MAX9929F [MAXIM]
-0.1V to +28V Input Range, Micropower Uni-/Bidirectional, Current-Sense Amplifiers; -0.1V至+ 28V输入范围，微功耗单向/双向电流检测放大器
| 型号： | MAX9929F |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | -0.1V to +28V Input Range, Micropower Uni-/Bidirectional, Current-Sense Amplifiers |
| 文件： | 总14页 (文件大小：257K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-4251; Rev 3; 4/12
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
8/MAX29
General Description
Features
The MAX9928/MAX9929 low-cost, uni-/bidirectional,
high-side, current-sense amplifiers are ideal for moni-
toring battery charge and discharge currents in note-
books, cell phones, and other portable equipment.
These devices feature a wide -0.1V to +28V input com-
mon-mode voltage range, low 20µA supply current with
o Wide -0.1V to +28V Common-Mode Range,
Independent of Supply Voltage
o 2.5V to 5.5V Operating Supply Voltage
o 20µA Quiescent Supply Current
o 0.4mV (max) Input Offset Voltage
o Gain Accuracy Better than 1% (max)
o SIGN Output Indicates Current Polarity
V
less than 0.4mV, and a gain accuracy better than
OS
1.0%. The input common-mode range is independent
of the supply voltage, ensuring that the current-sense
information remains accurate even when the measure-
ment rail is shorted to ground.
o Transconductance and Gain Versions Available
5µA/mV (MAX9928F)
The MAX9928F features a current output with a transcon-
ductance ratio of 5µA/mV. An external resistor converts
the output current to a voltage, allowing adjustable gain
so that the input sense voltage can be matched to the
maximum ADC input swing. The MAX9929F has a voltage
output and integrates a 10kΩ output resistor for a fixed
voltage gain of 50V/V.
50V/V (MAX9929F)
o Pin Compatible with the MAX4372 in UCSP
o Available in Ultra-Small, 3x2 UCSP
(1mm x 1.5mm) and 8-Pin µMAX Packages
A digital SIGN output indicates direction of current flow,
so the user can utilize the full ADC input range for mea-
suring both charging and discharging currents.
Applications
Monitoring Charge/Discharge Currents in
Portable/Battery-Powered Systems
The MAX9928/MAX9929 are fully specified over the -40°C
to +125°C automotive temperature range, and available
in 6-bump UCSP™ (1mm x 1.5mm) and 8-pin µMAX®
packages. The UCSP package is bump-to-bump com-
patible with the MAX4372_EBT.
Notebook Computers
General-System/Board-Level Current Monitoring
Smart-Battery Packs/Chargers
Precision Current Sources
UCSP is a trademark and µMAX is a registered trademark of
Maxim Integrated Products, Inc.
Smart Cell Phones
Super Capacitor Charge/Discharge
Pin Configurations and Typical Operating Circuit appear at
end of data sheet.
Ordering Information
PART
OUTPUT TYPE
Current
GAIN
PIN-PACKAGE
8 µMAX
TOP MARK
—
MAX9928FAUA+
MAX9928FABT+T
MAX9929FAUA+
MAX9929FABT+T
G
G
= 5µA/mV
= 5µA/mV
m
m
Current
3x2 UCSP
8 µMAX
+AAF
—
Voltage
A = 50V/V
V
Voltage
A = 50V/V
3x2 UCSP
+ADI
V
Note: All devices are specified over the -40°C to +125°C operating temperature range.
+Denotes a lead-free/RoHS-compliant package.
T = Tape and reel.
