Brightness automatic control circuit

Published:2011/7/19 8:15:00 Author:Fiona | Keyword: automatic control | From:SeekIC

When the ambient brightness turns dark obviously,LX1970 can automatically turn the LCD backlight to make white LED light.Brightness automatic control circuit is shown as above.Using resistors R1 and R2 can set to control the brightness's minimum and maximum.Changing the capacity of capacitor C the capacity can adjust the response time and filter out 50 Hz power grid interference.LX1970 uses +3.3 ~ +5 V power supply.When only using SRC end,SNK end should be hung in the air.Assumed that the circuit requires 0.25 ~ 1.25V output voltage to drive the white LED,0.25V represents the minimum of LED brightness,1.25V represents the brightness's maximum.



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