PIC18F1XK22 Datasheet, PDF (244/388 Pages) Microchip Technology – 20-Pin Flash Microcontrollers with nanoWatt XLP Technology

PIC18F1XK22/LF1XK22
20.2 FVR Reference Module
The FVR is a stable fixed voltage reference,
independent of VDD, with a nominal output voltage of
1.024V. This reference can be enabled by setting the
FVR1EN bit of the VREFCON0 register to ‘1’. The FVR
can be routed to the comparators or an ADC input
channel.
20.2.1 FVR STABILIZATION PERIOD
When the Fixed Voltage Reference module is enabled, it
will require some time for the reference and its amplifier
circuits to stabilize. The user program must include a
small delay routine to allow the module to settle. The
FVR1ST stable bit of the VREFCON0 register also
indicates that the FVR has been operating long enough
to be stable. See Section 25.0 “Electrical
Specifications” for the minimum delay requirement.
FIGURE 20-1:
VOLTAGE REFERENCE BLOCK DIAGRAM
D1EN
D1LPS
D1PSS<1:0> = 00
VDD
VREF+
D1PSS<1:0> = 01
FVR1 ^{D1PSS<1:0> = 10}
R
R
R
R
R
32 Steps
DAC1R<4:0>
R
R
D1EN
D1LPS
R
VREF
DAC1OE
CVREF pin
VREF-
D1NSS = 1
D1NSS = 0
FVR1S<1:0> ₂
FVR1EN
FVR1ST
X1
X2
X4
+ _{1.024V Fixed}
_ _Reference
FVR
DS41365D-page 244
Preliminary
 2010 Microchip Technology Inc.