Zxct1080, High voltage high-side current monitor, Application information – Diodes ZXCT1080 User Manual
Page 8
ZXCT1080
HIGH VOLTAGE HIGH-SIDE CURRENT MONITOR
ZXCT1080
Document number: DS33454 Rev. 4 - 2
8 of 11
December 2011
© Diodes Incorporated
Application Information
The ZXCT1080 has been designed to allow it to operate with 5V supply rails while sensing common mode signals up to 60V.
This makes it well suited to a wide range of industrial and power supply monitoring applications that require the interface to
5V systems while sensing much higher voltages.
To allow this its V
CC
pin can be used independently of S+.
Figure 1 shows the basic configuration of the ZXCT1080.
Fig. 20 Typical Configuration of ZXCT1080
Load current from the input is drawn through R
SENSE
developing a voltage V
SENSE
across the inputs of the ZXCT1080.
The internal amplifier forces V
SENSE
across internal resistance R
GT
causing a current to flow through MOSFET M1. This
current is then converted to a voltage by R
G
. A ratio of 10:1 between R
G
and R
GT
creates the fixed gain of 10. The output is
then buffered by the unity gain buffer.
The gain equation of the ZXCT1080 is:
10
R
x
I
1
R
R
R
I
V
SENSE
L
GT
G
SENSE
L
OUT
Ч
=
Ч
=
The maximum recommended differential input voltage, V
SENSE
, is 150mV; it will however withstand voltages up to 800mV.
This can be increased further by the inclusion of a resistor, R
LIM
, between S- pin and the load; typical value is of the order of
10k.