Temperature measuring circuit

Published:2012/12/3 21:38:00 Author:Ecco | Keyword: Temperature measuring | From:SeekIC

In the figure, S1 is the point / bar display mode changeover switch. When the power supply voltage Vcc> 8V, LED1 ~ LED10 don't need to use limiting resistor connected in series. When LED is lit, the cuttent is set by external resistor connected to pin 4,6, assuming pin 4,6 external resistor is 1.2kΩ ( inlcuding the resistance between the resistor R1, BP1 center head and pin 4), 10kΩ resistor is connected in parallel with the LM3914 internal divider, the equivalent resistance between pin 4 and pin 6 is about 10.7kΩ, the current of voltage divider circuit provided by 1.25V reference voltage is 1.25V/1.07kΩ ≈ 1.2mA.



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