Controlling the MT3608

If you look at the MT3608 datasheet, you’ll notice that pin 4 is the Enable pin, designed to toggle the chip’s operation.

A high level signal enables the chip, while a low level signal disables the voltage boosting. In the latter case, the output voltage will simply match the input voltage of the module.

As we can see, EN is connected to the adjacent pin (5) of the IC, which is our input positive VIN. Therefore, to control the EN input, this trace must be cut.

Initially, I wanted to use a rotary tool for this, but even the smallest burr turned out to be too large.

 

So, there was nothing left to do but cut the trace with a scalpel.

 

I’m doing all of this under a microscope, and in 15 seconds, the trace is gone.

 

Now it’s time to put everything together. I want to use the RCWL-0516 module as the control signal source. This module is a microwave motion sensor. As for the load, let’s use a 12V fan.

We’ll supply 5V to the input from a regulated power supply. The OUT signal from the motion sensor is connected to pin 4 of the IC.

Powering it up.

On the left—no motion. However, of course, the 5V input is enough for the fan to start spinning at low RPM. This nuance should be kept in mind, as this behavior is often undesirable.

On the right—the sensor detected motion and sent a signal to the boost module. The fan received 12V and spun up to full power.

A more practical application would be replacing the fan with an LED strip and powering it from a Li-Ion battery. This results in a DIY autonomous light that turns on when motion is detected.

Quiescent Current Consumption in Shutdown Mode

In the disabled state, the module’s current consumption remains independent of the potentiometer settings; there is only a linear dependency on the input voltage: