MEC1404 Datasheet, PDF (472/572 Pages) Microchip Technology – Keyboard and Embedded Controller Products for Notebook PC

MEC140X/1X
39.10 Description
FIGURE 39-2:
Digital to Analog Converter Block Diagram
DAC_PIN_EN
DAC_VREF
DAC_DATA
12
12-bit
Resistor
Ladder
Sample
&
Hold
DAC
To
Internal
Logic
DAC_BLANK_EN_MV
DAC_INTRL_EN
The DAC generates an analog output voltage based on a digital input code. The output of the DAC may be routed to a
pin, as well as to another internal device, such as an analog comparator. The DAC output is calculated according to the
following formula:
DAC = DAC_VREF  ^{D---4--A-0---9T---5-A---}
Where:
DAC = Output of the Digital Analog Converter, either on the pin or the internal logic
DAC_VREF = The voltage reference for the DAC
DATA = The contents of the DAC Data Register
The DAC features:
• Precision 12-bit resistor ladder
• 1M sample per second sample rates
• Reference input voltage from 0.5V to VTR
• Buffered output voltages
• A Sample and Hold circuit for reducing switching glitches on internal logic
39.10.1 DAC PROGRAMMING
The following sequence should be used to turn on the DAC:
1. Set the ACTIVATE bit to ‘1’
2. Program the DAC Configuration Register appropriately
3. Program the DAC Data Register with the required data value
DS00001956D-page 472
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