TPS54328_15 Datasheet, PDF (14/27 Pages) Texas Instruments – 4.5V to 18V Input, 3-A Synchronous Step-Down Converter with Eco-mode™

TPS54328
SLVSAN2C – NOVEMBER 2010 – REVISED NOVEMBER 2012
www.ti.com
LAYOUT CONSIDERATIONS
1. Keep the input switching current loop as small as possible.
2. Keep the SW node as physically small and short as possible to minimize parasitic capacitance and
inductance and to minimize radiated emissions. Kelvin connections should be brought from the output to the
feedback pin of the device.
3. Keep analog and non-switching components away from switching components.
4. Make a single point connection from the signal ground to power ground.
5. Do not allow switching current to flow under the device.
6. Keep the pattern lines for VIN and PGND broad.
7. Exposed pad of device must be connected to PGND with solder.
8. VREG5 capacitor should be placed near the device, and connected PGND.
9. Output capacitor should be connected to a broad pattern of the PGND.
10. Voltage feedback loop should be as short as possible, and preferably with ground shield.
11. Lower resistor of the voltage divider which is connected to the VFB pin should be tied to SGND.
12. Providing sufficient via is preferable for VIN, SW and PGND connection.
13. PCB pattern for VIN, SW, and PGND should be as broad as possible.
14. VIN Capacitor should be placed as near as possible to the device.
FEEDBACK
RESISTORS
TO ENABLE
CONTROL
BIAS
CAP
SLOW
START
CAP
EN
VFB
VREG5
SS
Connection to
POWER GROUND
on internal or
bottom layer
ANALOG
GROUND
TRACE
VIN
VIN
INPUT
BYPASS
CAPACITOR
VIN
HIGH FREQENCY
BYPASS
CAPACITOR
VIN
VBST
SW
GND
BOOST
CAPACITOR
OUTPUT _VOUT
INDUCTOR
EXPOSED
THERMAL PAD
AREA
OUTPUT
FILTER
CAPACITOR
POWER GROUND
VIA to Ground Plane
Figure 17. PCB Layout
14
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