DIODES ZXCT1041

ZXCT1041
Bidirectional precision high-side current monitor
Description
The ZXCT1041 is a bidirectional precision highside current sense monitor. The output voltage
is proportional to the differential input voltage.
Direction of current flow is indicated by the
Flag pin.
The very low offset voltage enables a typical
accuracy of 2% for sense voltages of only
10mV, giving better tolerances for small sense
resistors necessary at higher currents.
The wide input voltage range of 20V down to
as low as 2.7V make it suitable for a range of
applications.
The ZXCT1041 provides a fixed gain of 10 for
applications
where
minimal
external
components are required.
A minimum operating current of just 40␮A,
combined with a SOT23-5 package makes the
ZXCT1041 particularly suitable for portable
battery equipment.
Features
Applications
•
Bidirectional high side measurement
•
Battery management
•
Output voltage scaling x10
•
Over current monitor
•
2.7V to 20V high side voltage
•
Battery gas gauging
•
35µA quiescent current
•
Motor control
•
1% typical accuracy
•
SOT23-5 package
Typical application circuit
Pin connections
VIN-
RS
VIN+
4
Flag
5
S-
S+
S-
ZXCT1041
GND
GND
OUT
2
S+
1
Flag
OUT
3
VOUT
Ordering information
Order code
Package
Partmark
Reel size
(inches)
Tape width
(mm)
Quantity
per reel
ZXCT1041E5TA
SOT23-5
1041
7
8
3000
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ZXCT1041
Absolute maximum ratings
Voltage on VS- and VS+
-0.6 to 20V
Voltage on all other pins
-0.6V to (VS+ or VS-) +0.6V
Vsense [(VS+) - (VS-)]
+/-6V
Operating temperature, TA
-40 to 125°C
Storage temperature
-55 to 150°C
Maximum junction temperature, TJ
150°C
Package power dissipation
300mW at TA = 25°C (De-rate to zero at 150°C)
Operation above the absolute maximum rating may cause device failure. Operation at the absolute maximum ratings, for
extended periods, may reduce device reliability.
Recommended operating conditions
Parameter
Min.
Max.
Units
2.7
20
V
VS±
Common-mode sense input range
Flag
Current direction flag output
0
VS±
V
VSENSE
Differential sense input voltage range
0
±0.8
V
VOUT
Output voltage range
0
VS± -1.5
V
TA
Ambient temperature range
-40
125
°C
Pin function table
Pin
Name
Description
1
Flag
This is the current direction pin. It is open collector and allows the logic high
level to be set independent of VS+ voltage. Low indicates VS+ is greater than VS-
2
GND
Ground pin
3
OUT
Output voltage pin
4
S+
This is the positive input of the current monitor. It also acts as the supply
voltage pin providing current for internal circuitry. The current through this
pin varies with differential sense voltage
5
S-
This is the negative input of the current monitor. The current through this
pin varies with differential sense voltage
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ZXCT1041
Electrical characteristics
Test conditions TA = 25°C, VS+ = 10V, VSENSE = 100mV
Symbol
Parameter
IQ
Ground pin current
IS+
VS+ input current
ISVOUT
Conditions
Min.
Typ.
Max.
15
35
50
µA
VSENSE = 0V
10
17
24
µA
VS- input current
VSENSE = 0V
10
17
24
µA
Output voltage
[flag high]
VSENSE = +150mV
1.55
1.5
1.45
V
VSENSE = +100mV
1.02
1
0.98
V
VSENSE = +30mV
309
300
291
mV
15
mV
VSENSE = 0V
[flag low]
0
Units
VSENSE = -30mV
285
300
315
mV
VSENSE = -100mV
0.95
1
1.05
V
VSENSE = -150mV
1.42
1.50
1.58
V
VOUT TC
VOUT variation with
temperature
VSENSE = ±100mV
30
ppm/ºC
Gain
VOUT/VSENSE
Accuracy
Total output error
(Gain + offset)
VSENSE = 100mV
±2
%
Accuracy
Total output error
(Gain + offset)
VSENSE = -100mV
±5
%
BW
Bandwidth
VSENSE(DC) = 100mV
VSENSE(AC) = 63mVPP
300
kHz
CMRR
VS+ common mode
rejection ratio
VIN = 2.7 to 20V
60
dB
Flag TP
Flag trip point
Referred to VSENSE
VFL
Flag low output
voltage
ISINK = 100␮A
IFH
Flag high leakage
current
VOH = 5V
10
-2.5
60
+2.5
mV
200
mV
1
␮A
NOTES:
(a) VSENSE = "VS+" - "VS-"
(b) Temperature dependent measurements are extracted from characterisation and simulation results.
