MAX9938HEUK [MAXIM]
1レA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier; 1μA ， 4焊球UCSP / SOT23封装，高精度电流检测放大器
| 型号： | MAX9938HEUK |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 1レA, 4-Bump UCSP/SOT23, Precision Current-Sense Amplifier |
| 文件： | 总9页 (文件大小：172K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-4110; Rev 0; 4/08
1µA, 4-Bump UCSP/SOT23,
Precision Current-Sense Amplifier
MAX938
General Description
Features
The MAX9938 high-side current-sense amplifier offers
o Ultra-Low Supply Current of 1µA (max)
precision accuracy specifications of V
less than
OS
o Low 500µV (max) Input Offset Voltage
o Low < 0.5% (max) Gain Error
o Input Common Mode: +1.6V to +28V
o Voltage Output
500μV (max) and gain error less than 0.5% (max).
Quiescent supply current is an ultra-low 1μA. The
MAX9938 fits in a tiny, 1mm x 1mm UCSP™ package
size or a 5-pin SOT23 package, making the part ideal for
applications in notebook computers, cell phones, PDAs,
and all battery-operated portable devices where accura-
cy, low quiescent current, and small size are critical.
o Three Gain Versions Available
25V/V (MAX9938T)
50V/V (MAX9938F)
100V/V (MAX9938H)
The MAX9938 features an input common-mode voltage
range from 1.6V to 28V. These current-sense amplifiers
have a voltage output and are offered in three gain ver-
sions: 25V/V (MAX9938T), 50V/V (MAX9938F), and
100V/V (MAX9938H).
o Tiny 1mm x 1mm x 0.6mm, 4-Bump UCSP
or 5-Pin SOT23 Package
The three gain selections offer flexibility in the choice of
the external current-sense resistor. The very low 500μV
(max) input offset voltage allows small 25mV to 50mV
Ordering Information
PIN-
PART
GAIN (V/V)
TOP MARK
full-scale V
voltage for very low voltage drop at
SENSE
PACKAGE
full-current measurement.
MAX9938TEBS+ 4 UCSP
MAX9938FEBS+ 4 UCSP
MAX9938HEBS+ 4 UCSP
MAX9938TEUK+ 5 SOT23
MAX9938FEUK+ 5 SOT23
MAX9938HEUK+ 5 SOT23
+Denotes a lead-free package.
25
50
+AGD
+AGE
+AGF
The MAX9938 is offered in tiny 4-bump, UCSP (1mm x
1mm x 0.6mm footprint) and 5-pin SOT23 packages,
specified for operation over the -40°C to +85°C extend-
ed temperature range.
100
25
+AFFB
+AFFC
+AFFD
50
Applications
100
Cell Phones
PDAs
Note: All devices are specified over the -40°C to +85°C
extended temperature range.
Power Management Systems
Portable/Battery-Powered Systems
Notebook Computers
UCSP is a trademark of Maxim Integrated Products, Inc.
Pin Configurations
TOP VIEW
(BUMPS ON BOTTOM)
RS+
5
RS-
4
RS+
A1
A2
B2
RS-
MAX9938T/F/H
MAX9938T/F/H
GND
B1
OUT
1
2
3
UCSP
GND
GND
OUT
SOT23
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1µA, 4-Bump UCSP/SOT23,
Precision Current-Sense Amplifier
ABSOLUTE MAXIMUM RATINGS
RS+, RS- to GND....................................................-0.3V to +30V
OUT to GND .............................................................-0.3V to +6V
RS+ to RS- ........................................................................... 30V
Short-Circuit Duration: OUT to GND ..........................Continuous
Continuous Input Current (Any Pin).................................. 20mA
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range ............................-65°C to +150°C
Bump Temperature (soldering) Reflow............................+235°C
Lead Temperature (soldering, 10s) .................................+300°C
Continuous Power Dissipation (T = +70°C)
A
4-Bump UCSP (derate 3.0mW/°C above +70°C).........238mW
5-Pin SOT23 (derate 3.9mW/°C above +70°C)............312mW
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.
