AD5755 Analog Devices, AD5755 Datasheet - Page 48

• Manufacturer Part Number: AD5755
• Description: Quad Channel, 16-Bit, Serial Input,
• Manufacturer: Analog Devices

Specifications of AD5755

• Resolution (bits): 16bit
• Dac Update Rate: 91kSPS
• Dac Settling Time: 11µs
• Max Pos Supply (v): +33V
• Single-supply: No
• Dac Type: I or V Out
• Dac Input Format: SPI

AD5755
separate ground plane, but separating the lines helps). It is
essential to minimize noise on the REFIN line because it
couples through to the DAC output.
Avoid crossover of digital and analog signals. Traces on
opposite sides of the board should run at right angles to each
other. This reduces the effects of feedthrough on the board. A
microstrip technique is by far the best but not always possible
with a double-sided board. In this technique, the component
side of the board is dedicated to ground plane, whereas signal
traces are placed on the solder side.
Layout—DC-to-DC Converters
To achieve high efficiency, good regulation, and stability, a well-
designed printed circuit board layout is required.
Follow these guidelines when designing printed circuit boards
(see Figure 78):
•
•
•
•
Keep the low ESR input capacitor, C
PGND.
Keep the high current path from C
L
Keep the high current path from C
rectifier, D
possible.
Keep high current traces as short and as wide as possible.
The path from C
PGND should be able to handle a minimum of 1 A.
DCDC
, to SW
DCDC
X
and PGND as short as possible.
, and the output capacitor, C
IN
through the inductor, L
IN
IN
IN
through the inductor,
through L
, close to AV
DCDC
DCDC
, to SW
DCDC
, as short as
CC
, the
and
X
and
Rev. A | Page 48 of 52
•
•
GALVANICALLY ISOLATED INTERFACE
In many process control applications, it is necessary to provide
an isolation barrier between the controller and the unit being
controlled to protect and isolate the controlling circuitry from
any hazardous common-mode voltages that may occur. The
Analog Devices iCoupler® products can provide voltage isolation
in excess of 2.5 kV. The serial loading structure of the AD5755
makes it ideal for isolated interfaces because the number of
interface lines is kept to a minimum. Figure 86 shows a 4-
channel isolated interface to the AD5755 using an ADuM1400.
For more information, visit www.analog.com.
*ADDITIONAL PINS OMITTED FOR CLARITY.
MICROCONTROLLER
Place the compensation components as close as possible to
COMP
Avoid routing high impedance traces near any node
connected to SW
noise injection.
SERIAL CLOCK
CONTROL OUT
SERIAL DATA
SYNC OUT
DCDC_x
OUT
OUT
.
V
V
V
V
ADuM1400*
IA
IB
IC
ID
Figure 86. Isolated Interface
x
or near the inductor to prevent radiated
ENCODE
ENCODE
ENCODE
ENCODE
DECODE
DECODE
DECODE
DECODE
Data Sheet
V
V
V
V
OA
OB
OC
OD
TO SCLK
TO SDIN
TO SYNC
TO LDAC