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Powering a HT16K33 Backpack
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Powering a HT16K33 Backpack

by Datto_521 on Wed Jul 15, 2020 9:04 am

Hello, I'm trying to run an Arduino Nano and three backpacks in a car. I've been given a few options to regulate down to 5v but I need help powering the backpacks.

The Arduino can only power 1 backpack, the second one causes flickering so I want to power them all separately from the regulated 5v.

Is there a best way to power them? As plugged in directly I think they get too much current. I seem to have killed two chips this way... I tried to find a datasheet for the input current but all I could find was the one for the chip itself. Is there a specific max value?

Any help is appreciated.

Datto_521
 
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Re: Powering a HT16K33 Backpack

by adafruit_support_bill on Wed Jul 15, 2020 9:18 am

There are plenty of buck converters designed for automotive use. Many have 5v USB socket outputs. Others are designed for hard-wiring. Any 5v buck converter with sufficient current output should work.

The current requirements of the HT16K33 chip itself are miniscule compared to the displays they are driving. The current requirements for your displays will depend on the type of display.

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Re: Powering a HT16K33 Backpack

by Datto_521 on Wed Jul 15, 2020 10:12 am

Currently the LEDs I'm using are 2.2fV, 20mA typical forward current. Do I need current limiting resistors for the LEDs? As my understanding is the chip handles this?

Also do I need any current limiting to the backpack?

Because otherwise I don't understand what went wrong with my current setup. As the backpacks do not work at all now, even with a new backpack if I keep the old one connected via I2C (two different addresses) neither the new or old one work. I'm not sure if there's any potential troubleshooting?

Datto_521
 
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Re: Powering a HT16K33 Backpack

by adafruit_support_bill on Wed Jul 15, 2020 11:14 am

You generally do not need current limiting. The displays are multiplexed, so only one row is lit up at a time. So for example, if you have it set up as a matrix with 8 rows and 8 columns, only one column will be lit at a time, so the maximum current draw at any time would be about 20 x 8 = 160mA.

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Please be positive and constructive with your questions and comments.