紹了ADP1851主要特性,方框圖,典型應用電路,電壓和電流模式輸出25A應用電路圖,以及評估板ADP1851-EVALZ主要特性,電路圖,材料清單和PCB元件布局圖.

The ADP1851 is a wide range input, dc-to-dc, synchronous buck controller capable of running from commonly used 3.3 V to 12 V (up to 20 V) voltage inputs. The device nominally operates in current mode with valley current sensing providing the fastest step response for digital loads. It can also be config-ured as a voltage mode controller with low noise and crosstalk for sensitive loads.

The ADP1851 is ideal in system applications requiring multiple output voltages. The ADP1851 includes a synchronization feature to eliminate beat frequencies between switching devices. It also provides accurate tracking capability between supplies and includes precision enable and power-good functions for simple, robust sequencing.

The ADP1851 provides a high speed, high peak current gate driving capability to enable energy efficient power conversion. The device can be configured to operate in power saving mode by skipping pulses, reducing switching losses, and improving efficiency at light load and standby conditions.

The accurate current limit allows design within a narrower range of tolerances and can reduce overall converter size and cost. The ADP1851 can regulate down to 0.6 V output using a high accuracy reference with ±1% tolerance over the temperature range of ?0°C to +125°C.

With its wide range input voltage, the ADP1851 provides the designer with maximum flexibility for use in a variety of system configurations; loop compensation, soft start, frequency setting, power saving mode, current limit, and current sense gain can all be programmed using external components. In addition, the external RAMP resistor allows the selection of optimal slope and VIN feedforward in both current and voltage modes for excellent line rejection. The linear regulator and the bootstrap diode for the high-side driver are internal.

Protection features include undervoltage lockout, overvoltage, overcurrent/short circuit, and overtemperature.

ADP1851主要特性:

Input voltage range: 2.75 V to 20 V

Output voltage range: 0.6 V to 90% VIN

Maximum output current of more than 25 A

Current mode architecture

Configurable to voltage mode

±1% output voltage accuracy over temperature

Voltage tracking

Programmable frequency: 200 kHz to 1.5 MHz

Synchronization input

Power saving mode at light load

Precision enable input

Power good with internal pull-up resistor

Adjustable soft start

Programmable current sense gain

Integrated bootstrap diode

Starts into a precharged load

Externally adjustable slope compensation

Suitable for any output capacitor

Overvoltage and overcurrent-limit protection

Thermal overload protection

Input undervoltage lockout (UVLO)

Available in 16-lead, 4 mm × 4 mm LFCSP

Supported by ADIsimPower design tool

ADP1851應用:

Intermediate bus and POL systems requiring sequencing and tracking, including

Telecom base station and networking

Industrial and instrumentation

Medical and healthcare

圖1.ADP1851簡化框圖


圖2.ADP1851典型應用電路

圖3.ADP1851電流模式的25A應用電路

圖4.ADP1851電壓模式的25A應用電路

評估板ADP1851-EVALZ

This document describes the design, operation, and test results of the ADP1851-EVALZ. The input voltage range for this evaluation board is 9 V to 15 V, and the regulated output voltage (VOUT) is set to 1.8 V with the maximum output current up to 25 A. The switching frequency (fSW) of 600 kHz is set to achieve high efficiency. The switching frequency can be also synchro-nized to an external clock signal applied to the SYNC input.

評估板ADP1851-EVALZ主要特性:

Input voltage range: 9 V to 15 V

Output voltage: 1.8 V

Output current: up to 25 A

Switching frequency: 600 kHz

Operates in PWM or PSM

Designed for evaluation of the ADP1851 functionality

Flexible and easy to re-configure and modify

圖5.評估板ADP1851-EVALZ外形圖

圖6.評估板ADP1851-EVALZ電路圖

評估板ADP1851-EVALZ材料清單(BOM):



圖7.評估板ADP1851-EVALZ PCB元件布局圖(頂層)

圖8.評估板ADP1851-EVALZ PCB元件布局圖(底層)
詳情請見:
http://www.analog.com/static/imported-files/data_sheets/ADP1851.pdf
和
http://www.analog.com/static/imported-files/user_guides/UG-443.pdf