ZXCT1030 View Datasheet(PDF) - Zetex => Diodes
Part Name
Description
Manufacturer
ZXCT1030 Datasheet PDF : 10 Pages
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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.
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 (Iref source) is limited to
5µA, making potentiometers Ն250k⍀ suitable for setting a threshold level. Where a lower
potentiometer resistor value is used, an additional resistor value should be inserted between Vref
and VCC to maintain sufficient current for the reference. (as shown in Figure 1).
Figure 1: External resistor for reference level
The voltage reference has a maximum current sink capability. This magnitude of current will be
influenced by the value of R1 which is inserted between Vref and VCC. The value of current flowing
through R1 can be expressed as:
I = (VCC -Vref) / R1
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 VCC and ground connections. A ceramic 10F will be adequate.
Issue 2 - May 2007
6
© Zetex Semiconductors plc 2007
www.zetex.com
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