MAX4069-MAX4072 Maxim, MAX4069-MAX4072 Datasheet - Page 11

• Manufacturer Part Number: MAX4069-MAX4072
• Description: Bidirectional / High-Side / Current-Sense Amplifiers with Reference
• Manufacturer: Maxim

Figure 2. Bidirectional Current Monitor
The MAX4072 contains REFIN pin for external refer-
ence voltage. The allowable voltage range on REFIN is
1V (min) to 4V (max) with V
The REFOUT of the MAX4069/MAX4070/MAX4071 can
sink 100µA and source 500µA. Keep the total capaci-
tance on REFOUT under 500pF to maintain stability.
Ideally, the maximum load current develops the full-
scale sense voltage across the current-sense resistor.
Choose the gain needed to yield the maximum output
voltage required for the application:
where V
gain of 50V/V, or 50mV for gain of 100V/V. A
gain of the device.
In applications monitoring high current, ensure that
R
tor’s power dissipation is exceeded, its value may drift
or it may fail altogether, causing a differential voltage
across the terminals in excess of the absolute maxi-
mum ratings. Use resistors specified for current- sens-
ing applications.
SENSE
SENSE
is able to dissipate its own I
CELLS
Recommended Component Values
2
is the full-scale sense voltage, 75mV for
External Reference (MAX4072)
(MAX4069/MAX4060/MAX4071)
V
I
DISCHARGE
______________________________________________________________________________________
OUT
Bidirectional, High-Side, Current-Sense
= V
CC
SENSE
V
GSEL
SHDN
CC
RS-
5.1V.
Reference Output
x A
MAX4070
R
SENSE
2
GND
V
R loss. If the resis-
RS+
REFOUT
I
CHARGE
OUT
V
is the
TO ADC
2.5V
LOAD
Amplifiers with Reference
-25mV
The MAX4069–MAX4072 sense a wide variety of cur-
rents with different sense-resistor values. Table 1 lists
common resistor values for typical operation of these
devices. Listed output voltage is with respect to REF.
Choose R
Voltage Loss: A high R
source voltage to degrade through IR loss. For minimal
voltage loss, use the lowest R
Accuracy: A high R
to be measured more accurately. This is because off-
sets become less significant when the sense voltage is
larger. For best performance, select R
approximately 75mV (gain of 50V/V) or 50mV (gain of
100V/V) of sense voltage for the full-scale current in
each application.
Efficiency and Power Dissipation: At high-current lev-
els, the I
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 allowed to heat
up excessively.
Inductance: Keep inductance low if I
high-frequency component. Wire-wound resistors have
the highest inductance, while metal film is somewhat
better. Low-inductance metal-film resistors are also
available. Instead of being spiral-wrapped round a
V
DISCHARGE
CURRENT
OUT
2
- V
SENSE
R losses in R
REF
0
5V
2.5V
-2.5V
based on the following criteria:
SENSE
SENSE
SENSE
Sense Resistor, R
25mV
value allows lower currents
A
V
SENSE
= 100
value causes the power-
can be significant. Take
V
SENSE
CURRENT
CHARGE
value.
SENSE
SENSE
50mV
has a large
to provide
SENSE
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