PIC16F193X Datasheet, PDF (153/418 Pages) Microchip Technology – 28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver and nanoWatt Technology

13.0 DIGITAL-TO-ANALOG
CONVERTER (DAC) MODULE
The Digital-to-Analog Converter supplies a variable
voltage reference, ratiometric with VDD, with 32 select-
able output levels. The output of the DAC can be con-
figured to supply a reference voltage to the following:
• Comparator positive input
• ADC input channel
• DACOUT device pin
The Digital-to-Analog Converter (DAC) can be enabled
by setting the DACEN bit of the DACCON0 register.
13.1 Output Voltage Selection
The DAC has 32 voltage level ranges. The 32 levels
are set with the DACR<4:0> bits of the DACCON1
register.
The DAC output voltage is determined by the following
equations:
EQUATION 13-1:
VOUT = _{⎝⎛(}VSOURCE+ – VSOURCE-) × ^{D-----A----C-2---R-}_∧---<--5--4---:-0--->--_⎠⎞
+ VSOURCE-
VSOURCE+ = VDD, VREF+ or FVR1
VSOURCE+ = VSS or VREF-
13.2 Output Clamped to VSS
The DAC output voltage can be set to Vss with no
power consumption by setting the DACEN bit of the
DACCON0 register to ‘0’: This allows the comparator to
detect a zero-crossing while not consuming additional
current from the DAC.
13.3 Output Ratiometric to VDD
The DAC is VDD derived and therefore, the DAC output
changes with fluctuations in VDD. The tested absolute
accuracy of the DAC can be found in Section 28.0
“Electrical Specifications”.
13.4 Voltage Reference Output
The DAC can be output to the device DACOUT pin by
setting the DACOE bit of the DACCON0 register to ‘1’.
Selecting the 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 reference voltage output will always
return a ‘0’.
PIC16F193X/LF193X
Due to the limited current drive capability, a buffer must
be used on the voltage reference output for external
connections to DACOUT. Figure 13-1 shows an exam-
ple buffering technique.
13.5 Operation During Sleep
When the device wakes up from Sleep through an
interrupt or a Watchdog Timer time-out, the contents of
the DACCON0 register are not affected. To minimize
current consumption in Sleep mode, the voltage
reference should be disabled.
13.6 Effects of a Reset
A device Reset affects the following:
• Voltage reference is disabled
• Fixed voltage reference is disabled
• DAC is removed from the DACOUT pin
• The DACR<4:0> range select bits are cleared
© 2008 Microchip Technology Inc.
Preliminary
DS41364A-page 151