User`s guide

Rev. 1.10 112 November 14, 2014 Rev. 1.10 113 November 14, 2014
HT66FW2230
Wireless Charger A/D Flash 8-Bit MCU
OCP Function
OCPisanabbreviationforovercurrentprotection.TheOCPdetectsaninputvoltagewhichisproportional
tothemonitoredsourcecurrent.IftheinputvoltageislargerthanthereferencevoltagesetbytheDAC,
theOCPwillgenerateanoutputsignaltoindicatethatthesourcecurrentisoutwiththespecication.
OCP/AN1
Interrrupt
(OCF)
OC for PWM output
disable & MCU reading
AN1
8 bit
DAC
C
OCPREF[7:0]
Filter
Filter
clock
R1
R2
A
(R1=4K)
G=1/5/10/15/20/30/40/50
S1
S0
S2
S3
f
FLT
=f
H
/4
OCPM[1:0]
AN9
OCPG[2：0]
OCPFLT[2：0]
OCPAX
OCPCX
OCPO
Over Current Protect Circuit
OCP Circuit Operation
ThesourcevoltageissourcedfromtheOCP.FourswitchesS0~S3formofamodeselectfunction.
AnoperationalamplifierandtworesistorsformaPGAfunction.ThePGAgaincanbepositive
ornegativedeterminedbytheinputvoltageconnectedtothepositiveinputornegativeinputof
thePGA.TheOCPREFisusedtogenerateareferencevoltage.Thecomparatorcomparesthe
referencevoltageandtheamplifiedoutputvoltage.Finally thecomparatoroutputisfilteredto
generatetheOCPOoutputtodisablethePWMoutputandtheOCPinterrupttrigger.Theseare
debouncedversionsofDEMCXwhichareusedtoindicatewhetherthesourcecurrentisoutwiththe
specicationornot.
Notethatthelterclock;f
HXT
istheHXTclock.Theampliedoutputvoltagealsocanbereadout
bymeansofanotherADCfromOCPAX.TheDACoutputvoltageiscontrolledbytheOCPREF
registerandtheDACoutputisdenedas
DACV
OUT
=(DACV
REF
/256)×OCPREF[7:0](1)
Input Voltage Range
Theinputvoltagecanbepositiveornegative,whichtogetherwiththePGAoperatingmode,
providesforamoreexibleapplication.
(1)IfV
IN
>0andthePGAoperatesinthenon-invertingmode,theoutputvoltageofthePGAis
INPGA
VRRVO ×+= )/1(
12
(2)
(2)WhenthePGAoperatesinthenon-invertermode,italsoprovidesaunitygainbufferfunction.
IfOCPM[1:0]=01andOCPG[2:0]=000,thePGAgainwillbe1andisconguredasaunitygain
buffer.SwitchesS2andS3willbeopeninternallyandtheoutputvoltageofthePGAis
INPGA
VVO =
(3)
(3)If0>V
IN
>-0.7VandthePGAoperatesininvertermode,theoutputvoltageofthePGAis
INPGA
VRRVO ×−= )/(
12
(4)
Note:ifV
IN
isnegative,itshouldnotbelowerthan-0.7Vtoavoidleakagecurrent.