MAX938
ELECTRICAL CHARACTERISTICS
(V
RS+
= V
= 3.6V, V
= (V
- V ) = 0V, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)
RS-
SENSE
RS+
RS-
A
A
PARAMETER
SYMBOL
CONDITIONS
= 5V, T = +25°C
MIN
TYP
MAX
0.85
1.1
UNITS
V
V
V
V
0.5
RS+
RS+
RS+
RS+
A
= 5V, -40°C < T < +85°C
A
Supply Current (Note 2)
I
μA
CC
= 28V, T = +25°C
1.1
1.8
A
= 28V, -40°C < T < +85°C
2.5
A
Common-Mode Input Range
Common-Mode Rejection Ratio
V
Guaranteed by CMRR , -40°C < T < +85°C
1.6
94
28
V
CM
A
CMRR
1.6V < V
< 28V, -40°C < T < +85°C
130
100
dB
RS+
A
T
A
= +25°C
500
600
Input Offset Voltage (Note 3)
V
μV
OS
-40°C < T < +85°C
A
MAX9938T
MAX9938F
MAX9938H
25
50
Gain
G
V/V
100
0.1
T
A
= +25°C
0.5
0.6
13.2
15
Gain Error (Note 4)
Output Resistance
GE
%
-40°C < T < +85°C
A
R
(Note 5)
7.0
10
1.5
3
kΩ
OUT
Gain = 25
Gain = 50
Gain = 100
OUT Low Voltage
OUT High Voltage
V
30
mV
V
OL
6
60
V
V
V
V
V
= V
- V (Note 6)
OUT
0.1
125
60
0.2
OH
OH
RS-
= 50mV, gain = 25
= 50mV, gain = 50
= 50mV, gain = 100
SENSE
SENSE
SENSE
Small-Signal Bandwidth
(Note 5)
BW
kHz
30
Output Settling Time
Power-Up Time
t
1% final value, V
1% final value, V
= 50mV
= 50mV
100
200
μs
μs
S
SENSE
SENSE
t
ON
Note 1: All devices are 100% production tested at T = +25°C. All temperature limits are guaranteed by design.
A
Note 2: V
= 0. I
is the total current into RS+ plus RS- pins.
OUT
CC
Note 3: V is extrapolated from measurements for the gain-error test.
OS
Note 4: Gain error is calculated by applying two values of V
and calculating the error of the slope vs. the ideal:
SENSE
Gain = 25, V
Gain = 50, V
is 20mV and 120mV.
is 10mV and 60mV.
SENSE
SENSE
Gain = 100, V
is 5mV and 30mV.
SENSE
Note 5: The device is stable for any external capacitance value.
Note 6: V is the voltage from V to V with V = 3.6V/gain.
OH
RS-
OUT
SENSE
2
_______________________________________________________________________________________
1µA, 4-Bump UCSP/SOT23,
Precision Current-Sense Amplifier
MAX938
Typical Operating Characteristics
(V
= V
= 3.6V, T = +25°C, unless otherwise noted.)
RS- A
RS+
SUPPLY CURRENT
vs. TEMPERATURE
GAIN ERROR HISTOGRAM
INPUT OFFSET VOLTAGE HISTOGRAM
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
30
25
20
15
10
5
30
25
20
15
10
5
28V
3.6V
1.8V
0
0
-40
-15
10
35
60
85
-0.4 -0.3 -0.2 -0.1
0
0.1 0.2 0.3 0.4
-0.4 -0.3 -0.2 -0.1
0
0.1 0.2 0.3 0.4
TEMPERATURE (°C)
GAIN ERROR (%)
INPUT OFFSET VOLTAGE (mV)
INPUT OFFSET
vs. COMMON-MODE VOLTAGE
INPUT OFFSET
vs. TEMPERATURE
SUPPLY CURRENT
vs. COMMON-MODE VOLTAGE
-30
-35
-40
-45
-50
-55
60
50
40
30
20
10
0
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0
5
10
15
20
25
30
-40
-15
10
35
60
85
0
5
10
15
20
25
30
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
GAIN ERROR
vs. COMMON-MODE VOLTAGE
V
vs. V
GAIN ERROR
vs. TEMPERATURE
OUT SENSE
(SUPPLY = 3.6V)
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
0.1
0
G = 100
G = 50
-0.1
-0.2
-0.3
-0.4
-0.5
G = 25
0
5
10
15
20
25
30
0
50
100
150
-40
-15
10
35
60
85
VOLTAGE (V)
V
(mV)
SENSE
TEMPERATURE (°C)
_______________________________________________________________________________________
3
1µA, 4-Bump UCSP/SOT23,
Precision Current-Sense Amplifier
Typical Operating Characteristics (continued)
(V
= V
= 3.6V, T = +25°C, unless otherwise noted.)
