In the last issue, we talked about the relevant factors for determining load capacity. Today, we will talk about how to enhance load capacity.

First, you can choose a MOS tube with a relatively large drain-source current. For example, in some high-current motor drive circuits, a MOS tube with a high drain-source current rating can better meet the current requirements of the motor when it starts and runs. In addition, you can also use parallel MOS tubes.

 However, it should be noted that when MOS tubes are connected in parallel, the current will not be automatically and accurately evenly distributed. Due to differences in individual parameters of MOS tubes (such as on-resistance, etc.), the current will be unevenly distributed, which may cause a MOS tube to be damaged due to overcurrent.

Therefore, it is usually necessary to connect a small resistance current-sharing resistor in series with the source of each MOS tube to achieve balanced current distribution. From the overall effect of parallel connection, it is equivalent to reducing the internal resistance and can drive heavier loads.

Generally, high-power amplifiers use MOS tubes, which have smaller internal resistance. According to the voltage division formula (the figure below: U1 is the voltage divided by a certain resistor, R1 is the resistance value of the resistor, R2 is the resistance value of another resistor, and U is the total voltage), when the load internal resistance is small and the amplifier output impedance remains unchanged, the voltage ratio divided by the final stage of the amplifier will increase, which is conducive to improving power transmission efficiency, etc.

Voltage Divider Formula

In addition, using driver chips with high driving current capabilities can also improve the efficiency and load capacity of the circuit. For example, in a high-speed switching power supply circuit, a fast driver chip can enable the MOS tube to turn on and off quickly, reducing switching losses and thus improving the load performance of the entire circuit.