________________________________________________________________ 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.
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
ABSOLUTE MAXIMUM RATINGS
CC
RS+, RS- to GND....................................................-0.3V to +30V
OUT to GND ...............................................-0.3V to (V + 0.3V)
V
, SIGN to GND ...................................................-0.3V to +6V
Operating Temperature Range ........................-40°C to +125°C
Storage Temperature Range ............................-65°C to +150°C
Junction Temperature .....................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
CC
Differential Input Voltage (V
OUT, SIGN Short Circuit to V
- V ) .............................. 30V
or GND ...................Continuous
RS+
CC
RS-
Current into Any Pin.......................................................... 20mA
Continuous Power Dissipation (T = +70°C)
A
6-Bump 1mm x 1.5mm UCSP
(derate 3.9mW/°C above +70°C)............................308.3mW
8-Pin µMAX (derate 4.8mW/°C above +70°C).............388mW
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
= -0.1V to +28V, V
= 3.3V, V
= (V
- V ) = 0V, R
= 10kΩ for MAX9928F, T = -40°C to +125°C, unless other-
OUT A
RS+
CC
SENSE
RS+
RS-
wise noted. Typical values are at T = +25°C.) (Note 1)
A
8/MAX29
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
0.1
MAX
UNITS
AMPLIFIER DC ELECTRICAL CHARACTERISTICS
T
A
T
A
T
A
T
A
= +25°C
0.4
0.8
V
V
= 3.6V
RS+
RS+
= -40°C to +125°C
= +25°C
Input Offset Voltage (Note 2)
Common-Mode Input Range
Common-Mode Rejection Ratio
V
mV
V
OS
0.6
1.0
= -0.1V
= -40°C to +125°C
3.0
V
(Note 3)
2V ≤ V
-0.1
93
+28
CMR
T
A
T
A
T
A
T
A
= +25°C
104
72
≤ 28V
RS+
= -40°C to +125°C
= +25°C
87
CMRR
dB
60
-0.1V ≤ V
+2V
≤
RS+
= -40°C to +125°C
54
Full-Scale Sense Voltage (Note 2)
Gain (Note 2)
V
MAX992_F
MAX9929F
50
50
mV
V/V
SENSE
A
V
T
T
T
T
= +25°C
0.3
1.0
2.5
1.0
2.8
A
A
A
A
MAX9929F,
V
= 3.6V
RS+
= -40°C to +125°C
= +25°C
Gain Accuracy (Notes 2, 6)
Transconductance (Note 2)
%
0.3
MAX9929F,
= -0.1V
V
RS+
= -40°C to +125°C
G
MAX9928F
MAX9928F,
5
µA/mV
%
M
T
A
T
A
T
A
T
A
= +25°C
= -40°C to +125°C
= +25°C
0.3
1.0
2.5
1.0
2.8
6
V
= 3.6V
RS+
Transconductance Accuracy
(Note 2)
0.3
1.6
MAX9928F,
= -0.1V
V
= -40°C to +125°C
RS+
2V ≤ V
≤ 28V
0
RS+
Input Bias Current (Note 4)
I
I
, I
µA
RS+ RS-
-0.1V ≤ V
≤ +2V
-80
+6
1
RS+
2V ≤ V
≤ 28V
0.05
0.2
RS+
Input Offset Bias Current (Note 4)
Input Leakage Current
I
µA
µA
OS
-0.1V ≤ V
≤ +2V
2
RS+
, I
V
= 0V, V
= V
= 28V (Note 5)
0.05
1.0
RS+ RS-
CC
RS+
RS-
2
_______________________________________________________________________________________
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
8/MAX29
ELECTRICAL CHARACTERISTICS (continued)
(V
= -0.1V to +28V, V
= 3.3V, V
= (V
- V ) = 0V, R
= 10kΩ for MAX9928F, T = -40°C to +125°C, unless other-
RS+
CC
SENSE
RS+
RS-
OUT A
wise noted. Typical values are at T = +25°C.) (Note 1)
A
PARAMETER
Output Resistance
SYMBOL
CONDITIONS
MIN
TYP
5
MAX
UNITS
MΩ
MAX9928F
MAX9929F
R
OUT
6.4
10
13.6
kΩ
(V
0.1)
-
-
(V
0.45)
-
CC
CC
MAX9928F, R
= 10kΩ
OUT
Output High Voltage (Note 6)
V
V
OH
(V
CC
(V
CC
-
MAX9929F
MAX9929F
MAX9928F
0.1)
0.45)
T
A
T
A
T
A
T
A
= +25°C
= -40°C to +125°C
= +25°C
0.25
2.0
15
Minimum Output Voltage (Note 7)
Minimum Output Current (Note 7)
V
mV
µA
OL
0.025
0.2
1.5
I
OL
= -40°C to +125°C
