Download MAX4373/MAX4374/MAX4375 Low-Cost, Micropower, High-Side Current-Sense Amplifier + Comparator + Reference ICs General Description

19-1630; Rev 2; 10/03
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
The MAX4373/MAX4374/MAX4375 low-cost, micropower, high-side current-sense supervisors contain a highside current-sense amplifier, bandgap reference, and
comparator with latching output. They feature a voltage
output that eliminates the need for gain-setting resistors,
making them ideal for today’s notebook computers, cell
phones, and other systems where battery/DC current
monitoring is critical. High-side current monitoring is
especially useful in battery-powered systems since it
does not interfere with the ground path of the battery
charger. The 0 to +28V input common-mode range is
independent of the supply voltage, which ensures that
the current-sense feedback remains viable even when
connected to a battery pack in deep discharge.
The comparator output of the MAX4373/MAX4374/
MAX4375 is latched to provide a turn-off flag that
doesn’t oscillate. In addition, the MAX4374/MAX4375
contain a second comparator for use in window-detection functions. The MAX4373/MAX4374/MAX4375 are
available in three different gain versions (T = +20V/V,
F = +50V/V, H = +100V/V) and use an external sense
resistor to set the sensitivity of the input voltage to the
load current. These features offer a high level of integration, resulting in a simple and compact currentsense solution.
The MAX4373/MAX4374/MAX4375 operate from a single +2.7V to +28V supply and consume 50µA. They are
specified for the extended operating temperature range
(-40°C to +85°C) and are available in 8-pin and 10-pin
µMAX packages.
Features
♦ Current-Sense Amplifier plus Internal Comparator
and Bandgap Reference with Improved Accuracy
♦ 50µA Supply Current
♦ Single +2.7V to +28V Operating Supply
♦ 1mV (max) Input Offset Voltage
♦ 2% (max) Full-Scale Accuracy
♦ Internal Bandgap Reference (±1.6% Accuracy)
♦ Latching Comparator Output
♦ Three Gain Versions Available (+20V/V, +50V/V,
+100V/V)
♦ Wide 0 to +28V Common-Mode Range,
Independent of Supply Voltage
Ordering Information
PART
TEMP RANGE
PINPACKAGE
MAX4373TEUA
-40°C to +85°C
8 µMAX
+20
MAX4373TESA
-40°C to +85°C
8 SO
+20
MAX4373FEUA
-40°C to +85°C
8 µMAX
+50
MAX4373FESA
-40°C to +85°C
8 SO
+50
MAX4373HEUA
-40°C to +85°C
8 µMAX
+100
MAX4373HESA
-40°C to +85°C
8 SO
+100
Ordering Information continued at end of data sheet.
Applications
Typical Operating Circuit
Notebook Computers
Portable/Battery-Powered Systems
Smart Battery Packs/Chargers
RSENSE
RS+
General-System/Board-Level Current Monitoring
Precision Current Sources
ILOAD
+ VSENSE VIN = 0 TO 28V
Cell Phones
Power-Management Systems
GAIN
(V/V)
VCC = 2.7V TO 28V
LOAD/
BATTERY
RS-
VCC
C1
0.1µF
MAX4373
OUT
VPULL-UP
(UP TO 5V)
R1
R3
CIN
COUT
R2
RESET
Pin Configurations appear at end of data sheet.
