Power Supplies

Smart Power Supply for Microcontroller Projects Schematic Circuit Diagram

“Smart Power Supply for Microcontroller” is an essential tool for any electronics hobbyist, providing a reliable and user-friendly DC power source. Given that a stable smart power supply is of utmost importance for nearly all do-it-yourself microcontroller projects, we are introducing a straightforward and cost-effective DIY project for creating a power supply tailored to microcontroller needs.

Smart Power Supply for Microcontroller Projects Schematic Circuit Diagram 1

Circuit Description

The core of the design revolves around the TPS63000 (IC1), a highly efficient single-inductor buck-boost converter manufactured by Texas Instruments. This power supply delivers a steady 3.3V or 5.0V output, derived from an input voltage range spanning from 1.8V to 5.5V, achieving an impressive efficiency rate of up to 96%. The versatility of this power supply allows it to be powered by various sources, including a USB port (via J1), a two-cell or three-cell alkaline, NiCd, or NiMH battery, or even a Li-ion/Li-polymer battery (via J2). It’s worth noting that the TPS63000 performs buck-boost conversion through a fixed-frequency pulse width modulation controller, utilizing synchronous rectification to maximize its efficiency.

Smart Power Supply for Microcontroller Projects Schematic Circuit Diagram 2

Within the TPS6300x family, both fixed and variable output voltage versions are offered. In our setup, we utilized the adjustable output variant and established a connection with a resistor divider (R2-R4) connected between VOUT, FB, and GND of the TPS63000. When the jumper (JP1) remains open, the resulting output voltage (accessible at J3) is 5 V. Conversely, if the jumper is closed, the output voltage is fixed at 3.3 V.

Smart Power Supply for Microcontroller Projects Schematic Circuit Diagram 3

Circuit Construction

While employing integrated circuits within compact and finely-pitched surface-mount packages typically demands advanced skills, you can effortlessly assemble the entire circuit on a small universal SMD prototyping board. Of course, this process can be facilitated with the assistance of a QFN-10 to DIP adapter.

As per the datasheet’s guidance, for all switching power supplies, careful attention to layout is crucial. Input capacitors (C1 & C2), output capacitors (C3 & C4), and the inductor (L1) should be positioned as closely as feasible to IC1. To minimize ground noise, it’s advisable to utilize a shared ground node for power ground (pin 3) and a separate one for control ground (pin 9), connecting these ground nodes at a location near one of IC1’s ground pins. Additionally, the exposed thermal pad of IC1 should be connected to PGND, and the feedback resistor divider (R2-R4) should be placed in close proximity to the control ground pin of IC1.

Schematic Circuit Diagram 4

List of Components (all are SMT components)

  • IC1: TPS63000
  • D1: 1N5817
  • LED1: Red/5mA
  • R1: 100R 1%
  • R2, R3: 1M 1%
  • R4: 220K 1%
  • R5: 1K 1%
  • C1, C3, C4: 10uF/6.3V Ceramic
  • C2: 100nF/6.3V Ceramic
  • L1: 4.7uH/2A (<200R)
  • J1, J3: USB ‘A’ female socket
  • J2: DC jack
  • S1: SPST switch
  • JP1: 2-pin male Header

Lab Note

The prototype was tested on a “dirty” pcb, home-brewed by the author. If you want to make your own pcb at home, follow the tips shown below:

  • Refer the datasheet to know more about layout guidelines
  • Use toner transfer or your preferred method to make the pcb
  • Use a powerful microscope while applying solder flux and loading components
  • For the “reflow” process, use a toaster oven or similar device. If you are doing this for the first time, be very careful about the overall solder process

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