ZXCT1051EV1 User Guide Issue 4

ZXCT1051 EV1
ZXCT1051EV1 EVALUATION BOARD USER GUIDE
DESCRIPTION
The ZXCT1051EV1 is intended for the evaluation of the
ZXCT1051 device. The ZXCT1051 is a current monitor
providing a fixed voltage gain of 10. The device is
suitable for high side or low side sensing.
The device produces a voltage output proportional to the
current sampled by a small inline sensing resistor, Rsense.
The voltage output is scaled by the choice of Rsense.
As delivered the board is set up to provide an out put of
1.5V from a current of 1.5A using a 100 mΩ sampling
resistor.
FEATURES
•
Supply Range 4.2 to 40V for 1.5V output.
•
Selectable current measurement range
•
0 to (Vcc-2)V input Voltage
•
5 Pin SOT23-5 package
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There is a second (20mΩ) resistor that can be selected
by means of a solder link and provides an output of
1.5V for a load current of 7.5A.
Additionally provision is made for a wire ended
sampling resistor of the users choice.
The printed circuit board is common to other devices in
the ZXCT family. For the ZXCT1051, the FLAG pin is
not used.
APPLICATIONS
•
Battery Charging
•
Power Supplies
•
Over Current Monitoring
•
Short circuit detection
•
DC motor control
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ORDERING INFORMATION
ORDER NUMBER
ZXCT1051EV1
Please note evaluation boards are subject to availability and qualified leads.
PAD NAMES AND DEFINITIONS
.
NAME
DESCRIPTION
V1
Supply Voltage
V2
Connection to Load
VOUT
Output Voltage
FLAG
Not used
GND
0V / Ground
SL1,SL2
Solder Links
Vcc
Supply for the output buffer
The ZXCT1051EV1 is configured with SL1 shorted, which gives an output of 1.5V for a 1.5A current flow.
The input voltage range for the ZXCT1051EV1 is 20V, down to a minimum of (2.7V +Vout). For example, if the
required full scale output voltage is 1.5 V the input range is 4.2V to 20V.
The input Voltage for the output buffer must be between 2.7V and 20V.
Target applications are battery chargers, power supply units and other applications where current measurement is a
requirement.
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ZXCT1051 EV1
ZXCT1051EV1 Schematics
R3
SL1
R1
Vsupply
V1
100m
R2
SL2
V2
20m
Vsense+
VsenseLoad
Vcc
ZXCT1051
GND
Vout
Vout
High Side Sense Configuration.
GND
Sense resistor
The board has been designed with two selectable values of sense resistor. The value of the sense resistor can be
chosen by using the solder links SL1 and SL2.
The board is also tracked for a user defined through hole resistor (R3).
The 100mΩ resistor (R1) is selected by shorting SL1 and opening SL2. This results in an output of 1.5V for a load
current of 1.5A (assuming that R3 is not fitted).
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The 20mΩ resistor (R2) is selected by shorting SL2 and opening SL1, resulting in an output of 1.5V for a load current
of 7.5A (assuming that R3 is not fitted).
If both links are shorted the effective resistance is 33.33mΩ giving an output of 1.5V for a current of 9A (assuming
that R3 is not fitted).
If both links are open only the optional leaded resistor R3 (if fitted) is in circuit.
The maximum power dissipation rating of the resistor must be appropriate to the load current level.
N.B. The board is set by default with SL1 shorted and SL2 open, using the 100mΩ
Ω resistor.
For further information on choosing a value of sense resistor please refer to the ZXCT1051 datasheet.
Vout
If the preset selectable values of sense resistor are chosen, the device will produce 1.5V for a 1.5A load current or
1.5V for a 7.5A load current, depending on which link is closed. The output is directly proportional to the differential
voltage across the sense pins of the device.
Configuration table for ZXCT1081EV1
LOAD CURRENT
(A)
Rsense
(mΩ
Ω)
VOUT
(V)
SOLDER LINK
CONFIGURATION
1.5
100
1.5
Short SL1
7.5
20
1.5
Short SL2
9.0
16.67
1.5
Short SL1 & SL2
Vcc
The Vcc pin is the supply for Vout buffer and may be between 2.7V and 20V.
Configuring for High Side or Low Side Measurements.
As delivered the board is configured for Low side measurements and SL3 is closed. To configure for High side
measurements, open SL3. The connections for each case are shown in the diagrams above.
Configuration for different LOAD currents.
The board can be configured for different load currents by changing the smd resistors or fitting a suitable wire ended
resistor and opening both solder links. It is important to ensure an appropriate value of Rsense is selected to obtain the
desired accuracy for a given output current.
The value of Vout is 10 times the voltage dropped across the sensing resistor, (providing that the voltage on V1 is
more than 2.7V higher than the Vout.).
Choosing a larger value for Rsense gives a higher output voltage for a given current resulting in better resolution but at
the expense of increased voltage drop and higher dissipation in Rsense
The ZXCT1051 is optimized for values of Vsense between 0 and 150mV but may be used up to 800mV.
Example: Scaling for 1.5A load current and a 500mV output.
The ZXCT1051 has a fixed gain of 10. Vout = 10 x Vsense
To obtain a 500mV output, 50mV is required between Vsense+ and Vsense-.
The value for Rsense is thus 50mV /1.5A = 33mΩ.
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Accuracy
1
The ZXCT1051 current monitor IC is a 2% accurate device. The accuracy of the output voltage will be influenced by
the tolerance of the external sense used. The ZXCT1051EV1 utilizes 1% accurate sense resistors.
1
Total error at +100mV sense voltage
COMPONENTS LIST
Ref
Value
Package
Part Number
Manufacturer
R1
100mΩ
1206
LR1206-R10FI
R2
20mΩ
2512
LRF2512-R020FW
Welwyn
Welwyn
SOT235
ZXCT1051E5
ZETEX
ZXCT
Notes
SMD Sense Resistor 1%
SMD Sense Resistor 1%
SET-UP AND TEST
The board is preset to give an output Voltage of 1.5V for a load current of 1.5A (SL1 is shorted to connect in
the 100mΩ
Ω (R1) sense resistor). The default configuration is ‘low side sense’. To change the board to give an
output Voltage of 1.5V for a current of 7.5A, de-solder SL1 and short SL2. This connects the 20mΩ
Ω (R2) sense
resistor.
1.5 Ampere load test (low side sense)
1.
2.
3.
4.
5.
Ensure SL2 and SL3 are shorted.
Connect a 10Ω load capable of dissipating at least 15W between a linear 15V PSU and V1.
Connect a linear power supply of +5V between the Vcc and GND terminals.
Check with a DVM the supply voltage is +15V between the V1 and GND terminals.
Measure VOUT with a DVM. The nominal output voltage should read 1.5V.
The device may also be evaluated with lower power loads and lower currents by increasing the value of
Rsense. As the device reacts only to the voltage across this resistor such tests are equally valid.
CONNECTION DIAGRAM
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1.5 Ampere load test (high side sense)
6.
7.
8.
9.
10.
11.
Ensure SL2 is shorted and SL3 is open.
Connect a 10Ω load capable of dissipating at least 15W between V2 and GND.
Connect a linear power supply of +5V between the Vcc and GND terminals.
Connect a linear PSU of 15V between V1 and GND.
Check with a DVM the supply voltage is +15V between the V1 and GND terminals.
Measure VOUT with a DVM. The nominal output voltage should read 1.5V.
The device may also be evaluated with lower power loads and lower currents by increasing the value of
Rsense. As the device reacts only to the voltage across this resistor such tests are equally valid.
ZXCT1051EV1
Vcc
FLAG
Vout
PSU
5V
PSU
10V
V1
GND
V2
LOAD
GND
High Side Sense Configuration,
SL3 open
EVALUATION BOARD
CURRENT MONITOR
EVALUATION BOARD
www.zetex.com
Vcc
FLAG
ZXCT
R4 C1
R5
V1
R7 R8
Vout
R6
R1
SL1
R2
SL2
V2
R3
SL3
GND
GND
Refer to 'User Guide'
for details.
