A Product Line of
Diodes Incorporated
ZXCT1010
ENHANCED HIGH-SIDE CURRENT MONITOR
Description
The ZXCT1010 is a high side current sense monitor. Using this
device eliminates the need to disrupt the ground plane when sensing
a load current.
It is an enhanced version of the ZXCT1009 offering reduced typical
output offset and improved accuracy at low sense voltage.
Pin Assignments
SOT25
Package Suffix - E5
NC 1
GND 2
5 V
SENSE
-
The wide input voltage range of 20V down to as low as 2.5V make it
suitable for a range of applications. A minimum operating current of
just 4µA, combined with its SOT25 package make suitable for
portable battery equipment.
I
OUT
3
4 V
SENSE
+
Top View
Features
•
•
•
•
•
•
•
•
•
•
Low cost, accurate high-side current sensing
Output voltage scaling
Up to 2.5V sense voltage
2.5V to 20V supply voltage range
300nA typical offset current
3.5µA quiescent current
1% typical accuracy
SOT25 package
Totally Lead-Free & Fully RoHS Compliant(Note 1 & 2)
Halogen and Antimony Free. “Green” Device(Note 3)
1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"
and Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
Applications
•
•
•
•
•
•
Battery chargers
Smart battery packs
DC motor control
Over current monitor
Power management
Programmable current source
Notes:
Typical Applications Circuit
ZXCT1010
Document number: DS33442 Rev. 11 - 2
1 of 8
www.diodes.com
March 2014
© Diodes Incorporated
A Product Line of
Diodes Incorporated
ZXCT1010
Pin Descriptions
Pin Number
1
2
3
4
5
Pin Name
NC
GND
I
OUT
V
SENSE-
V
SENSE+
Function
No connection
Ground
Output current, proportional to V
IN
- V
LOAD
Supply voltage
Connection to load/battery
Functional Block Diagram
Absolute Maximum Ratings
(@T
A
= +25°C, unless otherwise specified.)
Parameter
Voltage on any pin (relative to I
OUT
)
Continuous output current, I
OUT
Continuous sense voltage, V
SENSE
(Note 4)
Operating temperature, T
A
Storage temperature
Package power dissipation(@T
A
= +25°C)
Note:
SOT25
Rating
-0.6 to +20
25
-0.5 to +0.5
-40 to +85
-55 to +125
300
Unit
V
mA
V
°C
°C
mW
4. Operation above the absolute maximum rating may cause device failure. Operation at absolute maximum ratings, for extended periods, may reduce
device reliability
Electrical Characteristics
(@T
A
= +25°C, unless otherwise specified.)
Symbol
V
IN
V
CC
range
Parameter
−
V
SENSE
= 0V
V
SENSE
= 10mV
V
SENSE
= 100mV
V
SENSE
= 200mV
V
SENSE
= 1V
V
SENSE
= 0V
−
R
SENSE
= 0.1Ω; V
SENSE
= 200mV
−
V
SENSE(DC)
= 10mV, RF P
IN
= -40dBm (Note 7)
V
SENSE(DC)
= 100mV, RF P
IN
= -20dBm (Note
7)
Conditions
Min
2.5
0
85
0.975
1.95
9.7
—
0
—
-2.5
—
—
—
Limits
Typ
−
0.3
100
1.0
2.0
10.0
3.5
—
—
—
10000
300
2
Max
20
10
115
1.025
2.05
10.3
8
2500
100
2.5
—
—
—
Units
V
µA
I
OUT
Output Current (Note 5)
mA
µA
mV
nA
%
µA/V
kHz
MHz
Iq
V
SENSE
I
SENSE-
A
CC
G
M
BW
Notes:
Ground pin current
Sense Voltage (Note 6)
V
SENSE -
Input Current
Accuracy
Transconductance, I
OUT
/V
SENSE
Bandwidth
5. Include input offset voltage contribution
6. V
SENSE
is defined as the differential voltage between V
SENSE+
and V
SENSE-
, V
SENSE
= V
SENSE+
-V
SENSE
- =V
IN
-V
LOAD
= I
LOAD
* R
SENSE
7. -20dBm = 63mV
P-P
into 50Ω
ZXCT1010
Document number: DS33442 Rev. 11 - 2
2 of 8
www.diodes.com
March 2014
© Diodes Incorporated
A Product Line of
Diodes Incorporated
ZXCT1010
Typical Performance Characteristics
ZXCT1010
Document number: DS33442 Rev. 11 - 2
3 of 8
www.diodes.com
March 2014
© Diodes Incorporated
A Product Line of
Diodes Incorporated
ZXCT1010
Power Dissipation
The maximum allowable power dissipation of the device for normal operation (P
MAX
), is a function of the package junction temperature (T
J(MAX)
),
and ambient temperature (T
AMB
), according to the expression.
P
MAX
= (T
J(MAX)
– T
AMB
)/θ
JA
The device power dissipation, PD is given by the expression:
P
D
= I
OUT
*(V
IN
– V
OUT
) Watts
Application Information
The following lines describes how to scale a load current to an output voltage.
V
SENSE
= V
IN
– V
LOAD
V
OUT
= 0.01 x V
SENSE
x R
OUT
E.g.
A 1.0A current is to be represented by a 100mV output voltage:
1)
Choose the value of R
SENSE
to give 50mV > V
SENSE
> 500mV at full load.
For example, V
SENSE
= 100mV at 1.0A. R
SENSE
= 0.1/1.0 = > 0.1ohms.
2)
Choose R
OUT
to give V
OUT
= 100mV, when V
SENSE
= 100mV.
Rearranging for R
out
gives:
R
OUT
= V
OUT
/(V
SENSE
x 0.01)
R
OUT
= 0.1/(0.1 x 0.01) = 100Ω
Typical Circuit Application:
specific requirements of accuracy, size and power rating.
Typical Application Circuit
When R
LOAD
represented any load including DC motors, a charging battery or further circuitry that requires monitoring, R
SENSE
can be selected on
ZXCT1010
Document number: DS33442 Rev. 11 - 2
4 of 8
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March 2014
© Diodes Incorporated
A Product Line of
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ZXCT1010
Application Information
(cont.)
Li-ion Charger Circuit:
The figure below shows the ZXCT1010 supporting the Benchmarq bq2954 Charge Management IC. Most of the support components for the
bq2954 are omitted for clarity. This design also uses the Zetex FZT789A high current Super-b PNP as the switching transistor in the DC-DC step
down converter and the FMMT451 as the drive NPN for the FZT789A. The circuit can be configured to charge up to four Li-ion cells at a charge
current of 1.25A. Charge can be terminated on maximum voltage, selectable minimum current, or maximum time out, switching frequency of the
PWM loop is approximately 120kHz.
Bi-Directional Current Sensing:
The ZXCT1010 can be used to measure current bi-directionally, if two devices are connected as show below:
If the voltage V1 is positive with respect to the voltage V2 the lower device will be active, delivering a proportional output current to R
out
. Due to the
polarity of the voltage across R
SENSE
, the upper device will be inactive and will not contribute to the current delivered to R
out
. When V2 is more
positive than V1, current will be flowing in the opposite direction, causing the upper device to be active instead.
Non-linearity will be apparent at small values of VSENSE due to offset current contribution. Devices can use separate output resistors if the current
direction is to be monitored independently.
ZXCT1010
Document number: DS33442 Rev. 11 - 2
5 of 8
www.diodes.com
March 2014
© Diodes Incorporated
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