MAX9928_V01 [MAXIM]
-0.1V to 28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense Amplifiers;
| 型号： | MAX9928_V01 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | -0.1V to 28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense Amplifiers |
| 文件： | 总13页 (文件大小：1475K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
EVALUATION KIT AVAILABLE
MAX9928/MAX9929
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
General Description
Features
● Wide -0.1V to +28V Common-Mode Range,
The MAX9928/MAX9929 low-cost, uni-/bidirectional,
high-side, current-sense amplifiers are ideal for monitor-
ing battery charge and discharge currents in notebooks,
cell phones, and other portable equipment. These devices
feature a wide -0.1V to +28V input common-mode voltage
Independent of Supply Voltage
● 2.5V to 5.5V Operating Supply Voltage
● 20μA Quiescent Supply Current
● 0.4mV (max) Input Offset Voltage
● Gain Accuracy Better than 1% (max)
● SIGN Output Indicates Current Polarity
range, low 20μA supply current with V
less than 0.4mV,
OS
and a gain accuracy better than 1.0%. The input common-
mode range is independent of the supply voltage, ensur-
ing that the current-sense information remains accurate
even when the measurement rail is shorted to ground.
● 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 volt-
age output and integrates a 10kΩ output resistor for a
fixed voltage gain of 50V/V.
• 50V/V (MAX9929F)
● Pin Compatible with the MAX4372 in UCSP
● Available in Ultra-Small, 3x2 UCSP
(1mm x 1.5mm) and 8-Pin μMAX Packages
Applications
A digital SIGN output indicates direction of current flow, so
the user can utilize the full ADC input range for measuring
both charging and discharging currents.
● Monitoring Charge/Discharge Currents in Portable/
Battery-Powered Systems
● Notebook Computers
● General-System/Board-Level Current Monitoring
● Smart-Battery Packs/Chargers
● Precision Current Sources
● Smart Cell Phones
● Super Capacitor Charge/Discharge
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
compatible with the MAX4372_EBT.
Pin Configurations and Typical Operating Circuit appear at
end of data sheet.
UCSP is a trademark and μMAX is a registered trademark of
Maxim Integrated Products, Inc.
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
—
+AAF
—
m
m
Current
3x2 UCSP
8 μMAX
Voltage
A
= 50V/V
= 50V/V
V
V
Voltage
A
3x2 UCSP
+ADI
Note: All devices are specified over the -40°C to +125°C operating temperature range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
19-4251; Rev 4; 9/14
MAX9928/MAX9929
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
Absolute Maximum Ratings
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
RS+, RS- to GND..................................................-0.3V to +30V
OUT to GND............................................. -0.3V to (V + 0.3V)
CC
Differential Input Voltage (V
- V
)..............................±30V
RS+
RS-
OUT, SIGN Short Circuit to V
or GND..................Continuous
CC
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 oth-
OUT A
RS+
CC
SENSE
RS+
RS-
erwise noted. Typical values are at T = +25°C.) (Note 1)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
AMPLIFIER DC ELECTRICAL CHARACTERISTICS
T
T
T
T
= +25°C
±0.1
±0.4
±0.8
±1.0
±3.0
+28
A
A
A
A
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
= -0.1V
= -40°C to +125°C
V
(Note 3)
2V ≤ V
-0.1
93
CMR
T
= +25°C
104
72
A
A
A
A
≤ 28V
≤
RS+
T
T
T
= -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
= +25°C
±0.3
±1.0
±2.5
±1.0
MAX9929F,