Bare board: ZDB341R2
Copyright Zetex PLC 2006
Top Silk
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DVM
ZXCT1051 EV1
Definitions
Product change
Zetex Semiconductors reserves the right to alter, without notice, specifications, design, price or conditions of supply of any product or service.
Customers are solely responsible for obtaining the latest relevant information before placing orders.
Applications disclaimer
The circuits in this design/application note are offered as design ideas. It is the responsibility of the user to ensure that the circuit is fit for the user’s
application and meets with the user’s requirements. No representation or warranty is given and no liability whatsoever is assumed by Zetex with
respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise.
Zetex does not assume any legal responsibility or will not be held legally liable (whether in contract, tort (including negligence), breach of statutory
duty, restriction or otherwise) for any damages, loss of profit, business, contract, opportunity or consequential loss in the use of these circuit
applications, under any circumstances.
Life support
Zetex products are specifically not authorized for use as critical components in life support devices or systems without the express written approval of
the Chief Executive Officer of Zetex Semiconductors plc. As used herein:
A.
Life support devices or systems are devices or systems which:
1. are intended to implant into the body
or
2. support or sustain life and whose failure to perform when properly used in accordance with instructions
for use provided in the labeling can be reasonably expected to result in significant injury to the user.
B.
A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the
failure of the life support device or to affect its safety or effectiveness.
Reproduction
The product specifications contained in this publication are issued to provide outline information only which (unless agreed by the company in writing)
may not be used, applied or reproduced for any purpose or form part of any order or contract or be regarded as a representation relating to the
products or services concerned.
Terms and Conditions
All products are sold subjects to Zetex’ terms and conditions of sale, and this disclaimer (save in the event of a conflict between the two when the
terms of the contract shall prevail) according to region, supplied at the time of order acknowledgement.
For the latest information on technology, delivery terms and conditions and prices, please contact your nearest Zetex sales office.
Quality of product
Zetex is an ISO 9001 and TS16949 certified semiconductor manufacturer.
To ensure quality of service and products we strongly advise the purchase of parts directly from Zetex Semiconductors or one of our regionally
authorized distributors. For a complete listing of authorized distributors please visit: www.zetex.com/salesnetwork
Zetex Semiconductors does not warrant or accept any liability whatsoever in respect of any parts purchased through unauthorized sales channels.
ESD (Electrostatic discharge)
Semiconductor devices are susceptible to damage by ESD. Suitable precautions should be taken when handling and transporting devices. The
possible damage to devices depends on the circumstances of the handling and transporting, and the nature of the device. The extent of damage can
vary from immediate functional or parametric malfunction to degradation of function or performance in use over time. Devices suspected of being
affected should be replaced.
Green compliance
Zetex Semiconductors is committed to environmental excellence in all aspects of its operations which includes meeting or exceeding regulatory
requirements with respect to the use of hazardous substances. Numerous successful programs have been implemented to reduce the use of
hazardous substances and/or emissions.
All Zetex components are compliant with the RoHS directive, and through this it is supporting its customers in their compliance with WEEE and ELV
directives.
Product status key:
“Preview”
“Active”
“Last time buy (LTB)”
“Not recommended for new designs”
“Obsolete”
Datasheet status key:
“Draft version”
Future device intended for production at some point. Samples may be available
Product status recommended for new designs
Device will be discontinued and last time buy period and delivery is in effect
Device is still in production to support existing designs and production
Production has been discontinued
This term denotes a very early datasheet version and contains highly provisional
information, which may change in any manner without notice.
This term denotes a pre-release datasheet. It provides a clear indication of anticipated performance. However,
changes to the test conditions and specifications may occur, at any time and without notice.
This term denotes an issued datasheet containing finalized specifications. However, changes to specifications
may occur, at any time and without notice.
“Provisional version”
“Issue”
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© 2006 Published by Zetex Semiconductors plc.
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