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1、ADI ADP1851 25A DCDC降压电源解决方案关键词：电源管理,DC/DC转换器,开关电源,ADI 公司的ADP1851是宽输入电压同步降压控制器,输入电压从2.75V到20V,输出电压从0.6 V 到90% VIN,输出电流大于25A,输出电压可跟踪,在整个温度*围内精度为1%,可编程频率200 kHz 到1.5 MHz,可编软起动,主要用在通信基站和网络,工业和仪表,医疗和保健.本文介绍了ADP1851主要特性,方框图,典型应用电路,电压和电流模式输出25A应用电路图,以及评估板ADP1851-EVALZ主要特性,电路图,材料清单和PCB元件布局图.The ADP1851 is
2、a wide range input, dc-to-dc, synchronous buck controller capable of running from monly 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 vol
3、tage 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
4、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 pul
5、ses, 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 w
6、ith 1% tolerance over the temperature range of 0C to +125C.With its wide range input voltage, the ADP1851 provides the designer with ma*imum fle*ibility for use in a variety of system configurations; loop pensation, soft start, frequency setting, power saving mode, current limit, and current sense g
7、ain can all be programmed using e*ternal ponents. In addition, the e*ternal RAMP resistor allows the selection of optimal slope and VIN feedforward in both current and voltage modes for e*cellent line rejection. The linear regulator and the bootstrap diode for the high-side driver are internal.Prote
8、ction features include undervoltage lockout, overvoltage, overcurrent/short circuit, and overtemperature.ADP1851主要特性:Input voltage range: 2.75 V to 20 VOutput voltage range: 0.6 V to 90% VINMa*imum output current of more than 25 ACurrent mode architectureConfigurable to voltage mode1% output voltage
9、 accuracy over temperatureVoltage trackingProgrammable frequency: 200 kHz to 1.5 MHzSynchronization inputPower saving mode at light loadPrecision enable inputPower good with internal pull-up resistorAdjustable soft startProgrammable current sense gainIntegrated bootstrap diodeStarts into a precharge
10、d loadE*ternally adjustable slope pensationSuitable for any output capacitorOvervoltage and overcurrent-limit protectionThermal overload protectionInput undervoltage lockout (UVLO)Available in 16-lead, 4 mm 4 mm LFCSPSupported by ADIsimPower design toolADP1851应用:Intermediate bus and POL systems requ
11、iring sequencing and tracking, includingTele base station and networkingIndustrial and instrumentationMedical and healthcare图1.ADP1851简化框图图2.ADP1851典型应用电路图3.ADP1851电流模式的25A应用电路图4.ADP1851电压模式的25A应用电路评估板ADP1851-EVALZThis document describes the design, operation, and test results of the ADP1851-EVALZ.
12、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 ma*imum 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 e*
13、ternal clock signal applied to the SYNC input.评估板ADP1851-EVALZ主要特性:Input voltage range: 9 V to 15 VOutput voltage: 1.8 VOutput current: up to 25 ASwitching frequency: 600 kHzOperates in PWM or PSMDesigned for evaluation of the ADP1851 functionalityFle*ible and easy to re-configure and modify图5.评估板ADP1851-EVALZ外形图图6.评估板ADP1851-EVALZ电路图评估板ADP1851-EVALZ材料清单(BOM):图7.评估板ADP1851-EVALZ PCB元件布局图(顶层)图8.评估板ADP1851-EVALZ PCB元件布局图(底层)