RS+
RS-
A
V
vs. V
SMALL SIGNAL GAIN
vs. FREQUENCY
CMRR
vs. FREQUENCY
OUT
SENSE
(SUPPLY = 1.6V)
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
5
0
0
-20
A
= 25V/V
V
G = 25
-40
MAX938
A
= 100V/V
V
-5
G = 50
-60
G = 100
G = 50
A
= 50V/V
V
-10
-15
-20
-25
-30
-80
G = 100
-100
-120
-140
-160
G = 25
0
20
40
60
80
100
1Hz 10Hz 100Hz 1kHz 10kHz 100kHz 1MHz
FREQUENCY (kHz)
1Hz 10Hz 100Hz 1kHz 10kHz 100kHz 1MHz
FREQUENCY (kHz)
V
(mV)
SENSE
SMALL-SIGNAL PULSE RESPONSE
(G = 100)
SMALL-SIGNAL PULSE RESPONSE
(G = 50)
MAX9938 toc13a
MAX9938 toc13b
15mV
10mV
30mV
V
SENSE
V
SENSE
20mV
1.5V
1.5V
1V
V
OUT
V
OUT
1V
20μs/div
25μs/div
SMALL-SIGNAL PULSE RESPONSE
(G = 25)
MAX9938 toc13c
60mV
V
SENSE
40mV
1.5V
V
OUT
1V
25μs/div
4
_______________________________________________________________________________________
1µA, 4-Bump UCSP/SOT23,
Precision Current-Sense Amplifier
MAX938
Typical Operating Characteristics (continued)
(V
= V
= 3.6V, T = +25°C, unless otherwise noted.)
RS- A
RS+
LARGE-SIGNAL PULSE RESPONSE
(G = 100)
LARGE-SIGNAL PULSE RESPONSE
(G = 50)
MAX9938 toc14a
MAX9938 toc14b
30mV
10mV
60mV
V
V
SENSE
SENSE
10mV
3V
3V
1V
V
OUT
V
OUT
0.5V
20μs/div
25μs/div
LARGE-SIGNAL PULSE RESPONSE
(G = 25)
MAX9938 toc14c
120mV
V
SENSE
20mV
3V
V
OUT
0.5V
25μs/div
Pin Description
PIN
NAME
FUNCTION
UCSP
A1
SOT23
5
4
RS+
RS-
External Sense Resistor Power-Side Connection
External Sense Resistor Load-Side Connection
Ground
A2
B1
1, 2
3
GND
OUT
B2
Output Voltage. V
is proportional to V
= V
- V
.
OUT
SENSE
RS+
RS-
_______________________________________________________________________________________
5
1µA, 4-Bump UCSP/SOT23,
Precision Current-Sense Amplifier
Typical Operating Circuit
I
LOAD
R
SENSE
V
BATT
= 1.6V TO 28V
RS+
RS-
9
R
1
R
1
V
DD
= 3.3V
LOAD
μC
P
MAX9938
OUT
ADC
R
OUT
10kΩ
GND
same value as R to minimize offset voltage. The cur-
1
Detailed Description
rent through R is sourced by a high-voltage p-channel
1
The MAX9938 unidirectional high-side, current-sense
amplifier features a 1.6V to 28V input common-mode
range. This feature allows the monitoring of current out
of a battery with a voltage as low as 1.6V. The
MAX9938 monitors current through a current-sense
resistor and amplifies the voltage across that resistor.
FET. Its source current is the same as its drain current,
which flows through a second gain resistor, R
. This
OUT
produces an output voltage, V
, whose magnitude is
OUT
I
x R
x R
/R . The gain accuracy is
LOAD
SENSE
OUT 1
based on the matching of the two gain resistors R and
1
R
(see Table 1). Total gain = 25V/V for the
OUT
The MAX9938 is a unidirectional current-sense amplifier
that has a well-established history. An op amp is used
to force the current through an internal gain resistor at
MAX9938T, 50V/V for the MAX9938F, and 100V/V for
the MAX9938H. The output is protected from input
overdrive by use of an output current limiting circuit of
7mA (typical) and a 6V clamp protection circuit.
RS+, which has a value of R , such that its voltage drop
1
equals the voltage drop across an external sense resis-
Applications Information
tor, R
. There is an internal resistor at RS- with the
SENSE
Choosing the Sense Resistor
Table 1. Internal Gain Setting Resistors
(Typical Values)
Choose R
based on the following criteria:
SENSE
Voltage Loss
value causes the power-source voltage
to drop due to IR loss. For minimal voltage loss, use the
lowest R value.
