DIODES ZXCT1051

ZXCT1051
Precision wide input range current monitor
Description
The ZXCT1051 is a wide input range current
monitor, which operates over a range of input
voltages from ground up to VCC-2V. As a result
the ZXCT1051 can be used on the high or low
side of the load.
The ZXCT1051 provides a fixed gain of 10
thereby removing the need for an additional
resistor.
The very low offset voltage enables a typical
accuracy of 1% for sense voltages of only
30mV, giving better tolerances for small sense
resistors necessary at higher currents.
Features
Applications
•
Accurate down to end current sensing
•
Power supply
•
Output voltage scaling x10
•
DC motor and solenoid control
•
0 to VCC-2V sense input range
•
Battery management
•
2.7 to 20V supply range
•
Over current monitor
•
50 µA quiescent current
•
Power management
•
1% typical accuracy
•
Short circuit detection
•
SOT23-5 package
Pin connections
Typical application circuit
VCC
VSENSEVSENSE+ VSENSE-
GND
VOUT
VSENSE-
RSENSE
VSENSE+
VCC
VSENSE+
ZXCT1051
GND
VOUT
VOUT
Ordering information
Order code
Package
Partmark
Reel size
(inches)
Tape width
(mm)
Quantity
per reel
ZXCT1051E5TA
SOT23-5
1051
7
8
3,000
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ZXCT1051
Absolute maximum ratings
VCC max.
20V
Voltage on VSENSE- and VSENSE+
-0.6 to VCC
Voltage on all other pins
-0.6V and VCC +0.6V
VSENSE "(VSENSE+) - (VSENSE-)
500mV
Operating temperature, Tamb
-40 to 125°C
Storage temperature
-55 to 150°C
Maximum junction temperature
150°C
Package power dissipation
300mW at Tamb = 25°C (de-rate to zero at 150°C)
Operation above the absolute maximum rating may cause device failure. Operation at the
absolute maximum ratings, for extended periods, may reduce device reliability.
Recommended operating conditions
Parameter
Min.
Max.
Units
0
VCC-2
V
2.7
20
V
VSENSE+
Common-mode sense input range
VCC
Supply voltage range
VSENSE
Differential sense input voltage range
0
0.3
V
VOUT
Output voltage range
0
VCC - 2
V
Tamb
Ambient temperature range
-40
125
°C
Pin function table
Pin
Name
Description
1
VCC
This is the analog supply and provides power to internal circuitry
2
GND
Ground pin
3
OUT
Output voltage pin.
4
VSENSE+
This is the positive input of the current monitor and has an input range from
0V up to VCC – 2V.
5
VSENSE-
This is the negative input of the current monitor and has an input range
from 0V up to VCC – 2V. The current through this pin varies with differential
sense voltage.
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ZXCT1051
Electrical characteristics
Test conditions Tamb = 25°C, VSENSE+ = 10V, VCC = 12V, VSENSE = 100mV
Symbol
Parameter
Conditions
Min.
Typ.
Max.
IQ
VCC pin current
VSENSE = 0V
VOUT
Output voltage
VSENSE = 0V
=30mV
=100mV
=150mV
45
70
µA
6
300
1.00
1.50
15
309
1.02
1.55
mV
mV
V
V
ISENSE+
VSENSE+ input current VSENSE = 0V
10
150
nA
ISENSE-
VSENSE- input current VSENSE = 0V
60
150
nA
VOUT TC
VOUT variation with
temperature
300
ppm/°C
ROUT
Output resistance
Gain
VOUT/VSENSE
Accuracy
Total output error
BW
Bandwidth
0
291
0.98
1.45
See note (b)
2.5
3.75
Units
5
k⍀
2
%
10
-2
VSENSE(DC) VSENSE(AC)
= 10mV
= 10mVPP
CL = 5pF,
VSENSE(DC)
= 100mV
300
kHz
1
MHz
PSRR
Power supply
VCC = 2.7V to 20V
rejection ratio refered VSENSE- = 0V
to output
58
dB
CMRR
Common mode
VCC = 20V
rejection ratio refered VSENSE+ = 0 to 18V
to output
66
dB
NOTES:
(a) VSENSE = "VSENSE+" - "VSENSE-"
(b) Temperature dependent measurements are extracted from characterization and simulation results.
