
REV. 0
AD9824
–21–
Internal Power-On Reset Circuitry
After power-on, the AD9824 will automatically reset all internal
registers and perform internal calibration procedures. This takes
approximately 1 ms to complete. During this time, normal
clock signals and serial write operations may occur. However,
serial register writes will be ignored until the internal reset opera-
tion is completed.
Grounding and Decoupling Recommendations
As shown in Figure 33, a single ground plane is recommended
for the AD9824. This ground plane should be as continuous as
possible, particularly around Pins 25 through 39. 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 AD9824, but a separate
digital driver supply may be used for DRVDD (Pin 13). DRVDD
should always be decoupled to DRVSS (Pin 14), which should
be connected to the analog ground plane. Advantages of using
a separate digital driver supply include using a lower voltage
(2.7 V) to match levels with a 2.7 V ASIC, and reducing digital
power dissipation and potential noise coupling. If the digital
outputs (Pins 1–12) must drive a load larger than 20 pF, buff-
ering is recommended to reduce digital code transition noise.
Alternatively, placing series resistors close to the digital out-
put pins may also help reduce noise.
36
35
34
33
32
31
30
29
28
27
26
25
13 14 15 16 17 18 19 20 21 22 23 24
1
2
3
4
5
6
7
8
9
10
11
12
37
48 47 46 45 44
39 38
43 42 41 40
PIN 1
IDENTIFIER
TOP VIEW
(Not to Scale)
AUX1IN
AVSS
AUX2IN
AVDD2
BYP3
NC
CCDIN
BYP2
BYP1
AVDD1
AVSS
D2
D3
D4
D5
D6
D7
D8
D9
D10
(MSB) D13
AD9824
D1
D0
(LSB)
SCK
SDATA
SL
STBY
DVSS
DVDD2
VRB
VRT
NC
DRVDD
DRVSS
DVSS
DATACLK
DVDD1
HD
PBLK
CLPOB
SHP
SHD
CLPDM
VD
0.1 F
3V
ANALOG SUPPLY
CCD SIGNAL
3V
ANALOG SUPPLY
14
DATA
OUTPUTS
3
SERIAL
INTERFACE
1.0 F
0.1 F
3V
ANALOG SUPPLY
8
CLOCK
INPUTS
0.1 F
3V
ANALOG SUPPLY
3V
DRIVER
SUPPLY
NC = NO CONNECT
D11
D12
NC
Figure 33. Recommended Circuit Configuration for CCD-Mode