Using the LM3914

I have few questions about the implementing the LM3914 Bar/Dot Display driver.

1) If the current required was low enough, could it drive a relay? If so, It appears you would connect the relays to the positive rail and allow the 3914 to pull down to turn on the relay. Yes?

2) Pin 7, Adjustable Current Limit and the maximum output current. I was reading the data sheet and it lists the maximum current as 13mA. But on the first page indicates it is adjustable from 2 to 30mA, and in the power dissapation application hint it indicates running at 20mA. So what is the maximum output current available to sink or source at each output pin?

hi,
Download and install this LM3914 simulator.
https://www.electro-tech-online.com/blogs/ericgibbs/136-single-dual-lm3914-v3-0-calculator.html

The quoted 13mA max LED current is for a Reference Load current of 1mA. By increasing this Reference current the LED current can be increased (up to 30mA per driver as per spec, but bear in mind the specified maximum power dissipation of the whole chip). If driving a relay instead of an LED (assuming you can get one with a low enough operating current) the maximum voltage rating of the drivers must not be exceeded, so spike suppression would be essential.

Alec

Spike protection!! Put a diode across the coil of the relay.
I went to digikey.com and looked for small relays (2A and under contacts), with 12 volt or less coils using 30mA or less. There were 1654 choices.

I've go my eyes on a 5V relay with a built in diode and 500ohm coil (10mA). Luckily I'm going to be in dot mode to boot.