zxct1051 Zetex Semiconductors plc., zxct1051 Datasheet - Page 7

• Manufacturer Part Number: zxct1051
• Description: Zxct1051 - Precision Wide Input Range Current Monitor
• Manufacturer: Zetex Semiconductors plc.

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 V
ZXCT1021.
This means that at very small sense voltages the ZXCT1051 draws very little current (<1µA) from
the lines being sensed.
The separate V
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.
Basic operation
Load current from V
ZXCT1051.
The internal amplifier forces V
through transistor Q1. This current is then converted to a voltage by R
R
characteristics for output current-voltage characteristics).
The gain equation of the ZXCT1051 is:
The maximum differential input voltage, V
500mV will not damage it. This can be increased further by the inclusion of a resistor, R
between V
For best performance R
minimizing any series resistance with R
Issue 2 - November 2006
© Zetex Semiconductors plc 2006
V
GND
SH
RAIL
and R
V
V
CC
SENSE
G
SENSE
creates the fixed gain of 10 with an output impedance equal to R
V
SENSE+
=
CC
- pin and the load.
I
L
pin enables the ZXCT1051 to be operated at sense line voltages down to 0V,
R
R
SENSE
SENSE
IN
SENSE
Q1
is drawn through R
GND
---------- -
R
R
SH
G
should be connected as close to the V
SENSE
×
1
R
SH
V
across internal resistance R
SENSE-
SENSE
SENSE
R
G
.
SENSE
7
CC
, is 150mV (I
V
input and is not ‘line powered’, unlike the
OUT
developing a voltage V
Load
L
* R
SENSE
SH
SENSE
causing a current to flow
G
); however voltages up to
. A ratio of 10:1 between
+ and V
ZXCT1051
SENSE
www.zetex.com
G
SENSE
(see electrical
across the
- pins thus
LIM
,