= 3.6V
A
A
A
V
= -40°C to +125°C
= +25°C
RS+
Gain Accuracy (Notes 2, 6)
Transconductance (Note 2)
%
±0.3
MAX9929F,
= -0.1V
V
T
= -40°C to +125°C
±2.8
RS+
A
G
MAX9928F
MAX9928F,
5
µA/mV
%
M
T
T
T
T
= +25°C
±0.3
±1.0
±2.5
±1.0
±2.8
6
A
A
A
A
V
= 3.6V
RS+
= -40°C to +125°C
= +25°C
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
0.05
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)
RS-
1.0
RS+ RS-
CC
RS+
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MAX9928/MAX9929
-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 oth-
OUT A
RS+
CC
SENSE
RS+
RS-
erwise noted. Typical values are at T = +25°C.) (Note 1)
A
PARAMETER
Output Resistance
SYMBOL
CONDITIONS
MIN
TYP
5
MAX
UNITS
MΩ
MAX9928F
R
OUT
MAX9929F
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
0.1)
(V
0.45)
-
CC
CC
MAX9929F
MAX9929F
T
T
T
T
= +25°C
0.25
2.0
15
A
A
A
A
Minimum Output Voltage (Note 7)
Minimum Output Current (Note 7)
V
mV
µA
OL
= -40°C to +125°C
= +25°C
0.025
0.2
1.5
I
MAX9928F
OL
= -40°C to +125°C
SIGN COMPARATOR DC ELECTRICAL CHARACTERISTICS
T
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
A
A
A
V
V
= 3.6V
RS+
= -40°C to +125°C
= +25°C
Discharge to Charge Trip Point
(Note 8)
V
mV
mV
TDC
= -0.1V
RS+
= -40°C to +125°C
= +25°C
-4.6
V
V
V
= 3.6V
-1.8
-1.8
0.6
Charge to Discharge Trip Point
(Note 8)
RS+
RS+
RS+
V
V
TCD
= -0.1V
= +25°C
Hysteresis Width
= 3.6V, -0.1V
= +25°C
mV
V
HYS
Common-Mode Input Range
(Note 9)
V
-0.1
+28
0.1
CMR
2V ≤ V
≤ 28V
102
74
Common-Mode Rejection Ratio
(Note 9)
RS+
CMRR
dB
-0.1V ≤ V
≤ +2V
RS+
Output Low Voltage
Output High Voltage
V
I
= 100µA
SINK
0.03
V
V
OL
(V
-
(V
-
CC
CC
V
OH
0.01)
0.04)
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
Amplifier Power-Supply Rejection
Ratio (Note 10)
RS+
RS+
RS+
RS+
PSRR
dB
dB
µA
A
66
90
Comparator Power-Supply
Rejection Ratio
PSRR
C
86
2V ≤ V
≤ 28V
20
30
RS+
Quiescent Supply Current
I
CC
-0.1V ≤ V
< +2V
115
200
RS+
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MAX9928/MAX9929
-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 oth-
OUT A
RS+
CC
SENSE
RS+
RS-
erwise 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
SENSE
5mV to 50mV step
=
=
V
= 3.6V,
RS+
C
= 10pF,
LOAD
OUT Settling to 1% of Final Value
t
µs
SET
R
= 10kΩ for
OUT
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
µs
µs
PROP_LH
SIGN Comparator Propagation
Delay (High to Low)
t
PROP_HL
Power-Up Time to 1% of Final
Value
V
V
= 50mV for MAX992_F,
SENSE
50
4
µs
= 3.6V, C
= 10pF
RS+
LOAD
100mV ≤ V
V
P 50mV for MAX992_F,
SENSE
Saturation Recovery Time
ms
= 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
is extrapolated from two point transconductance and gain accuracy tests. Measurements are made at V
= +5mV
OS
SENSE
and V
= +50mV for MAX992_F. These measurements are also used to test the full-scale sense voltage, transcon-
SENSE
ductance, and gain. These V
specifications are for the trimmed direction only (V
> V
). For current flowing in the
OS
RS+
RS-
opposite direction (V
> V
), V
is ±1mV (max) at +25°C and ±1.8mV (max) over temperature, when V
is at 3.6V.
RS-
RS+
OS
RS+
See the Detailed Description for more information.
Note 3: Guaranteed by common-mode rejection ratio. Extrapolated V
rejection ratio.
as described in Note 2 is used to calculate common-mode
OS
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
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MAX9928/MAX9929
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
Typical Operating Characteristics
(V
= 3.3V, V
= 12V, T = +25°C, unless otherwise noted.)
