“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.
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.
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.
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.
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
