ST2202A
15.2.3 Two-Pin Push Pull Mode (8-bit Accuracy)
TwoꢁPinꢀPushꢀPullꢀmodeꢀisꢀdesignedꢀforꢀbuzzer.ꢀItꢀrequiresꢀ
Figureꢀ13ꢁ7ꢀshowsꢀexamplesꢀofꢀDACꢀoutputꢀwaveformsꢀwithꢀ
twoꢀpinꢀthatꢀPSG0ꢀandꢀPSG1.ꢀWhenꢀtheꢀDACꢀvalueꢀisꢀ0,ꢀ
differentꢀoutputꢀvalues.ꢀEachꢀpulseꢀofꢀtheꢀDACꢀisꢀdividedꢀ
intoꢀ128ꢀsegmentsꢀperꢀsampleꢀperiod.ꢀForꢀaꢀpositiveꢀoutputꢀ
valueꢀx=0ꢀtoꢀ127,ꢀPSG1ꢀgoesꢀhighꢀforꢀXꢀsegmentsꢀwhileꢀ
PSG0ꢀstaysꢀlow.ꢀForꢀaꢀnegativeꢀoutputꢀvalueꢀx=0ꢀtoꢀꢁ127,ꢀ
PSG0ꢀgoesꢀhighꢀforꢀ|X|ꢀsegmentsꢀwhile PSG1ꢀstaysꢀlow.ꢀ
ꢀ
bothꢀpinsꢀareꢀlow.ꢀWhenꢀtheꢀDACꢀvalueꢀisꢀpositive,ꢀPSG1
goesꢀhighꢀ ꢀ withꢀaꢀdutyꢀcycleꢀproportionalꢀtoꢀtheꢀoutputꢀ
value,ꢀwhileꢀPSG0ꢀstaysꢀlow.ꢀWhenꢀtheꢀDACꢀvalueꢀisꢀ
negative,ꢀPSG0ꢀgoesꢀhighꢀ ꢀ withꢀaꢀdutyꢀcycleꢀproportionalꢀ
toꢀtheꢀoutputꢀvalue,ꢀwhileꢀPSG1ꢀstaysꢀlow.ꢀThisꢀmodeꢀoffersꢀ
aꢀresolutionꢀofꢀ8ꢀbits.ꢀ
ꢀ
High
PSG0
Low
128-X
96
32
1
High
Low
PSG1
X
32
DAC = 32
96
127
DAC = X
DAC = 96
DAC = 127
Where X=0 to 127
128+X
80
High
Low
PSG0
PSG1
|X|
48
High
Low
DAC = X
DAC = -48
DAC = 0
DAC = -128
Where X=0 to -128
FIGURE 15-5 Two-Pin Push Pull Mode Wave Form
ꢀ
ꢀ
Verꢀ2.5ꢀ
40
/75
ꢀ
9/16/2008ꢀ
SITRONIX [ SITRONIX TECHNOLOGY CO., LTD. ]
