...the world's most energy friendly microcontrollers
2014-07-02 - Gecko Family - d0001_Rev1.30
398
www.silabs.com
• Output to ADC
• Sine generation mode
• Optional high strength line driver
26.3 Functional Description
An overview of the DAC module is shown in Figure 26.1 (p. 398) .
Figure 26.1. DAC Overview
DACn_OUT0
DACn_OUT1
Ch 1
VDD
1.25 V
2.5 V
CH0DATA
CH1DATA
ADC
REFSEL
Ch 0
26.3.1 Conversions
The DAC consists of two channels (Channel 0 and 1) with separate 12-bit data registers
(DACn_CH0DATA and DACn_CH1DATA). These can be used to produce two independent single ended
outputs or the channel 0 register can be used to drive both outputs in differential mode. The DAC supports
three conversion modes, continuous, sample/hold, sample/off.
26.3.1.1 Continuous Mode
In continuous mode the DAC channels will drive their outputs continuously with the data in the
DACn_CHxDATA registers. This mode will maintain the output voltage and refresh is therefore not
needed.
26.3.1.2 Sample/Hold Mode
In sample/hold mode, the DAC core converts data on a triggered conversion and then holds the output
in a sample/hold element. When not converting, the DAC core is turned off between samples, which
reduces the power consumption. Because of output voltage drift the sample/hold element will only hold
the output for a certain period without a refresh conversion. The reader is referred to the electrical
characteristics for the details on the voltage drift. The sampling period in this mode is set to the length
of one prescaled clock cycle.
26.3.1.3 Sample/Off Mode
In sample/off mode the DAC and the sample/hold element is turned completely off between samples,
tri-stating the DAC output. This requires the DAC output voltage to be held externally. The references
are also turned off between samples, which means that a new warm-up period is needed before each
conversion. The sampling period in this mode is set to the length of one prescaled clock cycle.
26.3.1.4 Conversion Start
The DAC channel must be enabled before it can be used. When the channel is enabled, a conversion
can be started by writing to the DACn_CHxDATA register. These data registers are also mapped into
Summary of Contents for EFM32G
Page 505: ......