PIC16F1459-ESSQTP datasheet(149/418 Pages) MICROCHIP

149 / 418 page

 2012 Microchip Technology Inc.

Preliminary

DS41639A-page 149

PIC16(L)F1454/5/9

14.0 FIXED VOLTAGE REFERENCE

(FVR) (PIC16(L)F1455/9 ONLY)

The Fixed Voltage Reference, or FVR, is a stable

voltage reference, independent of VDD, 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

• DAC input channel

• Comparator positive input

• Comparator negative input

The FVR can be enabled by setting the FVREN bit of

the FVRCON register.

14.1

Independent Gain Amplifier

The output of the FVR supplied to the ADC and

comparators is routed through a programmable gain

amplifier. Each amplifier can be programmed for a gain

of 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 Section 16.0 “Analog-to-Digital Converter

(ADC) Module (PIC16(L)F1455/9 only)”

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 comparator modules.

Reference

Section 18.0

“Comparator

Module

(PIC16(L)F1455/9 only)”

for additional information.

14.2

FVR Stabilization Period

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

Section 29.0 “Electrical Specifications”

for the

minimum delay requirement.

FIGURE 14-1:

VOLTAGE REFERENCE BLOCK DIAGRAM

ADFVR<1:0>

CDAFVR<1:0>

FVR BUFFER1

(To ADC Module)

FVR BUFFER2

(To Comparators, DAC)

FVREN

FVRRDY

Any peripheral requiring the

Fixed Reference

(See Table 14-1)

TABLE 14-1:

PERIPHERALS REQUIRING THE FIXED VOLTAGE REFERENCE (FVR)

Peripheral

Conditions

Description

HFINTOSC

FOSC<2:0> = 010 and

IRCF<3:0> = 000x

INTOSC is active and device is not in Sleep.

BOR

BOREN<1:0> = 11

BOR always enabled.

BOREN<1:0> = 10 and BORFS = 1

BOR disabled in Sleep mode, BOR Fast Start enabled.

BOREN<1:0> = 01 and BORFS = 1

BOR under software control, BOR Fast Start enabled.

LDO

All PIC16F1454/5/9 devices, when

VREGPM = 1 and not in Sleep

The device runs off of the Low-Power Regulator when in

Sleep mode.

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