Layout considerations

ST1S10

14/26

6

Layout considerations

Layout is an important step in design for all switching power supplies.

High-speed operation (900 kHz) of the ST1S10 device demands careful attention to PCB

layout. Care must be taken in board layout to get device performance, otherwise the

regulator could show poor line and load regulation, stability issues as well as EMI problems.

It is critical to provide a low inductance, impedance ground path. Therefore, use wide and

short traces for the main current paths.

The input capacitor must be placed as close as possible to the IC pins as well as the

inductor and output capacitor. Use a common ground node for power ground and a different

one for control ground (AGND) to minimize the effects of ground noise. Connect these

ground nodes together underneath the device and make sure that small signal components

routed away from noisy components and traces (e.g., SW line). Its trace should be

minimized and shielded by a guard-ring connected to the ground.

Figure 6.

PCB layout suggestion

V

Input capacitor C1 must be placed

as close as possible to the IC

pins as well as the inductor L1

and output capacitor C2

Vias from thermal pad

to bottom layer

47mm

CN1=Input power supply

CN2=Enable/Disable

CN3=Input sync.

CN4=V

OUT

V

Input capacitor C1 must be placed

as close as possible to the IC

pins as well as the inductor L1

and output capacitor C2

Vias from thermal pad

to bottom layer

47mm

CN1=Input power supply

CN2=Enable/Disable

CN3=Input sync.

CN4=V

OUT