GND
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
www.BDTIC.com/maxim
1
MAX4373/MAX4374/MAX4375
General Description
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
ABSOLUTE MAXIMUM RATINGS
VCC, RS+, RS- to GND ...........................................-0.3V to +30V
OUT to GND ................................................-0.3V to the lesser of
(VCC + 0.3V) or +15V
CIN1, CIN2, RESET to GND ........................-0.3V to the lesser of
(VCC + 0.3V) or +12V
Differential Input Voltage (VRS+ - VRS-) ..............................±0.3V
COUT1, COUT2 to GND........................................-0.3V to +6.0V
Current into Any Pin..........................................................±10mA
Continuous Power Dissipation (TA = +70°C)
8-Pin µMAX (derate 4.1mW/°C above +70°C) .............330mW
8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW
10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW
14-Pin SO (derate 8.3mW/°C above +70°C)................667mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VCC = +2.7V to +28V, VRS+ = 0 to +28V, VSENSE = 0, V RESET = 0, RLOAD= 1MΩ, TA = TMIN to TMAX, unless otherwise noted. Typical
values are at TA = +25°C.) (Note 1)
PARAMETER
Operating Voltage Range
(Note 2)
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
VCC
2.7
28
V
Common-Mode Input Range
(Note 3)
VCMR
0
28
V
Common-Mode Rejection
CMR
Supply Current
ICC
Leakage Current
IRS+
IRS-
Input Offset Voltage
Total OUT Voltage Error
(Note 5)
85
VRS+ > 2V, VSENSE = 5mV
50
100
µA
±0.015
±0.5
µA
IRS+, IRS- VCC = 0
Input Bias Current
Full-Scale Sense Voltage
(Note 4)
VRS+ > 2V
VSENSE
VOS
VOUT
VRS+ > 2V
0
2.5
VRS+ ≤ 2V
-25
2.0
VRS+ > 2V
0
4
VRS+ ≤ 2V
-50
Gain = +20V/V, +50V/V
150
170
Gain = +100V/V
100
120
VCC = VRS+ = 12V
(Note 11)
VSENSE =
100mV
(Note 6)
TA = +25°C
VCC = 12V,
VRS+ = 12V
TA = +25°C
VCC = 28V,
VRS+ = 28V
TA = +25°C
0.1
±0.30
TA = TMIN to TMAX
VCC VOH
VCC = 2.7V, IOUT = -500µA
%
±5.0
8.5
OUT Voltage High
±2
±5.0
2.5
VCC = 2.7V
mV
±2
±3
IOUT = 100µA
VOUT
1
±3
±0.35
IOUT = 10µA
OUT Voltage Low
mV
2
TA = TMIN to TMAX
VCC = 12V, VRS+ = 0.1V
µA
4
TA = TMIN to TMAX
VSENSE = 6.25mV, VCC = 12V,
VRS+ = 12V (Note 7)
2
dB
65
0.25
_______________________________________________________________________________________
www.BDTIC.com/maxim
mV
V
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
(VCC = +2.7V to +28V, VRS+ = 0 to +28V, VSENSE = 0, V RESET = 0, RLOAD= 1MΩ, TA = TMIN to TMAX, unless otherwise noted. Typical
values are at TA = +25°C.) (Note 1)
PARAMETER
-3dB Bandwidth
SYMBOL
BW
CONDITIONS
VRS+ = 12V,
VCC = 12V,
CLOAD = 10pF
MIN
200
VSENSE = 100mV,
Gain = +50V/V
120
VSENSE = 100mV,
Gain = +100V/V
110
VSENSE = 6.25mV
AV
Gain Accuracy
∆AV
OUT Settling Time to 1% of
Final Value
Capacitive Load Stability
MAX
UNITS
kHz
50
MAX437_T
Gain
TYP
VSENSE = 100mV,
Gain = +20V/V
+20
MAX437_F
+50
MAX437_H
+100
VSENSE =
20mV to 150mV;
VCC = 12V; VRS+ =
12V; Gain = 20, 50
TA = +25°C
VSENSE =
20mV to 100mV,
VCC = 12V, VRS+ =
12V, Gain = 100
TA = +25°C
Gain = +20V/V,
VCC = 12V,
VRS+ = 12V,
CLOAD = 10pF
VSENSE = 6.25mV to
100mV
20
VSENSE = 100mV to
6.25mV
