ZXCT1009
HIGH-SIDE CURRENT MONITOR
DESCRIPTION
The ZXCT1009 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. A
minimum operating current of just 4 A, combined with
its SOT23 package make it a unique solution for
portable battery equipment.
APPLICATIONS
•
Battery chargers
•
Smart battery packs
•
DC motor control
•
Over current monitor
•
Power management
•
Level translating
•
Programmable current source
APPLICATION CIRCUIT
FEATURES
•
Low cost, accurate high-side current sensing
•
Output voltage scaling
•
Up to 2.5V sense voltage
•
2.5V – 20V supply range
•
4µA quiescent current
•
1% typical accuracy
•
SOT23 and SM8 packages
ORDERING INFORMATION
DEVICE
ZXCT1009FTA
ZXCT1009T8TA
REEL
SIZE
7”
7”
TAPE
WIDTH
8mm
12mm
QUANTITY PER
REEL
3,000 units
1,000 units
PARTMARKING
109
ZXCT1009
PACKAGE
SOT23
SM8
ISSUE 9 - OCTOBER 2005
1
SEMICONDUCTORS
ZXCT1009
ABSOLUTE MAXIMUM RATINGS
Voltage on any pin
Continuous output current
Continuous sense voltage
Operating temperature
Storage temperature
Package power dissipation
SOT23
SM8
-0.6V to 20V (relative to I
out
)
25mA
V
in
+ 0.5V > V
sense
†
> V
in
– 5V
-40 to 85°C
-55 to 125°C
(T
A
= 25°C)
450mW - derate to zero at 125°C
2W
Operation above the absolute maximum rating may cause device failure. Operation at the absolute maximum
ratings for extended 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 =1V
1
90
0.975
1.95
9.6
0
LIMITS
Typ
4
104
1.002
2.0
9.98
UNIT
Max
20
15
120
1.025
2.05
10.2
2500
100
V
µA
µA
mA
mA
mA
mV
nA
V sense
†
I sense -
Acc
Gm
BW
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
-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 9 - OCTOBER 2005
SEMICONDUCTORS
2
ZXCT1009
TYPICAL CHARACTERISTICS
5
10m
I
OUT
- Output Current (A)
Output Current Error (%)
1m
V
IN
= 5V
Tamb = 25°C
R
OUT
= 0
W
4
3
2
1
0
-1
-2
10m
100m
Typical
V
IN
= 5V
Tamb = 25°C
R
OUT
= 0
W
100µ
10µ
100µ
1m
10m
100m
1
1
V
SENSE
(V)
V
SENSE
(V)
Typical Output v Sense Voltage
3
10.2
V
IN
= 5V
V
SENSE
= 1V
R
OUT
= 0
W
Error v Sense Voltage
I
OUT
- Output Current (mA)
V
IN
= 5V, Tamb = 25°C, RF P
IN
= -20dBm
0
-3
DC V
SENSE
= 0.01V
10.0
9.8
Gain (dB)
-6
-9
-12
0.01
DC V
SENSE
= 0.1V
DC V
SENSE
= 1V
9.6
9.4
-40
-20
0
20
40
60
80
0.1
1
10
Temperature (°C)
Frequency (MHz)
Output Current v Temperature
12
0
V
IN
= 5V
Tamb = 25°C
R
OUT
= 0
W
V
SENSE
= 1V
V
SENSE
= 0.8V
V
SENSE
= 0.6V
V
SENSE
= 0.4V
V
SENSE
= 0.2V
Frequency Response
I
OUT
- Output Current (mA)
-10
-20
10
8
6
4
2
0
0
V
IN
= 5V
Tamb = 25°C
RF P
IN
= -20dBm
V
SENSE
= 1V
Rejection (dB)
-30
-40
-50
-60
-70
-80
-90
V
SENSE
= 0.1V
V
SENSE
= 0.01V
1
2
3
4
5
1
10
100
1k
10k
100k
1M
10M
V
IN
- Supply Voltage (V)
Frequency (Hz)
Transfer Characteristic
ISSUE 9 - OCTOBER 2005
3
Common Mode Rejection
SEMICONDUCTORS
ZXCT1009
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 DIAGRAMS
SOT23
Package Suffix – F
SM8
Package Suffix – T8
Top View
Top View
ISSUE 9 - OCTOBER 2005
SEMICONDUCTORS
4
ZXCT1009
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
E.g.
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 ohms.
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)
SM8
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
A 1A current is to be represented by a 100mV output
voltage:
R
out
= 0.1 / (0.1 x 0.01) = 100
Ω
SOT23
TYPICAL CIRCUIT APPLICATION
Where R
load
represents any load including DC motors,
a charging battery or further circuitry that requires
monitoring, R
sense
can be selected on specific
requirements of accuracy, size and power rating.
ISSUE 9 - OCTOBER 2005
5
SEMICONDUCTORS
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