LED Display driver (NOT seven segment)

R Pradeep Chandran 21 years ago

Hi All, I am looking for an LED driver IC that can drive a large number of LEDs. I am planning to make a digital clock with indiviudal LEDs for each minute/second mark. I searched the Net and all the drivers I could find are for seven segment displays. There are others for bar graphs but they need an analog control voltage. I just want an IC that will enable a set of outputs based on input commands. Input could be provided by memory mapping, SIO, I2C etc. I could probably do this with a set of buffers, latches and some high frequency multiplexing logic with the microcontroller that I am planning to use (AT90S8535). But, I would like some simpler solution so that I can use the micro's cycles for some thing more useful (programmable outputs, alarms etc.). Are there any ICs that meet my requirements? Have a nice day, Pradeep

R Pradeep Chandran pradeep DOT chandran AT sisl.co.in All opinions are mine and do not represent those of my employer.

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CWatters 21 years ago

16?

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The LP3943 is an integrated device capable of independently driving 16 LEDs. It takes incoming I2C data and feeds them into several registers that control the frequency and the duty cycle of the LEDs. Two prescaler registers and two PWM registers program an internal precision oscillator to provide two individual rates to dim or blink the LEDs.

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petrus bitbyter 21 years ago

"CWatters" schreef in bericht news:eob1e.46205$ snipped-for-privacy@phobos.telenet-ops.be...

What is a "large number" of LEDs? Sixteen? Fortyfive? Onehundredandfortyfour? The processor you mentioned, though not recommanded for new applications, is a powerfull micro that can drive up to 256 LEDs if neccessary with a minimum of extra hardware. To drive 144 LEDs you need 24 output pins, 12 resistors and 12 transistors. Still eight pins left for other purposes. The code required for multiplexing is not that long so is the execution time. But some programming skills are required.

The LP3943 CWATTERS mentioned is a good one. You will need quite some boardspace and some programming skills to implement I2C. AFAIK the AT90S8535 does not support I2C so you will have to do plenty of bitbanging.

petrus bitbyter

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Michael 21 years ago

MC14489. It can drive five 7-seg digits, AND it can address individual LEDs if you use its "no decode" mode. Multiples of this chip can be wired in a string.

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