AD9806 查看數據表（PDF） - Analog Devices
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AD9806 Datasheet PDF : 12 Pages
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AD9806
APPLICATION INFORMATION
Grounding and Decoupling Recommendations
As shown in Figure 10, a single ground plane is recommended
for the AD9806. This ground plane should be as continuous as
possible, particularly around Pins 25 through 37. This will ensure
that all analog decoupling capacitors provide the lowest possible
impedance path between the power and bypass pins and their
respective ground pins. All decoupling capacitors should be
located as close as possible to the package pins. A single clean
power supply is recommended for the AD9806, but a separate
digital driver supply may be used for DRVDD (Pin 12). DRVDD
should always be decoupled to DRVSS (Pin 13), which should
be connected to the analog ground plane. The advantages of
using a separate digital driver supply include using a lower volt-
age (2.7 V) to match levels with a 2.7 V ASIC, reducing digital
power dissipation, and reducing potential noise coupling.
Using the AD9806 in AD9803 Sockets
The AD9806 may be easily used in existing AD9803 designs
without any circuit modifications. Most of the pin assignments
are the same for both ICs. Table I outlines the differences. The
circuit of Figure 10 shows the necessary connections for the
AD9806 when used in an existing AD9803 socket. If the two
auxiliary DACs are not used, then Pins 39 and 40 (DAC1 and
DAC2) may be grounded. If the AUX or ADC modes are needed,
then the input signal should be connected to either AUXIN or
ADCIN through a 0.1 µF capacitor, in the same way that
CCDIN is used with the input signal.
Table I. AD9806/AD9803 Pin Differences
Pin
No. AD9803
AD9806
Circuit Connection
1
NC
NC
Ground
15 ACLP
NC
Ground
24 NC
NC
Ground
25 CCDBYP2
CLPOUT Decoupled with 0.1 µF
to Ground
27 PIN
NC
Shorted to Pin 26
28 CCDBYP2
CLPREF
Decoupled with 0.1 µF
to Ground
29 PGABYP1
NC
Decoupled with 0.1 µF
to Ground
30 PGABYP2
NC
Shorted to Pin 29
35 AUXCONT AUXMID Ground, or decoupled
with 0.1 µF to Ground
38 VTRBYP
NC
Decoupled with 0.1 µF
to Ground
Using the AD9806 in New Designs
Figure 11 shows the recommended circuit for using the AD9806
in new designs. Three external decoupling capacitors have been
removed from the circuit shown in Figure 9, one from Pin 29,
one from Pin 38, and one from between Pins 47 and 48. Note
that the decoupling capacitors for Pins 47 (VRB) and 48 (VRT)
must be increased to 1.0 µF when used in this configuration.
0.1F
0.1F
1.0F
VDD
0.1F
SDATA
SCK
SL
0.1F
0.1F
VOUT2
VOUT1
48 47 46 45 44 43 42 41 40 39 38 37
DIGITAL
OUTPUT
DATA
1 NC
2 D0 (LSB)
3 D1
4 D2
5 D3
6 D4
7 D5
8 D6
9 D7
10 D8
11 D9 (MSB)
12 DRVDD
AD9806
ADCIN 36
AUXMID 35
AUXIN 34
ACVDD 33
CLPBYP 32
ACVSS 31
NC 30
NC 29
CLPREF 28
NC 27
DIN 26
CLPOUT 25
0.1F
0.1F
0.1F
0.1F
VDD
0.1F
CCD
SIGNAL
INPUT
VDD
13 14 15 16 17 18 19 20 21 22 23 24
0.1F
VDD
0.1F
NC = NO CONNECT
0.1F
CLPDM
SHD
SHP
CLPOB
PBLK
ADCCLK
Figure 10. CCD-Mode Circuit Configuration Used in AD9803 Socket
REV. 0
–11–
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