MCP6041T-I Datasheet, PDF (15/40 Pages) Microchip Technology – 600 nA, Rail-to-Rail Input/Output Op Amps

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.
.
1.4V
to
6.0V
I_DD
10
100 k
MCP604X
V_DD
V_OUT
1 M
I_DD = -_--₁---_0V----^D-_V---^D-_/-_V---–-_---^V-_---_^O--₁--^U-₀--^T--_-----_
FIGURE 4-7:
Sensor.
High-Side Battery Current
MCP6041/2/3/4
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.
.
R_G
V_REF ^R1
R₂
R₂
R₁
V_OUT
V₂
½
½
MCP6042
MCP6042
V₁
V_OUT
=
V₁
–
V₂



1
+
-^R---¹-
R₂
+
-2-_R--^R--_G--¹_
+ V_REF
FIGURE 4-8:
Two Op Amp
Instrumentation Amplifier.
 2001-2013 Microchip Technology Inc.
DS21669D-page 15