SIGN COMPARATOR DC ELECTRICAL CHARACTERISTICS
T
T
T
T
T
T
= +25°C
-1.6
-2.15
-2.5
-1.2
-1.2
-0.5
-0.15
+0.25
+2.3
A
A
A
A
V
V
= 3.6V
RS+
RS+
= -40°C to +125°C
= +25°C
Discharge to Charge Trip Point
(Note 8)
V
mV
TDC
= -0.1V
= -40°C to +125°C
= +25°C
= +25°C
-4.6
V
V
V
= 3.6V
= -0.1V
= 3.6V,
-1.8
-1.8
Charge to Discharge Trip Point
(Note 8)
RS+
RS+
RS+
A
A
V
V
mV
mV
V
TCD
HYS
Hysteresis Width
T
A
= +25°C
0.6
-0.1V
Common-Mode Input Range
(Note 9)
V
-0.1
+28
0.1
CMR
2V ≤ V
≤ 28V
102
74
RS+
Common-Mode Rejection Ratio
(Note 9)
CMRR
dB
V
-0.1V ≤ V
≤ +2V
RS+
Output Low Voltage
V
I
= 100µA
0.03
OL
SINK
(V
0.01)
-
(V
0.04)
-
CC
CC
Output High Voltage
V
V
OH
Internal Pullup Resistor
R
1
MΩ
PULL-UP
POWER SUPPLY
T
T
= +25°C
2.5
2.8
72
5.5
5.5
A
Supply Voltage Range (Note 10)
V
V
CC
= -40°C to +125°C
A
V
V
V
V
= 3.6V
= -0.1V
= 3.6V
= -0.1V
90
86
RS+
RS+
RS+
RS+
Amplifier Power-Supply Rejection
Ratio (Note 10)
PSRR
PSRR
dB
dB
µA
A
C
66
90
Comparator Power-Supply
Rejection Ratio
86
2V ≤ V
≤ 28V
20
30
RS+
Quiescent Supply Current
I
CC
-0.1V ≤ V
< +2V
115
200
RS+
_______________________________________________________________________________________
3
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
ELECTRICAL CHARACTERISTICS (continued)
(V
= -0.1V to +28V, V
= 3.3V, V
= (V
- V ) = 0V, R
= 10kΩ for MAX9928F, T = -40°C to +125°C, unless other-
RS+
CC
SENSE
RS+
RS-
OUT A
wise noted. Typical values are at T = +25°C.) (Note 1)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
AC ELECTRICAL CHARACTERISTICS
-3dB Bandwidth
BW
MAX992_F, V
= 50mV
150
6
kHz
SENSE
MAX992_F, V
5mV to 50mV step
=
=
SENSE
V
= 3.6V,
RS+
C
= 10pF,
LOAD
OUT Settling to 1% of Final Value
t
µs
SET
R
OUT
= 10kΩ for
MAX992_F, V
50mV to 5mV step
SENSE
15
MAX9928F
Overdrive = 1mV
Overdrive = 5mV
Overdrive = 1mV
Overdrive = 5mV
80
30
50
13
SIGN Comparator Propagation
Delay (Low to High)
t
t
µs
µs
µs
ms
PROP_LH
SIGN Comparator Propagation
Delay (High to Low)
PROP_HL
Power-Up Time to 1% of Final
Value
V
= 50mV for MAX992_F,
SENSE
50
4
8/MAX29
V
= 3.6V, C
= 10pF
RS+
LOAD
100mV ≤ V
≤ 50mV for MAX992_F,
SENSE
Saturation Recovery Time
V
= 3.6V, C
= 10pF
RS+
LOAD
Note 1: All devices are 100% production tested at T = +25°C. All temperature limits are guaranteed by design.
A
Note 2:
V
OS
is extrapolated from two point transconductance and gain accuracy tests. Measurements are made at V
=
SENSE
+5mV and V
= +50mV for MAX992_F. These measurements are also used to test the full-scale sense voltage,
SENSE
transconductance, and gain. These V specifications are for the trimmed direction only (V
> V ). For current flowing
OS
RS+
RS-
in the opposite direction (V
> V
), V is 1mV (max) at +25°C and 1.8mV (max) over temperature, when V
is at
RS-
RS+
OS
RS+
3.6V. See the Detailed Description for more information.
Note 3: Guaranteed by common-mode rejection ratio. Extrapolated V as described in Note 2 is used to calculate common-mode
OS
rejection ratio.
Note 4: Includes input bias current of SIGN comparator.
Note 5: Leakage in to RS+ or RS- when V
= 0V. Includes input leakage current of SIGN comparator. This specification does not
CC
add to the bias current.
Note 6: Output voltage should be 650mV below V
to achieve full accuracy.
CC
Note 7:
I
is the minimum output current in the V
- I
transfer characteristics. V is the minimum output voltage in the
OL
SENSE OUT OL
V
V
- V
transfer characteristic.
