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

七,功能概述6SH嘉泰姆

VCC and VIN Power-On-Reset (POR)6SH嘉泰姆
TThe CXSD62152/A keeps monitoring the voltage on VIN and VCC pins to prevent wrong logic operations which6SH嘉泰姆
may occur when VIN or VCC voltage is not high enough for internal control circuitry to operate. The VCC POR ris-6SH嘉泰姆
ing threshold is 2.7V (typical) with 0.2V hysteresis and VIN POR rising threshold is 2.3V with 0.05V hysteresis.6SH嘉泰姆
During startup, the VCC and VIN voltage must exceed the POR threshold. Then the IC starts a starts-up process6SH嘉泰姆
and ramps up the output voltage to the voltage target. 6SH嘉泰姆
Output Under-Voltage Protection (UVP)6SH嘉泰姆
In the operational process, if a short-circuit occurs, the output voltage will drop quickly. Before the current-limit6SH嘉泰姆
circuit responds, the output voltage will fall out of the required regulation range. The under-voltage continually6SH嘉泰姆
monitors the FB voltage after soft-start is completed. If a load step is strong enough to pull the output voltage lower6SH嘉泰姆
than the under-voltage threshold, the IC shuts down converter’s output.The under-voltage threshold is 50% of the6SH嘉泰姆
nominal out put voltage. The under-voltage comparator has a built-in 3μs noise filter to prevent the chips from wrong6SH嘉泰姆
UVP shut down being caused by noise. The CXSD62152/A will be latched after under-voltage protection.6SH嘉泰姆
Over-Voltage Protection (OVP)6SH嘉泰姆
The over-voltage function monitors the output voltage by FB pin. When the FB voltage increases over 125% of the6SH嘉泰姆
reference voltage due to the high-side MOSFET failure or for other reasons, the over-voltage protection comparator6SH嘉泰姆
will force the low-side MOSFET gate driver high till the occurence of low-side current limit. This action actively6SH嘉泰姆
pulls down the output voltage. As soon as the output voltage is less than 0.2V, the CXSD62152/A will be latched off6SH嘉泰姆
and needs a POR or enable to recover to normal operation.6SH嘉泰姆
Over-Temperature Protection (OTP)6SH嘉泰姆
The over-temperature circuit limits the junction tempera ture of the CXSD62152/A. When the junction temperature6SH嘉泰姆
exceeds TJ = 160oC, a thermal sensor turns off the both power MOSFETs, allowing the devices to cool.6SH嘉泰姆
The thermal sensor allows the converters to start a start up process and to regulate the output voltage again after6SH嘉泰姆
the junction temperature cools by 50oC. The OTP is designed with a 50oC hysteresis to lower the average TJ6SH嘉泰姆
during continuous thermal overload conditions, increasing lifetime of the CXSD62152/A.6SH嘉泰姆
Current-Limit Protection 6SH嘉泰姆
The CXSD62152/A monitors the output current, flows through the high-side and low-side power MOSFETs, and limits6SH嘉泰姆
the current peak at current-limit level to prevent the IC from damaging during overload, short-circuit and over-6SH嘉泰姆
voltage conditions. Typical high side power MOSFET current limit is 3A, and low side MOSFET current limit is 1.9A.6SH嘉泰姆
 Soft-Start6SH嘉泰姆
The CXSD62152/A has a built-in soft-start to control the rise rate of the output voltage and limit the input current surge6SH嘉泰姆
during start-up. During soft-start, an internal voltage ramp connected to one of the positive inputs of the error6SH嘉泰姆
amplifier, rises up from 0V to 0.95V to replace the reference voltage (0.8V) until the voltage ramp reaches the6SH嘉泰姆
reference voltage. During soft-start without output overvoltage, the CXSD62152/A converter¡|s sinking capability is6SH嘉泰姆
disabled until the output voltage reaches the voltage target.6SH嘉泰姆
Soft-Stop6SH嘉泰姆
At the moment of shutdown controlled by EN signal, under-voltage event or over-temperature protection, theCXSD62152/A initiates a soft-stop process to discharge the output voltage in the output capacitors. Certainly, the load6SH嘉泰姆
current also discharges the output voltage. During softstop, the internal voltage ramp (VRAMP) falls down from 0.6SH嘉泰姆
95V to 0V to replace the reference voltage. Therefore, the output voltage falls down slowly at the light load. After the6SH嘉泰姆
soft-stop interval elapses, the soft-stop process ends and the IC turns on the low-side power MOSFET.6SH嘉泰姆
八,相关产品                更多同类产品.......6SH嘉泰姆

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