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LM822/LM823: LED function FAQ

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Introduction

The LED function is possible with the LM822 and LM823. As described on the datasheet the LED is a factory option that has to be specifically ordered and is disabled by default.

For enquiries about ordering this variant please contact a member of our sales team: https://www.lm-technologies.com/contact/

If I apply 5V to the led(Vf=2V) with 15mA flowing through it, is a 200 Ohm resistor the right value to use?

This would be correct.

15mA*200ohm=3V

2V+3V=5V

Driving the LED with 3.3V instead of 5V, what resistor should I use?

Please refer to the Relative Luminous Intensity VS Forward Current as shown in the graphic, you can design the resistor accordingly.

3.3V / 6mA = 550 ohms

3.3V / 15mA = 220 ohms

3.3V/ 25mA = 130 ohms

LM823: Linux error “wlan0: link is not ready”

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Edit the /etc/NetworkManager/NetworkManager.conf file

And add:

[device]

wifi.scan-rand-mac-address=no

Restart the networkmanager service and use your wireless connection.

You can apply this fix by opening a Terminal and typing “sudo gedit /etc/NetworkManager/NetworkManager.conf”, adding the text described and rebooting the machine.

If the fix does not work, please contact LM Technologies to see if new drivers are available.