Power Supply for PIC Development – Part 2

As was previously stated, in Part 1 the ProtoDev PCBs have jumpers which allow the user to configure the power supply. In the instances of both PCBs, a selection can be made between either 5VDc or 3V3CD.

Voltage Drop

The input voltage to the PCB, should be in the region of 7 > Vdc < 9. 7.5 volts is usually sufficient for the regulator to produce the 5 VDc. For the 3V3 DC regulator between 5 – 6 volts is sufficient to achieve the 3v3 on the output. A linear voltage regulator has a forward voltage drop between the input and output which must first be overcome.

FIG : Voltage Regulator diagram

FIG : Voltage Regulator diagram

NOTE: If the power supply does provide sufficient voltage on the input, the voltage regulator will not produce the required voltage on the output. This may prevent the PIC from operating reliably, but PICs can operate at voltages other than 5Vdc, etc.

Jumper Configuration

On each of the two PCBs, there is a set of jumpers which configure the power requirements for the PCB. See below for more details.

ProtoDev 20 | DX Power Supply configuration
Power Supply >5Vdc < 7Vdc Reverse polarity protection built in
ProtoDev 40 PWRSET Position 8 – 5Vdc,
Position 6 – 3V3 DC
ProtoDev 20 PW Position 8 – 5Vdc,
Position 6 – 3V3 DC


Power Supply AreasĀ 

The ProtoDev PCBs include a prototyping area which has the pads interconnected from left to right simulating strip board. This feature enables additional components and circuitry to be added to the PCB.

NOTE: The voltage regulators are capable of handling up to 1 Amp. When the current maximum is drawn, the voltage regulators can run very hot and may overheat and burn them out. To avoid the voltage regulators overheating heat sinks can be installed to help dissipate the heat.

Small heat sinks can be obtained, and heat sink paste used to enhance the heat dissipation.