CXSD6286将脉宽调制和线性控制器以及监控和保护功能集成到一个软件包中驱动双N通道mosfet的同步PWM控制器

目录vOl嘉泰姆

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

一,产品概述(General Description)         vOl嘉泰姆

         The CXSD6286 integrates PWM and linear controller, as well as the monitoring and protection functions into a single package. The synchronous PWM controller which drives dual N-channel MOSFETs, which provides one controlled power outputs with under-voltage and over-current protections. Linear controller drives an external N-channel MOSFET with under-voltage protection.vOl嘉泰姆
         CXSD6286 provides excellent regulation for output load variation. An internal 0.8V temperature-compensated ref-erence voltage is designed to meet the arious low out-put voltage applications. CXSD6286 includes a 250kHz free-running triangle-wave oscillator that is adjustable from 70kHz to 800kHz.A power-on-reset (POR) circuit limits the VCC minimum opearting supply voltage to assure the controller working well. Over current protection is achieved by monitoring the voltage drop across the low side MOSFET, eliminat-ing the need for a current sensing resistor and short cir-cuit condition is detected through the FB pin. The over-current protection triggers the soft-start function until the fault events be removed, but Under-voltage protection will shutdown IC directly.Pull the COMP pin below 0.4V will shutdown the controller,and both gate drive signals will be lowvOl嘉泰姆
二.产品特点(Features)vOl嘉泰姆

1.）Provide Two Regulated VoltagesvOl嘉泰姆
      - Synchronous Rectified Buck PWM ControllervOl嘉泰姆
      - Linear ControllervOl嘉泰姆
2.）Fast Transient ResponsevOl嘉泰姆
      - 0~85% Duty RatiovOl嘉泰姆
3.）Excellent Output Voltage RegulationvOl嘉泰姆
     - 0.8V Internal ReferencevOl嘉泰姆
     - ±1% Over Line Voltage and TemperaturevOl嘉泰姆
4.）Over Current ProtectionvOl嘉泰姆
     - Sense Low-Side MOSFET’s RDS(ON)vOl嘉泰姆
5.）Under Voltage LockoutvOl嘉泰姆
6.）Small Converter SizevOl嘉泰姆
      - 250kHz Free-Running OscillatorvOl嘉泰姆
      - Programmable From 70kHz to 800kHzvOl嘉泰姆
7.）14-Lead SOIC PackagevOl嘉泰姆
8.）Lead Free and Green Devices AvailablevOl嘉泰姆
       (RoHS Compliant)vOl嘉泰姆
三,应用范围 (Applications)vOl嘉泰姆

Graphic CardsvOl嘉泰姆
Memory Power SuppliesvOl嘉泰姆
DSL or Cable MODEMsvOl嘉泰姆
Set Top BoxesvOl嘉泰姆
Low-Voltage Distributed Power SuppliesvOl嘉泰姆
四.下载产品资料PDF文档 vOl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！vOl嘉泰姆

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五,产品封装图 (Package)vOl嘉泰姆

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六.电路原理图vOl嘉泰姆

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七,功能概述vOl嘉泰姆

MOSFET SelectionvOl嘉泰姆
The selection of the N-channel power MOSFETs is deter-mined by the RDS(ON), reverse transfervOl嘉泰姆
capacitance (CRSS),and maximum output current requirement.The losses in the MOSFETs have twovOl嘉泰姆
components: conduction loss and transition loss. For the upper and lower MOSFET, the losses arevOl嘉泰姆
approximately given by the following equations:vOl嘉泰姆
PUPPER = Iout (1+ TC)(RDS(ON))D + (0.5)(Iout)(VIN)(tsw)FSvOl嘉泰姆
where IOUT is the load currentvOl嘉泰姆
TC is the temperature dependency of RDS(ON)vOl嘉泰姆
FS is the switching frequencyvOl嘉泰姆
tsw is the switching intervalvOl嘉泰姆
D is the duty cyclevOl嘉泰姆
Note that both MOSFETs have conduction losses while the upper MOSFET include an additional transitionvOl嘉泰姆
loss.The switching internal, tsw, is the function of the reverse transfer capacitance CRSS. Figure 7 illustratesvOl嘉泰姆
the switch-ing waveform internal of the MOSFET.The (1+TC) term factors in the temperature dependencyvOl嘉泰姆
of the RDS(ON) and can be extracted from the “RDS(ON) vs Tem-perature” curve of the power MOSFET.vOl嘉泰姆
Linear Regulator Input/Output Capacitor SelectionvOl嘉泰姆
The input capacitor is chosen based on its voltage rating.Under load transient condition, the input capacitor willvOl嘉泰姆
momentarily supply the required transient current. A 1μF ceramic capacitor will be sufficient in most applications.vOl嘉泰姆
The output capacitor for the linear regulator is chosen to minimize any droop during load transient condition. InvOl嘉泰姆
addition, the capacitor is chosen based on its voltage rating.vOl嘉泰姆
Linear Regulator MOSFET SelectionvOl嘉泰姆
The maximum DRIVE voltage is determined by the VCC.Since this pin drives an external N-channel MOSFET, vOl嘉泰姆

the maximum output voltage of the linear regulator is depen-dent upon the VGS.vOl嘉泰姆
VOUT2MAX = VCC- VGSvOl嘉泰姆
Another criteria is its efficiency of heat removal. The power dissipated by the MOSFET is given by:vOl嘉泰姆
Pdiss = Iout * (VIN - VOUT2)vOl嘉泰姆
where Iout is the maximum load current vOl嘉泰姆
Vout2 is the nominal output voltage In some applications, heatsink may be required to helpvOl嘉泰姆
maintain the junction temperature of the MOSFET below its maximum rating.vOl嘉泰姆
Layout ConsiderationvOl嘉泰姆
In high power switching regulator, a correct layout is im-portant to ensure proper operation of the regulator. InvOl嘉泰姆
general, interconnecting impedances should be mini-mized by using short and wide printed circuit traces. Sig-vOl嘉泰姆
nal and power grounds are to be kept separate and finally combined using ground plane construction or single point grounding. Figure 8 illustrates the layout, with bold lines indicating high current paths. Components along the bold lines should be placed close together. Below is a check-list for your layout:vOl嘉泰姆
· Keep the switching nodes (UGATE, LGATE, and PHASE)away from sensitive small signal nodes since thesevOl嘉泰姆
nodes are fast moving signals. Therefore, keep traces to these nodes as short as possible.vOl嘉泰姆
· The ground return of CIN must return to the combine COUT (-) terminal.vOl嘉泰姆

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