Datasheet

AVDD
DVDD
CHSEL
SCLK
SDO
CS
4 3 2 1
5
6
7
8
9 10 11 12
16
15
14
13
PDEN
NC
GND REF REFGND
AIN0P
AIN1P
AIN0N
AIN1N
NC
470pF
C
2
470pF
C
1
5 W
DifferentialInput Signals
1 Fm
C
3
Common Analog/
DigitalGroundPlane
Reference
Input
Analog
Supply
1 Fm
C
4
47 W
R
1
0.1 Fm
C
5
1 Fm
C
6
Digital
Supply
DigitalSignalsfromHost
ADS7945
U0
5 W
5 W
5 W
ADS7945
ADS7946
www.ti.com SBAS539B –JUNE 2011– REVISED SEPTEMBER 2011
PCB LAYOUT/SCHEMATIC GUIDELINES: ADS7945
The ADS7945 is a mixed-signal device. For maximum performance, proper decoupling, grounding, and proper
termination of digital signals are essential. Figure 90 shows the essential components around the ADC. All
capacitors shown are ceramic. These decoupling capacitors must be placed close to the respective signal pins.
There is a 47 Ω source series termination resistor shown on the SDO signal. This resistor must be placed as
close to pin 15 as possible. Series terminations for SCLK and CS must be placed close to the host.
Figure 90. Recommended ADS7945 ADC Schematic
Copyright © 2011, Texas Instruments Incorporated Submit Documentation Feedback 39
Product Folder Link(s): ADS7945 ADS7946