EVAL-AD5821EBZ Analog Devices Inc, EVAL-AD5821EBZ Datasheet - Page 12

• Manufacturer Part Number: EVAL-AD5821EBZ
• Description: BOARD EVALUATION FOR AD5821
• Manufacturer: Analog Devices Inc

Specifications of EVAL-AD5821EBZ

• Number Of Dac's: 1
• Number Of Bits: 10
• Outputs And Type: 1, Single Ended
• Sampling Rate (per Second): 400k
• Data Interface: I²C
• Settling Time: 250µs
• Dac Type: Current
• Voltage Supply Source: Single
• Operating Temperature: -30°C ~ 80°C
• Utilized Ic / Part: AD5821
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD5821
Table 6. Data Format
Serial Data-Words
Serial Data Bits
Input Register
Function
1
POWER SUPPLY BYPASSING AND GROUNDING
When accuracy is important in an application, it is beneficial to
consider power supply and ground return layout on the PCB.
The PCB for the AD5821 should have separate analog and digital
power supply sections. Where shared AGND and DGND is
necessary, the connection of grounds should be made at only
one point, as close as possible to the AD5821.
Special attention should be paid to the layout of the AGND return
path and, and it should be tracked between the voice coil motor
and I
output current sink of the AD5821 and illustrates the importance
of reducing the effective series impedance of AGND and the track
resistance between the motor and I
as Inductor L
is effectively a dc current that results in a voltage drop, V
the AD5821 is sinking current. The effect of any series inductance
is minimal.
SDA
SDA
SCL
SCL
XSHUTDOWN = soft power-down; X = unused/don’t care; and D9 to D0 = DAC data.
START BY
START BY
MASTER
MASTER
SINK
to minimize any series resistance. Figure 24 shows the
1
1
0
0
C
and Resistor R
0
0
ADDRESS BYTE
ADDRESS BYTE
0
0
SERIAL BUS
SERIAL BUS
High Byte
SD7
R15
XSHUTDOWN
1
FRAME 1
FRAME 1
1
1
C
. The current through the voice coil
1
1
1
1
SINK
SD6
R14
X
. The voice coil is modeled
1
1
R/W
R/W
ACK BY
AD5821
ACK BY
AD5821
SD5
R13
D9
9
9
PD
PD
1
1
SD4
R12
D8
X
X
C
, when
Figure 22. Write Operation
Figure 23. Read Operation
SD3
R11
D7
D9
D9
MOST SIGNIFICANT
MOST SIGNIFICANT
Rev. 0 | Page 12 of 16
DATA BYTE
DATA BYTE
D8
D8
FRAME 2
FRAME 2
SD2
R10
D6
D7
D7
D6
D6
SD1
R9
D5
XSHUTDOWN
D5
D5
SD0
R8
D4
D4
D4
DGND
Figure 24. Effect of PCB Trace Resistance and Inductance
SDA
SCL
ACK BY
ACK BY
AD5821
AD5821
Low Byte
SD7
R7
D3
1
1
DGND
V
D3
D3
DD
SD6
R6
D2
D2
D2
R
D1
D1
AD5821
SD5
R5
D1
LEAST SIGNIFICANT
LEAST SIGNIFICANT
R
D0
D0
SENSE
DATA BYTE
DATA BYTE
FRAME 3
FRAME 3
R
L
SD4
R4
D0
G
G
X
X
Q1
AGND
VOICE
COIL
X
X
GROUND
RETURN
SD3
R3
X
X
X
V
R
I
R
SINK
BATTERY
L
C
T
C
V
SD2
R2
X
DROP
X
X
ACK BY
AD5821
ACK BY
AD5821
TRACE
RESISTANCE
9
9
V
SD1
R1
X
COIL
STOP BY
STOP BY
MASTER
MASTER
R0
SD0
X