MAX4080TAUA+ Maxim Integrated Products, MAX4080TAUA+ Datasheet - Page 9

• Manufacturer Part Number: MAX4080TAUA+
• Description: IC AMP CURRENT SENSE 8-UMAX
• Manufacturer: Maxim Integrated Products

Specifications of MAX4080TAUA+

• Amplifier Type: Current Sense
• Number Of Circuits: 1
• Gain Bandwidth Product: 250kHz
• Current - Input Bias: 5µA
• Voltage - Input Offset: 100µV
• Current - Supply: 75µA
• Voltage - Supply, Single/dual (±): 4.5 V ~ 76 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Product: Current Monitors
• Operating Temperature Range: + 125 C
• Mounting Style: SMD/SMT
• Accuracy: 0.6 %
• Bandwidth: 250 KHz
• Sense Voltage (max): 250 mV
• Supply Current (max): 0.075 mA (Typ) @ 76 V
• Supply Voltage (max): 76 V
• Supply Voltage (min): 4.5 V
• No. Of Amplifiers: 1
• Input Bias Current: 12µA
• Input Offset Voltage: 600µV
• Cmrr: 124dB
• Supply Voltage Range: 4.5V To 76V
• Supply Current: 75µA
• Amplifier Case Style: µMAX
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Output Type: -
• Current - Output / Channel: -
• -3db Bandwidth: -
• Slew Rate: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

The MAX4080/MAX4081 unidirectional and bidirectional
high-side, current-sense amplifiers feature a 4.5V to
76V input common-mode range that is independent of
supply voltage. This feature allows the monitoring of
current out of a battery as low as 4.5V and also enables
high-side current sensing at voltages greater than the
supply voltage (V
current through a current-sense resistor and amplifies
the voltage across the resistor. The MAX4080 senses
current unidirectionally, while the MAX4081 senses cur-
rent bidirectionally.
The 76V input voltage range of the MAX4080/MAX4081
applies independently to both supply voltage (V
and common-mode, input-sense voltage (V
side current monitoring does not interfere with the
ground path of the load being measured, making the
MAX4080/MAX4081 particularly useful in a wide range
of high-voltage systems.
Battery-powered systems require a precise bidirectional
current-sense amplifier to accurately monitor the bat-
tery’s charge and discharge. The MAX4081 charging
current is represented by an output voltage from V
to V
GND. Measurements of OUT with respect to V
a positive and negative voltage during charge and dis-
charge, as illustrated in Figure 1 for the MAX4081T.
MAX4080
3, 6, 7
CC
76V, High-Side, Current-Sense Amplifiers with
—
—
1
2
4
5
8
, while discharge current is given from V
PIN
MAX4081
CC
_______________________________________________________________________________________
1
2
3
4
5
8
6
7
). The MAX4080/MAX4081 monitors
Detailed Description
REF1B
REF1A
NAME
GND
OUT
RS+
N.C.
V
RS-
CC
RS+
Power connection to the external-sense resistor.
Supply Voltage Input. Decouple V
bypass line transients.
No Connection. No internal connection. Leave open or connect to ground.
Ground
Voltage Output. For the unidirectional MAX4080, V
V
proportional to V
Load connection to the external sense resistor.
Reference Voltage Input: Connect REF1B to REF1A or to GND (see the External
Reference section).
Reference Voltage Input: Connect REF1A and REF1B to a fixed reference
voltage (V
Reference section).
REF
SENSE
). High-
REF
yield
CC
REF
. For the bidirectional MAX4081, the difference voltage (V
to
REF
)
). V
SENSE
OUT
The MAX4080 operates as follows: current from the
source flows through R
ating a sense voltage, V
amplifier’s inverting input has high impedance, negligible
current flows through RG2 (neglecting the input bias
current). Therefore, the sense amplifier’s inverting input
voltage equals V
fier’s open-loop gain forces its noninverting input to the
same voltage as the inverting input. Therefore, the drop
across RG1 equals V
multiplies I
β
current to a voltage and then sent through amplifier A3.
Total gain = 5V/V for MAX4080F, 20V/V for the
MAX4080T, and 60V/V for the MAX4080S.
The MAX4081 input stage differs slightly from the
MAX4080 (Figure 3). Its topology allows for monitoring
of bidirectional currents through the sense resistor.
When current flows from RS+ to RS-, the MAX4081
matches the voltage drop across the external sense
resistor, R
Q1 and RG1. In this way, the voltages at the input ter-
minals of the internal amplifier A1 are kept constant and
an accurate measurement of the sense voltage is
achieved. In the following amplifier stages of the
MAX4081, the output signal of amplifier A2 is level-
shifted to the reference voltage (V
V
REF1B

is equal to V
IRG1. Amplifier A2 is used to convert the output
and indicates the correct polarity.
), resulting in a voltage at the output pin (OUT)
SENSE
RG1
CC
REF
FUNCTION
by a current gain factor, β, to give I
, by increasing the current through the
SOURCE
to GND with at least a 0.1µF capacitor to
when V
Voltage Output
SENSE
SENSE
SENSE
SENSE
- (I
. The internal current mirror
LOAD
OUT
to the load (Figure 2), cre-
is zero (see the External
. Since the internal-sense
Pin Description
Current Monitoring
is proportional to
)(R
SENSE
REF
OUT
). The ampli-
= V
- V
REF1A
REF
) is
A2
=
=
9