20
±0.3
TA = -40°C to +85°C
V/V
±1.7
±2.7
%
±0.3
TA = -40°C to +85°C
±2.7
µs
No sustained oscillations
OUT Output Resistance
ROUT
VSENSE = 100mV
Power-Supply Rejection
PSR
VOUT = 2V, VRS+ > 2V
±1.7
1000
72
pF
1.5
Ω
87
dB
Power-Up Time to 1% of Final
Value
VSENSE = 100mV, CLOAD = 10pF,
VCC = 12V, VRS+ = 12V
0.5
ms
Saturation Recovery Time
(Note 8)
VCC = 12V, VRS+ = 12V, CLOAD = 10pF
0.1
ms
COMPARATOR (Note 9)
Comparator Threshold
VTH
TA = +25°C
590
TA = TMIN to TMAX
586
Comparator Hysteresis
Input Bias Current
610
614
-9
IB
±2.2
CL = 10pF, RL = 10kΩ pull-up to 5V,
5mV of overdrive
Propagation Delay
Output Low Voltage
600
VOL
ISINK = 1mA
mV
mV
±15
4
nA
µs
0.6
V
_______________________________________________________________________________________
www.BDTIC.com/maxim
3
MAX4373/MAX4374/MAX4375
ELECTRICAL CHARACTERISTICS (continued)
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +2.7V to +28V, VRS+ = 0 to +28V, VSENSE = 0, V RESET = 0, RLOAD= 1MΩ, TA = TMIN to TMAX, unless otherwise noted. Typical
values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
Output High Leakage Current
CONDITIONS
MIN
TYP
MAX
UNITS
1
µA
VCC = 28V, VPULL-UP = 5V (Note 10)
RESET Input High Voltage
VIH
RESET Input Low Voltage
VIL
2.0
0.5
µA
IIL, IIH
tRPW
1.5
µs
RESET Propagation Delay
tRPD
3
µs
Note 7:
Note 8:
Note 9:
Note 10:
Note 11:
-0.5
V
Minimum RESET Pulse Width
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
VIL = 0, VIH = 5.5V, VCC = 28V
V
0.8
Logic Input Current
All devices are 100% production tested at TA = +25°C. All temperature limits are guaranteed by design.
Guaranteed by PSR test.
Guaranteed by OUT Voltage Error test.
Guaranteed by Gain Accuracy test. Output voltage is internally clamped not to exceed 12V.
Total OUT Voltage Error and Full-Scale Accuracy are the sum of gain and offset voltage errors.
Measured at IOUT = -500µA (RLOAD = 4kΩ for gain of +20V/V, RLOAD = 10kΩ for gain of +50V/V, RLOAD = 20kΩ for gain of
+100V/V).
+6.25mV = 1/16 of +100mV full-scale voltage.
The device will not experience phase reversal when overdriven.
All comparator tests are done with VRS+ = +12V.
VPULL-UP is defined as an externally applied voltage through a resistor to pull up the comparator output.
VOS is extrapolated from the gain accuracy test.
Typical Operating Characteristics
(VRS+ = +12V, VCC = +12V, R LOAD = 1MΩ, V RESET = 0, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA = +25°C, unless
otherwise noted.)
SUPPLY CURRENT
vs. COMMON-MODE VOLTAGE
51
MAX4373
30
20
50
1.0
49
48
47
MAX4373
5
10
15
20
SUPPLY VOLTAGE (V)
4
AV = +20V/V
-0.5
VSENSE = 100mV
-2.0
44
0
25
30
AV = +50V/V
0
VSENSE = 5mV
0
AV = +100V/V
-1.5
45
VSENSE = 5mV
0.5
-1.0
46
10
1.5
MAX4374/MAX4375
OUTPUT ERROR (%)
SUPPLY CURRENT (µA)
50
2.0
MAX4373 toc02
MAX4374/MAX4375
40
52
MAX4373 toc01
60
TOTAL OUTPUT ERROR
vs. SUPPLY VOLTAGE
MAX4373 toc03
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SUPPLY CURRENT (µA)
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
0
5
10
15
20
25
COMMON-MODE VOLTAGE (V)
30
2 4 6 8 10 12 14 16 18 20 22 24 26 28
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
