ADA4051-2_VB AD [Analog Devices], ADA4051-2_VB Datasheet - Page 4
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ADA4051-2_VB
Manufacturer Part Number
ADA4051-2_VB
Description
Low Cost, Level Shifted Low Side Current Monitor for Negative High Voltage Rails
Manufacturer
AD [Analog Devices]
Datasheet
1.ADA4051-2_VB.pdf
(5 pages)
Figure 3 shows an alternate circuit which can be used when
galvanic isolation is required. The "ground" for the entire circuit
is connected to the −48 V source. The isolated +3.3 V from the
ADuM5402
configuration does not require the op amp/MOSFET level
shifter (see Figure 1) because the level shifting function is
accomplished by the
ground reference (GND1) to be established for the digital
signals.
A single zero-drift
shunt voltage. Resistor R1 provides a positive offset voltage of
100 mV at the op amp output that allows the circuit to operate
down to zero load current. If this offset is added, then R3
should be reduced to 46.4 kΩ to maintain a full-scale ADC
input voltage of 2.5 V for a 50 mV shunt voltage. Without the
offset, the
voltages less than about 40 mV.
CIRCUIT EVALUATION AND TEST
This circuit uses the EVAL-CN0188-SDPZ circuit board and
the EVAL-SDP-CB1Z System Demonstration Platform (SDP)
evaluation board. The two boards have 120-pin mating
connectors, allowing for the quick setup and evaluation of the
circuit’s performance. The EVAL-CN0188-SDPZ board
contains the circuit to be evaluated, as described in this note,
and the SDP evaluation board is used with the CN0188
evaluation software to capture the data from the
EVAL-CN0188-SDPZ circuit board.
Equipment Needed
• PC with a USB port and Windows® XP or Windows Vista®
• EVAL-CN0188-SDPZ circuit evaluation board
• EVAL-SDP-CB1Z SDP evaluation board
• CN0188 evaluation software
• Power supply: +6 V, or +6 V “wall wart”
• Shunt resistor with maximum voltage of 50 mV at the
• Electronic load
Getting Started
Load the evaluation software by placing the CN0188 evaluation
software disc in the CD drive of the PC. Using "My Computer,"
locate the drive that contains the evaluation software disc and
open the Readme file. Follow the instructions contained in the
Readme file for installing and using the evaluation software.
Functional Block Diagram
See Figure 1 of this circuit note for the circuit block diagram
and the “EVAL-CN0188-SDPZ-SCH” pdf file for the circuit
CN-0188
(32-bit), or Windows® 7 (32-bit)
maximum load current.
ADA4051-1
is used to power the circuit. Note that this
ADA4051-1
ADuM5402
output will become nonlinear for output
provides a gain of 49.7 to the
isolator which allows a new
Rev. B | Page 4 of 5
schematics. This file is contained in the
Support Package.
Setup
Connect the 120-pin connector on the EVAL-CN0188-SDPZ
circuit board to the connector marked “CON A” on the
EVAL-SDP-CB1Z evaluation (SDP) board. Nylon hardware
should be used to firmly secure the two boards, using the holes
provided at the ends of the 120-pin connectors.
Connect a shunt resistor across the input terminals (R
with a load to ground as indicated in Figure 1. With power to
the supply off, connect a +6 V power supply to the pins marked
“+6 V” and “GND” on the board. If available, a +6 V "wall wart"
can be connected to the barrel connector on the board and used
in place of the +6 V power supply. Connect the USB cable
supplied with the SDP board to the USB port on the PC.
Note: Do not connect the USB cable to the mini USB connector
on the SDP board at this time.
It is important to connect the system ground and the PCB
isolated ground to guarantee correct voltage levels and
operation. Test point 31 and test point 32 give access to the
GND_ISO required to properly make this connection.
Test
Apply power to the +6 V supply (or “wall wart”) connected to
the EVAL-CN0188-SDPZ circuit board. Launch the evaluation
software and connect the USB cable from the PC to the USB
mini-connector on the SDP board.
Once USB communications are established, the SDP board
can be used to send, receive, and capture serial data from the
EVAL-CN0188-SDPZ board. Data can be recorded for various
values of load current as the electronic load is stepped.
Information and details regarding how to use the evaluation
software for data capture can be found in the CN0188
evaluation software Readme file.
Information regarding the SDP board can be found in the
SDP User
LEARN MORE
CN0188 Design Support Package:
Sino, Henri. “High-Side Current Sensing: Difference Amplifier
Cantrell, Mark. Application Note AN-0971, Recommendations
http://www.analog.com/CN0188-DesignSupport
vs.Current-Sense Amplifier, ” Analog Dialogue 42-01,
January (2008).
for Control of Radiated Emissions with isoPower Devices.
Analog Devices.
Guide.
CN0188 Design
Circuit Note
SHUNT
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