PIC16F1824-ESLASHML datasheet(161/420 Pages) MICROCHIP

161 / 420 page

 2010 Microchip Technology Inc.

Preliminary

DS41419A-page 161

PIC16F/LF1824/1828

16.0 DIGITAL-TO-ANALOG

CONVERTER (DAC) MODULE

The Digital-to-Analog Converter supplies a variable

voltage reference, ratiometric with the input source,

with 32 selectable output levels.

The input of the DAC can be connected to:

•External VREF pins

•VDD supply voltage

• FVR (Fixed Voltage Reference)

The output of the DAC can be configured to supply a

reference voltage to the following:

• Comparator positive input

• ADC input channel

•DACOUT pin

The Digital-to-Analog Converter (DAC) can be enabled

by setting the DACEN bit of the DACCON0 register.

16.1

Output Voltage Selection

The DAC has 32 voltage level ranges. The 32 levels

are set with the DACR<4:0> bits of the DACCON1

The DAC output voltage is determined by the following

equations:

EQUATION 16-1:

DAC OUTPUT VOLTAGE

16.2

Ratiometric Output Level

The DAC output value is derived using a resistor ladder

with each end of the ladder tied to a positive and

negative voltage reference input source. If the voltage

of either input source fluctuates, a similar fluctuation will

result in the DAC output value.

The value of the individual resistors within the ladder

can

found

Section 29.0

“Electrical

Specifications”.

16.3

DAC Voltage Reference Output

The DAC can be output to the DACOUT pin by setting

the DACOE bit of the DACCON0 register to ‘1’. Selecting

the DAC reference voltage for output on the DACOUT

pin automatically overrides the digital output buffer and

digital input threshold detector functions of that pin.

Reading the DACOUT pin when it has been configured

for DAC reference voltage output will always return a ‘0’.

Due to the limited current drive capability, a buffer must

be used on the DAC voltage reference output for

external connections to DACOUT. Figure 16-2 shows

an example buffering technique.

VOUT

VSOURCE+VSOURCE-

–

 DACR<4:0>

-------------------------------







+ VSRC-

Note:

VSOURCE+ can equal FVR Buffer 2, VDD or

VREF+. VSOURCE- can equal VSS or VREF-.

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