ZXCT1008
AUTOMOTIVE HIGH-SIDE CURRENT MONITOR
DESCRIPTION
The ZXCT1008 is a high side current sense monitor.
Using this device eliminates the need to disrupt the
ground plane when sensing a load current.
It takes a high side voltage developed across a current
shunt resistor and translates it into a proportional
output current.
A user defined output resistor scales the output
current into a ground-referenced voltage.
The wide input voltage range of 20V down to as low as
2.5V make it suitable for a range of applications. The
ability to withstand high voltage transients and
reverse polarity connection, makes this part very
suitable for automotive and other transient rich
environments.
APPLICATIONS
•
Automotive current measurement
•
DC motor and solenoid control
•
Over current monitor
•
Power management
FEATURES
•
Low cost, accurate high-side current sensing
•
-40 to +125°C temperature range
•
Up to 500mV sense voltage
•
2.5V – 20V supply range
•
4µA quiescent current
•
1% typical accuracy
•
SOT23
APPLICATION CIRCUIT
ORDERING INFORMATION
DEVICE
ZXCT1008FTA
REEL
SIZE
7”
TAPE
WIDTH
8mm
QUANTITY PER
REEL
3,000 units
DEVICE MARKING
•
108
ISSUE 3 - FEBRUARY 2007
1
ZXCT1008
ABSOLUTE MAXIMUM RATINGS
Voltage on any pin
Continuous output current
Continuous sense voltage
Operating temperature
Storage temperature
Package power dissipation (T
A
= 25°C)
-0.6V to 20V (relative to I
out
)
10mA
V
in
+ 0.5V > V
sense
†
> V
in
– 5V
-40 to 125°C
-55 to 150°C
450mW Derate to zero at 150°C
Operation above the absolute maximum rating may cause device failure. Operation at the absolute maximum
ratings, for extented periods, may reduce device reliability.
ELECTRICAL CHARACTERISTICS
Test Conditions T
A
= 25°C, V
in
= 5V, R
out
= 100Ω.
SYMBOL
V
in
I
out
1
PARAMETER
V
CC
range
Output current
CONDITIONS
Min
2.5
V
sense
=0V
V
sense
=10mV
V
sense
=100mV
V
sense
=200mV
V
sense
=500mV
1
90
0.975
1.95
4.8
0
LIMITS
Typ
4
104
1.0
2.0
5.0
UNIT
Max
20
15
120
1.025
2.05
5.2
500
100
V
µA
µA
mA
mA
mA
mV
nA
V
sense
†
Sense voltage
V
sense
-
input current
Accuracy
Transconductance,
I
out
/ V
sense
Bandwidth
RF P
in
= -20dBm‡
V
sense
= 10mV dc
V
sense
= 100mV dc
R
sense
= 0.1Ω
V
sense
=200mV
I
sense
-
Acc
Gm
BW
-2.5
10000
2.5
%
µA/V
300
2
kHz
MHz
1
†
Includes input offset voltage contribution
V
sense
=V
in
-V
load
‡ -20dBm=63mVp-p into 50Ω
ISSUE 3 - FEBRUARY 2007
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ZXCT1008
TYPICAL CHARACTERISTICS
ISSUE 3 - FEBRUARY 2007
3
ZXCT1008
TYPICAL CHARACTERISTICS (Cont.)
SCHEMATIC DIAGRAM
PIN DESCRIPTION
Pin Name
V
sense
+
V
sense
-
I
out
Pin Function
Supply voltage
Connection to load/battery
Output current, proportional to V
in
-V
load
CONNECTION DIAGRAM
SOT23
Package Suffix – F
Top View
ISSUE 3 - FEBRUARY 2007
4
ZXCT1008
POWER DISSIPATION
The maximum allowable power dissipation of the
device for normal operation (Pmax), is a function of
the package junction to ambient thermal resistance
(θja), maximum junction temperature (Tjmax), and
ambient temperature (Tamb), according to the
expression:
P
max
= (Tj
max
– T
amb
) /
θ
ja
The device power dissipation, P
D
is given by the
expression:
P
D
=I
out
.(V
in
-V
out
) Watts
1) Choose the value of R
sense
to give 50mV >
V
sense
> 500mV at full load.
For example V
sense
= 100mV at 1.0A.
R
sense
= 0.1/1.0 => 0.1
Ω
2) Choose R
out
to give V
out
= 100mV,
when V
sense
= 100mV.
Rearranging
1
for R
out
gives:
R
out
= V
out
/(V
sense
x 0.01)
R
out
= 0.1 / (0.1 x 0.01) = 100
Ω
APPLICATIONS INFORMATION
The following lines describe how to scale a load
current to an output voltage.
V
sense
= V
in
- V
load
V
out
= 0.01 x V
sense
x R
out
1
E.g.
A 1A current is to be represented by a 100mV output
voltage:
ISSUE 3 - FEBRUARY 2007
5
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