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10 µF
1 µF
+VBD
1 µF
1 µF
+VA
+VA
R
EF
P
Pin 1
SPI
GPIO
GPIO
Analog Ground
Analog Inputs
Analog Inputs
52
ADS7950, ADS7951, ADS7952, ADS7953, ADS7954, ADS7955
ADS7956, ADS7957, ADS7958, ADS7959, ADS7960, ADS7961
SLAS605C – JUNE 2008 – REVISED JULY 2018
Product Folder Links:
ADS7950 ADS7951 ADS7952 ADS7953 ADS7954 ADS7955 ADS7956 ADS7957 ADS7958
Copyright © 2008–2018, Texas Instruments Incorporated
11 Layout
11.1 Layout Guidelines
•
A copper fill area underneath the device ties the AGND, BDGND, AINM, and REFM pins together. This
copper fill area must also be connected to the analog ground plane of the PCB using at least four vias.
•
The power sources must be clean and properly decoupled by placing a capacitor close to each of the three
supply pins, as shown in
and
. To minimize ground inductance, ensure that each
capacitor ground pin is connected to a grounding via by a very short and thick trace.
•
The REFP pin requires a 10-
μ
F ceramic capacitor to meet performance specifications. Place the capacitor
directly next to the device. This capacitor ground pin must be routed to the REFM pin by a very short trace,
as shown in
and
.
•
Do not place any vias between a capacitor pin and a device pin.
NOTE
The full-power bandwidth of the converter makes the ADC sensitive to high frequencies in
digital lines. Organize components in the PCB by keeping digital lines apart from the
analog signal paths. This design configuration is critical to minimize crosstalk. For
example, in
, input drivers are expected to be on the left of the converter and the
microcontroller on the right.
11.2 Layout Examples
Figure 69. Recommended Layout for the TSSOP Packaged Device