Datasheet

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SBAS274H − MARCH 2003 − REVISED MAY 2007
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26
POWER SUPPLIES
Three supplies are used on the ADS1605/6: analog
(AVDD), digital (DVDD) and digital I/O (IOVDD). Each
supply must be suitably bypassed to achieve the best
performance. It is recommended that a 1µF and 0.1µF
ceramic capacitor be placed as close to each supply pin
as possible. Connect each supply-pin bypass capacitor
to the associated ground, as shown in Figure 27. Each
main supply bus should also be bypassed with a bank
of capacitors from 47µF to 0.1µF, as shown.
The IO and digital supplies (IOVDD and DVDD) can be
connected together when using the same voltage. In
this case, only one bank of 47µF to 0.1µF capacitors is
needed on the main supply bus, though each supply pin
must still be bypassed with a 1µF and 0.1µF ceramic ca-
pacitor.
C
P
C
P
C
P
C
P
C
P
C
P
C
P
C
P
1
2
3
9
10
11
12
18
58 57 55 54 53 52 51
19 25 26
AVDD
AVDD
AGND
AGND
C
P
6
7
AVDD
AGND
AGND
AVDD
47
µ
F
47
µ
F
47
µ
F4.7
µ
F1
µ
F0.1
µ
F
0.1
µ
F
0.1
µ
F
1
µ
F
1
µ
F
4.7
µ
F
4.7
µ
F
DVDD AVDD
AGND AGND
DGND
IOVDD
DVDD
DGND
DGND DGND DVDD
ADS1605
ADS1606
If using separate analog and
digital ground planes, connect
together on the ADS1605/6 PCB.
DGND
NOTE: C
P
=1
µ
F

0.1
µ
F
AGND
AVDD
IOVDD
DVDD
Figure 27. Recommended Power-Supply Bypassing