www.BDTIC.com/maxim
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
TOTAL OUTPUT ERROR
vs. SUPPLY VOLTAGE
1.0
0
AV = +20V/V
-1
-2
-3
-4
1.5
0.5
OUTPUT ERROR (%)
OUTPUT ERROR (%)
1
AV = +100V/V
0
AV = +20V/V
-0.5
-1.0
MAX4373 toc06
VCC = +5.5V
2
AV = +50V/V
1.0
AV = +100V/V
AV = +20V/V
0.5
0
AV = +50V/V
-0.5
-1.5
-1.0
-2.0
-1.5
VSENSE = 6.25mV
-2.0
-2.5
2 4 6 8 10 12 14 16 18 20 22 24 26 28
0
25
SUPPLY VOLTAGE (V)
50
75
100
125
10
AV = +100V/V
2.0
AV = +50V/V
AV = +20V/V
4
-2
125
AV = +50V/V
2
0
100
AV = +20V/V
2 4 6 8 10 12 14 16 18 20 22 24 26 28
150
COMMON-MODE VOLTAGE (V)
VSENSE (mV)
SMALL-SIGNAL PULSE RESPONSE
(AV = +20V/V)
30mV
INPUT
INPUT
30mV
10mV
10mV
10mV
600mV
1.5V
3V
200mV
OUTPUT
INPUT
MAX4373 toc11
MAX4373 toc10
MAX4373 toc09
20µs/div
SMALL-SIGNAL PULSE RESPONSE
(AV = +100V/V)
SMALL-SIGNAL PULSE RESPONSE
(AV = +50V/V)
30mV
150
6
0
75
125
AV = +100V/V
8
0.5
50
100
MAX4373 toc08
12
OUTPUT ERROR (%)
OUTPUT ERROR (%)
2.5
1.5
75
TOTAL OUTPUT ERROR
vs. COMMON-MODE VOLTAGE
VCC = +28V
25
50
VSENSE (mV)
MAX4373 toc07
3.0
0
25
VSENSE (mV)
TOTAL OUTPUT ERROR
vs. SENSE VOLTAGE
1.0
0
150
OUTPUT
-5
OUTPUT
OUTPUT ERROR (%)
AV = +50V/V
2.0
MAX4373 toc05
4
AV = +100V/V
1.5
MAX4373 toc04
5
3
TOTAL OUTPUT ERROR
vs. SENSE VOLTAGE
TOTAL OUTPUT ERROR
vs. SENSE VOLTAGE
1V
500mV
20µs/div
20µs/div
_______________________________________________________________________________________
www.BDTIC.com/maxim
5
MAX4373/MAX4374/MAX4375
Typical Operating Characteristics (continued)
(VRS+ = +12V, VCC = +12V, R LOAD = 1MΩ, V RESET = 0, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA = +25°C, unless
otherwise noted.)
Typical Operating Characteristics (continued)
(VRS+ = +12V, VCC = +12V, R LOAD = 1MΩ, V RESET = 0, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA = +25°C, unless
otherwise noted.)
LARGE-SIGNAL PULSE RESPONSE
(AV = +50V/V)
LARGE-SIGNAL PULSE RESPONSE
(AV = +20V/V)
MAX4373 toc14
150mV
5mV
3V
7.5V
9.5V
2.5V
20µs/div
POWER-SUPPLY REJECTION
vs. FREQUENCY
COMMON-MODE REJECTION
vs. FREQUENCY
-20
-30
-30
-40
-40
PSR (dB)
-50
-60
-70
-70
-80
-80
-90
-90
-100
-100
100
1k
10k
100
1k
10k
FREQUENCY (Hz)
SMALL-SIGNAL GAIN
vs. FREQUENCY
LARGE-SIGNAL GAIN
vs. FREQUENCY
5
MAX4373 toc17
3
2
3
2
AV = +20V/V
AV = +50V/V
0
AV = +100V/V
-3
-4
-4
-5
-5
1000k
AV = +50V/V
-1
-3
100k
100k
0
-2
FREQUENCY (Hz)
AV = +20V/V
1
-2
10k
VIN = 100mVp-p (20, 50)
VIN = 50mVp-p (100)
4
GAIN (dB)
GAIN (dB)
10
100k
FREQUENCY (Hz)
4
1k
MAX4373 toc16
-50
-60
MAX4373 toc18
CMR (dB)
-10
-20
5
6
0
MAX4373 toc15
0
-10
-1
500mV
20µs/div
20µs/div
1
OUTPUT
50mV
OUTPUT
50mV
1V
10
95mV
INPUT
INPUT
150mV
INPUT
LARGE-SIGNAL PULSE RESPONSE
(AV = +100V/V)
MAX4373 toc13
MAX4373 toc12
OUTPUT
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
AV = +100V/V
1k
10k
100k
FREQUENCY (Hz)
_______________________________________________________________________________________
www.BDTIC.com/maxim
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
COMPARATOR POWER-UP DELAY
POWER-UP DELAY
MAX4373 toc20
MAX4373 toc19
VCC = VPULL-UP
AV = +20V/V
5V
6V
VCC
VCC
0
0
2V
5V
OUTPUT
OUTPUT
0
10µs/div
COMPARATOR TRIP POINT vs.