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ZXCT1041
Typical characteristics
Conditions VSENSE+=10V, VSENSE=100mV, TA=25°C unless otherwise stated.
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ZXCT1041
Typical characteristics
Conditions VSENSE+=10V, VSENSE=100mV, TA=25°C unless otherwise stated.
300
250
200
150
100
50
IGND(µA)
8
FLAG VCC = 5V
RFLAG = 50k
4
VFLAG (V)
Voltage (V)
6
2
0
-0.8 -0.6 -0.4 -0.2
0.0
0.2
0.4
VSENSE (V)
0.6
4
RFLAG = 50k
0
-0.15
0.8
-0.10
-0.05
0.00
0.05
0.10
VSENSE (V)
0.15
IGND & VFLAG v Sense Voltage
700
600
Sense- Pin Current (µA)
700
Sense+ Pin Current (µA)
FLAG VCC = 5V
2
VOUT & VFLAG v Sense Voltage
TA = -40°C to 125°C
500
400
300
200
100
0
-0.8 -0.6 -0.4 -0.2
0.0
0.2
0.4
VSENSE (V)
0.6
0.8
600
400
300
200
100
0
-0.8 -0.6 -0.4 -0.2
Output Voltage Error (mV)
-10
6
10
7
Output Load Resistance (Ω)
10
8
Error v Resistive Loading
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0.2
0.4
0.6
0.8
ISENSE- v Sense Voltage
-5
10
0.0
VSENSE (V)
0
-15
5
10
TA = -40°C to 125°C
500
ISENSE+ v Sense Voltage
Gain Error (%)
Flag Current 100µA
150
100
50
0
-50
-100
-150
-10
-5
0
5
Output Load Current (µA))
10
Error v Current Loading
5
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ZXCT1041
Typical characteristics
Conditions VSENSE+=10V, VSENSE=100mV, TA=25°C unless otherwise stated.
2.0
1.5
Voltage (V)
Voltage (V)
2.0
VOUT
1.0
VSENSE
0.5
1.5
VOUT
1.0
0.5
VSENSE
0.0
-5
0.0
0
5
10
15
Time (µs)
20
25
30
-5
0
5
10
15
Time (µs)
20
25
30
Reverse Large Signal Step Response
0.20
0.20
0.15
0.15
Voltage (V)
Voltage (V)
Forward Large Signal Step Response
VOUT
VOUT
0.10
0.10
VSENSE
0.05
0.05
VSENSE
0.00
0.00
-5
0
5
10
15
20
Time (µs)
25
30
-5
35
5
10
15
20
Time (µs)
25
30
35
Reverse Small Signal Step Response
Forward Small Signal Step Response
5
2.0
VFLAG
Voltage (V)
4
Voltage (V)
0
3
2
1
0
-1
1.5
1.0
VOUT
0.5
VSENSE X10
-2
-4
-2
0
2
4
Time (µs)
6
8
0.0
-4
10
Large Sig Zero Crossing Response
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0
2
4
Time (µs)
6
8
10
Large Sig Zero Crossing Response
6
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ZXCT1041
Typical characteristics
Conditions VSENSE+=10V, VSENSE=100mV, TA=25°C unless otherwise stated.