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ZXCT1051
ICC Supply Current (A)
ICC Supply Current (A)
Typical characteristics
Supply Current v Input Voltage
IS- Sense Current (A)
ICC Supply Current (A)
Supply Current v Supply Voltage
Sense- Current v Supply Voltage
IS- Sense Current (A)
Percentage Change IS- (%)
Supply Current v Sense Voltage
Sense- Current v Temperature
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Sense- Current v Sense Voltage
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ZXCT1051
10
1
∆VOUT Output Voltage (mV)
VOUT - Output Voltage (V)
Typical characteristics
100m
10m
1E-3
0.01
0.1
5
0
-5
-40 -20
0
20
40
60
80 100 120
Temperature Characteristic
10.1
Incremental Gain
VOUT - Output Voltage (mV)
1100
1050
1000
950
900
-20
10.0
9.9
-15
-10
-5
0
5
10
µ
15
20
0
18
16
14
12
10
8
6
4
2
0
-2
-4
-6
-8
0
2
4
6
8
10 12
14 16
18 20
Common Mode Characteristic
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100m
150m
Incremental Gain v Sense Voltage
∆VOUT - Output Voltage (mV)
∆VOUT - Output Voltage (mV)
VOUT v Load Current
50m
12
8
4
0
-4
-8
-12
0
5
10
15
20
Supply Characteristic
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ZXCT1051
Typical characteristics
70
Supply Rejection (dB)
20
Gain (dB)
10
0
-10
-20
-30
-40
-50
-60
100
1k
10k
100k
1M
60
50
40
30
20
10
0
10M
1000
10000
100000
1E7
PSRR
1.2
90
VOUT - Output Voltage (V)
Common Mode Rejection (dB)
Bandwidth
1000000
80
70
60
50
40
30
20
10
0
100
1k
10k
100k
1.0
0.8
0.6
0.4
0.2
0.0
0
1M
CMRR
2
4
µ
6
8
10
Large Signal Pulse Response
12
VOUT - Output Voltage (V)
VOUT - Output Voltage (V)
1.02
1.00
10
0.98
0.96
0.94
0.92
0.90
0.88
0
2
4
µ
6
8
10
© Zetex Semiconductors plc 2006
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4
2
0
0
Small Signal Pulse Response
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8
5
10
15
20
25
µ
30
35
40
Turn on/off Characteristic
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ZXCT1051
Application information
The ZXCT1051 is Zetex’ first current monitor with a separate power supply pin. All biasing for the
internal amplifiers comes from its separate VCC input and is not ‘line powered’, unlike the
ZXCT1021.
This means that at very small sense voltages the ZXCT1051 draws very little current (<1µA) from
the lines being sensed.
The separate VCC pin enables the ZXCT1051 to be operated at sense line voltages down to 0V,
where the ZXCT1021 would switch off. This feature enables the ZXCT1051 to be used to sense the
currents flowing through lines that have been shorted to ground and is Zetex’ first current
monitor to do this.
RSENSE
VRAIL
VSENSE+
VSENSE-
VCC
Load
Q1
RSH
VOUT
RG
GND
GND
Basic operation
Load current from VIN is drawn through RSENSE developing a voltage VSENSE across the
ZXCT1051.
The internal amplifier forces VSENSE across internal resistance RSH causing a current to flow
through transistor Q1. This current is then converted to a voltage by RG. A ratio of 10:1 between
RSH and RG creates the fixed gain of 10 with an output impedance equal to RG (see electrical
characteristics for output current-voltage characteristics).
The gain equation of the ZXCT1051 is:
RG
V SENSE = I L R SENSE ----------- × 1
R SH
The maximum differential input voltage, VSENSE, is 150mV (IL * RSENSE); however voltages up to
500mV will not damage it. This can be increased further by the inclusion of a resistor, RLIM,
between VSENSE- pin and the load.
For best performance RSENSE should be connected as close to the VSENSE+ and VSENSE- pins thus
minimizing any series resistance with RSENSE.
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ZXCT1051
The ZXCT1051 has been designed to allow it to operate from supplies (VCC) ranging from 2.7V to
20V while sensing common mode signals from 0V up to VCC -2V.
When choosing appropriate values for RSENSE a compromise must be reached between in-line
signal loss (including potential power dissipation effects) and small signal accuracy.
Higher values for RSENSE gives better accuracy at low load currents by reducing the inaccuracies
due to internal offsets. For best operation the ZXCT1051 has been designed to operate with
VSENSE of the order of 50mV to 150mV.
Due to the very nature of current monitors they tend to saturate at very low sense voltages. This
is due to them being operated from single supply and that the basic configuration is that of a
unipolar voltage to current to voltage converter. The internal amplifiers at the heart of the current
monitor may well have a bipolar offset voltage but the output cannot go negative.
For this reason the ZXCT1051 has been designed to operate in a linear manner over a VSENSE
range of 10mV to 150mV range, however it will still be monotonic down to VSENSE of 0V.
The device has a fixed DC voltage gain of 10; no external scaling resistors are required for the
output. Output voltage is simply defined as:
VOUT = gain x VSENSE (V)
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ZXCT1051
Packaging details - SOT23-5
DIM
A
A1
A2
b
C
D
E
E1
e
e1
L
a°
Millimeters
Min.
0.90
0.00
0.90
0.20
0.09
2.70
2.20
1.30
Inches
Max.
1.45
0.15
1.30
0.50
0.26
3.10
3.20
1.80
Min.
0.0354
0.00
0.0354
0.0078
0.0035
0.1062
0.0866
0.0511
0.95 REF
1.90 REF
0.10
0°
Max.
0.0570
0.0059
0.0511
0.0196
0.0102
0.1220
0.1181
0.0708
0.0374 REF
0.0748 REF
0.60
30°
0.0039
0°
0.0236
30°
Note: Controlling dimensions are in millimeters. Approximate dimensions are provided in inches
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ZXCT1051
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
labelling 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 or visit: www.zetex.com
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”
Future device intended for production at some point. Samples may be available
“Active”
Product status recommended for new designs
“Last time buy (LTB)”
Device will be discontinued and last time buy period and delivery is in effect
“Not recommended for new designs” Device is still in production to support existing designs and production
“Obsolete”
Production has been discontinued
Datasheet status key:
“Draft version”
This term denotes a very early datasheet version and contains highly provisional information, which
may change in any manner without notice.
“Provisional version”
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.
“Issue”
This term denotes an issued datasheet containing finalized specifications. However, changes to
specifications may occur, at any time and without notice.
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© 2006 Published by Zetex Semiconductors plc
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