MCP6142 Microchip Technology, MCP6142 Datasheet - Page 15

• Manufacturer Part Number: MCP6142
• Description: 600 nA, Non-Unity Gain Rail-to-Rail Input/Output Op Amps
• Manufacturer: Microchip Technology

4.9
4.9.1
The MCP6141/2/3/4 op amps’ Common Mode Input
Range, which goes 0.3V beyond both supply rails, sup-
ports their use in high side and low side battery current
sensing applications. The very low quiescent current
(0.6 A, typ.) help prolong battery life, and the
rail-to-rail output supports detection low currents.
Figure 4-9 shows a high side battery current sensor
circuit. The 1 k
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 at V
within its allowed range. When no current is flowing, the
output will be at its Maximum Output Voltage Swing
(V
FIGURE 4-9:
Sensor.
© 2005 Microchip Technology Inc.
.
1.4V to
OH
5.5V
1 k
), which is virtually at V
Application Circuits
BATTERY CURRENT SENSING
V
V
SS
DD
I
DD
100 k
resistor is sized to minimize power
High Side Battery Current
DD
.
DD
MCP6141
) through the 1 k
1 M
V
V
DD
SS
DD
, which is
V
OUT
4.9.2
The MCP6141/2/3/4 op amp is well suited for the
inverting summing amplifier shown in Figure 4-10
when the resistors at the input (R
the noise gain at least 10 V/V. The output voltage
(V
and is shifted by the V
calculations follow in Equation 4-3.
FIGURE 4-10:
EQUATION 4-3:
.
OUT
Noise Gain:
Signal Gains:
Output Signal:
) is a weighted sum of the inputs (V
V
V
V
1
2
3
G
G
G
G
V
V
OUT
N
1
2
3
INVERTING SUMMING AMPLIFIER
REF
=
=
=
=
R
R
R
MCP6141/2/3/4
1
2
3
–
–
–
=
1
R
R
R
+
F
F
F
V
1
R
G
R
R
R
F
Summing Amplifier.
1
2
3
1
⎛
⎝
MCP614X
----- -
R
+
1
1
V
REF
+
2
R
G
----- -
R
F
1
2
2
input. The necessary
+
+
V
1
----- -
R
, R
1
3
3
G
DS21668B-page 15
⎞
⎠
2
3
, and R
+
10 V/V
1
V
, V
V
REF
2
OUT
, and V
3
G
) make
N
3
),