Datasheet

 2001-2013 Microchip Technology Inc. DS21669D-page 15
MCP6041/2/3/4
4.9 Application Circuits
4.9.1 BATTERY CURRENT SENSING
The MCP6041/2/3/4 op amps’ Common Mode Input
Range, which goes 0.3V beyond both supply rails,
supports their use in high-side and low-side battery
current sensing applications. The very low quiescent
current (0.6 µA, typical) helps prolong battery life, and
the rail-to-rail output supports detection low currents.
Figure 4-7 shows a high-side battery current sensor
circuit. The 10 resistor is sized to minimize power
losses. The battery current (I
DD
) through the 10
resistor causes its top terminal to be more negative
than the bottom terminal. This keeps the Common
mode input voltage of the op amp below V
DD
, which is
within its allowed range. The output of the op amp will
also be below V
DD
, which is within its Maximum Output
Voltage Swing specification.
.
FIGURE 4-7: High-Side Battery Current
Sensor.
4.9.2 INSTRUMENTATION AMPLIFIER
The MCP6041/2/3/4 op amp is well suited for
conditioning sensor signals in battery-powered
applications. Figure 4-8 shows a two op amp instru-
mentation amplifier, using the MCP6042, that works
well for applications requiring rejection of Common
mode noise at higher gains. The reference voltage
(V
REF
) is supplied by a low impedance source. In single
supply applications, V
REF
is typically V
DD
/2.
.
FIGURE 4-8: Two Op Amp
Instrumentation Amplifier.
V
DD
I
DD
MCP604X
100 k
1M
1.4V
V
OUT
10
to
6.0V
I
DD
V
DD
V
OUT
–
10 V/V10
  
----------------------------------------- -=
V
OUT
V
1
V
2
–1
R
1
R
2
----- -
2R
1
R
G
---------++


V
REF
+=
V
REF
R
1
R
2
R
2
R
1
V
OUT
R
G
V
2
V
1
½
MCP6042
½
MCP6042