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T8j嘉泰姆

1.产品概述                       2.产品特点T8j嘉泰姆
3.应用范围                       4.下载产品资料PDF文档 T8j嘉泰姆
5.产品封装图                     6.电路原理图                   T8j嘉泰姆
7.功能概述                        8.相关产品T8j嘉泰姆

一,产品概述(General Description)     T8j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 loadT8j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.T8j嘉泰姆
二.产品特点(Features)T8j嘉泰姆

1A Output Current on Each ChannelT8j嘉泰姆
2.7V to 5.5V Input Voltage RangeT8j嘉泰姆
1.5MHz Constant Frequency OperationT8j嘉泰姆
Low Dropout Operation at 100% Duty CycleT8j嘉泰姆
Synchronous TopologyT8j嘉泰姆
0.6V Low Reference VoltageT8j嘉泰姆
Current Mode OperationT8j嘉泰姆
Over-Temperature ProtectionT8j嘉泰姆
Over-Current ProtectionT8j嘉泰姆
Up to 94% EfficiencyT8j嘉泰姆
Internally CompensatedT8j嘉泰姆
Lead Free and Green Devices AvailableT8j嘉泰姆
(RoHS Compliant)T8j嘉泰姆
三,应用范围 (Applications)T8j嘉泰姆

TV Tuner/BoxT8j嘉泰姆
Portable InstrumentT8j嘉泰姆
四.下载产品资料PDF文档 T8j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！T8j嘉泰姆

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五,产品封装图 (Package)T8j嘉泰姆

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六.电路原理图T8j嘉泰姆

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七,功能概述T8j嘉泰姆

Main Control LoopT8j嘉泰姆

The CXSD62129 has dual independent constant frequency,current-mode PWM step-down converters. During nor-T8j嘉泰姆
mal operation, the internal P-channel power MOSFET is turned on each cycle when the oscillator sets an internalT8j嘉泰姆
RS latch and is turned off when an internal comparator (ICMP) resets the latch. The peak inductor current at whichT8j嘉泰姆
ICMP resets the RS latch is controlled by the voltage on the COMP, which is the output of the error amplifierT8j嘉泰姆
(EAMP). An external resistive divider connected between VOUT and ground allows the EAMP to receive an outputT8j嘉泰姆
feedback voltage VFB at FB pin. When the load current increases, it causes a slightly decrease in VFB associatedT8j嘉泰姆
with the 0.6V reference, which in turn causes the COMP voltage to increase until the average inductor currentT8j嘉泰姆
matches the new load current.T8j嘉泰姆
Soft-StartT8j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.T8j嘉泰姆
Short Circuit ProtectionT8j嘉泰姆
For each channel, when the output is shortened to the ground, the frequency of the oscillator will be reduced toT8j嘉泰姆
210kHz. This lower frequency allows the inductor current to safely discharge, thereby preventing current runaway.T8j嘉泰姆
The oscillator’s frequency will gradually increase to its designed rate when the feedback voltage on the FB againT8j嘉泰姆
approaches 0.6V.T8j嘉泰姆
Over-Temperature Protection (OTP)T8j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 againT8j嘉泰姆
after the junction temperature cools by 40ïC. The OTP is designed with a 40ïC hysteresis to lower the averageT8j嘉泰姆
Junction Temperature (TJ) during continuous thermal overload conditions, increasing the lifetime of the device. T8j嘉泰姆
Enable/ShutdownT8j嘉泰姆
For each channel, driving EN to the ground places the channel in shutdown mode. When in shutdown, the inter-T8j嘉泰姆
nal power MOSFETs are turned off, all internal circuitry shuts down, and the quiescent supply current reduces toT8j嘉泰姆
1μA maximally. T8j嘉泰姆
Automoatic PFM/PWM mode SwitchT8j嘉泰姆
The CXSD62129 is a fixed frequency PWM peak current modulation control step-down converter. At light loads,T8j嘉泰姆
the CXSD62129 will automatically enter in pulse frequency modulation operation to reduce the dominant switchingT8j嘉泰姆
losses. In PFM operation, the inductor current may reach zero or reverse on each pulse. A zero current comparatorT8j嘉泰姆
turns off the N-channel synchronous MOSFET, forcing DCM (Discontinuous Current Mode) operation at lightT8j嘉泰姆
load. These controls get very low quiescent, help to main- tain high efficiency over the complete load range.T8j嘉泰姆

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