SENSE
SENSE
OUT
Note 8:
voltage required to switch comparator.
Note 9: Discharge to charge trip point is functionally tested at V
= -0.1V, +3.6V, and +28V.
CM
Note 10: Guaranteed by PSRR test. Extrapolated V as described in Note 2 is used to calculate the power-supply rejection ratio.
OS
V
has to be such that the output voltage is 650mV below V
to achieve full accuracy.
SENSE
CC
4
_______________________________________________________________________________________
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
8/MAX29
Typical Operating Characteristics
(V
= 3.3V, V
= 12V, T = +25°C, unless otherwise noted.)
RS+ A
CC
OFFSET VOLTAGE
vs. COMMON-MODE VOLTAGE
GAIN ACCURACY
HISTOGRAM
V
HISTOGRAM
OS
2.0
1.5
1.0
0.5
0
45
40
30
25
20
15
10
A
= 50V/V
A
= 50V/V
V
V
35
30
25
20
15
10
5
-0.5
-1.0
-1.5
-2.0
5
0
0
-0.40 -0.30-0.20 -0.10
0.10 0.20 0.30 0.40
-1
0
1
2
3
28
0
-1.0 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1.0
GAIN ACCURACY (%)
COMMON-MODE VOLTAGE (V)
V
(mV)
OS
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SUPPLY CURRENT
vs. COMMON-MODE VOLTAGE
OFFSET VOLTAGE vs. TEMPERATURE
1.0
0.8
150
125
100
75
150
120
90
60
30
0
V
= 0V
V
= 3.6V
SENSE
CM
0.6
V
= 0V
RS+
0.4
0.2
V
= 5.5V
CC
0
-0.2
-0.4
-0.6
-0.8
-1.0
50
V
= 2.5V
CC
0
V
= 3.6V
RS+
3.5
25
0
-40 -25 -10
5
20 35 50 65 80 95 110 125
2.5
3.0
4.0
4.5
5.0
5.5
-0.5
0.5
1.0
1.5
2.0
28
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
COMMON-MODE VOLTAGE (V)
INPUT BIAS CURRENT
vs. COMMON-MODE VOLTAGE
SUPPLY CURRENT
vs. TEMPERATURE
10
0
150
125
100
75
V
= 0V
SENSE
V
= 0V
-10
-20
-30
-40
-50
-60
-70
-80
RS+
50
V
= 3.6V
RS+
25
0
28
-0.1
-2
0
2
4
6
8
10
-50 -25
0
25
50
75 100 125
COMMON-MODE VOLTAGE (V)
TEMPERATURE (°C)
_______________________________________________________________________________________
5
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
Typical Operating Characteristics (continued)
(V
= 3.3V, V
= 12V, T = +25°C, unless otherwise noted.)
A
CC
RS+
MAX9928F
MAX9929F
vs. V
MAX9929F
V vs. V
OUT
I
vs. V
V
OUT
SENSE
OUT
SENSE
SENSE
2500
3.4
3.2
3.0
2.8
2.6
2.4
2.2
2.0
6
5
4
3
2
1
0
V
= 0V
OUT
T
= -40°C
T
= -40°C
A
A
2000
V
= 5.5V
CC
T
= +25°C
A
T
= +25°C
A
1500
1000
500
0
T
= +125°C
A
T
= +125°C
A
V
= 3.3V
CC
V
= 2.7V
CC
V
= 2.5V
CC
0
0.1
0.2
0.3
(V)
0.4
0.5
30
40
50
60
70
80
90
0
20
40
60
V
80 100 120 140
(mV)
8/MAX29
V
V
(mV)
SENSE
SENSE
SENSE
MINIMUM OUTPUT VOLTAGE
vs. TEMPERATURE
GAIN ACCURACY
vs. SUPPLY VOLTAGE
GAIN ACCURACY vs. TEMPERATURE
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
1.0
0.8
1.0
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0
0
-0.2
-0.4
-0.6
-0.8
-1.0
-0.2
-0.4
-0.6
-0.8
-1.0
-40 -25 -10
5
20 35 50 65 80 95 110 125
-40 -25 -10
5
20 35 50 65 80 95 110 125
2.5
3.0
3.5
4.0
4.5
5.0
5.5
TEMPERATURE (°C)
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
SMALL-SIGNAL GAIN
vs. FREQUENCY
CMRR vs. FREQUENCY
120
90
60
30
0
35
V
= 3.6V
CM
MAX992_F
32
29
26
23
20
10
100
1k
10k
100k
1M
0.01
0.1
1
10
100
1000
FREQUENCY (Hz)
FREQUENCY (kHz)
6
_______________________________________________________________________________________
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
8/MAX29
Typical Operating Characteristics (continued)
(V
= 3.3V, V
= 12V, T = +25°C, unless otherwise noted.)
