目录TQF嘉泰姆

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

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

                The CXSD6279B is a voltage mode and synchronous PWM controllerTQF嘉泰姆
which drives dual N-Channel MOSFETs. It inte-grates the control, monitoring,TQF嘉泰姆
and protection functions into a single package, provides one controlled powerTQF嘉泰姆
outputs with under-voltage and over-current protection.CXSD6279B providesTQF嘉泰姆
excellent regulation for output load variation. An internal 0.8V temperature-TQF嘉泰姆
compensated reference voltage is designed to meet the requirement ofTQF嘉泰姆
low output voltage applications. It includes a 200kHz free-runningTQF嘉泰姆
triangle-wave oscillator that is adjustable from 70kHz to 800kHz.TQF嘉泰姆
        The power-on-reset (POR) circuit monitors the VCC, EN,and OCSETTQF嘉泰姆
input voltage to start-up or shutdown the IC.The over-current protection (OCP)TQF嘉泰姆
monitors the output current by using the voltage drop across the upperTQF嘉泰姆
MOSFET’s RDS(ON), eliminating the need for a current sens-ing resistor.TQF嘉泰姆
The under-voltage protection (UVP) moni-tors the voltage of the FB pin forTQF嘉泰姆
short-circuit protection.The over-current protection trip cycle the soft-startTQF嘉泰姆
func-tion until the fault events be removed. Under-voltage pro-tection willTQF嘉泰姆
shutdown the IC directly.TQF嘉泰姆
二.产品特点(Features)TQF嘉泰姆

1.)Simple Single-Loop Control DesignTQF嘉泰姆
   Voltage-Mode PWM ControlTQF嘉泰姆
2.)Fast Transient ResponseTQF嘉泰姆
    Full 0–100% Duty RatioTQF嘉泰姆
3.)Excellent Output Voltage RegulationTQF嘉泰姆
   0.8V Internal ReferenceTQF嘉泰姆
    ± 1% Over Line Voltage and TemperatureTQF嘉泰姆
4.)Over Current Fault MonitorTQF嘉泰姆
   Uses Upper MOSFETs RDS (ON)TQF嘉泰姆
5.)Converter Can Source and Sink CurrentTQF嘉泰姆
6.)Small Converter SizeTQF嘉泰姆
    200kHz Free-Running OscillatorTQF嘉泰姆
   Programmable from 70kHz to 800kHzTQF嘉泰姆
7.)14-Lead SOIC PackageTQF嘉泰姆
8.)Lead Free and Green Devices Available (RoHS Compliant)TQF嘉泰姆
三,应用范围 (Applications)TQF嘉泰姆

Graphic CardsTQF嘉泰姆
DDR Memory Power SupplyTQF嘉泰姆
DDR Memory Termination VoltageTQF嘉泰姆
Low-Voltage Distributed Power SuppliesTQF嘉泰姆
四.下载产品资料PDF文档 TQF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！TQF嘉泰姆

 TQF嘉泰姆

五,产品封装图 (Package)TQF嘉泰姆

TQF嘉泰姆
RT (Pin1)TQF嘉泰姆
This pin can adjust the switching frequency. Connect a resistor from the RT to the GND for increasing the switch-TQF嘉泰姆
OCSET (Pin2)TQF嘉泰姆
This pin serves two functions: a shutdown control and the setting of over current-limit threshold. Pulling this pinTQF嘉泰姆
below 1.27V will shutdown the controller, forcing the UGATE and LGATE signals to be at 0V.TQF嘉泰姆
A resistor (Rocset) connected between this pin and the drain of the high side MOSFET will determine the over TQF嘉泰姆

current limit. An internal 200μA current source will flow through this resistor, creating a voltage drop, which TQF嘉泰姆

will be com-pared with the voltage across the high side MOSFET.TQF嘉泰姆
SS (Pin3)TQF嘉泰姆
Connect a capacitor from the pin to the GND to set the soft-start interval of the converter. An internal 10μA TQF嘉泰姆

current source charges this capacitor to 5.8V. The SS voltage clamps the error amplifier output, and Figure1TQF嘉泰姆

 shows the soft-start interval. At t1, the SS voltage reaches the valley of the oscillator’s triangle wave. TheTQF嘉泰姆

PWM comparator starts to generate a PWM signal to control logic, and theTQF嘉泰姆
COMP (Pin4)TQF嘉泰姆
This pin is the output of the error amplifier. Add an exter-nal resistor and capacitor network to provide theTQF嘉泰姆

 loop com- pensation for the PW M converter (see Application Information).TQF嘉泰姆
FB (Pin5)TQF嘉泰姆
FB pin is the inverter input of the error amplifier and it receives the feedback voltage from an external TQF嘉泰姆

resis-tive divider across the output (V OUT). The output voltage is determined by:TQF嘉泰姆
EN (Pin6)TQF嘉泰姆
Pull the pin higher than 2V to enable the device, and pull the pin lower than 0.8V to shutdown the TQF嘉泰姆

device. In shutdown, the SS is discharged and the UGATE and LGATE pins are held low. The EN pin TQF嘉泰姆

is the open-collector, and it will not be floating. TQF嘉泰姆
GND (Pin7)TQF嘉泰姆
Signal ground for the IC. TQF嘉泰姆
PHASE (Pin8)TQF嘉泰姆
This pin is connected to the source of the high-side MOSFET and is used to monitor the voltage dropTQF嘉泰姆

 across the high-side MOSFET for over-current protection. TQF嘉泰姆
UGATE (Pin9)TQF嘉泰姆
Connect the pin to external MOSFET, and provides the gate drive for the upper MOSFET.TQF嘉泰姆

