ADP1851降壓DC－DC控制器參考方案

ADI公司的ADP1851是一款寬輸入范圍、同步降壓DC-DC控制器，具有電壓跟蹤和同步的能力。多功能的ADP1851可配置為輸入前饋電壓模式或電流模式。輸入電壓范圍：2.75-20V，輸出電壓范圍為0.6V-0.9Vin。本文檔描述了ADP1851-EVALZ評估板的設計、運行和測試結果。本評估板輸入電壓范圍為9-15V，輸出電壓調節設置為1.8V，輸出最大電流可達25A。ADP1851評估板包括外部可調軟啟動、輸出過壓保護、外部可編程的限流、功率輸出和一個可編程的好振蕩器頻率，范圍從200KHz至1.5MHz。本文介紹了ADP1851主要特性、方框圖、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 ?40℃ to +125℃.

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.LT3791方框圖

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

ADP1851-EVALZ電路圖：


圖2. ADP1851-EVALZ電路圖

ADP1851-EVALZ材料清單：


PCB元件布局圖：