CXSD6295电压模式固定300kHz开关频率同步降压变换器许宽输入电压对于vario为单个5~12V或两个电源电压

目录39B嘉泰姆

1.产品概述                       2.产品特点39B嘉泰姆
3.应用范围                       4.下载产品资料PDF文档 39B嘉泰姆
5.产品封装图                     6.电路原理图                   39B嘉泰姆
7.功能概述                        8.相关产品39B嘉泰姆

一,产品概述(General Description)   39B嘉泰姆

 The CXSD6295 is a voltage mode, fixed 300kHz switching frequency, synchronous buck converter. The CXSD6295 allows wide input voltage that is either a single 5~12V or two supply voltage(s) for various applications. A power-on-reset (POR) circuit monitors the VCC supply voltage to prevent wrong logic controls. A built-in soft-start circuit prevents the output voltages from overshoot as well as limits the input current. An internal 0.8V tempera ture-compensated reference voltage with high accuracy is designed to meet the requirement of low output voltage applications. The CXSD6295 provides excellent out put voltage regulations against load current variation.The controller’s over-current protection monitors the out-put current by using the voltage drop across the RDS(ON) of low-side MOSFET, eliminating the need for a current sensing resistor that features high efficiency and low cost. In addition, the CXSD6295 also integrates excellent protection functions: The over-voltage protection (OVP) , under voltage protection (UVP). OVP circuit which monitors the FB voltage to prevent the PWM output from over-voltage,and UVP circuit which monitors the FB voltage to prevent the PWM output from under-voltage or short-circuit.39B嘉泰姆
  The CXSD6295 is available in SOP-8P and TDFN3x3-10 packages.39B嘉泰姆
二.产品特点(Features)39B嘉泰姆

1.)Wide 5V to 12V Supply Voltage39B嘉泰姆
2.)Power-On-Reset Monitoring on VCC39B嘉泰姆
3.)Excellent Output Voltage Regulations39B嘉泰姆
     0.8V Internal Reference39B嘉泰姆
     ±1% Over-Temperature Range39B嘉泰姆
4.)Integrated Soft-Start39B嘉泰姆
5.)Voltage Mode PWM Operation with External Compensation39B嘉泰姆
6.)Up to 90% Duty Ratio for Fast Transient Response39B嘉泰姆
7.)Constant Switching Frequency  300kHz ±10%39B嘉泰姆
8.)9V Driver Voltage for BOOT Supply with Internal Bootstrap Diode39B嘉泰姆
9.)Drive Dual Low Cost N-MOSFETs with Adaptive Dead-Time Control39B嘉泰姆
10.)50% Under-Voltage Protection39B嘉泰姆
11.)125% Over-Voltage Protection39B嘉泰姆
12.)Adjustable Over-Current Protection Threshold39B嘉泰姆
     Using the RDS(ON) of Low-Side MOSFET39B嘉泰姆
13.)Shutdown Control by COMP39B嘉泰姆
14.)Power Good Monitoring (TDFN-10 3mmx3mm Package Only)39B嘉泰姆
    SOP-8P and TDFN3x3-10 Packages39B嘉泰姆
15.)Lead Free and Green Devices Available (RoHS Compliant)39B嘉泰姆
三,应用范围 (Applications)39B嘉泰姆

Graphic Cards39B嘉泰姆
DSL, Switch HUB39B嘉泰姆
Wireless Lan39B嘉泰姆
Notebook Computer39B嘉泰姆
Mother Board39B嘉泰姆
LCD Monitor/TV39B嘉泰姆
四.下载产品资料PDF文档 39B嘉泰姆

需要详细的PDF规格书请扫一扫微信联系我们，还可以获得免费样品以及技术支持！39B嘉泰姆

 39B嘉泰姆

五,产品封装图 (Package)39B嘉泰姆

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六.电路原理图39B嘉泰姆

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七,功能概述39B嘉泰姆

Output Capacitor Selection39B嘉泰姆
The selection of COUT is determined by the required effec-tive series resistance (ESR) and voltage39B嘉泰姆
rating rather than the actual capacitance requirement. Therefore, selecting high performance low ESR39B嘉泰姆
capacitors is intended for switching regulator applications. In some applications,multiple capacitors have39B嘉泰姆
to be paralleled to achieve the desired ESR value. If tantalum capacitors are used, make sure they are39B嘉泰姆
surge tested by the manufactures. If in doubt,consult the capacitors manufacturer. 39B嘉泰姆
Input Capacitor Selection39B嘉泰姆
The input capacitor is chosen based on the voltage rat-ing and the RMS current rating. For reliable operation,39B嘉泰姆
select the capacitor voltage rating to be at least 1.3 times higher than the maximum input voltage. The maximum39B嘉泰姆
RMS current rating requirement is approximately IOUT/2 where IOUT is the load current. During power up, the39B嘉泰姆
input capacitors have to handle large amount of surge current.If tantalum capacitors are used, make sure they39B嘉泰姆
are surge tested by the manufactures. If in doubt, consult the ca-pacitors manufacturer.For high frequency39B嘉泰姆
decoupling, a ceramic capacitor be-tween 0.1μF to 1μF can connect between VCC and ground pin.39B嘉泰姆
Inductor Selection39B嘉泰姆
The inductance of the inductor is determined by the out-put voltage requirement. The larger the inductance, 39B嘉泰姆

the lower the inductor’s current ripple. This will translate into lower output ripple voltage. The ripple current 39B嘉泰姆

and ripple voltage can be approximated by:39B嘉泰姆
×   OUT39B嘉泰姆
FSW × L    VIN39B嘉泰姆
where Fs is the switching frequency of the regulator.39B嘉泰姆
∆VOUT = IRIPPLE x ESR39B嘉泰姆
A tradeoff exists between the inductor’s ripple current and the regulator load transient response time. A smaller39B嘉泰姆

 in-ductor will give the regulator a faster load transient re-sponse at the expense of higher ripple current and vice39B嘉泰姆
versa. The maximum ripple current occurs at the maxi-mum input voltage. A good starting point is to choose the39B嘉泰姆
ripple current to be approximately 30% of the maximum output current.Once the inductance value has been chosen, selecting an inductor is capable of carrying the required peak cur-rent without going into saturation. In some types of inductors, especially core that is make of ferrite, the ripple current will increase abruptly when it saturates. This will result in a larger output ripple voltage. 39B嘉泰姆
Compensation39B嘉泰姆
The output LC filter of a step down converter introduces a double pole, which contributes with -40dB/decade gain39B嘉泰姆
slope and 180 degrees phase shift in the control loop. A compensation network between COMP pin and ground39B嘉泰姆
should be added. The simplest loop compensation net-work is shown in Figure 5.39B嘉泰姆
The output LC filter consists of the output inductor and output capacitors. The transfer function of the LC filter is39B嘉泰姆
given by:39B嘉泰姆
The FLC is the double poles of the LC filter, and FESR is the zero introduced by the ESR of the output capacitor.39B嘉泰姆

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