Texas Instruments TPS40345EVM-353, User Manual, Page: 13 / 23

Vin = 14V, Vout = 1.2 V, Iout = 20 A
Output Ripple
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TPS40345EVM-353 Test Data
13 SNVU588 – November 2017
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TPS40345EVM-353 Evaluation Module
6.6 Additional Waveforms
6.6.1 Output Ripple With Frequency Spread Spectrum (FSS) Enabled
FSS varies the output switching frequency. This change in switching frequency can produce a small
change in the output voltage at the modulation frequency.
Figure 10 shows the approximately 10-mV
modulation of the output voltage generated when FSS is enabled.
Figure 10. TPS40345EVM-353 Output Ripple With FSS Enabled
7 TPS40345EVM-353 Assembly Drawings and Layout
The following figures ( Figure 11 through Figure 16 ) show the design of the TPS40345EVM-353 printed
circuit board. The EVM has been designed using a 4-layer, 2-oz. copper-clad circuit board 3-inch × 3-inch
with all components on the top to allow the user to easily view, probe, and evaluate the
TPSxxxxx control
IC in a practical double-sided application. Moving components to both sides of the PCB or using additional
internal layers can offer additional size reduction for space constrained systems.