SN8P275X Series
8-bit micro-controller build-in 12-bit ADC
SONiX TECHNOLOGY CO., LTD
Page 142
Version 0.7
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DIGITAL TO ANALOG CONVERTER
12.1 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
DAM REGISTER
DAO OUTPUT
LADDER RESISTORS
DAM REGISTER
DAO OUTPUT
The DA converter Block Diagram
In order to get a proper linear output, a Loading Resistor R
L
is usually added between DAO and Ground. The example
shows the result of Vdd = 5V, R
L
=150ohm and Vdd = 3V, R
L
=150ohm.
DAO Circuit with R
L
DAC Output Voltage in Vdd=5V and 3V
Note:
1: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.
2:For best linearity performance, the max. Loading Resistance R
L
is 150 ohm @5V, 100 ohm @3V
Vdd=3V
Vdd=5V