CC
RS+ A
GAIN ACCURACY
HISTOGRAM
OFFSET VOLTAGE
vs. COMMON-MODE VOLTAGE
V
HISTOGRAM
OS
45
40
30
25
20
15
10
2.0
1.5
1.0
0.5
0
A
V
= 50V/V
A
V
= 50V/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
V
0.10 0.20 0.30 0.40
(mV)
0
-1.0 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1.0
GAIN ACCURACY (%)
-1
0
1
2
3
28
OS
COMMON-MODE VOLTAGE (V)
SUPPLY CURRENT
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
vs. COMMON-MODE VOLTAGE
OFFSET VOLTAGE vs. TEMPERATURE
1.0
0.8
0.6
0.4
0.2
0
150
125
100
75
150
120
90
60
30
0
V
= 0V
SENSE
V
CM
= 3.6V
V
= 0V
RS+
V
CC
= 5.5V
-0.2
-0.4
-0.6
-0.8
-1.0
50
V
CC
= 2.5V
V
RS+
= 3.6V
25
0
-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
-0.5
0
0.5
1.0
1.5
2.0
28
TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
COMMON-MODE VOLTAGE (V)
SUPPLY CURRENT
vs. TEMPERATURE
INPUT BIAS CURRENT
vs. COMMON-MODE VOLTAGE
150
125
100
75
10
0
V
= 0V
SENSE
V
= 0V
RS+
-10
-20
-30
-40
-50
-60
-70
-80
50
V
= 3.6V
RS+
25
0
28
-0.1
-50 -25
0
25
50
75 100 125
-2
0
2
4
6
8
10
TEMPERATURE (°C)
COMMON-MODE VOLTAGE (V)
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MAX9928/MAX9929
-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.)
CC
RS+
A
MAX9929F
vs. V
MAX9928F
MAX9929F
V vs. V
OUT
V
I
vs. V
OUT
SENSE
OUT
SENSE
SENSE
2500
2000
1500
1000
500
6
5
4
3
2
1
0
3.4
3.2
3.0
2.8
2.6
2.4
2.2
2.0
V
OUT
= 0V
T
= -40°C
T
A
= -40°C
A
V
= 5.5V
CC
T
A
= +25°C
T
A
= +25°C
T
= +125°C
A
T
= +125°C
A
V
= 3.3V
CC
V
= 2.7V
CC
V
= 2.5V
60
CC
0
0
0.1
0.2
0.3
(V)
0.4
0.5
0
20
40
80 100 120 140
(mV)
30
40
50
60
70
80
90
V
V
V (mV)
SENSE
SENSE
SENSE
GAIN ACCURACY
vs. SUPPLY VOLTAGE
MINIMUM OUTPUT VOLTAGE
vs. TEMPERATURE
GAIN ACCURACY vs. TEMPERATURE
1.0
0.8
0.6
0.4
0.2
0
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
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1.0
-0.2
-0.4
-0.6
-0.8
-1.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
-40 -25 -10
5
20 35 50 65 80 95 110 125
-40 -25 -10
5
20 35 50 65 80 95 110 125
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
TEMPERATURE (°C)
SMALL-SIGNAL GAIN
vs. FREQUENCY
CMRR vs. FREQUENCY
35
32
29
26
23
20
120
90
60
30
0
V
CM
= 3.6V
MAX992_F
0.01
0.1
1
10
100
1000
10
100
1k
10k
100k
1M
FREQUENCY (kHz)
FREQUENCY (Hz)
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MAX9928/MAX9929
-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.)
