19-4110; Rev 3; 10/09
KIT
ATION
EVALU
BLE
AVAILA
1µA, 4-Bump UCSP/SOT23,
Precision Current-Sense Amplifier
General Description
Features
o
Ultra-Low Supply Current of 1µA (max)
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
o
Three Gain Versions Available
25V/V (MAX9938T)
50V/V (MAX9938F)
100V/V (MAX9938H)
200V/V (MAX9938W)
o
Tiny 1mm x 1mm x 0.6mm, 4-Bump UCSP,
5-Pin SOT23, or 2mm x 2mm x 0.8mm, 6-Pin
µDFN Packages
MAX9938
The MAX9938 high-side current-sense amplifier offers
precision accuracy specifications of V
OS
less than
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.
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 four gain versions:
25V/V (MAX9938T), 50V/V (MAX9938F), 100V/V
(MAX9938H), and 200V/V (MAX9938W).
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
full-scale V
SENSE
voltage for very low voltage drop at
full-current measurement.
The MAX9938 is offered in tiny 4-bump, UCSP (1mm x
1mm x 0.6mm footprint), 5-pin SOT23, and 6-pin µDFN
(2mm x 2mm x 0.8mm) packages specified for operation
over the -40°C to +85°C extended temperature range.
Ordering Information
PART
MAX9938TEBS+G45
MAX9938FEBS+G45
MAX9938HEBS+G45
MAX9938WEBS+G45
MAX9938TEUK+
MAX9938FEUK+
MAX9938HEUK+
MAX9938WEUK+
MAX9938FELT+
PIN-
PACKAGE
4 UCSP
4 UCSP
4 UCSP
4 UCSP
5 SOT23
5 SOT23
5 SOT23
5 SOT23
6 µDFN
GAIN
(V/V)
25
50
100
200
25
50
100
200
50
TOP
MARK
+AGD
+AGE
+AGF
+AGI
+AFFB
+AFFC
+AFFD
+AFGZ
+ACM
Applications
Cell Phones
PDAs
Power Management Systems
Portable/Battery-Powered Systems
Notebook Computers
+Denotes
a lead(Pb)-free/RoHS-compliant package.
G45 indicates protective die coating.
Note:
All devices are specified over the -40°C to +85°C
extended temperature range.
UCSP is a trademark of Maxim Integrated Products, Inc.
Pin Configurations
TOP VIEW
(BUMPS ON BOTTOM)
RS+
5
RS-
RS-
4
OUT
1
TOP VIEW
(PADS ON BOTTOM)
RS+
A1
A2
6
RS-
MAX9938T/F/H/W
GND
B1
B2
OUT
MAX9938T/F/H/W
N.C.
2
MAX9938FELT
5
N.C.
GND
UCSP
DRAWINGS NOT TO SCALE
1
GND
2
GND
SOT23
3
OUT
3
4
RS+
µDFN
________________________________________________________________
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
MAX9938
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
Continuous Power Dissipation (T
A
= +70°C)
4-Bump UCSP (derate 3.0mW/°C above +70°C).........238mW
5-Pin SOT23 (derate 3.9mW/°C above +70°C)............312mW
6-Pin µDFN (derate 4.5mW/°C above +70°C) .............358mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range ............................-65°C to +150°C
Bump Temperature (soldering) Reflow............................+260°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°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
(V
RS+
= V
RS-
= 3.6V, V
SENSE
= (V
RS+
- V
RS-
) = 0V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
V
RS+
= 5V, T
A
= +25°C
Supply Current (Note 2)
I
CC
V
RS+
= 5V, -40°C < T
A
< +85°C
V
RS+
= 28V, T
A
= +25°C
V
RS+
= 28V, -40°C < T
A
< +85°C
Common-Mode Input Range
