Output Voltage Calculation

flux

The output voltage for a buck converter using a resistor divider is given by:
Vout=VFB(1+R1R2)\Large V_{\text{out}} = V_{\text{FB}}\left(1 + \frac{R_1}{R_2}\right)
For the TPS5430DDA, the typical feedback reference voltage, ( V_{\text{FB}} ), is 0.8 V.
With the resistor values provided:
  • ( R_1 = 33,kΩ )
  • ( R_2 = 10,kΩ )
the calculation is:
Vout=0.8 V(1+33 kΩ10 kΩ)=0.8 V×(1+3.3)=0.8 V×4.3=3.44 V\Large V_{\text{out}} = 0.8\,V \left(1 + \frac{33\,kΩ}{10\,kΩ}\right) = 0.8\,V \times (1 + 3.3) = 0.8\,V \times 4.3 = 3.44\,V
Thus, using the current resistor divider, the output voltage is approximately 3.44 V.
Note:
To obtain a 5 V output, you would need to adjust the resistor values. For example, if ( V_{\text{out}} = 5,V ) is desired with ( V_{\text{FB}} = 0.8,V ), then:
5 V=0.8 V(1+R1R2)⟹R1R2=50.8−1=6.25−1=5.25\Large 5\,V = 0.8\,V\left(1+\frac{R_1}{R_2}\right) \quad \Longrightarrow \quad \frac{R_1}{R_2} = \frac{5}{0.8} - 1 = 6.25 - 1 = 5.25
If you set ( R_2 = 10,kΩ ), then ideally:
R1=5.25×10 kΩ=52.5 kΩ\Large R_1 = 5.25 \times 10\,kΩ = 52.5\,kΩ
You may choose the nearest standard resistor value (e.g., 51 kΩ or 56 kΩ) and recalculate to fine-tune the output voltage.
toastedsteve

toastedsteve

is this capable of 5A output

flux

The TPS5430DDA is typically rated for an output current around 3A. This means that as configured, it is not capable of supporting a continuous 5A load.
For a 5A output, you would need to select a buck converter that is specified to handle currents in excess of 5A or consider paralleling appropriate devices designed for such loads.
Let me know if you need recommendations for alternative components or additional design adjustments.
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    This project involves designing a DC-DC buck converter circuit to efficiently step down a 12V input voltage to a stable 5V output voltage. The converter is suitable for various electronic applications requiring 5V DC supply from a 12V source.

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