MCP6041-I/OT Microchip Technology, MCP6041-I/OT Datasheet - Page 13

• Manufacturer Part Number: MCP6041-I/OT
• Description: 600 nA, Rail-to-Rail Input/Output Op Amp
• Manufacturer: Microchip Technology

3.7.2
Separate digital from analog and low speed from high
speed. This helps prevent crosstalk.
Keep sensitive traces short and straight. Separate
them from interfering components and traces. This is
especially important for high frequency (low rise time)
signals.
Use a 0.1 µF supply bypass capacitor within 0.1”
(2.5 mm) of the V
ground plane.
3.7.3
The input pins of the MCP6041/2/3/4 family of op amps
are high impedance, which allows noise injection. This
noise can be capacitively or magnetically coupled. In
either case, using a ground plane helps reduce noise
injection.
When noise is coupled capacitively, the ground plane
provides shunt capacitance to ground for high fre-
quency signals. Figure 3-6 shows the equivalent cir-
cuit. The coupled current, I
(V
plane capacitance (C
resistor (R
traces, and using wider traces, also helps.
FIGURE 3-6:
capacitive coupling between traces on a PC
board (with ground plane).
When noise is coupled magnetically, ground plane
reduces the mutual inductance between traces. This
occurs because the ground return current at high fre-
quencies will follow a path directly beneath the signal
trace. Increasing the separation between traces makes
a significant difference. Changing the direction of one
of the traces can also reduce magnetic coupling.
If these techniques are not enough, it may help to place
guard traces next to the victim trace. They should be on
both sides of the victim trace and be as close as possi-
ble. Connect the guard traces to ground plane at both
ends, and in the middle, for long traces.
V
2002 Microchip Technology Inc.
TRACE 2
TRACE 1
) on the victim trace when the trace to ground
T2
C
COMPONENT PLACEMENT
SIGNAL COUPLING
SH1
) is small. Increasing the distance between
DD
pin. It must connect directly to the
SH2
Equivalent circuit for
C
C
) is large and the terminating
M
SH2
M
, produces a lower voltage
I
M
V
TRACE 2
R
T2
3.8
3.8.1
The MCP6041/2/3/4 op amps’ Common Mode Input
Range, which goes 300 mV 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, typ) help prolong battery life while the
rail-to-rail output allows you to detect low currents.
Figure 3-7 shows a high side battery current sensor cir-
cuit. The 10
losses. The battery current (I
resistor causes its top terminal to be more negative
than the bottom terminal. This keeps the common
mode input voltage of the op amp V
its allowed range. The output of the op amp can reach
V
error than the offset voltage.
FIGURE 3-7:
Sensor.
3.8.2
The MCP6041/2/3/4 op amp is well suited for condition-
ing sensor signals in battery-powered applications.
Figure 3-8 shows a two op amp instrumentation
amplifier, using the MCP6042, that works well for appli-
cations requiring rejection of common mode noise at
higher gains. The reference voltage (V
by a low impedance source. In single supply
applications, V
FIGURE 3-8:
Instrumentation Amplifier.
DD
V
V
V
REF
2
1
- 0.1 mV (see Figure 2-32), which is a smaller
+2.5 V
5.5 V
10
V
to
O UT
Typical Applications
R
BATTERY CURRENT SENSING
INSTRUMENTATION AMPLIFIER
1
=
½ MCP6042
REF
V
resistors are sized to minimize power
MCP6041/2/3/4
DD
V
I
DD
100 k
R
1
is typically V
–
1
V
High Side Battery Current
Two Op Amp
2
R
G
1
+
R
R
----- -
R
MCP604X
1
DD
1
2
DD
+
) through the 10
/2.
1 M
2R
-------- -
R
DD
G
DS21669B-page 13
V
V
½ MCP6042
1
REF
DD
SS
, which is within
R
+
1
V
) is supplied
REF
V
OUT