CXMD3257单相恒定时间同步的脉宽调制控制器驱动N通道mosfet逐步降低高压在笔记本电脑中生成低压芯片组或RAM电源功率因数调制或脉宽调制模式下提供出色的瞬态响应和精确的直流电压输出

CXMD3257是一个单相、恒定时间、同步的脉宽调制控制器，它驱动N通道mosfet。CXMD3257逐步降低高压，在笔记本电脑中生成低压芯片组或RAM电源。CXMD3257在功率因数调制或脉宽调制模式下提供出色的瞬态响应和精确的直流电压输出。在脉冲频率模式（PFM）中，CXMD3257在负载调制开关频率的轻到重负载上提供非常高的效率。在PWM模式下，为了达到低噪声的要求，变换器几乎以恒定频率工作。CXMD3257配备了精确的正电流限制、输出欠压和输出过压保护，非常适合NB应用。通电复位功能监控VCC上的电压，以防止通电期间出现错误操作。CXMD3257具有1毫秒数字软启动和内置的软停止综合输出放电方法。内部集成的软启动以可编程的转换率提高输出电压，以降低启动电流。软停止功能利用受控的反向电感电流对输出电容器进行主动放电。CXMD3257提供10针TDFN 3x3产品包。
l可调输出电压从+0.7V到+5.5V
l 0.7V参考电压
l±1%超温精度
l在蓄电池输入电压为+1.8V至+32V的范围内工作
l VCC引脚上电复位监控
l卓越的线路和负载瞬态响应
l PFM模式，提高轻载效率
l从4个预设值中选择脉宽调制频率
集成MOSFET驱动器
集成自举正向P-CH MOSFET
l可调集成软启动和软停止
l可选择强制脉冲宽度调制或自动脉冲频率调制/脉冲宽度调制模式
l电源良好监控
l 70%欠压保护
l 125%过电压保护
l可调限流保护
l使用感测低边MOSFET的RDS（开）
l过热保护

目录

1.产品概述       2.产品特点     

3.应用范围       4.技术规格书下载（PDF文档）

5.产品封装       6.电路原理图  

7.相关产品

   产品概述 返回TOP

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The CXMD3257 is a single‐phase, constant‐on‐time, synchronous PWM controller, which drives N‐channel MOSFETs. The CXMD3257 steps down high voltage to generate low‐voltage chipset or RAM supplies in notebook computers. The CXMD3257 provides excellent transient response and accurate DC voltage output in either PFM or PWM Mode. In Pulse Frequency Mode (PFM), the CXMD3257 provides very high efficiency over light to heavy loads with loading‐ modulated switching frequencies. In PWM Mode, the converter works nearly at constant frequency for low‐noise requirements. The CXMD3257 is equipped with accurate positive current‐ limit, output under‐voltage, and output over‐voltage protections, perfect for NB applications. The Power‐On‐  Reset function monitors the voltage on VCC to prevent wrong operation during power‐on. The CXMD3257 has a 1ms digital soft‐start and built‐in an integrated output discharge method for soft‐stop. An internal integrated soft‐start ramps up the output voltage with programmable slew rate to reduce the start‐up current. A soft‐stop function actively discharges the output capacitors with controlled reverse inductor current. The CXMD3257 is available in 10pin TDFN 3x3 package.

   产品特点 返回TOP

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l  Adjustable Output Voltage from +0.7V to +5.5V

l  0.7V Reference Voltage

l  ±1% Accuracy Over-Temperature

l  Operates from an Input Battery Voltage Range of +1.8V to +32V

l  Power-On-Reset Monitoring on VCC Pin

l  Excellent Line and Load Transient Responses

l  PFM Mode for Increased Light Load Efficiency

l  Selectable PWM Frequency from 4 Preset Values

l  Integrated MOSFET Drivers

l  Integrated Bootstrap Forward P-CH MOSFET

l  Adjustable Integrated Soft-Start and Soft-Stop

l  Selectable Forced PWM or Automatic PFM/PWM Mode

l  Power Good Monitoring

l  70% Under-Voltage Protection

l  125% Over-Voltage Protection

l  Adjustable Current-Limit Protection

l  Using Sense Low-Side MOSFET’s RDS(ON)

l  Over-Temperature Protection

l  TDFN-10 3x3 Package

l  Lead Free and Green Devices Available (RoHS Compliant)

   应用范围 返回TOP

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l  Notebook

l  Table PC

l  Hand-Held Portable

l  AIO PC

l  LCD Monitor / TV

l  Battery Charger

l  ADSL Modem

   技术规格书（产品PDF) 返回TOP 

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产品封装图 返回TOP

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电路原理图 返回TOP

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PWM Controller(脉宽调制控制器)
Part No.	Input Voltage	Output  Voltage	Frequency	Efficiency	Package	precision	Over	Over	Short Protection
							Current	Temperature
							Protection	Protection
CXMD3255	16V	ADJ	300KHZ	93%	SOP8/DFN3*3-10DFN3*3-10	2%	Y	Y	Y
CXMD3256	16V	ADJ	200KHz/300KHZ /600KHz	93%	SOP8 DFN3*3-10	2%	Y	Y	Y
CXMD3257	35V	ADJ	290-430KHz	93%	DFN3*3-10	2%	Y	Y	Y
CXMD3258	35V	ADJ	290-430KHz	93%	DFN3*3-10	2%	Y	Y	Y
CXMD3259	35V	ADJ	135-215KHz	93%	DFN3*3-10	2%	Y	Y	Y
CXMD3260	35V	ADJ	135-215KHz	93%	DFN3*3-10	2%	Y	Y	Y
CXMD3261	40V	-	100-300KHz	-	QFN20		Y	Y	Y