为什么用这个IC短路输入功率高呀,我输出功率为5W,电感量为2.8MH
是不是我变压器电感量有问题呀
VIPER22A短路保护
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@jerry-lin
可以搞定的,在供电上下工夫,调整供电电路参数,可以加大供电电容试试.电容太小就会不保护.
1.Please check the Vdd voltage during short circuit, could it come down to below 8V?
2. the Current limit of this IC is very wide, from 0.56A to 0.84A. This will make design very difficult for wide range input. Normally, will design the transformer to operate with Ip of 0.56A at lowest line input. To cut conner, can assume operation at nominal input voltage and current limit is 0.7A, then design transformer to operate at this condition, then at high input voltage, make sure that the Vdd will fall below 8V durign short circuit.
2. the Current limit of this IC is very wide, from 0.56A to 0.84A. This will make design very difficult for wide range input. Normally, will design the transformer to operate with Ip of 0.56A at lowest line input. To cut conner, can assume operation at nominal input voltage and current limit is 0.7A, then design transformer to operate at this condition, then at high input voltage, make sure that the Vdd will fall below 8V durign short circuit.
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@fqy0931
Vipper22A有短路保护吗?还请赐教!据我所知,此IC只有过功率保护,且是通过VCC电压实现,保护模式也是限功率的方式当短路输出后,反馈增益跑出范围,使得VCC电压升高到其保护点实现保护,看看资料
1. Peak current limit Idlim, this will switch off the MOsfet when Id+Ifb reach this level, during short circuit, Vfb will be zero, therefore, the maximum current through the transformer winding will be Idlim. You can then estimate the power into the power supply during short circuit, by knowing the Idlim, Lp.
2. OVP protection by Vddovp, the voltage is 42V. During short circuit, the reflected voltage on the Vdd may reduce, depends on different transformer workmanship, the performance will be different. This feature is good for OVP, but for short circuit, if you rely on this feature,the performance may vary during Mass Production.
2. OVP protection by Vddovp, the voltage is 42V. During short circuit, the reflected voltage on the Vdd may reduce, depends on different transformer workmanship, the performance will be different. This feature is good for OVP, but for short circuit, if you rely on this feature,the performance may vary during Mass Production.
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