7 major factors in the selection of dcdc module power supply
2022-08-16

For dcdc module power products with TRIM or ADJ (adjustable) output pins, the output working voltage can be adjusted within a certain range according to resistors or adjustable potentiometers, usually the adjustment range is ±10%.


For the TRIM output pin, connect the potentiometer to TRIM. In all modules with +S and -S pins, the other two ends are connected to +S and -S respectively. When there is no +S, -S, connect the two ends to the output positive and negative poles of the corresponding main circuit (+S to +Vin, -S to -Vin), and then adjust the resistor. The resistance of the resistor is usually 5 to 10kΩ.


For ADJ output pins, it is divided into input side adjustment and output side adjustment. The adjustment method of the output side is the same as that of the TRIM pin. The input side adjustment of the power supply module can only increase the output working voltage. At this time, at least one side of the resistor is connected to the management, and the other end is connected to the ground of the input terminal.


Type maintenance power circuit


Usually, module power supply products often have built-in filters, which can take into account the requirements of normal switching power supply applications. If a higher specified electrical system is required, the input filter should be upgraded to the Internet. LC or π-type internets can be used, but special care should be taken to choose the smallest inductors and larger capacitors possible.


In order to avoid the transient high voltage of the input switching power supply from destroying the power supply of the module, it is recommended that customers connect transient digestion and absorption diodes at the input end and cooperate with each other in the application of fuses to ensure that the control module is within the safe input operating voltage range. In order to reduce common mode noise, the Y(Cy) capacitor can be boosted, usually a few nf high frequency capacitors are selected. R is a fuse, D1 is a maintenance diode, and D2 is a transient absorption diode (P6KE series).


Remote control circuit


The actual operation of the remote control switch of the dcdc module power supply is carried out according to the REM terminal. There are usually two methods of manipulation:


REM is connected to -VIN (reference ground), the remote control is turned off, and the standard VREF<0.4V. REM is suspended or connected to +VIN, the module works, and VREM>1V is required.


REM is connected to VIN, the remote control is turned off, and VREM<0.4V is specified. REM is connected to +VIN, the module works, VREM>1V is required. REM is floating, remote control is turned off, that is, the so-called "floating shutdown" (-R).


If the control is to be isolated from the input end, the dcdc module power supply can use the optocoupler as the transmission control signal.