SUPPLY VOLTAGE
COMPARATOR PROPAGATION DELAY
MAX4373 toc21
599
598
597
MAX4373 toc22
100µs/div
600
TRIP POINT (mV)
0
VOD = 5mV
INPUT
125mV/div
596
595
594
593
OUTPUT
2.5V/div
592
591
590
0
5
10
15
20
25
30
2µs/div
SUPPLY VOLTAGE (V)
COMPARATOR PROPAGATION DELAY
vs. OVERDRIVE VOLTAGE
VOD = 5mV
6
PROPAGATION DELAY (µs)
3.4
3.2
3.0
2.8
2.6
2.4
MAX4373 toc26
3.6
PROGAGATION DELAY (µs)
7
MAX4373 toc24
3.8
COMPARATOR PROPAGATION DELAY
vs. TEMPERATURE
5
4
3
2
1
2.2
2
0
0
20 40 60 80 100 120 140 160 180 200
OVERDRIVE VOLTAGE (mV)
-50
-30
-10
10
30
50
70
90
TEMPERATURE (°C)
_______________________________________________________________________________________
www.BDTIC.com/maxim
7
MAX4373/MAX4374/MAX4375
Typical Operating Characteristics (continued)
(VRS+ = +12V, VCC = +12V, R LOAD = 1MΩ, V RESET = 0, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA = +25°C, unless
otherwise noted.)
Typical Operating Characteristics (continued)
(VRS+ = +12V, VCC = +12V, R LOAD = 1MΩ, V RESET = 0, VSENSE = 100mV, VPULL-UP = +5V, RPULL-UP = 10kΩ, TA = +25°C, unless
otherwise noted.)
COMPARATOR RESET VOLTAGE
vs. SUPPLY VOLTAGE
MAX4373 toc28
1.8
80
70
60
1.6
VOL (mV)
RESET VOLTAGE (V)
COMPARATOR VOL vs. ISINK
90
MAX4373 toc27
2.0
1.4
50
40
30
1.2
20
1.0
10
0
0.8
10
15
20
25
0
30
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
ISINK (mA)
SUPPLY VOLTAGE (V)
TOTAL OUTPUT ERROR
vs. TEMPERATURE
SUPPLY CURRENT
vs. TEMPERATURE
COMPARATOR AC RESPONSE
MAX4373 toc31
750mV
60
MAX4374
MAX4375
5V
OUTPUT
SUPPLY CURRENT (µA)
INPUT
250mV
MAX4373 toc32
70
50
40
MAX4373
30
20
1.0
MAX4373 toc33
5
TOTAL OUTPUT ERROR (%)
0
0.8
0.6
0.4
0.2
0
10
VSENSE = 5mV
0
0
10µs/div
-60
-40
-20
0
20
40
60
80
-60
100
-40
-20
GAIN ACCURACY
vs. TEMPERATURE
20
40
COMPARATOR TRIP POINT
vs. TEMPERATURE
AV = +20V/V, +50V/V
AV = +100V/V
0.4
0.2
MAX4373 toc35
0.8
605
604
COMPARATOR TRIP POINT (mV)
MAX4373 toc34
1.0
0.6
0
TEMPERATURE (°C)
TEMPERATURE (°C)
GAIN ACCURACY (%)
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
603
602
601
600
599
598
597
596
595
0
-60
-40
-20
0
20
40
TEMPERATURE (°C)
8
60
80
100
-60
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
_______________________________________________________________________________________
www.BDTIC.com/maxim
60
80
100
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
PIN
NAME
FUNCTION
MAX4373
MAX4374/MAX4375
µMAX/SO
µMAX
SO
1
1
1
VCC
Supply Voltage Input
2
2
2
OUT
Voltage Output. VOUT is proportional to VSENSE (VRS+ - VRS-).
3
3
4
CIN1
Comparator Input 1. Positive input of an internal comparator. The negative terminal is connected to a 0.6V internal reference.