RS+ A
CC
MAX9929F LARGE-SIGNAL
TRANSIENT RESPONSE
PSRR vs. FREQUENCY
MAX9928 toc18
20
0
V
SENSE
50mV/div
-20
-40
-60
-80
-100
-120
V
1V/div
OUT
0.1
1
10
100
1k
10k
100k
100μs/div
FREQUENCY (Hz)
V
AND V
OUT
SIGN
vs. V
OVERDRIVE RECOVERY
SENSE
MAX9928 toc20
4
3
2
V
SENSE
100mV/div
1
0
150
100
50
0
V
OUT
500mV/div
-3
-2
-1
0
1
2
3
400μs/div
V
(mV)
SENSE
COMPARATOR PROPAGATION DELAY
(RS+ = 3.6V, 5mV OVERDRIVE)
POWER-UP DELAY
MAX9928 toc21
MAX9928 toc22
V
CC
1V/div
V
SENSE
2mV/div
V
OUT
1V/div
V
OUT
1V/div
40μs/div
40μs/div
_______________________________________________________________________________________
7
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
Pin/Bump Description
PIN
µMAX
1
BUMP
UCSP
B3
NAME
FUNCTION
RS-
Negative Current-Sense Input. Load-side connection for the external sense resistor.
SIGN Output. Indicates polarity of V
.
SENSE
2
B2
SIGN
SIGN = H indicates V
SIGN = L indicates V
> V
< V
RS+
RS+
RS-
RS-
3
4, 5
6
B1
—
RS+
N.C.
Positive Current-Sense Input. Power-side connection to the external sense resistor.
No Connection. Not internally connected.
A1
A2
V
Supply Voltage Input. Bypass to GND with a 0.1µF capacitor.
Circuit Ground
CC
7
GND
Current-Sense Output. MAX9928: Current output (I
is proportional to |V |). MAX9929:
SENSE
OUT
8
A3
OUT
Voltage output (V
is proportional to |V |).
SENSE
OUT
8/MAX29
+V
vs. -V
SENSE
SENSE
or
Detailed Description
The amplifier is configured for either positive V
SENSE
The MAX9928F/MAX9929F micropower uni-/bidirectional,
current-sense amplifiers feature -0.1V to +28V input
common-mode range that is independent of the supply
voltage. This wide input voltage range feature allows the
monitoring of the current flow out of a power supply dur-
ing short-circuit/fault conditions, and also enables high-
side current sensing at voltages far in excess of the
negative V
by the SIGN comparator. The com-
SENSE
parator has a built-in offset skew of -1.2mV so that ran-
dom offsets in the comparator do not affect the
precision of I
(V
) with positive V
. The
SENSE
OUT
OUT
comparator has a small amount of hysteresis (typically
0.6mV) to prevent its output from oscillating at the
crossover sense voltage. The ideal transfer characteris-
supply voltage (V ). The MAX9928F/MAX9929F oper-
CC
ate from a 2.5V to 5.5V single supply and draw a low
20µA quiescent supply current.
tic of I
(V
) and the output of the comparator
OUT
(SIGN) is shown in Figure 2.
OUT
The amplifier V is only trimmed for the positive V
OS
RS+
SENSE
Current flows through the sense resistor, generating a
voltages (V
> V ). The SIGN comparator reconfig-
RS-
sense voltage V
(Figure 1). The comparator sens-
SENSE
ures the internal structure of the amplifier to work with
negative V voltages (V > V ) and the preci-
es the direction of the sense voltage and configures the
amplifier for either positive or negative sense voltages
by controlling the S1 and S2 switches.
SENSE
RS-
RS+
sion V trim is no longer effective and the resulting V
OS
OS
is slightly impacted. See details in the Electrical
Characteristics Note 2. The user can choose the direc-
tion that needs the best precision to be the direction
For positive V
voltage, the amplifier’s inverting
SENSE
input is high impedance and equals V - V
The
SENSE.
