Datasheet

0.01
0.1
1
10
10 100 1000 10000 100000 1000000 10000000
f - Frequency - Hz
Output Spectral Noise Density ( V/SQRT(Hz))m
V = 12 V, V = 3.3 V,
C = 100 F, C = 0.1 F,
I = 400 mA, F = 480 kHz,
L1 = 22 H
IN OUT
OUT NR
OUT SW
m m
m
www.ti.com Test Results
4.1 Output Voltage Ripple
Figure 1 shows the output voltage ripple of the LDO and SWITCHER converter for the TPS54120EVM
with Vin = 12V, SW OUT = 4.1V, LDO OUT = 3.3V, Iout = 400mA, Fswitching = 480kHz.
Figure 1. Output Voltage of Both the SW and LDO with 400mA Load
4.2 Output Noise
Figure 2 shows the output voltage noise spectrum for the TPS54120EVM with Vin = 12V, LDO OUT =
3.3V, SW OUT = 4.1V, Iout = 400mA, Fswitching = 480kHz.
Figure 2. Output Spectrum Noise Density vs. Frequency
5
SLVU641– January 2012 TPS54120EVM, Low Noise 1A Power Supply Evaluation Module
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