CC
RS+
A
MAX9929F LARGE-SIGNAL
TRANSIENT RESPONSE
PSRR vs. FREQUENCY
MAX9928 toc18
20
0
V
SENSE
50mV/div
-20
-40
-60
-80
-100
-120
V
OUT
1V/div
0.1
1
10
100
1k
10k 100k
100µs/div
FREQUENCY (Hz)
V
AND V
OUT
SIGN
OVERDRIVE RECOVERY
vs. V
SENSE
MAX9928 toc20
4
3
2
V
SENSE
100mV/div
1
0
150
100
50
0
V
OUT
500mV/div
400µs/div
-3
-2
-1
0
1
2
3
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
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MAX9928/MAX9929
-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
Pin Configuration
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
+VSENSE vs. -VSENSE
The amplifier is configured for either positive V
Detailed Description
or
The MAX9928F/MAX9929F micropower uni-/bidirection-
al, 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 during
short-circuit/fault conditions, and also enables highside
current sensing at voltages far in excess of the supply
SENSE
negative V
by the SIGN comparator. The compara-
SENSE
tor has a built-in offset skew of -1.2mV so that random
offsets in the comparator do not affect the precision of
I
(V
) with positive V
OUT
. The comparator has
OUT
SENSE
a small amount of hysteresis (typically 0.6mV) to prevent
its output from oscillating at the crossover sense voltage.
The ideal transfer characteristic of I
output of the comparator (SIGN) is shown in Figure 2.
(V
) and the
voltage (V ). The MAX9928F/MAX9929F operate from
a 2.5V to 5.5V single supply and draw a low 20μA quies-
OUT
OUT
CC
cent supply current.
The amplifier V is only trimmed for the positive
OS
V
voltages (V
> V
). The SIGN comparator
Current flows through the sense resistor, generating a
SENSE
RS+
RS-
reconfigures the internal structure of the amplifier to work
sense voltage V
(Figure 1). The comparator sens-
SENSE
with negative V
voltages (V
> V
) and the
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+
precision V
trim is no longer effective and the result-
OS
ing V
is slightly impacted. See details in the Electrical
OS
Characteristics Note 2. The user can choose the direction
that needs the best precision to be the direction where
For positive V
input is high impedance and equals V - V
amplifier’s output drives the base of Q1, forcing its non-
inverting input terminal to (V - V ); this causes
a current to flow through RG1 equal to |V
voltage, the amplifier’s inverting
SENSE
. The
IN
SENSE
V
> V
. For example, when monitoring Li+ battery
RS+
RS-
currents, the discharge current should be V
> V
to
RS+
RS-
IN
SENSE
give the best accuracy over the largest dynamic range.
When the battery charger is plugged in, the charge cur-
rent flows in the opposite direction and is usually much
|/R
.
SENSE G1
Transistor Q2 and the current mirror amplify the current
by a factor of M.
larger, and a higher V
error can be tolerated. See the
OS
For negative V
voltage, the amplifier’s noninverting
SENSE
Typical Operating Circuit.
input is high impedance and the voltage on RS- terminal
equals V + V . The amplifier’s output drives the
For applications with unidirectional currents (e.g., battery
discharge only), the SIGN output can be ignored.
IN
SENSE
base of Q1 forcing its inverting input terminal to match
Note that as V
increases, the output current (I
OUT
the voltage at the noninverting input terminal; this causes
SENSE
for the MAX9928 or V
increases. This additional current is supplied from V
/10kΩ for the MAX9929) also
a current to flow through R
Again, transistor Q2 and the current mirror amplify the
equal to |V
|/R
.
OUT
G2
SENSE G2
.
CC
current by a factor of M.
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-0.1V to +28V Input Range, Micropower,
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V
CC
V
CC
R
80kΩ
C1
2.5V TO 5.5V
MAX9928F
MAX9929F
1MΩ
SIGN
R
C2
C
TO C
80kΩ
CURRENT
MIRROR
V
IN
-0.1V TO +28V
(V
S2
OUT
R
80kΩ
G1
)
BATT
TO ADC
RS+
RS-
+
-
R
80kΩ
10kΩ*
G2
A
S1
Q2
Q1
TO
LOAD/CHARGER
GND
*INTERNAL 10kΩ RESISTOR FOR MAX9929_ ONLY.
Figure 1. Functional Diagram
For both positive and negative V
voltages, the cur-
SENSE
rent 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 the
OUT SENSE
comparator indicates the polarity of V
.
