PIC16F1939-I/P Microchip Technology Inc., PIC16F1939-I/P Datasheet - Page 169

• Manufacturer Part Number: PIC16F1939-I/P
• Description: 28KB Flash, 1KB RAM, 256B EEPROM, LCD, 1.8-5.5V
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F1939-I/P

• A/d Inputs: 14-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 8 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 36
• Interface: I2C/SPI/UART/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 40-pin PDIP
• Programmable Memory: 28K Bytes
• Ram Size: 1K Bytes
• Speed: 32 MHz
• Temperature Range: –40 to 125 °C
• Timers: 4-8-bit, 1-16-bit
• Voltage, Range: 1.8-5.5 V

16.0
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 V
• V
• 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
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 16-1:
16.2
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
Specifications”.
16.3
In order for the DAC module to consume the least
amount of power, one of the two voltage reference input
sources to the resistor ladder must be disconnected.
Either the positive voltage source, (V
negative voltage source, (V
 2009 Microchip Technology Inc.
V
DD
V
V
SRC
SRC
OUT
supply voltage
be
+ = V
- = V
DIGITAL-TO-ANALOG
CONVERTER (DAC) MODULE
Output Voltage Selection
Ratiometric Output Level
Low Power Voltage State
=


REF
found

V
DD
SS
SRC
or V
, V
pins
+ V
REF
REF
–
+ or FVR1
in
DAC OUTPUT VOLTAGE
-
SRC
-

Section 29.0
SRC

DACR<4:0>
------------------------------ -
-) can be disabled.
2 5
SRC


+ V
“Electrical
+), or the
SRC
-
Preliminary
The negative voltage source is disabled by setting the
DACLPS bit in the DACCON0 register. Clearing the
DACLPS bit in the DACCON0 register disables the
positive voltage source.
16.4
The DAC output voltage can be set to V
least amount of power consumption by performing the
following:
• Clearing the DACEN bit in the DACCON0 register.
• Setting the DACLPS bit in the DACCON0 register.
• Configuring the DACPSS bits to the proper
• Configuring the DACRx bits to ‘11111’ in the
This is also the method used to output the voltage level
from the FVR to an output pin. See Section 16.6 “DAC
Voltage Reference Output” for more information.
16.5
The DAC output voltage can be set to V
least amount of power consumption by performing the
following:
• Clearing the DACEN bit in the DACCON0 register.
• Clearing the DACLPS bit in the DACCON0 register.
• Configuring the DACPSS bits to the proper
• Configuring the DACRx bits to ‘00000’ in the
This allows the comparator to detect a zero-crossing
while not consuming additional current through the DAC
module.
16.6
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.
PIC16F193X/LF193X
positive source.
DACCON1 register.
negative source.
DACCON1 register.
Output Clamped to Positive
Voltage Source
Output Clamped to Negative
Voltage Source
DAC Voltage Reference Output
DS41364D-page 169
SRC
SRC
+ with the
- with the