IN
amplifier’s output drives the base of Q1, forcing its non-
inverting input terminal to (V - V ); this causes a
where V
> V . For example, when monitoring Li+
RS-
RS+
IN
G1
SENSE
equal to |V
battery currents, the discharge current should be V
>
RS+
current to flow through R
|/R
.
SENSE G1
V
RS-
to give the best accuracy over the largest dynamic
Transistor Q2 and the current mirror amplify the current
by a factor of M.
range. When the battery charger is plugged in, the
charge current flows in the opposite direction and is
usually much larger, and a higher V
tolerated. See the Typical Operating Circuit.
error can be
OS
For negative V
voltage, the amplifier’s noninvert-
SENSE
ing input is high impedance and the voltage on RS- ter-
minal equals V + V The amplifier’s output
IN
SENSE.
For applications with unidirectional currents (e.g., bat-
tery discharge only), the SIGN output can be ignored.
drives the base of Q1 forcing its inverting input terminal
to match the voltage at the noninverting input terminal;
Note that as V
increases, the output current (I
OUT
SENSE
for the MAX9928 or V
this causes a current to flow through R
equal to
G2
/10kΩ for the MAX9929) also
OUT
|V
|/R . Again, transistor Q2 and the current mir-
SENSE G2
increases. This additional current is supplied from V
.
CC
ror amplify the current by a factor of M.
8
_______________________________________________________________________________________
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
8/MAX29
V
CC
V
CC
R
C1
2.5V TO 5.5V
80kΩ
MAX9928F
MAX9929F
1MΩ
SIGN
R
C
C2
TO μC
80kΩ
CURRENT
MIRROR
V
IN
-0.1V TO +28V
(V
S2
OUT
R
G1
)
BATT
TO ADC
80kΩ
RS+
RS-
+
-
R
10kΩ*
G2
A
S1
Q2
80kΩ
Q1
TO
LOAD/CHARGER
GND
*INTERNAL 10kΩ RESISTOR FOR MAX9929_ ONLY.
Figure 1. Functional Diagram
For both positive and negative V
voltages, the
SENSE
current flowing out of the current mirror is equal to:
I
= M x |V |/R
OUT
SENSE G1
For the MAX9928F, the transconductance of the device
is trimmed so that I /|V | = 5µA/mV. For the
OUT SENSE
MAX9929F, the voltage gain of the device is trimmed
so that V /|V | = 50V/V. The SIGN output from
OUT SENSE
the comparator indicates the polarity of V
.
SENSE
Current Output (MAX9928F)
The output voltage equation for the MAX9928_ is given
below:
-3.0
-1.8
-1.2
0
1.0
2.0
3.0
V
(mV)
SENSE
V
OUT
= (R
x I
) x (G
LOAD
R
)
SENSE
m X OUT
where V
LOAD
the current-sense resistor, R
resistor, and G = MAX9928F transconductance
(5µA/mV).
= the desired full-scale output voltage,
OUT
I
= the full-scale current being sensed, R
=
SENSE
= the voltage-setting
OUT
m
The full-scale output voltage range can be set by
changing the R
can be modified to determine the R
particular full-scale range:
resistor value. The above equation
OUT
required for a
OUT
-3.0
-1.8
-1.2
0
1.0
2.0
3.0
V
(mV)
SENSE
( ) FOR THE MAX9929F.
R
= (V
)/(I
x R
x G )
SENSE m
OUT
OUT LOAD
OUT is a high-impedance current source and can drive
an unlimited amount of capacitance.
Figure 2. Ideal Transfer Characteristics with 0mV Amplifier Input
Offset Voltage and -1mV Comparator Input Offset Voltage
_______________________________________________________________________________________
9
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
tor value and power dissipation (wattage) rating.
Also, if the sense resistor is allowed to heat up exces-
sively, its value could drift.
Voltage Output (MAX9929F)
The output voltage equation for the MAX9929_ is given
below:
• Inductance: If there is a large high-frequency com-
V
= (R
x I
) x (A )
LOAD V
OUT
SENSE
ponent to I
, keep inductance low. Wire-wound
SENSE
where V
LOAD
= the desired full-scale output voltage,
OUT
resistors have the highest inductance, while metal
film is somewhat better. Low-inductance metal-film
resistors are available. Instead of being spiral
wrapped around a core, as in metal film or wire-
wound resistors, these are a straight band of metal.