Common-Mode Rejection Ratio
Input Offset Voltage (Note 3)
V
CM
CMRR
V
OS
Guaranteed by CMRR , -40°C < T
A
< +85°C
1.6V < V
RS+
< 28V, -40°C < T
A
< +85°C
T
A
= +25°C
-40°C < T
A
< +85°C
MAX9938T
Gain
G
MAX9938F
MAX9938H
MAX9938W
Gain Error (Note 4)
Output Resistance
GE
R
OUT
T
A
= +25°C
-40°C < T
A
< +85°C
(Note 5)
Gain = 25
OUT Low Voltage
V
OL
Gain = 50
Gain = 100
Gain = 200
OUT High Voltage
Small-Signal Bandwidth
(Note 5)
Output Settling Time
Power-Up Time
V
OH
V
OH
= V
RS-
- V
OUT
(Note 6)
V
SENSE
= 50mV, gain = 25
BW
V
SENSE
= 50mV, gain = 50
V
SENSE
= 50mV, gain = 100
V
SENSE
= 50mV, gain = 200
t
S
t
ON
1% final value, V
SENSE
= 50mV
1% final value, V
SENSE
= 50mV
MAX9938T/F/H
MAX9938W
7.0
14.0
10
20
1.5
3
6
12
0.1
125
60
30
15
100
200
µs
µs
kHz
25
50
100
200
±0.1
±0.5
±0.6
13.2
26.4
15
30
60
120
0.2
V
mV
%
kΩ
V/V
1.6
94
130
±100
±500
±600
1.1
MIN
TYP
0.5
MAX
0.85
1.1
1.8
2.5
28
V
dB
µV
µA
UNITS
Note 1:
All devices are 100% production tested at T
A
= +25°C. All temperature limits are guaranteed by design.
Note 2:
V
OUT
= 0. I
CC
is the total current into RS+ plus RS- pins.
2
_______________________________________________________________________________________
1µA, 4-Bump UCSP/SOT23,
Precision Current-Sense Amplifier
ELECTRICAL CHARACTERISTICS (continued)
(V
RS+
= V
RS-
= 3.6V, V
SENSE
= (V
RS+
- V
RS-
) = 0V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
Note 3:
V
OS
is extrapolated from measurements for the gain-error test.
Note 4:
Gain error is calculated by applying two values of V
SENSE
and calculating the error of the slope vs. the ideal:
Gain = 25, V
SENSE
is 20mV and 120mV.
Gain = 50, V
SENSE
is 10mV and 60mV.
Gain = 100, V
SENSE
is 5mV and 30mV.
Gain = 200, V
SENSE
is 2.5mV and 15mV.
Note 5:
The device is stable for any external capacitance value.
Note 6:
V
OH
is the voltage from V
RS-
to V
OUT
with V
SENSE
= 3.6V/gain.
MAX9938
Typical Operating Characteristics
(V
RS+
= V
RS-
= 3.6V, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. TEMPERATURE
MAX9938 toc02
MAX9938 toc03
INPUT OFFSET VOLTAGE HISTOGRAM
MAX9938 toc01
GAIN ERROR HISTOGRAM
30
25
20
N (%)
15
10
5
0
1.4
1.2
SUPPLY CURRENT (µA)
1.0
0.8
30
25
20
N (%)
15
10
5
0
-0.4 -0.3 -0.2 -0.1
0
0.1 0.2
0.3 0.4
INPUT OFFSET VOLTAGE (mV)
28V
3.6V
0.6
0.4
0.2
1.8V
-0.4 -0.3 -0.2 -0.1
0
0.1 0.2
0.3 0.4
0
-40
-15
10
35
60
85
TEMPERATURE (°C)
GAIN ERROR (%)
INPUT OFFSET
vs. COMMON-MODE VOLTAGE
MAX9938 toc04
INPUT OFFSET
vs. TEMPERATURE
MAX9938 toc05
SUPPLY CURRENT
vs. COMMON-MODE VOLTAGE
MAX9938 toc06
-30
60
50
INPUT OFFSET (µV)
40
30
20
10
0
1.4
1.2
SUPPLY CURRENT (µA)
1.0
0.8
0.6
0.4
0.2
0
-35
INPUT OFFSET (µV)
-40
-45
-50
-55
0
5
10
15
20
25
30
SUPPLY VOLTAGE (V)
-40
-15
10
35
60
85
0
5
10
15
20
25
30
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
3
1µA, 4-Bump UCSP/SOT23,
Precision Current-Sense Amplifier
MAX9938
Typical Operating Characteristics (continued)
(V
RS+
= V
RS-
= 3.6V, T
A
= +25°C, unless otherwise noted.)
