Datasheet

Application information ST1S41
20/27 DocID023654 Rev 2
The input capacitor connected to VINSW must be placed as close as possible to the device,
to avoid spikes on VINSW due to the stray inductance and the pulsed input current.
In order to prevent dynamic unbalance between VINSW and VINA, the trace connecting the
VINA pin to the input must be derived from VINSW.
The feedback pin (FB) connection to the external resistor divider is a high impedance node,
so the interference can be minimized routing the feedback node with a very short trace and
as far as possible from the high current paths.
A single point connection from signal ground to power ground is suggested.
Thanks to the exposed pad of the device, the ground plane helps to reduce the thermal
resistance junction-to-ambient; so a large ground plane, soldered to the exposed pad,
enhances the thermal performance of the converter allowing high power conversion.
Figure 8. Suggested PCB layout
Input cap as close as possible
to VINSW pin
Star center for common ground
Short FB trace
VINA derived from Cin
to avoid dynamic voltage drop
between VINA and VINSW
Short high switching
current loop
Via to connect the thermal pad
To bottom or inner ground plane
AM15065v1