LM3914: No signal is input. But the LED lights up.

HIROKI IIJIMA

Part Number: LM3914

Use the reference schematic below.
Pin No.5(signal INPUT) is OPEN.
But LED is lights up.

Please tell me the reason and how to improve.

over 2 years ago

+1 Liaqat Khan over 2 years ago

TI__Mastermind 18550 points

Hello,

Input signal at pin 5 is not supposed to be left floating/open and it should always be driven with a voltage level. This is a high impedance input and if left floating, any noise/residual signal has the potential to cause erratic behavior of the LEDs.

Kind Regards,

Liaqat

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LM3914: No signal is input. But the LED lights up.