ZXCT1051E5TA(2006_11) データシートの表示（PDF） - Zetex => Diodes
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ZXCT1051E5TA Datasheet PDF : 10 Pages
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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.
VRAIL
VCC
RSENSE
VSENSE+
VSENSE-
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:
VSENSE
=
ILRSENSE
--R----G---- × 1
RSH
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.
Issue 2 - November 2006
7
© Zetex Semiconductors plc 2006
www.zetex.com
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