Thin Component Availability

[electronicsfreak]

Hi all,

Working on a hobby project, in this case a means for driving an LED matrix display.

Now, as attractive as the HT16K33 is from Holtek, I just can't help but ask the question: Why isn't this component available from larger distributors? I can see that Newark carries some of Holtek's other products, but I am having a hard time understanding why a part like this wouldn't be available from places such as Digikey, Mouser, etc.

Does it have to do with low demand, or perhaps is there an industry standard that Holtek's components don't quite match up to in comparison to other suppliers of similar devices?

I'd like to hear your thoughts on this.

-EF

 

[jpanhalt]

I am not familiar with that particular part, but I am familiar with its encoders and decoders. I did take a quick look at its datasheet. It has an I2C interface. The question is whether Holtek's products fill a general need or a niche. I suspect it is more the latter. High volume users probably do the same function with a microprocessor.

As for why DigiKey and Mouser don't carry it in stock, I suspect it is a matter of demand. DigiKey used to carry Holtek's encoders/decoders, but as of this morning, it appears they are all non-stock items.

John

 

[gophert]

Hi all,

Working on a hobby project, in this case a means for driving an LED matrix display.

Now, as attractive as the HT16K33 is from Holtek, I just can't help but ask the question: Why isn't this component available from larger distributors? I can see that Newark carries some of Holtek's other products, but I am having a hard time understanding why a part like this wouldn't be available from places such as Digikey, Mouser, etc.

Does it have to do with low demand, or perhaps is there an industry standard that Holtek's components don't quite match up to in comparison to other suppliers of similar devices?

I'd like to hear your thoughts on this.

-EF

why would you add a chip to a device. Another layer of communication. Another chip to learn about, more PCB footprint, more traces to design, connect, solder and worry about errors. Another datasheet to interpret. It seems that the only practical use for this chip is a remote keyboard/display driven by a master MCU when you are trying to cut down on the number of wires (width of ribbon cable) from master MCU to remote keyboard/display.

It seems to me that demand for such a device is limited - a niche of a niche application.
- remote keyboard and display
- limited number of wires to remote system
- no desire to use a familiar microcontroller on the remote board to drive display and keypad.

If it were me, I would use a microcontroller that I am familiar with to act as the controller of the remote slave keyboard/display board.

 

[electronicsfreak]

This definitely gives a little more perspective, Thanks!

-EF

 

[electronicsfreak]

why would you add a chip to a device. Another layer of communication. Another chip to learn about, more PCB footprint, more traces to design, connect, solder and worry about errors. Another datasheet to interpret. It seems that the only practical use for this chip is a remote keyboard/display driven by a master MCU when you are trying to cut down on the number of wires (width of ribbon cable) from master MCU to remote keyboard/display.

It seems to me that demand for such a device is limited - a niche of a niche application.
- remote keyboard and display
- limited number of wires to remote system
- no desire to use a familiar microcontroller on the remote board to drive display and keypad.

If it were me, I would use a microcontroller that I am familiar with to act as the controller of the remote slave keyboard/display board.

I would much prefer to use spare I/O from the MCU. However, the max current from all I/O combined, Sunk=200mA, Sourced=185mA, and I will exceed both if/when driving a full row of 16 LED's, 15-20mA a piece. I could limit the LED current further, but I certainly don't want to drop it too much. The more "eye-catching", the better. Is there any chance I'm overlooking something here?

This part is just one of many I've come across during my search that solve this problem, though, maybe I'm over engineering this.

Thank-you for the input!

-EF

 

[Mikebits]

You could multiplex the LED's for less current demand?

 

[jpanhalt]

LED's only draw current when on. How does multiplexing reduce the on current?

John

 

[KeepItSimpleStupid]

adafruit has it and some other stuff in a hobby friendly form (breakout): https://www.adafruit.com/products/1427

Parts are such a pain anymore. I was searching for a 12 V 6W wall wart and basically found them all discontinued by the manufacturer by searching at Mouser, Newark and Digikey. I "suppose" they don't meet the new quiescent standard.

You can't stock everything, but unfortunately some of the data disapears when the item does. e.g. the picture at Digikey.

 

[KeepItSimpleStupid]

I would much prefer to use spare I/O from the MCU. However, the max current from all I/O combined, Sunk=200mA, Sourced=185mA, and I will exceed both if/when driving a full row of 16 LED's, 15-20mA a piece. I could limit the LED current further, but I certainly don't want to drop it too much. The more "eye-catching", the better. Is there any chance I'm overlooking something here?

You can pulse and/or multiplex because not all are on at once, e.g. something pulsed at 60 Hz with a duty cycle of 50% will draw less power than something at 100%. Your eye may perceive this as continuous. The eye also has different sensitivities to colors.

 

[Mikebits]

LED's only draw current when on. How does multiplexing reduce the on current?

John

See post #9

 

[DirtyLude]

Not diving too deep into this, but this just looks like a led driver for 7 segments and grids. The MAX7219 tends to be the goto hobbyist one and you can get it pretty cheap on flea-bay.

 

[Mikebits]

MAX7219

Thats a cool part Lude

 

[Tony Stewart]

I would much prefer to use spare I/O from the MCU. However, the max current from all I/O combined, Sunk=200mA, Sourced=185mA, and I will exceed both if/when driving a full row of 16 LED's, 15-20mA a piece. I could limit the LED current further, but I certainly don't want to drop it too much. The more "eye-catching", the better. Is there any chance I'm overlooking something here?

This part is just one of many I've come across during my search that solve this problem, though, maybe I'm over engineering this.

Thank-you for the input!

-EF

Don't know how bright you needed, but I have thousands of 10 to 20 Candela 30 deg 5 mm LEDs which are blinding at 20 mA so you operate them at lower currents. Mainly White, Yellow, & some other colours.

 

[JonSea]

Rather than tell you that what you want to do doesn't make sense (which I don't agree with by the way), let me offer a suggestion.

The AMS AS1115 is similar to the Holtek chip the original poster mentioned and is widely available. It's an I2C chip that can drive 8x8 LEDs with keyscan.

I like offloading LED multiplexing from my micro and often a remote display board with a minimal number of connections is desirable.

 

[Tony Stewart]

40 years ago we would offload tasks of muxing 96 keys and 96 lights to a 1 of 16 decoder, 6800mcu with addressable latches. Along with high speed SCADA I/O's with robotics and macro commands. But you must know how to define tasks and code very well.