GAIN ERROR
vs. COMMON-MODE VOLTAGE
MAX9938 toc07
GAIN ERROR
vs. TEMPERATURE
MAX9938 toc08
V
OUT
vs. V
SENSE
(SUPPLY = 3.6V)
3.5
3.0
G = 100
V
OUT
(V)
2.5
G = 50
2.0
1.5
1.0
0.5
0
0
50
V
SENSE
(mV)
100
150
G = 25
MAX9938 toc09
0.1
0
GAIN ERROR (%)
-0.1
-0.2
-0.3
-0.4
-0.5
0
5
10
15
VOLTAGE (V)
20
25
0.08
0.07
0.06
GAIN ERROR (%)
0.05
0.04
0.03
0.02
0.01
0
4.0
30
-40
-15
10
35
60
85
TEMPERATURE (°C)
V
OUT
vs. V
SENSE
(SUPPLY = 1.6V)
MAX9938 toc10
SMALL SIGNAL GAIN
vs. FREQUENCY
A
V
= 25V/V
0
-5
A
V
= 100V/V
A
V
= 50V/V
GAIN (dB)
MAX9938 toc11
CMRR
vs. FREQUENCY
-20
G = 25
-40
-60
-80
-100
-120
-140
-160
G = 100
G = 50
MAX9938 toc12
1.8
1.6
1.4
1.2
V
OUT
(V)
1.0
0.8
0.6
0.4
0.2
0
0
20
40
60
80
G = 100
G = 50
G = 25
5
0
GAIN (dB)
-10
-15
-20
-25
-30
100
1Hz
10Hz 100Hz
1kHz
10kHz 100kHz 1MHz
1Hz
10Hz 100Hz
1kHz
10kHz 100kHz 1MHz
V
SENSE
(mV)
FREQUENCY (kHz)
FREQUENCY (kHz)
SMALL-SIGNAL PULSE RESPONSE
(GAIN = 100)
MAX9938 toc13a
SMALL-SIGNAL PULSE RESPONSE
(GAIN = 50)
MAX9938 toc13b
15mV
V
SENSE
10mV
V
SENSE
30mV
20mV
1.5V
1.5V
V
OUT
1V
V
OUT
1V
20µs/div
25µs/div
4
_______________________________________________________________________________________
1µA, 4-Bump UCSP/SOT23,
Precision Current-Sense Amplifier
Typical Operating Characteristics (continued)
(V
RS+
= V
RS-
= 3.6V, T
A
= +25°C, unless otherwise noted.)
MAX9938
SMALL-SIGNAL PULSE RESPONSE
(GAIN = 25)
MAX9938 toc13c
LARGE-SIGNAL PULSE RESPONSE
(GAIN = 100)
MAX9938 toc14a
60mV
V
SENSE
V
SENSE
40mV
1.5V
30mV
10mV
3V
V
OUT
V
OUT
1V
1V
25µs/div
20µs/div
LARGE-SIGNAL PULSE RESPONSE
(GAIN = 50)
MAX9938 toc14b
LARGE-SIGNAL PULSE RESPONSE
(GAIN = 25)
MAX9938 toc14c
60mV
V
SENSE
10mV
3V
V
SENSE
120mV
20mV
3V
V
OUT
0.5V
V
OUT
0.5V
25µs/div
25µs/div
Pin Description
PIN
UCSP
A1
A2
B1
B2
—
SOT23
5
4
1, 2
3
—
µDFN
4
6
3
1
2, 5
NAME
RS+
RS-
GND
OUT
N.C.
FUNCTION
External Sense Resistor Power-Side Connection
External Sense Resistor Load-Side Connection
Ground
Output Voltage. V
OUT
is proportional to V
SENSE
= V
RS+
- V
RS-
.
No Connection. Not internally connected.
_______________________________________________________________________________________
5
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