PIC16F193X Datasheet, PDF (157/418 Pages) Microchip Technology – 28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver and nanoWatt Technology

PIC16F193X/LF193X
14.0 FIXED VOLTAGE REFERENCE
The Fixed Voltage Reference, or FVR, is a stable
voltage reference, independent of VDD, with 1.024V,
2.048V or 4.096V selectable output levels. The output
of the FVR can be configured to supply a reference
voltage to the following:
• ADC input channel
• ADC positive reference
• Comparator positive input
• Programmable voltage reference
• LCD bias generator
The FVR can be enabled by setting the FVREN bit of
the FVRCON register.
14.1 Independent Gain Amplifiers
The output of the FVR supplied to the ADC and
comparator modules is routed through two
independent programmable gain amplifiers. Each
amplifier can be configured to amplify the reference
voltage by 1x, 2x or 4x.
The ADFVR<1:0> bits of the FVRCON register are
used to enable and configure the gain amplifier settings
for the reference supplied to the ADC module. Refer-
ence Section 11.0 “Analog-to-Digital Converter
(ADC) Module” for additional information on selecting
the appropriate input channel.
The CDAFVR<1:0> bits of the FVRCON register are
used to enable and configure the gain amplifier settings
for the reference supplied to the comparator module.
Reference Section 12.0 “Comparator Module” for
additional information on selecting the appropriate
input channel.
14.2 FVR Stabilization Period
When the fixed voltage reference module is enabled, it
requires time for the reference and amplifier circuits to
stabilize. Once the circuits stabilize and are ready for use,
the FVRRDY bit of the FVRCON register will be set. See
Section 28.0 “Electrical Specifications” for the
minimum delay requirement.
FIGURE 14-1:
VOLTAGE REFERENCE BLOCK DIAGRAM
ADFVR<1:0> ₂
X1
X2
X4
FVR_BUFFER1
(To ADC Module)
CDAFVR<1:0> ₂
X1
X2
X4
FVREN
FVRRDY
+ _{1.024V Fixed}
_ _Reference
FVR_BUFFER2
(To Comparators, DAC)
FVR_VREF
(To LCD Bias Generator)
FIGURE 14-2:
VOLTAGE REFERENCE OUTPUT BUFFER EXAMPLE
PIC16F193X/
PIC16LF193X
CVREF
Module
R
Voltage
Reference
Output
Impedance
CVREF
+
–
Buffered CVREF Output
© 2008 Microchip Technology Inc.
Preliminary
DS41364A-page 155