SN8P1700
8-bit micro-controller build-in 12-bit ADC
13 7-BIT DIGITAL TO ANALOG
CONVERTER
OVERVIEW
The D/A converter uses 7-bit structure to synthesize 128 steps' analog signal with current source output. After DAENB
bit is set to “1”, DAC circuit will turn to be enabled and the DAM register, from bit0 to bit6, will send digital signal to
ladder resistors in order to generate analog signal on DAO pin.
LADDER RESISTORS
Figure 13-1. The DA converter Block Diagram
In order to get a proper linear output, a Loading Resistor R is usually added between DAO and Ground. The example
DAM REGISTER
DAO OUTPUT
L
shows the result of Vdd = 5V, R =150ohm and Vdd = 3V, R =150ohm.
L
L
Vdd=5V
Vdd=3V
Figure 13-2 DAO Circuit with RL
Figure 13-3. DAC Output Voltage in Vdd=5V and 3V
The D/A converter is not designed for a precise DC voltage output and is suitable for a simple audio application e.g.
Tone or Melody generation.
DAM REGISTER
DAM initial value = 0000 0000
0B0H
DAM
Bit 7
DAENB
R/W
Bit 6
DAB6
R/W
Bit 5
DAB5
R/W
Bit 4
DAB4
R/W
Bit 3
DAB3
R/W
Bit 2
DAB2
R/W
Bit 1
DAB1
R/W
Bit 0
DAB0
R/W
DAENB: Digital to Analog converter control bit. 0 = disable, 1 = enable.
DABn: Digital input data.
SONiX TECHNOLOGY CO., LTD
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Revision 1.94
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