ADP1851降压DC－DC控制器参考方案

发布时间：2012-9-28 12:34 发布者：1770309616

ADI公司的ADP1851是一款宽输入范围、同步降压DC-DC控制器，具有电压跟踪和同步的能力。多功能的ADP1851可配置为输入前馈电压模式或电流模式。输入电压范围：2.75-20V，输出电压范围为0.6V-0.9Vin。本文档描述了ADP1851-EVALZ评估板的设计、运行和测试结果。本评估板输入电压范围为9-15V，输出电压调节设置为1.8V，输出最大电流可达25A。ADP1851评估板包括外部可调软启动、输出过压保护、外部可编程的限流、功率输出和一个可编程的好振荡器频率，范围从200KHz至1.5MHz。本文介绍了ADP1851主要特性、方框图、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 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应用：

Intermediate bus and POL systems requiring sequencing and tracking, including

Telecom base station and networking

Industrial and instrumentation

Medical and healthcare

图1.LT3791方框图

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电路图：