—
4
5
CIN2
Comparator Input 2. Terminal of a second internal comparator. The positive terminal for the MAX4374 and the negative terminal for the
MAX4375. The other terminal is connected to a 0.6V internal reference.
4
5
7
GND
Ground
5
6
8
RESET
Reset Input. Resets the output latch of the comparator at CIN1.
6
8
11
COUT1
Open-Drain Comparator Output. Latching output of the comparator controlled by CIN1. Connect RESET to GND to disable the latch.
—
7
10
COUT2
Open-Drain Comparator Output. Output of the second unlatched internal comparator.
7
9
13
RS-
Load-Side Connection for the External Sense Resistor
8
10
14
RS+
Power Connection to the External Sense Resistor
—
—
3, 6, 9, 12
N.C.
No Connection. Not internally connected.
FUNCTION
Detailed Description
+ VSENSE -
VIN = 0 TO 28V
RSENSE
RS+
LOAD
RS-
VCC
CURRENTSENSE
AMPLIFIER
VPULL-UP
(UP TO 5V)
R3
VPULL-UP
(UP TO 5V)
R6
COUT1
+
-
OUT
R1
+(-)
-(+)
0.6V
BANDGAP
REFERENCE
MAX4374
(MAX4375)
GND
Figure 1. Functional Diagram
Current-Sense Amplifier
R2
RESET
COUT2
R4
CIN1
The MAX4373 high-side current-sense supervisor features a high-side current-sense amplifier, bandgap reference, and comparator with latching output to monitor
a supply for an overcurrent condition (Figure 1). The
latching output allows the comparator to shut down a
power supply without oscillations. The MAX4374/
MAX4375 offer an additional comparator to allow window detection of the current.
CIN2
R5
The internal current-sense amplifier features a 0V to
+28V input common-mode range that is independent of
the supply voltage. With this feature, the device can
monitor the output current of a battery in deep discharge and also high-side current-sensing voltages
exceeding VCC.
The current-sense amplifier is also suitable for low-side
current sensing. However, the total output voltage error
will increase when VRS+ falls below 2V, as shown in
the Electrical Characteristics and Typical Operating
Characteristics.
_______________________________________________________________________________________
www.BDTIC.com/maxim
9
MAX4373/MAX4374/MAX4375
Pin Description
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
Internal Comparator(s)
The MAX4373/MAX4374/MAX4375 contain an opendrain output comparator for current limiting. The comparator’s negative terminal is connected to the internal
600mV reference. The positive terminal is accessible at
CIN1. When RESET is high, the internal latch is active,
and once CIN1 rises above 600mV, the output latches
into the open state. Pulsing RESET low for 1.5µs resets
the latch, and holding RESET low makes the latch
transparent. See RESET at Power-Up section
The MAX4374/MAX4375 contain an additional opendrain comparator. The negative terminal of the
MAX4374’s additional comparator and the positive terminal of the MAX4375’s additional comparator are connected to the internal 600mV reference as shown in
Figure 1. The positive terminal of the MAX4374’s additional comparator and the negative terminal of the
MAX4375’s additional comparator are accessible at
CIN2.
LOAD
RS+
RS-
2.7V TO 5.5V
OUT
COUT1
VCC
MAX4373
R
CIN1
RESET
PUSHBUTTON
C
GND
___________Applications Information
Figure 2. MAX4373 Overcurrent Protection Circuit
Recommended Component Values
Ideally, the maximum load current will develop the fullscale sense voltage across the current-sense resistor.
Choose the gain version needed to yield the maximum
output voltage required for the application:
VOUT = VSENSE × AV
where VSENSE is the full-scale sense voltage, 150mV for
gains of +20V/V and +50V/V or 100mV for a gain of
+100V/V. AV is the gain of the device. The minimum
supply voltage is VOUT + 0.25V. Note that the output for
the gain of +100V/V is internally clamped at 12V.
Calculate the maximum value for RSENSE so that the
differential voltage across RS+ and RS- does not
exceed the full-scale sense voltage:
RSENSE(MAX) =
VSENSE(MAX)
ILOAD
Choose the highest value resistance possible to maximize VSENSE and thus minimize total output error.
