Datasheet

 2013-2014 Microchip Technology Inc. DS70000689D-page 369
dsPIC33EPXXXGM3XX/6XX/7XX
26.1.2 OP AMP CONFIGURATION B
Figure 26-6 shows a typical inverting amplifier circuit with
the output of the op amp (OAxOUT) externally routed to
a separate analog input pin (ANy) on the device. This
op amp configuration is slightly different in terms of the
op amp output and the ADCx input connection, therefore,
R
INT1 is not included in the transfer function. However,
this configuration requires the designer to externally
route the op amp output (OAxOUT) to another analog
input pin (ANy). See Table 33-52 in Section 33.0 “Elec-
trical Characteristics” for the typical value of RINT1.
Table 33-57 and Table 33-58 in Section 33.0 “Electrical
Characteristics” describe the minimum sample time
(T
SAMP) requirements for the ADCx module in this
configuration.
Figure 26-6 also defines the equation to be used to
calculate the expected voltage at point, V
OAXOUT. This
is the typical inverting amplifier equation.
26.2 Op Amp/Comparator Resources
Many useful resources are provided on the main prod-
uct page of the Microchip web site for the devices listed
in this data sheet. This product page, which can be
accessed using this link, contains the latest updates
and additional information.
26.2.1 KEY RESOURCES
• “Op Amp/Comparator” (DS70000357) in the
“dsPIC33/PIC24 Family Reference Manual”
• Code Samples
• Application Notes
• Software Libraries
• Webinars
• All Related “dsPIC33/PIC24 Family Reference
Manual” Sections
• Development Tools
FIGURE 26-6: OP AMP CONFIGURATION B
Note: In the event you are not able to access the
product page using the link above, enter
this URL in your browser:
http://www.microchip.com/wwwproducts/
Devices.aspx?dDocName=en555464
ADCx
(3)
OAxOUT
RFEEDBACK
(2)
ANy
Note 1: See Table 33-56 for the Typical value.
2: See Table 33-52 for the Minimum value for the feedback resistor.
3: See Table 33-59 and Table 33-60 for the Minimum Sample Time (T
SAMP).
4: CV
REF1O or CVREF2O are two options that are available for supplying bias voltage to the op amps.
–
+
Op Amp x
(V
OA X OUT )
RINT1
(1)
V
OAxOUT
R
FEEDBACK
R
1
------------------------------


Bias Voltage V–
IN
=
CxIN1-
CxIN1+
R
1
VIN
Bias Voltage
(4)