ST2202A
15.2 PWM DAC Mode Options
TheꢀPWMꢀDACꢀgeneratorꢀhasꢀthreeꢀmodes,ꢀSingleꢁpinꢀ
mode,ꢀTwoꢁpinꢀtwoꢁendedꢀmodeꢀandꢀTwoꢁpinꢀpushꢀpullꢀ
mode.ꢀTheyꢀareꢀdependedꢀonꢀtheꢀapplicationꢀused.ꢀTheꢀ
DACꢀmodeꢀisꢀcontrolledꢀbyꢀDMD[1~0].ꢀ ꢀ (TABLEꢀ13ꢁ3)ꢀ
ꢀ
ꢀ
15.2.1 Single-Pin Mode (7-bit Accuracy)
Singleꢁpinꢀmodeꢀisꢀdesignedꢀforꢀuseꢀwithꢀaꢀsingleꢁtransistorꢀ
amplifier.ꢀItꢀhasꢀ7ꢀbitsꢀofꢀresolution.ꢀTheꢀdutyꢀcycleꢀofꢀtheꢀ
PSG1ꢀisꢀproportionalꢀtoꢀtheꢀoutputꢀvalue.ꢀIfꢀtheꢀoutputꢀvalueꢀ
isꢀ0,ꢀtheꢀdutyꢀcycleꢀisꢀ50%.ꢀAsꢀtheꢀoutputꢀvalueꢀincreasesꢀ
fromꢀ0ꢀtoꢀ63,ꢀtheꢀdutyꢀcycleꢀgoesꢀfromꢀbeingꢀhighꢀ50%ꢀofꢀ
theꢀtimeꢀupꢀtoꢀ100%ꢀhigh.ꢀAsꢀtheꢀvalueꢀgoesꢀfromꢀ0ꢀtoꢀꢁ64,ꢀ
theꢀdutyꢀcycleꢀdecreasesꢀfromꢀ50%ꢀhighꢀtoꢀ0%.ꢀPSG0ꢀisꢀ
inverseꢀofꢀPSG1’sꢀwaveform.ꢀFigureꢀ13ꢁ3ꢀshowsꢀtheꢀPSG1ꢀ
waveforms.
64
96
32
64+X
High
Low
PSG1
64
32
DAC = 32
96
DAC = -32
64-X
DAC = X
DAC = 0
ꢀ
FIGURE 15-3 Single-Pin Mode Wave Form
ꢀ
ꢀ
Verꢀ2.5ꢀ
38
/75
ꢀ
9/16/2008ꢀ
SITRONIX [ SITRONIX TECHNOLOGY CO., LTD. ]
