Adjustment of the output voltage of the power module
For module power products with TRIM or ADJ (adjustable) output pins, the output voltage can be adjusted within a certain range by resistors or potentiometers. The general adjustment range is ±10%.
For the TRIM output pin, connect the center of the potentiometer to the TRIM. In all modules of the +S and -S pins, the other ends are connected to +S and -S respectively. When there is no +S or -S, connect the two ends to the positive and negative outputs of the corresponding main circuit (+S is connected to +Vin, -S is connected to -Vin), and then the potentiometer can be adjusted. The resistance of the potentiometer is generally 5 to 10 kΩ.
For the ADJ output pin, it is divided into input side adjustment and output side adjustment. The output side adjustment is the same as the TRIM pin. The input module of the power module can only adjust the output voltage. At this time, one end of the potentiometer is connected to the center, and the other end is connected to the ground of the input end.
Input protection circuit
General module power products have built-in filters to meet the requirements of general power applications. If you need a higher power system, you should increase the input filter network. LC or π-type networks can be used, but care should be taken to select smaller inductors and larger capacitors.
In order to prevent the input power supply transient high voltage from damaging the module power supply, it is recommended that the user connect the transient absorbing diode to the input terminal and use it with the fuse to ensure that the module is within the safe input voltage range. In order to reduce the common mode noise, you can increase the Y (Cy) capacitance, generally choose a few nf high frequency capacitors. R is a fuse, D1 is a protection diode, and D2 is a transient absorption diode (P6KE series).
Remote control switch circuit
The remote control switch operation of the module power supply is performed through the REM terminal. There are two general control methods:
REM is connected to -VIN (reference ground) and is turned off remotely, requiring VREF <0.4V. The REM is left floating or connected to +VIN. The module works and requires VREM >1V.
REM is connected to VIN and is turned off remotely, requiring VREM <0.4V. REM is connected to +VIN and the module works, requiring VREM >1V. The REM is suspended and remotely turned off, which is called "dang-off" (-R).
If the control is to be isolated from the input, the power module can use the optocoupler as the transfer control signal.