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UCC21520: 计算拉电流公式怎么来的，不是特别明白

bo liu
Prodigy 10 points
Part Number: UCC21520

UCC21520数据手册里面9.2节计算电流出现了这个公式。但是对于这个公式怎么来的不是很明白，可以具体详细解释一下吗

  • 0
    TI__Guru**** 308311 points

    Hi

        解释第二个公式驱动放电电路，VDD-Vgdf是驱动电压减去驱动MOS压降，Rol+Roff//Ron+Rgfet_int  放电回路的阻抗，Rol是芯片内部驱动电阻的导通阻抗，Ron//Roff是驱动电阻，Rgfet_int 是外部MOS G极阻抗。

        同样第一个公式是高边驱动放电电路。

  • 0 in reply to Johnsin Tao
    Prodigy 10 points

    手册里面说是VGDF是The anti-parallel diode forward voltage drop which is in series with ROFF，RGFET_INT是Power transistor internal gate resistance，这个那一个说法是正确的呢，另外这里说的驱动电压是指芯片引脚的电压吗

    可以按照这个图说一下吗

  • 0 in reply to bo liu
    TI__Guru**** 308311 points

    Hi

        不看这个图，看图第20页图9-2，路径从VDD到Vout， 然后经过驱动电阻RON,  最后到MOS.  电流计算就是，VDD-Vgdf/(Rol+Roff//Ron+Rgfet_int )