In applications monitoring high current, ensure that
RSENSE is able to dissipate its own I2R loss. If the resistor’s power dissipation is exceeded, its value may drift
or it may fail altogether, causing a differential voltage
across the terminals in excess of the absolute maximum ratings. Use resistors specified for current-sensing applications.
10
Overcurrent Protection Circuit
The overcurrent protection circuit, shown in Figure 2,
uses the MAX4373 to control an external P-channel
MOSFET. The MOSFET controlled by the MAX4373
opens the current path under overload conditions. The
latched output of the MAX4373’s comparator prevents
the circuit from oscillating, and the pushbutton resets
the current path after an overcurrent condition.
Window Detection Circuit
Figure 3 shows a simple circuit suitable for window
detection. Let I OVER be the minimum load current
IUNDER =
VREF
RSENSE
×
 R4 + R5 


AV 
R5 
and
IOVER =
VREF
RSENSE
×
 R1 + R2 


AV  R2 
(ILOAD) required to cause a low state at COUT2, and let
IUNDER be the maximum load current required to cause
a high state at COUT1:
where AV is the gain of the device and VREF is the internal reference voltage (0.6V typ).
Connect COUT1 and COUT2; the resulting comparator
output will be high when the current is inside the current window and low when the current is outside the
window. The window is defined as load currents less
than IOVER and greater than IUNDER.
______________________________________________________________________________________
www.BDTIC.com/maxim
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
The RESET pin is used to control the latch function of
comparator 1. Holding RESET low (<0.8V) makes the
latch transparent and COUT1 will respond to changes
at CIN1, above and below the internal 600mV reference
threshold voltage. When RESET is high (>2.0V), once
CIN1 rises above 600mV, COUT1 latches into the
open-drain OFF state and remains in this state even if
CIN1 drops below 600mV. Pulsing RESET low for at
least 1.5µs resets the latch.
VIN = 0 TO 28V
RSENSE
LOAD
RS+
VCC = 2.7V TO 28V
RS-
VCC
OUT
VPULL-UP
(UP TO 5V)
R1
MAX4375
R3
CIN2
COUT1
R4
R2
CIN1
COUT2
GND
RESET
R5
GND
There is no internal circuitry to control the reset function
during power-up. To prevent false latching, RESET
must be held low until the VCC power has risen above
the 2.7V minimum operating supply voltage. This is
easily accomplished when RESET is driven under µC or
logic gate control. However, if RESET is to be always
connected high, add an RC between VCC, RESET and
GND (see Figure 2). Note that RESET cannot exceed
VCC + 0.3V or +12V, whichever is less.
The following formula can be used to determine the
appropriate RC value.
Figure 3. MAX4375 Window Detector
RC =
Power-Supply Bypassing
It is recommended that VCC be bypassed to GND with
at least a 0.1µF ceramic capacitor to isolate the IC from
supply voltage transients. It is possible that plugging
in/out a battery or AC adapter/charger could cause
large, fast line transients (>5V/µs) at VCC. The simplest
solution is to run VCC from a better regulated supply
(+5V for example), since VCC and RS+ (or RS-) do not
have to be connected together.
T
T
=
ln(2.7V /(2.7V − 0.8V)) 0.3514
where T is the maximum time for VCC to reach 2.7V and
0.8V is the maximum RESET logic low voltage. For
example, a 470kΩ resistor and 0.22µF capacitor will
keep RESET low during a power-up time of up to 36ms.
A faster power-up time is also safe with the calculated
R and C since the capacitor will have even less time to
charge.
For high-speed VCC transients, another solution is to
add a resistor in series with the VCC pin and a 0.1µF
capacitor to create an RC time constant to slow the rise
time of the transient. Since these current-sense amplifiers consume less than 100µA, even a 2.5kΩ resistor
only drops an extra 250mV at VCC. For most applications with fast transients, 1kΩ in conjunction with a
0.1µF bypass capacitor works well.
