These are very useful miniature Switch-Mode Current Regulator modules. Excellent for use in many applications where current limiting is required, such as LED Drivers, Battery Chargers, etc… They can also be used as dimmer or speed /power PWM controller.
They come as pre-assembled PCB modules with a range of pre-set current values :
Switch-mode operation means the most efficient energy use with minimum waste heat produced.
High operating frequency of up to 1MHz allows for a very small size of the module and low cost of it’s components.
Continuous Conduction Mode Regulator IC means that when the input voltage is below the pre-set load current value – the circuit will conduct the power directly from input to output.. but when the load current reaches the pre-set value the circuit begins to regulate the load output current .
Typical Input voltage range for these modules is between 6v and 30v and they may be able to tolerate the input voltage up to 45v
The modules include the on-board bridge-rectifier and can operate from either AC or DC current of any polarity.
Thermal shutdown protection : Automatic built-in over-heating protection will cause the circuit to shut down if the chip temperature reaches 160 degrees C. – It will turn back on again after the circuit temperature falls to 140 degrees C.
The modules come with the following output current denominations :
150mA (type A)
230mA ; 280mA ; 330mA ; 500mA (type B )
680mA (type C)
Dim-pin: the on-board controller IC has a separate pin that can be used for ON-OFF control and for Dimming / PWM control (optional). When the Dim-pin is below 0.3v the circuit is in the OFF state.
Applying a control voltage to the Dim-pin between 0.3v – and 2.5v will result in varying the output brightness (or speed) between 0% and 100% … Dim-pin voltage above 2.5v will keep the circuit 100% ON.
This provides a very easy way to control the output load current with analog signal such as a simple potentiometer (see Fig1).
Maximum Dim-pin voltage should not reach above 6v.
If Dim-pin is not used / not connected – it is pulled up to +VCC by the internal resistor so that the circuit is “ON” by default.
Direct PWM modulation is possible by interfacing the DIM-pin to an output of MCU (eg: Arduino, Picaxe, PIC…) or any other Logic-Level signals between 0 and 3.3v or 0 and 5v.
Soft-start : An external capacitor from the DIM pin to ground will provide additional soft-start delay, Adding capacitance increases this delay by approximately 0.8ms/nF.
type A : 6.7mm x 15mm x 5.4mm
type B : 7.9mm x 9.5mm x 5.1mm
type C : 8.1mm x 14.7mm x 8mm
Weight : approx. 1g
All these modules are functionally the same , The only difference (apart from Coil size for type-C) is that they have different Current-Sensing Resistor Values. This resistor pre-sets the output current and is typically a fraction of an Ohm.
It is possible therefore to tweak the desired output current by varying the value of the Current-Sensing Resistor.
The simple formula for calculating the nominal output current versus Resistor value is :
OutputCurrent(A) = 0.1 divided by ResistorValue in Ohms.
for example: 0.1 / 0.300 OHM resistor = 0.33A – or 330mA. The 0.300 Ohm resistor in this example would be marked: R30