PIC16LF1904 Datasheet, PDF (121/288 Pages) Microchip Technology – 28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver and nanoWatt XLP Technology

PIC16LF1904/6/7
13.0 FIXED VOLTAGE REFERENCE
(FVR)
The Fixed Voltage Reference (FVR) is a stable voltage
reference, independent of VDD, 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
ADFVR<1:0>
2
x1
FVR BUFFER1
x2
(To ADC Module)
FVREN
Any peripheral requiring
the Fixed Reference
(See Table 13-1)
1.024V Fixed
Reference
+
FVRRDY
-
TABLE 13-1: PERIPHERALS REQUIRING THE FIXED VOLTAGE REFERENCE (FVR)
Peripheral
Conditions
Description
HFINTOSC
BOR
FOSC<2:0> = 100 and
IRCF<3:0> = 000x
BOREN<1:0> = 11
BOREN<1:0> = 10 and BORFS = 1
BOREN<1:0> = 01 and BORFS = 1
INTOSC is active and device is not in Sleep.
BOR always enabled.
BOR disabled in Sleep mode, BOR Fast Start enabled.
BOR under software control, BOR Fast Start enabled.
 2011 Microchip Technology Inc.
Preliminary
DS41569A-page 121