PIC16F753 Datasheet, PDF (125/238 Pages) Microchip Technology – 14/16-Pin, Flash-Based 8-Bit CMOS Microcontrollers

PIC16F753/HV753
13.0 FIXED VOLTAGE REFERENCE
(FVR)
The Fixed Voltage Reference (FVR) is a stable voltage
reference, independent of VDD, with 1.2V output level.
The output of the FVR can be configured to supply a
reference voltage to the following:
• ADC input channel
• Comparator 1 positive input (C1VP)
• Comparator 2 positive input (C2VP)
• REFOUT pin
• Shunt regulator
On the PIC16F753, the FVR is enabled by setting the
FVREN bit of the FVRCON register. The FVR is always
enabled on the PIC16HV753 device.
13.1 Fixed Voltage Reference Output
The FVR output can be applied to the REFOUT pin by
setting the FVRBUFSS and FVRBUFEN bits of the
FVRCON register. The FVRBUFSS bit selects the op
amp, FVR or DAC output reference to the REFOUT pin
buffer. The FVRBUFEN bit enables the output buffer to
the REFOUT pin.
Enabling the REFOUT pin automatically overrides any
digital input or output functions of the pin. Reading the
REFOUT pin when it has been configured for a
reference voltage output will always return a ‘0’.
13.2 FVR Stabilization Period
When the Fixed Voltage Reference module is enabled, it
requires time for the reference circuit to stabilize. Once
the circuit stabilizes and is ready for use, the FVRRDY bit
of the FVRCON register will be set. See Section 22.0
“Electrical Specifications” for the minimum delay
requirement.
13.3 Operation During Sleep
When the device wakes up from Sleep through an
interrupt or a Watchdog Timer time-out, the contents of
the FVRCON register are not affected. To minimize
current consumption in Sleep mode, the FVR voltage
reference should be disabled.
13.4 Effects of a Reset
A device Reset clears the FVRCON register. As a result:
• The FVR module is disabled
• The FVR voltage output is disabled on the
REFOUT pin
FIGURE 13-1:
VOLTAGE REFERENCE BLOCK DIAGRAM
FVR_ref
To Peripherals
VDD
FVR_buffer
To Peripherals
FVREN⁽¹⁾ EN
+
1.2V
-
rdy
VSS
00
DAC_out 01
OPA_out 10
FVRIN 11
FVRRDY
x1
FVRBUFEN
FVRBUFSS
FVROE
FVR_out
Note 1: If using PIC16HV753, the FVR will be enabled.
 2013 Microchip Technology Inc.
Preliminary
DS40001709A-page 125