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Rev. 1.00
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Standard 8051 8-Bit Flash MCU
HT85F2260/HT85F2270/HT85F2280
Digital to
Analog Converter – DAC
Digital to
Analog Converter – DAC
DAC Operation
The DAL and DAH registers contain the digital value to be converted. The DACEN bit in the
DACTRL register provides overall enable/disable control. When set high, the DAC output pin will
be enabled and the original I/O pin shared function disabled. Clearing this bit to zero will disable
the DAC and reduce any associated power consumption. The DAC attenuation control is provided
by the VOL0~VOL2 bits in the DACTRL register providing an 8-level attenuation control. These
bits rotate the digital DAC value thus providing a divide or multiply by two functions for each shift
left or right. If the DAC circuit is not enabled, any DAH/DAL values will be invalid. The VREFDS
and VREFIS bits select if the DAC reference is to be sourced from VCCA2, VREF pin or the
internal reference voltage. Bits 0~3 of the DAL register are always read as zero.
The accompanying diagram illustrates the DAC basic operational block diagram.
DACEN
DAC
VOL[�:0]
/
/
1�-bit D/A
Conve�te�
MUX
VCCA�
VREFDS
Inte�nal Voltage Refe�ence
VREFIS
VREF
Data B�s
Low B�te B�ffe�
DAL
DAH
Refe�ence Voltage
Atten�ation
Cont�ol
DAC Basic Operational Block Diagram