BOOT (Pin 10)TQF嘉泰姆
This pin provides the supply voltage to the high side MOSFET driver. For driving logic level N-channel TQF嘉泰姆

MOSEFT,a bootstrap circuit can be used to create a suitable driver’s supply. TQF嘉泰姆
PGND (Pin11)TQF嘉泰姆
Power ground for the gate diver. Connect the lower MOSFET source to this pin. TQF嘉泰姆
LGATE (Pin 12)TQF嘉泰姆

Connect the pin to the external MOSFET, and provides the gate drive signal for the lower MOSFET.TQF嘉泰姆
PVCC (Pin13)TQF嘉泰姆
This pin provides a supply voltage for the lower gate drive, connect it to the VCC pin in common use. TQF嘉泰姆
VCC (Pin14)TQF嘉泰姆
This pin provides a supply voltage for the device. When the VCC is above the rising threshold 10.4V, TQF嘉泰姆

the device is turned on; conversely, when the VCC is below the falling threshold, the device is turned off.TQF嘉泰姆
六.电路原理图TQF嘉泰姆

TQF嘉泰姆
七,功能概述TQF嘉泰姆

Output Capacitor SelectionTQF嘉泰姆
The selection of COUT is determined by the required effec-tive series resistance (ESR) and voltage ratingTQF嘉泰姆

 rather than the actual capacitance requirement. Therefore, select highperformance low ESR capacitors TQF嘉泰姆

that are intended for switching regulator applications. In some applications,multiple capacitors have toTQF嘉泰姆

 be paralled to achieve the desired ESR value. If tantalum capacitors are used, makesure they are surgeTQF嘉泰姆

 tested by the manufactures. If in doubt,consult the capacitors manufacturer.TQF嘉泰姆
 Input Capacitor SelectionTQF嘉泰姆
The input capacitor is chosen based on the voltage rating and the RMS current rating. For reliable TQF嘉泰姆

operation, select the capacitor voltage rating to be at least 1.3 times higher than the maximum inputTQF嘉泰姆

 voltage. The maximum RMS current rating requirement is approximately IOUT/2 , where IOUT is the TQF嘉泰姆

load current. During power up, the input capaci-tors have to handle large amount of surge current.TQF嘉泰姆

 If tanta-lum capacitors are used, make sure they are surge tested by the manufactures. If in doubt, TQF嘉泰姆

consult the capacitors manufacturer.For high frequency decoupling, a ceramic capacitor be-tweenTQF嘉泰姆

 0.1μF to 1μF can be connected between the VCC and the ground pin.TQF嘉泰姆
Inductor SelectionTQF嘉泰姆
The inductance of the inductor is determined by the out-put voltage requirement. The larger the TQF嘉泰姆

inductance, the lower the inductor’s current ripple. This will translate into lower output ripple voltage.TQF嘉泰姆

 The ripple current and ripple voltage can be approximated by:TQF嘉泰姆
where Fs is the switching frequency of the regulator.There is a tradeoff exists between the inductor’sTQF嘉泰姆

 ripple current and the regulator load transient response time. A smaller inductor will give the regulator TQF嘉泰姆

a faster load tran-sient response at the expense of higher ripple current and vice versa. The maximumTQF嘉泰姆

 ripple current occurs at the maximum input voltage. A good starting point is to choose the ripple TQF嘉泰姆

current to be approximately 30% of the maxi-mum output current.Once the inductance value has TQF嘉泰姆

been chosen, select an inductor that is capable of carrying the required peak cur-rent without going TQF嘉泰姆

into saturation. In some types of inductors, especially core that is make of ferrite, the rippleTQF嘉泰姆
current will increase abruptly when it saturates. This will result in a larger output ripple voltage.TQF嘉泰姆
CompensationTQF嘉泰姆
The output LC filter introduces a double pole, which con-tributes with –40dB/decade gain slope and TQF嘉泰姆

180 degrees phase shift in the control loop. A compensation network between the COMP pin and the TQF嘉泰姆

ground should be added. The simplest loop compensation network is shown inTQF嘉泰姆
Figure 5.TQF嘉泰姆
The output LC filter consists of the output inductor and output capacitors. The transfer function ofTQF嘉泰姆

 the LC filter is given by:TQF嘉泰姆
八,相关产品                     更多同类产品...... TQF嘉泰姆

 TQF嘉泰姆