GAIN
(V/V)
R
R
OUT
(kΩ)
1
A high R
SENSE
(Ω)
100
200
400
100
50
10
SENSE
10
25
10
6
_______________________________________________________________________________________
1µA, 4-Bump UCSP/SOT23,
Precision Current-Sense Amplifier
MAX938
OUT Swing vs. V
and V
Efficiency and Power Dissipation
RS+
SENSE
The MAX9938 is unique since the supply voltage is the
input common-mode voltage (the average voltage at
At high current levels, the I2R losses in R
can be
SENSE
significant. Take this into consideration when choosing
the resistor value and its power dissipation (wattage)
rating. Also, the sense resistor’s value might drift if it is
RS+ and RS-). There is no separate V
supply voltage
CC
pin. Therefore, the OUT voltage swing is limited by the
minimum voltage at RS+.
allowed to heat up excessively. The precision V
of
OS
the MAX9938 allows the use of small sense resistors to
reduce power dissipation and reduce hot spots.
V
(max) = V
R
(min) - V
(max) - V
OUT
RS+
SENSE OH
and
Kelvin Connections
Because of the high currents that flow through R
,
SENSE
V
(max)
OUT
=
take care to eliminate parasitic trace resistance from
causing errors in the sense voltage. Either use a four-
terminal current-sense resistor or use Kelvin (force and
sense) PCB layout techniques.
SENSE
G×I
(max)
LOAD
V
full scale should be less than V
/gain at the
OUT
SENSE
minimum RS+ voltage. For best performance with a
3.6V supply voltage, select R to provide approxi-
mately 120mV (gain of 25V/V), 60mV (gain of 50V/V), or
30mV (gain of 100V/V) of sense voltage for the full-
scale current in each application. These can be
increased by use of a higher minimum input voltage.
Optional Output Filter Capacitor
When designing a system that uses a sample-and-hold
stage in the ADC, the sampling capacitor momentarily
loads OUT and causes a drop in the output voltage. If
sampling time is very short (less than a microsecond),
consider using a ceramic capacitor across OUT and
SENSE
Accuracy
GND to hold V
constant during sampling. This also
OUT
In the linear region (V
components to accuracy: input offset voltage (V ) and
gain error (GE). For the MAX9938, V
< V
), there are two
OUT
OUT(max)
decreases the small-signal bandwidth of the current-
sense amplifier and reduces noise at OUT.
OS
= 500μV (max)
OS
and gain error is 0.5% (max). Use the linear equation:
V
OUT
= (gain GE) x V (gain x V
)
OS
SENSE
to calculate total error. A high R
value allows lower
SENSE
currents to be measured more accurately because off-
sets are less significant when the sense voltage is larger.
_______________________________________________________________________________________
7
1µA, 4-Bump UCSP/SOT23,
Precision Current-Sense Amplifier
I
LOAD
R
SENSE
TO WALL-CUBE/
CHARGER
V
BATT
= 1.6V TO 28V
RS+
RS-
RS+
RS-
LOAD
MAX938
R
1
R
1
R
1
R
1
P
P
V = 3.3V
DD
MAX9938
MAX9938
OUT
OUT
R
OUT
R
OUT
10kΩ
10kΩ
μC
GND
GND
ADC
ADC
Figure 1. Bidirectional Application
Bidirectional Application
Battery-powered systems may require a precise bidi-
rectional current-sense amplifier to accurately monitor
the battery’s charge and discharge currents.
Measurements of the two separate outputs with respect
to GND yields an accurate measure of the charge and
discharge currents respectively (Figure 1).
UCSP Applications Information
For the latest application details on UCSP construction,
dimensions, tape carrier information, PCB techniques,
bump-pad layout, and recommended reflow tempera-
ture profile, as well as the latest information on reliability
testing results, refer to the Application Note UCSP—A
Wafer-Level Chip-Scale Package available on Maxim’s
website at www.maxim-ic.com/ucsp.
Chip Information
PROCESS: BiCMOS
8
_______________________________________________________________________________________
1µA, 4-Bump UCSP/SOT23,
Precision Current-Sense Amplifier
MAX938
Package Information
For the latest package outline information, go to www.maxim-ic.com/packages.
PACKAGE TYPE
2 x 2 UCSP
PACKAGE CODE
DOCUMENT NO.
21-0117
B4-1
U5-2
5 SOT23
21-0057
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 _____________________ 9
© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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