They are made in values under 1Ω.
I
= the full-scale current being sensed, R
=
SENSE
the current-sense resistor, A = MAX9929F voltage
V
gain (50V/V).
SIGN Output
The current/voltage at OUT indicates magnitude. The
SIGN output indicates the current’s direction. The SIGN
comparator compares RS+ to RS-. The sign output is
high when RS+ is greater than RS- indicating positive
current flow. The sign output is low when RS- is greater
than RS+ indicating negative current flow. In battery-
operated systems, this is useful for determining
whether the battery is charging or discharging. The
SIGN output might not correctly indicate the direction of
Use in Systems with Super Capacitors
Since the input common-mode voltage range of the
MAX9928/MAX9929 extends all the way from -0.1V to
28V, they are ideal to use in applications that require
use of super capacitors for temporary or emergency
energy storage systems. Some modern industrial and
automotive systems use multifarad (1F–50F) capacitor
banks to supply enough energy to keep critical sys-
tems alive even if the primary power source is removed
or temporarily disabled. Unlike batteries, these capaci-
tors can discharge all the way down to 0V. The
MAX9928/MAX9929 can continuously help monitor their
health and state of charge/discharge.
8/MAX29
load current when V
is between -1.8mV to -1.2mV
SENSE
(see Figure 2). Comparator hysteresis of 0.6mV pre-
vents oscillation of SIGN output. If current direction is
not needed, leave SIGN unconnected.
Applications Information
UCSP Applications Information
Choosing R
SENSE
The MAX9928F/MAX9929F operate over a wide variety
of current ranges with different sense resistors. Adjust
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, go to Maxim’s website at www.maxim-
ic.com/ucsp to find Application Note 1891:
Understanding the Basics of the Wafer-Level Chip-
Scale Package (WL-CSP).
the R
value to monitor higher or lower current lev-
SENSE
els. Select R
using these guidelines:
SENSE
• Voltage Loss: A high R
value causes the
SENSE
power-source voltage to drop due to IR loss. For
least voltage loss, use the lowest R value.
SENSE
• Accuracy: A high R
value allows lower cur-
SENSE
rents to be measured more accurately. This is
because offsets become less significant when the
sense voltage is larger.
Chip Information
PROCESS: BiCMOS
• Efficiency and Power Dissipation: At high current
levels, the I2R losses in R
might be significant.
SENSE
Take this into consideration when choosing the resis-
10 ______________________________________________________________________________________
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
8/MAX29
Pin Configurations
TOP VIEW
(BUMPS ON THE BOTTOM)
TOP VIEW
1
2
3
+
RS-
SIGN
RS+
1
2
3
4
8
7
6
5
OUT
GND
V
GND
OUT
A
B
CC
MAX9928F
MAX9929F
V
CC
MAX9928F
MAX9929F
N.C.
N.C.
μMAX
RS+
SIGN
RS-
UCSP
(1mm x 1.5mm)
Typical Operating Circuit
WALL-CUBE
CHARGER
R
SENSE
V
IN
-0.1V TO
+28V
LOAD
RS+
RS-
μC
2.5V TO
5.5V
DIGITAL
INPUT
MAX9928F
MAX9929F
V
CC
SIGN
OUT
0.1μF
ADC
R
OUT
*
GND
GND
*FOR THE MAX9928F ONLY
______________________________________________________________________________________ 11
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
Package Information
For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a "+", "#", or
"-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing per-
tains to the package regardless of RoHS status.
PACKAGE TYPE
8 µMAX
PACKAGE CODE
U8+1
OUTLINE NO.
21-0036
LAND PATTERN NO.
90-0092
6 UCSP
B6+1
21-0097
—
8/MAX29
α
α
12 ______________________________________________________________________________________
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
8/MAX29
Package Information (continued)
For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a "+", "#", or
"-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing per-
tains to the package regardless of RoHS status.
______________________________________________________________________________________ 13
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
Revision History
REVISION REVISION
PAGES
CHANGED
DESCRIPTION
NUMBER
DATE
0
1
2
3
12/08
8/09
4/11
4/12
Initial release
—
Removed MAX9928T and MAX9929T from data sheet
Updated top marks
1–5, 7–12
1
1
Removed the R61A1+1 package code note and references
8/MAX29
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. The parametric values (min and max limits) shown in
the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2012 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
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