5
2.0
Voltage (V)
Voltage (V)
4
VFLAG
3
2
1
0
1.0
VOUT
0.5
VSENSE X10
-1
1.5
-2
16
18
20
22
24
26
Time (µs)
28
0.0
16
30
Large Sig Zero Crossing Response
20
22
24
26
Time (us)
28
30
Large Sig Zero Crossing Response
5
0.20
4
VFLAG
3
0.15
2
VOUT (V)
VOUT (V)
18
1
0
-1
VOUT
0.10
0.05
VSENSE X100
-2
-4
-2
0
2
4
6
Time (µs)
8
10
12
0.00
-4
14
Small Sig Zero Crossing Response
-2
0
2
4
6
Time (µs)
8
10
12
14
Small Sig Zero Crossing Response
5
0.20
4
VFLAG
0.15
Vout (V)
Vout (V)
3
2
1
0
VOUT
0.05
VSENSE X100
-1
0.10
-2
16
18
20
22
24
26
Time (µs)
28
30
32
0.00
16
34
© Zetex Semiconductors plc 2008
20
22
24
26
28
Time (µs)
30
32
34
Small Sig Zero Crossing Response
Small Sig Zero Crossing Response
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ZXCT1041
Typical characteristics
70
70
VSENSE=+100mVrms
60
VAC=63mVP-P
50
40
30
Vs+=2.7V
Vs+=5.0V
Vs+=10V
Vs+=15V & 20V
20
10
0
-10
100
1k
10k
40
30
20
Vs+=15V & 20V
Vs+=10V
Vs+=5.0V
Vs+=2.7V
10
0
100k
1M
1k
10k
100k
Frequency (Hz)
Frequency (Hz)
Forward CMRR
Reverse CMRR
1M
25
20
15
VS+=2.7V
Gain (dB)
Gain (dB)
VAC=63mVP-P
50
-10
100
25
20
15
10
5
0
-5
-10
-15
-20
-25
VSENSE=-100mVrms
60
Rejection (dB)
Rejection (dB)
Conditions VSENSE+=10V, VSENSE=100mV, TA=25°C unless otherwise stated.
VS+=5.0V
VS+=10V
VSENSE=+100mV
VAC=63mVP-P
100k
VS+=15V
VS+=20V
Frequency (Hz)
1M
© Zetex Semiconductors plc 2008
VS+=2.7V
VS+=5.0V
VS+=10V
VSENSE=-100mV
VAC=63mVP-P
100k
VS+=15V
VS+=20V
Frequency (Hz)
1M
Reverse Frequency Response
Forward Frequency Response
Issue 2 - January 2008
10
5
0
-5
-10
-15
-20
-25
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ZXCT1041
Application information
The ZXCT1041 uses two current monitors in anti-parallel to provide bidirectional current
measurement. The integrated resistors while having a broad actual value variance provide very
good matching to one another; this provides very tight gain matching from forward current
measurement to reverse current management and removes the need to trim the resistor values.
The internal transconductance setting resistors have a nominal value of 1.5k⍀ thereby setting the
internal transconductance to 0.67mA/V of VSENSE-. The outputs of both current monitors (current)
are summed into an internal common gain-setting resistor of 15k⍀. This sets the overall gain to
10 which has a very small variance due to the very good matching of internal transistors.
To improve accuracy the offset of amplifier 1 is trimmed.
The direction of measured current flow is determined by comparing the voltages applied to the
bases of transconductance transistors (Q1 and Q2). For maximum versatility the flag output uses
an open collector; this allows the ZXCT1041 to monitor rails at a much higher potential than what
the flag output is interfacing to.
S+
S-
1.5k
1.5k
OUT
Flag
15k
GND
A common application for micro-power current monitors is measuring the discharge current of a
rechargeable lithium ion/polymer battery. The ZXCT1041 enables measuring both the charge and
discharge current into the battery and with its wide operating voltage of 2.5 to 20V enables it to
measure the currents in to/ out of up to 4 cells connected in series.
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ZXCT1041
Load
Battery
charger
control
S+
S-
ZXCT1041
Battery
Flag
GND
OUT
When choosing appropriate values for RSENSE a compromise must be reached between in-line
signal loss (including potential power dissipation effects) and small signal accuracy.
Higher values for RSENSE gives better accuracy at low load currents by reducing the inaccuracies
due to internal offsets. For best operation the ZXCT1041 has been designed to operate with
VSENSE of the order of 50mV to 150mV.
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ZXCT1041
Package outline - SOT23-5
DIM
A
A1
A2
b
C
D
E
E1
e
e1
L
a°
Millimeters
Min.
0.90
0.00
0.90
0.20
0.09
2.70
2.20
1.30
Inches
Max.
1.45
0.15
1.30
0.50
0.26
3.10
3.20
1.80
Min.
0.0354
0.00
0.0354
0.0078
0.0035
0.1062
0.0866
0.0511
0.95 REF
1.90 REF
0.10
0°
Max.
0.0570
0.0059
0.0511
0.0196
0.0102
0.1220
0.1181
0.0708
0.0374 REF
0.0748 REF
0.60
30°
0.0039
0°
0.0236
30°
Note: Controlling dimensions are in millimeters. Approximate dimensions are provided in inches
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ZXCT1041
Definitions
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or
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Future device intended for production at some point. Samples may be available
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Product status recommended for new designs
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This term denotes a very early datasheet version and contains highly provisional information, which
may change in any manner without notice.
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