ZXCT1030
HIGH-SIDE CURRENT MONITOR WITH COMPARATOR
DESCRIPTION
The ZXCT1030 is a high side current sense monitor
containing an internal reference and comparator with a
non-latching output. Using this device eliminates the
need to disrupt the ground plane when sensing a load
current.
The wide input voltage range of 20V down to as low as
2.2V make it suitable for a range of applications.
Dynamics and supply current are optimised for the
processing of fast pulses, associated with switch mode
applications.
APPLICATIONS
•
Battery chargers
•
Electronic fuse
•
DC motor control
•
Over current monitor
•
Power management
•
Inrush current limiting
FUNCTIONAL BLOCK DIAGRAM
FEATURES
•
Low cost, accurate high-side current sensing.
•
Output voltage scaling.
•
Up to 18V output.
•
2.2V – 20V supply range.
•
270 A quiescent current.
•
1.5% typical accuracy.
•
MSOP8 Package.
•
Voltage reference on chip
•
Comparator on chip
ZXCT1030
Comp_in
Vref_out
+
-
Vin
sense+
Current
Monitor
Vout
Rcomp
Rsense
sense-
To load
Vcc
5V Vcomp_supply
Comp_out
ORDERING INFORMATION
Device
ZXCT1030X8TA
ZXCT1030X8TC
Reel size
7”
13”
Tape width
12mm
12mm
Quantity per reel
500 units
2500 units
DEVICE MARKING
•
ZXCT
1030
PROVISIONAL ISSUE J - MAY 2004
1
SEMICONDUCTORS
ZXCT1030
Voltage output Current Monitor
Referring to the block diagram, the current monitor
takes the small voltage developed across the sense
resistor (Vsense) and transfers it from the large
common mode supply voltage to a ground-referenced
signal with a gain of 10. The sense input common
mode range is 2.2V to 20V. In this range, a linear output
voltage is delivered.
Comparator
The open collector output is active low and is asserted
when Vsense x 10 (Vout) > Vcomp_in.
It can be connected to any voltage rail up to Vin via a
pull-up resistor. Suggest values for the resistor are in
the range of 10-100k .
In the case where high load currents or a short circuit
occurs, thus reducing the common mode signals (V+,
V-) typically below 2.2V, the comparator will default to
the asserted state. This can eliminate a closed loop
system ‘latch-up’ condition, allowing the controller to
remove the applied power.
Reference
The bandgap reference allows the comparator to
compare the translated Vsense with threshold value
chosen by the user which can be any voltage from 0 to
1.24V, configured by two external resistors which
forms Vcomp_in.
The output current which can be drawn from the
comparator reference (I
ref
source) is limited to 5µA,
making potentiometers
≥
250k suitable for setting a
threshold level. Where a lower potentiometer resistor
value is used, an additional resistor value should be
inserted between V
ref
and V
cc
to maintain sufficient
current for the reference. (as shown in figure 1.0).
Stability
To ensure stable operation of the ZXCT1030, it is
recommended a decoupling capacitor is placed across
the V
CC
and ground connections. A ceramic 10 F will
be adequate.
FIGURE 1.0
External resistor for reference level
PIN CONNECTIONS
MSOP8
Vcc
1
Sense-
2
Sense+
3
GND
4
8
7
Comp_out
Vout
6
Vref_out
5
Comp_in
Pin Name
Vcc
Sense-
Sense+
Pin Function
Supply voltage
Negative sense input
Positive sense input
Ground
Comparator input, usually a
ratio of the reference or other
control signal.
Reference output
Current Monitor output
voltage
Open collector comparator
output
The Voltage reference has a maximum current sink
capability. This magnitude of current will be influenced
by the value of R
1
which is inserted between V
ref
and
V
cc.
The value of current flowing through R
1
can be
expressed as:
I = (Vcc -Vref) / R
1
GND
Comp_in
Vref_out
Vout
Comp_out
PROVISIONAL ISSUE J - MAY 2004
5
SEMICONDUCTORS
RF/Wirelessly
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