Kenwood TH-25A Service Manual

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BC-11 (RAPID CHARGER)4) Battery Recognition Circuit PB-?7 : ““L" CURRENT LIMITINGThebatteryrecognitioncircuit usesNANDlogictofimFie“INPUTICS———circuirrecognizethebattery typefromtheoutputsfromthe®Deasabatterypackdetectcircuit.Outputsfromthiscircuitare®senttothechargingcurrentlimitingcircuitandsensorrreylevelswitchingcircuit.PB-5: “H""OUTPUTSENSOR LEVELSWITCHING CIRCUITtoa |to Q14Table 35) 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 currentICR is detected as a voltage drop across R1 (0.1582),-whichis provided to pin 3 of the operational amplifier 1C4(1/2) :LAG393A. Pin 4 receives a reference voltage {Vrer ) used asé a comparison standard for limiting the charging current.The Vrer is changed by ON and OFF of O5 and Q6 (SeeQspB-5 | OFFpB-7 | ONpa-8 | OFFpa-9 | OFF|pag | OFF||Table 4). Table 4Pin 2 of IC4 : LA6393S provides L’’ output when Vrer<> Ver, stopping the operation of the chopper regulatér(IC1. : STK772B) and reducing the charging current. TKe Vee Saicharging current is limited by the formula :ter MAX (A) = Veer (V)/0.15(Q) from Fig. (id©PB-5,6,8,9 : “H"PB-7 :*L""REFERENCEVOLTAGE\ (VREF}trom Fig.3OICR :CHARGING CURRENTVCR0.15ICRFig. 4 Charging Current Limiting Circuit Block Diagram