Datasheet

Using a PC Board Trace as R
SENSE
If the cost of R
SENSE
is an issue and accuracy is not
critical, use the alternative solution shown in Figure 2.
This solution uses copper PC board traces to create a
sense resistor. The resistivity of a 0.1-inch-wide trace of
2-ounce copper is about 30mΩ/ft. The resistance tem-
perature coefficient of copper is fairly high (approxi-
mately 0.4%/°C), so systems that experience a wide
temperature variance must compensate for this effect.
In addition, self-heating will introduce a nonlinearity
error. Do not exceed the maximum power dissipation of
the copper trace.
For example, the MAX4372T (with a maximum load cur-
rent of 10A and an R
SENSE
of 5mΩ) creates a full-scale
V
SENSE
of 50mV that yields a maximum V
OUT
of 1V.
R
SENSE
, in this case, requires about 2 inches of 0.1-
inch-wide copper trace.
UCSP Applications Information
For the latest application details on UCSP construction,
dimensions, tape carrier information, printed circuit
board techniques, bump-pad layout, and recommend-
ed reflow temperature profile, as well as the latest infor-
mation on reliability testing results, go to the Maxim's
website at www.maxim-ic.com/ucsp to find the
Application Note:
UCSP—A Wafer-Level Chip-Scale
Package.
Table 1. Recommended Component Values
FULL-SCALE LOAD
CURRENT,
I
LOAD
(A)
GAIN
(V/V)
CURRENT-SENSE
RESISTOR,
R
SENSE
(mΩ)
2.0
FULL-SCALE OUTPUT
VOLTAGE (FULL-SCALE
V
SENSE
= 100mV),
V
OUT
(V)
5.0
10.0
0.1 1000
20
100
50
2.0
100
50 5.0
10.0
1 100
20
2.0
100
50 5.0
2.0
100
50 5.0
10.0
5 20
20
10.0
10 10
20
0.1in COPPER 0.3in COPPER0.3in COPPER
INPUT LOAD/BATTERY
V
CC
V
SENSE
R
SENSE
GND
2.7V TO 28V
RS+
RS-
OUT
MAX4372T/F/H
Figure 2. Connections Showing Use of PC Board
Low-Cost, UCSP/SOT23, Micropower, High-Side
Current-Sense Amplifier with Voltage Output
Maxim Integrated
7
MAX4372T/F/H