Design of an H Bridge
Figures 8 and 9 show the finished layout and figure 10 shows the
assembly drawing. I like to work with surface mount components and all
components except for the pin header are surface mount. The layout was
done as a two layer board where most of the components are on the top
layer and most of the bottom layer is a solid ground plane. Extensive
gate and pin swapping was performed to simplify the layout and
minimize the amount of tracks that would have to be placed on the
bottom side and disrupt the ground plane. The pinout of the connector
was also chosen to ease layout, but with signal and power integrity in
Figure 8. The layout of the top and bottom layers.
(Click to enlarge.)
The layout of the dual H bridge as a PDF.
Figure 9. A 3D rendering of the H bridge PCBA.
(Click image to enlarge.)
Figure 10. The top assembly drawing.
The assembly drawing of the dual H bridge as a
I think the layout turned out all right as it is compact and pretty
much limited by the size of the connector and the area of the
components. It is good for EMC (electromagnetic compatibility, i.e.
the ability to not disturb and not be disturbed through
electromagnetic fields) that the ground plane is kept quite solid. The
components that were chosen are all relatively thin (U2 is thickest at
about 2.7 mm maximum) so several boards can be stacked tightly
The layout could however be made more compact if it were necessary.
0402 components could be chosen instead of 0603 and SC70/SOT323
packages might be available instead of the SOT23 packages that were
used. U1 and U2 may also be available in smaller packages. I did
however want to keep this design easy to assemble even without a
microscope and that took priority over shrinking it further.
© Per Magnusson, Axotron