MCP6295T Microchip Technology, MCP6295T Datasheet - Page 13

• Manufacturer Part Number: MCP6295T
• Manufacturer: Microchip Technology

FIGURE 4-6:
for Inverting Gain.
1.
2.
 2004 Microchip Technology Inc.
For
Amplifiers (convert current to voltage, such as
photo detectors):
a.
b.
Non-inverting Gain and Unity-Gain Buffer:
a.
b.
Connect the guard ring to the non-inverting
input pin (V
to the same reference voltage as the op
amp (e.g., V
Connect the inverting pin (V
with a wire that does not touch the PCB
surface.
Connect the non-inverting pin (V
input with a wire that does not touch the
PCB surface.
Connect the guard ring to the inverting input
pin (V
common mode input voltage.
Inverting
IN
–). This biases the guard ring to the
V
IN
IN
DD
Guard Ring
Gain
+). This biases the guard ring
Example Guard Ring Layout
–
/2 or ground).
and
V
IN
+
Transimpedance
IN
–) to the input
IN
V
SS
+) to the
4.8
4.8.1
The MCP6291/2/3/4/5 op amp can be used in active-
filter applications. Figure 4-7 shows an inverting, third-
order, multiple feedback low-pass filter that can be
used as an anti-aliasing filter.
FIGURE 4-7:
Pass Filter.
This filter, and others, can be designed using
Microchip’s FilterLab
our web site (www.microchip.com).
4.8.2
Figure 4-8 shows a photodiode biased in the photovol-
taic mode for high precision. The resistor R converts
the diode current I
is used to limit the bandwidth or to stabilize the circuit
against the diode’s capacitance (it is not always
needed).
FIGURE 4-8:
V
light
IN
V
DD
/2
V
Application Circuits
R
DD
C
I
1
D
MCP6291/2/3/4/5
MULTIPLE FEEDBACK LOW-PASS
FILTER
PHOTODIODE AMPLIFIER
1
/2
D
to the voltage V
R
®
MCP6291
3
Multiple Feedback Low-
Photodiode Amplifier.
software, which is available on
MCP6291
R
C
2
3
C
R
OUT
DS21812D-page 13
R
. The capacitor
C
4
4
V
OUT
V
OUT