ZXCT1030X8TC ZETEX [Zetex Semiconductors], ZXCT1030X8TC Datasheet - Page 5

• Manufacturer Part Number: ZXCT1030X8TC
• Description: HIGH-SIDE CURRENT MONITOR WITH COMPARATOR
• Manufacturer: ZETEX [Zetex Semiconductors]

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.
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
making potentiometers ≥ 250k
threshold level. Where a lower potentiometer resistor
value is used, an additional resistor value should be
inserted between V
current for the reference. (as shown in figure 1.0).
The Voltage reference has a maximum current sink
capability. This magnitude of current will be influenced
by the value of R
V
expressed as:
PROVISIONAL ISSUE J - MAY 2004
FIGURE 1.0
External resistor for reference level
cc.
The value of current flowing through R
I = (Vcc -Vref) / R
1
which is inserted between V
ref
and V
ref
1
source) is limited to 5µA,
cc
to maintain sufficient
suitable for setting a
1
can be
ref
and
5
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.
Stability
To ensure stable operation of the ZXCT1030, it is
recommended a decoupling capacitor is placed across
the V
be adequate.
PIN CONNECTIONS
MSOP8
Pin Name
Vcc
Sense-
Sense+
GND
Comp_in
Vref_out
Vout
Comp_out
CC
and ground connections. A ceramic 10 F will
Sense+
Sense-
GND
V cc
1
2
3
4
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
8
7
6
5
S E M I C O N D U C T O R S
ZXCT1030
Comp_out
V out
Vref_out
Comp_in