目录64t嘉泰姆

1.产品概述                       2.产品特点64t嘉泰姆
3.应用范围                       4.下载产品资料PDF文档 64t嘉泰姆
5.产品封装图                     6.电路原理图                   64t嘉泰姆
7.功能概述                        8.相关产品64t嘉泰姆

一,产品概述(General Description)     64t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 load64t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.64t嘉泰姆
二.产品特点(Features)64t嘉泰姆

1A Output Current on Each Channel64t嘉泰姆
2.7V to 5.5V Input Voltage Range64t嘉泰姆
1.5MHz Constant Frequency Operation64t嘉泰姆
Low Dropout Operation at 100% Duty Cycle64t嘉泰姆
Synchronous Topology64t嘉泰姆
0.6V Low Reference Voltage64t嘉泰姆
Current Mode Operation64t嘉泰姆
Over-Temperature Protection64t嘉泰姆
Over-Current Protection64t嘉泰姆
Up to 94% Efficiency64t嘉泰姆
Internally Compensated64t嘉泰姆
Lead Free and Green Devices Available64t嘉泰姆
(RoHS Compliant)64t嘉泰姆
三,应用范围 (Applications)64t嘉泰姆

TV Tuner/Box64t嘉泰姆
Portable Instrument64t嘉泰姆
四.下载产品资料PDF文档 64t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！64t嘉泰姆

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五,产品封装图 (Package)64t嘉泰姆

64t嘉泰姆

六.电路原理图64t嘉泰姆

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七,功能概述64t嘉泰姆

Main Control Loop64t嘉泰姆

The CXSD62129 has dual independent constant frequency,current-mode PWM step-down converters. During nor-64t嘉泰姆
mal operation, the internal P-channel power MOSFET is turned on each cycle when the oscillator sets an internal64t嘉泰姆
RS latch and is turned off when an internal comparator (ICMP) resets the latch. The peak inductor current at which64t嘉泰姆
ICMP resets the RS latch is controlled by the voltage on the COMP, which is the output of the error amplifier64t嘉泰姆
(EAMP). An external resistive divider connected between VOUT and ground allows the EAMP to receive an output64t嘉泰姆
feedback voltage VFB at FB pin. When the load current increases, it causes a slightly decrease in VFB associated64t嘉泰姆
with the 0.6V reference, which in turn causes the COMP voltage to increase until the average inductor current64t嘉泰姆
matches the new load current.64t嘉泰姆
Soft-Start64t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.64t嘉泰姆
Short Circuit Protection64t嘉泰姆
For each channel, when the output is shortened to the ground, the frequency of the oscillator will be reduced to64t嘉泰姆
210kHz. This lower frequency allows the inductor current to safely discharge, thereby preventing current runaway.64t嘉泰姆
The oscillator’s frequency will gradually increase to its designed rate when the feedback voltage on the FB again64t嘉泰姆
approaches 0.6V.64t嘉泰姆
Over-Temperature Protection (OTP)64t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 again64t嘉泰姆
after the junction temperature cools by 40ïC. The OTP is designed with a 40ïC hysteresis to lower the average64t嘉泰姆
Junction Temperature (TJ) during continuous thermal overload conditions, increasing the lifetime of the device. 64t嘉泰姆
Enable/Shutdown64t嘉泰姆
For each channel, driving EN to the ground places the channel in shutdown mode. When in shutdown, the inter-64t嘉泰姆
nal power MOSFETs are turned off, all internal circuitry shuts down, and the quiescent supply current reduces to64t嘉泰姆
1μA maximally. 64t嘉泰姆
Automoatic PFM/PWM mode Switch64t嘉泰姆
The CXSD62129 is a fixed frequency PWM peak current modulation control step-down converter. At light loads,64t嘉泰姆
the CXSD62129 will automatically enter in pulse frequency modulation operation to reduce the dominant switching64t嘉泰姆
losses. In PFM operation, the inductor current may reach zero or reverse on each pulse. A zero current comparator64t嘉泰姆
turns off the N-channel synchronous MOSFET, forcing DCM (Discontinuous Current Mode) operation at light64t嘉泰姆
load. These controls get very low quiescent, help to main- tain high efficiency over the complete load range.64t嘉泰姆

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