5962-0924001VXC Datasheet, PDF (39/46 Pages) Texas Instruments – 12-Bit, 1-GSPS Analog-to-Digital Converter

ADS5400-SP
www.ti.com
SLAS669C – SEPTEMBER 2010 – REVISED AUGUST 2012
Power Supplies
The ADS5400 uses three power supplies. For the analog portion of the design, a 5-V and 3.3-V supply (AVDD5
and AVDD3) are used, while the digital portion uses a 3.3-V supply (DVDD3). The use of low-noise power
supplies with adequate decoupling is recommended. Linear supplies are preferred to switched supplies; switched
supplies generate more noise components that can be coupled to the ADS5400. The PSRR value and the plot
shown in Figure 38 were obtained without bulk supply decoupling capacitors. When bulk (0.1 μF) decoupling
capacitors are used, the board-level PSRR is much higher than the stated value for the ADC. The power
consumption of the ADS5400 does not change substantially over clock rate or input frequency as a result of the
architecture and process.
100
90
80
DVDD3
70
60
50
40
AVDD5
30
20
AVDD3
10
0
0.01
0.1
1
10
Frequency − MHz
100
G022
Figure 38. PSRR versus Supply Injected Frequency
Copyright © 2010–2012, Texas Instruments Incorporated
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