ADI 公司的ADP1874/ADP1875" title="DP1874/ADP1875">DP1874/ADP1875是電流模式同步降壓電源控制器，提供優(yōu)異的瞬態(tài)響應(yīng)，最佳的穩(wěn)定性和限流保護，輸入電壓2.95V-20V，輸出電壓最低可達(dá)0.6V，開關(guān)頻率有300 kHz, 600 kHz和1.0 MHz三種選擇，不需要電流檢測電阻，主要用在通信和網(wǎng)絡(luò)系統(tǒng)，中高端服務(wù)器，STB和DSP核電源。本文介紹了ADP1874/ADP1875主要特性，方框圖以及多種12A輸出電流應(yīng)用電路圖，大電流評估板電路圖和布局圖。
The ADP1874/ADP1875 are versatile current mode, synchronous step-down controllers. They provide superior transient response, optimal stability, and current-limit protection by using a constant on-time, pseudo fixed frequency with a programmable current limit, current control scheme. In addition, these devices offer optimum performance at low duty cycles by using a valley, current mode control architecture. This allows the ADP1874/ADP1875 to drive all N-channel power stages to regulate output voltages to as low as 0.6 V.
The ADP1875 is the power saving mode (PSM) version of the device and is capable of pulse skipping to maintain output regulation while achieving improved system efficiency at light loads (see the ADP1875 Power Saving Mode (PSM) section for more information).
Available in three frequency options (300 kHz, 600 kHz, and 1.0 MHz, plus the PSM option), the ADP1874/ADP1875 are well suited for a wide range of applications that require a single-input power supply range from 2.95 V to 20 V. Low voltage biasing is supplied via a 5 V internal low dropout regulator (LDO).
In addition, soft start programmability is included to limit input in-rush current from the input supply during startup and to provide reverse current protection during precharged output conditions. The low-side current sense, current gain scheme, and integration of a boost diode, along with the PSM/forced pulse-width modulation (PWM) option, reduce the external part count and improve efficiency.
The ADP1874/ADP1875 operate over the −40℃to +125℃ junction temperature range and are available in a 16-lead QSOP package.
ADP1874/ADP1875主要特性：
Power input voltage range: 2.95 V to 20 V
On-board bias regulator
Minimum output voltage: 0.6 V
0.6 V reference voltage with ±1.0% accuracy
Supports all N-channel MOSFET power stages
Available in 300 kHz, 600 kHz, and 1.0 MHz options
No current-sense resistor required
Power saving mode (PSM) for light loads (ADP1875 only)
Resistor programmable current limit
Power good with internal pull-up resistor
Externally programmable soft start
Thermal overload protection
Short-circuit protection
Standalone precision enable input
Integrated bootstrap diode for high-side drive
Starts into a precharged output
Available in a 16-lead QSOP package
ADP1874/ADP1875應(yīng)用：
Telecom and networking systems
Mid- to high-end servers
Set-top boxes
DSP core power supplies
圖1。ADP1874/ADP1875方框圖
圖2。ADP1874/5大電流評估板電路圖（藍(lán)色為大電流通路）
圖3。ADP1874/5大電流評估板布局圖
圖4。ADP1874/5應(yīng)用電路圖：12V輸入，輸出1.8V/12A,300kHz（Q2/Q4不連接）
圖5。ADP1874/5應(yīng)用電路圖：5.5V輸入，輸出2.5V/12A,600kHz（Q2/Q4不連接）
圖6。ADP1874/5應(yīng)用電路圖：13V輸入，輸出1.8V/12A,300kHz（Q2/Q4不連接）
詳情請見：
http://www.analog.com/static/imported-files/data_sheets/ADP1874_1875.pdf
