MAX4072 Maxim, MAX4072 Datasheet - Page 12

• Manufacturer Part Number: MAX4072
• Description: The MAX4069–MAX4072 low-cost, bidirectional, high-side, current-sense amplifiers are ideal for monitoring battery charge and discharge currents in notebooks, cell phones, and other portable equipment
• Manufacturer: Maxim

Bidirectional, High-Side, Current-Sense
Amplifiers with Reference
core, as in metal-film or wire-wound resistors, they are
a straight band of metal and are available in values
under 1Ω.
Peak Current: The maximum current through R
must be limited to:
where R
and RS- to R
back diodes between the differential input, the absolute
maximum of the differential input voltage is 0.3V.
Although the MAX4069–MAX4072 have fully symmetri-
cal, bidirectional, V
voltage range is usually higher from REF to V
lower from REF to GND (unless the supply voltage is at
the lowest end of the operating range). Therefore, the
user must consider the dynamic range of current moni-
tored in both directions and choose the supply voltage
and the reference voltage (REFOUT or REFIN) to make
sure the output swing above and below REF is ade-
quate to handle the swings without clipping or running
out of headroom.
When SHDN is low, the MAX4069–MAX4072 are shut
down and consume only 10µA. In shutdown mode,
OUT is high impedance and turns off. Connect SHDN
to V
Table 1. Recommended Component Values
12
CC
______________________________________________________________________________________
Dynamic Range Considerations
FULL-SCALE
for normal operation.
CURRENT
TRACE
I
0.075
PEAK
0.05
0.75
3.75
15.0
10.0
(A)
0.5
2.5
7.5
5.0
SENSE
is the total stray resistance from RS+
= 0.3V / (R
. To prevent forwarding the back-to-
SENSE
input capability, the output-
SENSE
Shutdown Mode
CURRENT-SENSE
RESISTOR (mΩ)
+ R
1000
100
TRACE
20
10
5
)
CC
SENSE
and
GAIN
(V/V)
100
100
100
100
100
50
50
50
50
50
The MAX4069–MAX4072 do not require special
bypassing and respond quickly to transient changes in
line current. You can place a large capacitor at the RS-
terminal (or “load” side) to decouple the load and,
thereby, reduce the current transients. These capaci-
tors are not required for operation or stability and their
use does not degrade performance.
The MAX4069–MAX4072 have been designed as a high-
side current monitor to ease the task of grounding any
battery charger, thermistor, etc., that may be a part of
the battery pack. Grounding these devices requires no
special precautions; follow the same cautionary steps
that apply to the system as a whole. High-current sys-
tems can experience large voltage drops across a
ground plane, and this drop may add to or subtract from
V
and REF prevents this problem. For highest current-mea-
surement accuracy, use a single-point star ground.
On thin QFN packages, there is an exposed paddle that
does not carry any current, but should also be connect-
ed to the ground plane for rated power dissipation.
OUT.
Using differential measurement between V
V
SENSE
(mV)
Power-Supply Bypassing
75
50
75
50
75
50
75
50
75
50
VOLTAGE WITH RESPECT
FULL-SCALE OUTPUT
and Grounding
TO REF (V)
3.75
3.75
3.75
3.75
3.75
5.0
5.0
5.0
5.0
5.0
OUT