CXSD62129由两个独立的1.5MHz恒定频率电流模式和PWM降压转换器组成同步整流器

目录ynn嘉泰姆

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

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

  The CXSD62129 consists of two independent 1.5MHz constant frequency, current mode, and PWM step-down converters. Each converter integrates a main switch with a synchronous rectifier for high efficiency without an external Schottky diode. The CXSD62129 is ideal for powering portable equipment that runs from a single cell Lithium Ion (Li+) battery. Each converter can supply 1A of loadynn嘉泰姆
current from a 2.7V to 5.5V input voltage. The output volt age can be regulated as low as 0.6V. The CXSD62129 can also run at 100% duty cycle for low dropout applications.ynn嘉泰姆
二.产品特点(Features)ynn嘉泰姆

1A Output Current on Each Channelynn嘉泰姆
2.7V to 5.5V Input Voltage Rangeynn嘉泰姆
1.5MHz Constant Frequency Operationynn嘉泰姆
Low Dropout Operation at 100% Duty Cycleynn嘉泰姆
Synchronous Topologyynn嘉泰姆
0.6V Low Reference Voltageynn嘉泰姆
Current Mode Operationynn嘉泰姆
Over-Temperature Protectionynn嘉泰姆
Over-Current Protectionynn嘉泰姆
Up to 94% Efficiencyynn嘉泰姆
Internally Compensatedynn嘉泰姆
Lead Free and Green Devices Availableynn嘉泰姆
(RoHS Compliant)ynn嘉泰姆
三,应用范围 (Applications)ynn嘉泰姆

TV Tuner/Boxynn嘉泰姆
Portable Instrumentynn嘉泰姆
四.下载产品资料PDF文档 ynn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！ynn嘉泰姆

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五,产品封装图 (Package)ynn嘉泰姆

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六.电路原理图ynn嘉泰姆

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七,功能概述ynn嘉泰姆

Main Control Loopynn嘉泰姆

The CXSD62129 has dual independent constant frequency,current-mode PWM step-down converters. During nor-ynn嘉泰姆
mal operation, the internal P-channel power MOSFET is turned on each cycle when the oscillator sets an internalynn嘉泰姆
RS latch and is turned off when an internal comparator (ICMP) resets the latch. The peak inductor current at whichynn嘉泰姆
ICMP resets the RS latch is controlled by the voltage on the COMP, which is the output of the error amplifierynn嘉泰姆
(EAMP). An external resistive divider connected between VOUT and ground allows the EAMP to receive an outputynn嘉泰姆
feedback voltage VFB at FB pin. When the load current increases, it causes a slightly decrease in VFB associatedynn嘉泰姆
with the 0.6V reference, which in turn causes the COMP voltage to increase until the average inductor currentynn嘉泰姆
matches the new load current.ynn嘉泰姆
Soft-Startynn嘉泰姆
Each channel in the CXSD62129 has a built-in soft-start to control the output voltage rise during start-up. During soft-start, an internal ramp, connected to the one of the posi- tive inputs of the error amplifier, raise up to replace the reference voltage (0.6V typical) until the ramp voltage reaches the reference voltage.ynn嘉泰姆
Short Circuit Protectionynn嘉泰姆
For each channel, when the output is shortened to the ground, the frequency of the oscillator will be reduced toynn嘉泰姆
210kHz. This lower frequency allows the inductor current to safely discharge, thereby preventing current runaway.ynn嘉泰姆
The oscillator’s frequency will gradually increase to its designed rate when the feedback voltage on the FB againynn嘉泰姆
approaches 0.6V.ynn嘉泰姆
Over-Temperature Protection (OTP)ynn嘉泰姆
For each channel, the over-temperature circuit limits the junction temperature of the CXSD62129. When the junction temperature exceeds 150oC, a thermal sensor turns off the power MOSFETs, allowing the channels to cool down.The thermal sensor allows the converter to start a soft- start process and to regulate the output voltage againynn嘉泰姆
after the junction temperature cools by 40ïC. The OTP is designed with a 40ïC hysteresis to lower the averageynn嘉泰姆
Junction Temperature (TJ) during continuous thermal overload conditions, increasing the lifetime of the device. ynn嘉泰姆
Enable/Shutdownynn嘉泰姆
For each channel, driving EN to the ground places the channel in shutdown mode. When in shutdown, the inter-ynn嘉泰姆
nal power MOSFETs are turned off, all internal circuitry shuts down, and the quiescent supply current reduces toynn嘉泰姆
1μA maximally. ynn嘉泰姆
Automoatic PFM/PWM mode Switchynn嘉泰姆
The CXSD62129 is a fixed frequency PWM peak current modulation control step-down converter. At light loads,ynn嘉泰姆
the CXSD62129 will automatically enter in pulse frequency modulation operation to reduce the dominant switchingynn嘉泰姆
losses. In PFM operation, the inductor current may reach zero or reverse on each pulse. A zero current comparatorynn嘉泰姆
turns off the N-channel synchronous MOSFET, forcing DCM (Discontinuous Current Mode) operation at lightynn嘉泰姆
load. These controls get very low quiescent, help to main- tain high efficiency over the complete load range.ynn嘉泰姆

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