______________________________________________________________________________________
www.BDTIC.com/maxim
11
MAX4373/MAX4374/MAX4375
RESET at Power-Up
ILOAD
+ VSENSE -
MAX4373/MAX4374/MAX4375
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
Pin Configurations
TOP VIEW
VCC 1
8
OUT 2
CIN1
MAX4373
7
RS+
RS-
3
6
COUT1
GND 4
5
RESET
VCC 1
OUT 2
CIN1 3
MAX4374
MAX4375
CIN2 4
GND 5
Ordering Information (continued)
PART
TEMP RANGE
PINPACKAGE
MAX4374TEUB
-40°C to +85°C
10 µMAX
MAX4374TESD
-40°C to +85°C
14 SO
+20
MAX4374FEUB
-40°C to +85°C
10 µMAX
+50
MAX4374FESD
-40°C to +85°C
14 SO
+50
MAX4374HEUB
-40°C to +85°C
10 µMAX
+100
MAX4374HESD
-40°C to +85°C
14 SO
+100
MAX4375TEUB
-40°C to +85°C
10 µMAX
+20
MAX4375TESD
-40°C to +85°C
14 SO
+20
MAX4375FEUB
-40°C to +85°C
10 µMAX
+50
MAX4375FESD
-40°C to +85°C
14 SO
+50
MAX4375HEUB
-40°C to +85°C
10 µMAX
+100
MAX4375HESD
-40°C to +85°C
14 SO
+100
12
GAIN
(V/V)
14 RS+
13 RS-
10 RS+
N.C. 3
12 N.C.
9
RS-
CIN1 4
8
COUT1
CIN2 5
7
COUT2
N.C. 6
9
N.C.
RESET
GND 7
8
RESET
6
µMAX
µMAX/SO
VCC 1
OUT 2
MAX4374
MAX4375
11 COUT1
10 COUT2
SO
___________________Chip Information
TRANSISTOR COUNT: 390
SUBSTRATE CONNECTED TO GND
+20
______________________________________________________________________________________
www.BDTIC.com/maxim
Low-Cost, Micropower, High-Side Current-Sense
Amplifier + Comparator + Reference ICs
E
ÿ 0.50±0.1
8
H
MIN
0.002
0.030
0.6±0.1
L
1
α
0.6±0.1
S
BOTTOM VIEW
D
MAX
0.043
0.006
0.037
0.05
0.75
1.10
0.15
0.95
0.25
0.36
0.13
0.18
2.95
3.05
0.65 BSC
2.95
3.05
4.78
5.03
0.41
0.66
0∞
6∞
0.5250 BSC
0.014
0.010
0.007
0.005
0.120
0.116
0.0256 BSC
0.120
0.116
0.198
0.188
0.026
0.016
6∞
0∞
0.0207 BSC
c
D
e
E
H
1
MILLIMETERS
MAX
MIN
INCHES
DIM
A
A1
A2
b
8LUMAXD.EPS
4X S
8
TOP VIEW
A1
A2
A
c
e
α
L
b
SIDE VIEW
FRONT VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
DOCUMENT CONTROL NO.
21-0036
e
REV.
J
1
1
10LUMAX.EPS
APPROVAL
4X S
10
INCHES
10
H
ÿ 0.50±0.1
0.6±0.1
1
1
0.6±0.1
BOTTOM VIEW
TOP VIEW
D2
MILLIMETERS
MAX
DIM MIN
0.043
A
A1
0.002
0.006
A2
0.030
0.037
D1
0.116
0.120
D2
0.114
0.118
E1
0.116
0.120
E2
0.114
0.118
H
0.187
0.199
L
0.0157 0.0275
L1
0.037 REF
0.0106
b
0.007
e
0.0197 BSC
c
0.0035 0.0078
0.0196 REF
S
α
0∞
6∞
MAX
MIN
1.10
0.05
0.15
0.75
0.95
2.95
3.05
2.89
3.00
2.95
3.05
2.89
3.00
4.75
5.05
0.40
0.70
0.940 REF
0.177
0.270
0.500 BSC
0.090
0.200
0.498 REF
0∞
6∞
E2
GAGE PLANE
A2
c
A
b
D1
A1
α
FRONT VIEW
E1
L
L1
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 10L uMAX/uSOP
APPROVAL
DOCUMENT CONTROL NO.
21-0061
REV.
I
1
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 13
© 2003 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
www.BDTIC.com/maxim
MAX4373/MAX4374/MAX4375
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)