PIC18F-LF1XK50 MICROCHIP [Microchip Technology], PIC18F-LF1XK50 Datasheet - Page 245

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PIC18F-LF1XK50

Manufacturer Part Number
PIC18F-LF1XK50
Description
20-Pin USB Flash Microcontrollers
Manufacturer
MICROCHIP [Microchip Technology]
Datasheet
21.0
There are two independent voltage references
available:
• Programmable Voltage Reference
• 1.024V Fixed Voltage Reference
21.1
The Voltage Reference module provides an internally
generated voltage reference for the comparators and
the DAC module. The following features are available:
• Independent from Comparator operation
• Single 32-level voltage ranges
• Output clamped to V
• Ratiometric with V
• 1.024V Fixed Reference Voltage (FVR)
The REFCON1 register
Voltage Reference module shown in
EQUATION 21-1:
21.1.3
The comparator voltage reference is V
therefore, the V
V
Voltage Reference can be found in
“Electrical
21.1.4
The V
CV
register to ‘1’. Selecting the reference voltage for out-
put on the V
output buffer and digital input threshold detector func-
tions of that pin. Reading the CV
been configured for reference voltage output will
always return a ‘0’.
Due to the limited current drive capability, a buffer must
be used on the voltage reference output for external
connections to CV
buffering technique.
 2010 Microchip Technology Inc.
DD
V
IF D1EN = 1
IF D1EN = 0 & D1LPS = 1 & DAC1R[4:0] = 11111:
IF D1EN = 0 & D1LPS = 1 & DAC1R[4:0] = 00000:
V
V
REF
OUT
. The tested absolute accuracy of the Comparator
OUT
OUT
REF
pin by setting the DAC1OE bit of the REFCON1
=
VOLTAGE REFERENCES
Voltage Reference
=
=
voltage reference can be output to the device
OUTPUT RATIOMETRIC TO V
Specifications”.
VOLTAGE REFERENCE OUTPUT
V
V
REF
V
SOURCE
SOURCE
SOURCE
REF
pin automatically overrides the digital
REF
output changes with fluctuations in
DD
-
+
.
V
+
SS
Figure 21-2
REF
(Register
V
SOURCE
OUTPUT VOLTAGE
REF
-
shows an example
21-2) controls the
 x
Figure
pin when it has
--------------------------------
DD
DAC1R[4:0]
Section 27.0
derived and
21-1.
2
5
DD
Preliminary
+
V
SOURCE
-
21.1.1
The
comparator configuration. Setting the D1EN bit of the
REFCON1 register will enable the voltage reference by
allowing current to flow in the V
When the D1EN bit is cleared, current flow in the V
voltage divider is disabled minimizing the power drain
of the voltage reference peripheral.
21.1.2
The
ranges. The 32 levels are set with the DAC1R<4:0>
bits of the REFCON2 register.
The V
equations:
21.1.5
When the device wakes up from Sleep through an
interrupt or a Watchdog Timer time-out, the contents of
the RECON1 register are not affected. To minimize
current consumption in Sleep mode, the voltage
reference should be disabled.
21.1.6
A device Reset affects the following:
• Voltage reference is disabled
• Fixed voltage reference is disabled
• V
• The DAC1R<4:0> range select bits are cleared
REF
V
voltage
REF
REF
is removed from the CV
PIC18F/LF1XK50
output voltage is determined by the following
INDEPENDENT OPERATION
OUTPUT VOLTAGE SELECTION
OPERATION DURING SLEEP
EFFECTS OF A RESET
voltage reference has 32 voltage level
reference
is
REF
independent
REF
DS41350E-page 245
pin
voltage divider.
of
REF
the

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