Microchip Technology DM164130-7 Data Sheet

 2010-2012 Microchip Technology Inc.

DS41414D-page 157

The Fixed Voltage Reference, or FVR, is a stable
voltage reference, independent of V

DD

, with 1.024V,

2.048V or 4.096V 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
• Comparator positive input
• Comparator negative input
• Digital-to-Analog Converter (DAC)
• Capacitive Sensing (CPS) module
• LCD bias generator
The FVR can be enabled by setting the FVREN bit of
the FVRCON register.

The output of the FVR supplied to the ADC,
Comparators, DAC and CPS module is routed through
two independent programmable gain amplifiers. Each
amplifier can be configured to amplify the reference
voltage by 1x, 2x or 4x, to produce the three 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 

 for additional information.

The CDAFVR<1:0> bits of the FVRCON register are
used to enable and configure the gain amplifier settings
for the reference supplied to the Comparators, DAC
and CPS module. Reference 

, 

 and 

 for additional information.

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

 for the

minimum delay requirement.

ADFVR<1:0>

CDAFVR<1:0>

X

1

X

2

X

4

X

1

X

2

X

4

2

2

FVR BUFFER1

(To ADC Module)

FVR BUFFER2

(To Comparators, DAC, CPS)

FVR VREF

(To LCD Bias Generator)

+
_

FVREN

FVRRDY

1.024V Fixed

Reference

Any peripheral requiring the 

Fixed Reference
(See 

)