PIC18F-LF1XK50 Datasheet, PDF (246/420 Pages) Microchip Technology – 20-Pin USB Flash Microcontrollers

PIC18F/LF1XK50
21.2 FVR Reference Module
The FVR reference 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 REFCON0 register to ‘1’. The FVR
voltage reference can be routed to the comparators or
an ADC input channel.
21.2.1 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 REFCON0 register also
indicates that the FVR reference has been operating long
enough to be stable. See Section 27.0 “Electrical
Specifications” for the minimum delay requirement.
FIGURE 21-1:
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
DS41350E-page 246
Preliminary
 2010 Microchip Technology Inc.