P MOS 和 N MOS

实物图

Figure 2:
The naming of the pins of a P-channel MOSFET is identical to that of an N-channel MOSFET. Here, too the names are Source, Drain and Gate. An IRLZ34N (N-channel) and an IRF9Z34N (P-channel) MOSFET are shown here. The assignment of the pins of both transistors is identical, but this does not always have to be the case. A look at the data sheet is essential to identify the pins!

P 沟道 MOSFET 引脚的命名与 N 沟道 MOSFET 相同。这里的名称也是源极、漏极和栅极。这里显示的是 IRLZ34N（N 沟道）和 IRF9Z34N（P 沟道）MOSFET。这两个晶体管的引脚分配完全相同，但并非总是如此。要识别引脚，必须查看数据表！

At the latest when connecting a P-channel MOSFET, the differences to an N-channel MOSFET have to be kept in mind:
With the P-channel MOSFET, the source pin is connected to the positive supply voltage, while the drain pin is connected to ground via a load resistor. Reminder: With the N-channel MOSFET, the source pin is connected to ground, while the drain pin is connected to the positive supply voltage via the load resistor.
In both cases, the potential at the drain pin is somewhere between 0V and the value of the positive supply voltage. The maximum drain-source voltage (V_DS) is listed in the data sheet, and in both cases the voltage drop from the drain pin to the source pin is recorded. Since the source pin of an N-channel MOSFET is (usually) at ground, but for P-channel MOSFET at the level of the positive supply voltage, we get a positive reading for V_GS at N-channel MOSFETs, but a negative reading at P-channel MOSFETs.

接线方法

• N MOS, Source 与电源负连接, Drop 接负载后, 接到电源 +, 所以 Vgs > 0
• P MOS, Source 与电源正连接, Drop 后面接负载, 再接到地. 0V.  Vgs < 0

This becomes clear when a multimeter is used for voltage measurement. The red probe is connected to the drain pin of each MOSFET, the black probe to the source pin. It can be seen that when the transistor is switched off (0V across the gate-source path), almost the entire supply voltage of 12V drops across the drain-source path of each MOSFET, but the value at the P-channel MOSFET is displayed with a negative sign.

验证

将N MOS, 和 P MOS 按照上图的方式连接, 用万用表量测结果如左图所示. 

Same as with N-channel MOSFETs, the resistance of the drain-source path changes on changing gate-source voltage. Here too, the resistance for enhancement types is maximum if the potential difference between gate and source is 0V which is the case when the entire supply voltage is present between gate and ground of the P-channel MOSFET. At the N-channel MOSFET to the left there is 0V between gate and ground and between the positive supply voltage and gate pin the entire supply voltage can be measured. Both MOSFETSs are switched off, the resistance of the drain-source path is in the range of one megohm, which means that the total supply voltage drops more or less across the transistors that form a voltage divider with the 1kΩ resistors:
V_DS = 12V * 1MΩ / (1MΩ + 1kΩ) = 11.99V
Again, for the P-channel MOSFET, the reference point of voltage measurement is not the ground, but the +12V cable. Accordingly, the reading on the drain-source path is -12V.

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