Datasheet

Table Of Contents
2011 Microchip Technology Inc. Preliminary DS41569A-page 121
PIC16LF1904/6/7
13.0 FIXED VOLTAGE REFERENCE
(FVR)
The Fixed Voltage Reference (FVR) is a stable voltage
reference, independent of V
DD, with 1.024V or 2.048V
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
The FVR can be enabled by setting the FVREN bit of
the FVRCON register.
13.1 Independent Gain Amplifiers
The output of the FVR supplied to the ADC is routed
through two independent programmable gain
amplifiers. Each amplifier can be configured to amplify
the reference voltage by 1x or 2x, to produce the two
possible voltage levels.
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 15.0 “Analog-to-Digital Converter
(ADC) Module” for additional information.
13.2 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 22.0 “Electrical Specifications” for the
minimum delay requirement.
FIGURE 13-1: VOLTAGE REFERENCE BLOCK DIAGRAM
FVR BUFFER1
(To ADC Module)
x1
x2
+
-
1.024V Fixed
Reference
FVREN
FVRRDY
2
ADFVR<1:0>
Any peripheral requiring
the Fixed Reference
(See Table 13-1)
TABLE 13-1: PERIPHERALS REQUIRING THE FIXED VOLTAGE REFERENCE (FVR)
Peripheral Conditions Description
HFINTOSC FOSC<2:0> = 100 and
IRCF<3:0> = 000x
INTOSC is active and device is not in Sleep.
BOR
BOREN<1:0> = 11 BOR always enabled.
BOREN<1:0> = 10 and BORFS = 1 BOR disabled in Sleep mode, BOR Fast Start enabled.
BOREN<1:0> = 01 and BORFS = 1 BOR under software control, BOR Fast Start enabled.