Posted on Feb 6, 2014

The picutre 3-6 is thermistor temperature or frequency conversion circuit. Because thermistors resistance changes with the temperature in linear way, the change can be used in voltage controlled oscillator. In the circuit, A1-A4 uses current type operational amplifier LM390O, RP1 and RP2 are used to adjust thermistors temperature-resistance properties

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and the voltage controlled oscillator voltage frequency characteristics. RP3 is used to regulate work range center of voltage controlled oscillator. Adjustment Process:When voltage controlled oscillator output voltage Ui is 7. 5V and RP3are regulated, which makes output frequency f ‚ become 635Hz. lOk © calibrating resistance substitutes for thermistor RT and RP2 is regulated to make the output frequency f ‚ become 635Hz. Then 13 ·3k ©calibrating resistance substitutes for thermistor RT again, RP1 is regulated to make the output frequency f ‚ become 143Hz. Please adjust like this for many times until the satisfying result is obtained. (View) The above charging circuit is composed of SM6781BV. SM6781BV is charging control integrated controller and the tube feet functions are as follows. Feet 1-Timing Choosing Port The value ofinput port voltage is set as UDD, UDD/2 or 0. Feet 2(LEDN)-Charging Display LED Driving Output Port It adopts leakage output and the low PWL is output when it is fast charging. When the charging is abnormal and INH port is high PWL, the output pulse is 1HZ. And it is in high impedance condition when the charging is finished. Feet 3(BATT) ”Battery voltage Detection Input End This feet inputs every battery voltage and it adopts resistance to divide the voltage when there are many batteries. Feet 7 (INH) ”Fast Charging Interruptting Input Port It stops fast charging when it is high PWL. It stops charging...

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