Kenwood TK-230 Service Manual

TK-230/230(SC)KSC-4 (RAPID CHARGER)4) Battery Recognition Circuit KNB-4: “L" CURRENT LIMITINGThebatteryrecognitioncircuitusesNANDlogic totrom Fig.'NPUTIcsCIRCUITrecognizethebatterytypefromtheoutputsfromthe®—1ae)y0O5|batterypackdetectcircuit.Outputsfromthiscircuitareaig> toQ6senttothechargingcurrentlimitingcircuitandsensorlevelswitchingcircuit.NORMALLY : “L"’INPUT OUTPUTBATT. |AIB;/C/DiE|FIGNone {tft ftfHiHi cht SEE curKNB-3A }H/ LILITH] H]LIH ———ais |KNB4 [H[H{L{L[H|[L[H 5 12) Lp roars |Table 3 , |kne-3A/KNB-4 pyFig. 3 Battery Recognition Circuit Block Diagram5) Charging Current Limiting CircuitThis circuit receives the output of the battery recogni-tion circuit and limits the charging current according tothe type (current capacity) of battery.The charging current ICR is detected as a valtagedrop across R1 (0.15Q}, which is provided to pin 3 ofthe operational amplifier 1C4(1/2) : LA6393A. Pin 4 BATT. | O5 | Q6 | VrEF |IcR MAXreceives a reference voltage (VREF) used as a comparison KNB-3A | OFF | OFF | 0.28V | 1.8Astandard for limiting the charging current. The VREF is KNB-4 | ON | OFF | 0.36V | 2.4Achanged by ON and OFF by QS and O6. (See Table 4.)When a KNB-3A or KNB-4 is charged, Q6 is off. Pin 2 Table4of I1C4 provides ''L’’ output when VREF VCR, stoppingthe operation of the chopper regulator (IC1 : STK772B)andreducingthechargingcurrent.Thecharging currentisCHOPPERREGULATORlimitedbytheformula:R21 VecSWITCHINGICRMAX(A)=VREF(V})/0.15(Q)fromFig.3R22a}c12a6x©c>—>R16KNB-4:°L”O8>Wrod3 1C4(1/2)rz-aR20al;REFERENCEfromFig.3R24VOLTAGE©(VREF)C}<—IcR :CHARGING CURRENTVCR=0.15ICRFig. 4 Charging Current Limiting Circuit Block Diagram96