SENSE
Current Output (MAX9928F)
-3.0
-1.8
-1.2
0
1.0
2.0
3.0
The output voltage equation for the MAX9928_ is given
below:
V
(mV)
SENSE
V
OUT
= (R
x I
) x (G X R
)
SENSE
LOAD
m
OUT
where V
= the desired full-scale output voltage, I
LOAD
OUT
= the full-scale current being sensed, R
= the
SENSE
current-sense resistor, R
= the voltage-setting resis-
OUT
tor, and G = MAX9928F transconductance (5μA/mV).
m
The full-scale output voltage range can be set by chang-
ing the R
resistor value. The above equation can be
OUT
modified to determine the R
full-scale range:
required for a particular
OUT
-3.0
-1.8
-1.2
0
1.0
2.0
3.0
V
(mV)
SENSE
R
= (V
)/(I
x R x G )
SENSE m
OUT
OUT LOAD
( ) FOR THE MAX9929F.
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
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-0.1V to +28V Input Range, Micropower,
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tor value and power dissipation (wattage) rating. Also,
if the sense resistor is allowed to heat up excessively,
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 compo-
nent to I , keep inductance low. Wire-wound re-
V
= (R
x I
) x (A )
OUT
SENSE
LOAD V
SENSE
where V
= the desired full-scale output voltage,
OUT
sistors have the highest inductance, while metal film
is somewhat better. Low-inductance metal-film resis-
tors are available. Instead of being spiral wrapped
around a core, as in metal film or wirewound resistors,
these are a straight band of metal. They are made in
values under 1Ω.
I
= the full-scale current being sensed, R
the current-sense resistor, A = MAX9929F voltage gain
=
LOAD
SENSE
V
(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 sys-
tems, this is useful for determining whether the battery is
charging or discharging. The SIGN output might not cor-
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 systems use
multifarad (1F–50F) capacitor banks to supply enough
energy to keep critical systems alive even if the primary
power source is removed or temporarily disabled. Unlike
batteries, these capacitors can discharge all the way down
to 0V. The MAX9928/MAX9929 can continuously help
monitor their health and state of charge/discharge.
rectly indicate the direction of load current when V
SENSE
is between -1.8mV to -1.2mV (see Figure 2). Comparator
hysteresis of 0.6mV prevents oscillation of SIGN output. If
current direction is not needed, leave SIGN unconnected.
Applications Information
UCSP Applications Information
Choosing R
SENSE
For the latest application details on UCSP construc-
tion, dimensions, tape carrier information, PCB tech-
niques, bump-pad layout, and recommended reflow
temperature profile, as well as the latest information
on reliability testing results, go to Maxim’s website at
www.maximintegrated.com/ucsp to find Application
Note 1891: Wafer-Level Packaging (WLP) and its
Applications.
The MAX9928F/MAX9929F operate over a wide variety
of current ranges with different sense resistors. Adjust the
R
value to monitor higher or lower current levels.
SENSE
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 be-
cause offsets become less significant when the sense
voltage is larger.
Chip Information
PROCESS: BiCMOS
●
Efficiency and Power Dissipation: At high current
2
levels, the I R losses in R
might be significant.
SENSE
Take this into consideration when choosing the resis-
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-0.1V to +28V Input Range, Micropower,
Uni-/Bidirectional, Current-Sense Amplifiers
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
CC
GND
OUT
A
MAX9928F
MAX9929F
MAX9928F
MAX9929F
V
CC
N.C.
N.C.
µMAX
B
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
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Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.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
pertains 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
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-0.1V to +28V Input Range, Micropower,
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Revision History
REVISION REVISION
PAGES
DESCRIPTION
CHANGED
NUMBER
DATE
12/08
8/09
0
1
2
3
4
Initial release
—
Removed MAX9928T and MAX9929T from data sheet
Updated top marks
1–5, 7–12
4/11
1
1
4/12
Removed the R61A1+1 package code note and references
Removed automotive reference from data sheet.
9/14
10
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated 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.
©
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
2014 Maxim Integrated Products, Inc.
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