EVAL-CN0188-SDPZ Analog Devices Inc, EVAL-CN0188-SDPZ Datasheet - Page 3

• Manufacturer Part Number: EVAL-CN0188-SDPZ
• Description: BOARD, EVAL, FOR CN0188
• Manufacturer: Analog Devices Inc
• Series: -r

Specifications of EVAL-CN0188-SDPZ

• Rohs Compliant: YES
• Svhc: No SVHC (15-Dec-2010)
• Main Purpose: Power Management, Current Monitor
• Embedded: No
• Utilized Ic / Part: ADA4051-2, ADR381, ADUM5402, AD7171
• Primary Attributes: -
• Secondary Attributes: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Circuit Note
PCB Layout Considerations
In any circuit where accuracy is crucial, it is important to
consider the power supply and ground return layout on the
board. The PCB should isolate the digital and analog sections as
much as possible. This PCB was constructed in a four layer
stack up with large area ground plane layers and power plane
polygons. See the
layout and grounding and the
on decoupling techniques.
The power supply to the
decoupled with 10 µF and 0.1 µF capacitors to properly suppress
noise and reduce ripple. The capacitors should be placed as
close to the device as possible with the 0.1 µF capacitor having a
low ESR value. Ceramic capacitors are advised for all high
frequency decoupling.
Care should be taken in considering the isolation gap between
the primary and secondary sides of the ADuM5402. The
EVAL-CN0188-SDPZ board maximizes this distance by pulling
back any polygons or components on the top layer and aligning
them with the pins on the ADuM5402.
Power supply lines should have as large a trace width as possible
to provide low impedance paths and reduce glitch effects on the
Figure 3. Alternate Galvanically Isolated Negative Rail Current Sense Circuit Powered Directly from −48 V Source and ADuM5402 Isolator (All Connections and Decoupling Not Shown)
−48V
GND
−
+
ISO
SOURCE
MT-031 Tutorial
AD7171
R1*
1.24MΩ
1%
R2
1kΩ
1%
–
MT-101 Tutorial
R
V
SHUNT
SHUNT
and
for more discussion on
ADuM5402
+
I
LOAD
R4
1kΩ
1%
ADA4051-1
U1:
for information
48.7kΩ, 1%
should be
R3*
U1
LOAD
ADR381
GND
+3.3V
ISO
GND
VIN
Rev. A | Page 3 of 5
ISO
*R1 ADDS 100mV OFFSET TO U1 OUTPUT
AND ALLOWS MEASUREMENT AT ZERO LOAD CURRENT.
IF R1 IS USED, REDUCE R3 TO 46.4kΩ TO MAINTAIN 2.5V FULL-SCALE
GND
VOUT
ISO
AIN+
AIN−
supply line. Clocks and other fast switching digital signals
should be shielded from other parts of the board by digital
ground.
A complete design support package for this circuit note,
including board layouts, can be found at
http://www.analog.com/CN0188-DesignSupport.
COMMON VARIATIONS
There are a number of solutions available for high-side sensing
of positive sources. IC solutions using current sense amplifiers,
difference amplifiers, or a combination of these are available.
“High-Side Current Sensing: Difference Amplifier vs, Current-
Sense Amplifier,” Analog Dialogue, January
use of current sense and difference amplifiers. The article is
available at
The following URLs link to Analog Devices products which are
useful in solving the current sense problem:
Current sense amplifiers:
Difference amplifiers:
Instrumentation amplifiers:
REFIN(+)
REFIN(–)
AD7171
+2.5V
GND
GND
VDD
www.analog.com/HighSide_CurrentSensing.
ISO
PDRST
DOUT
SCLK
+3.3V
ISO
www.analog.com/DifferenceAmps
www.analog.com/CurrentSenseAmps
www.analog.com/InstrumentationAmps
GND
V
V
V
GND
V
OA
OB
IC
ISO
ADuM5402
ISO
ISO
GND
GND
V
V
DD1
V
V
OC
IA
IB
2008, describes the
1
1
+3.3V
CN-0188