LED Display driver (NOT seven segment)

[R Pradeep Chandran]

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

 

[CWatters]

Hi All,
I am looking for an LED driver IC that can drive a large number of
LEDs.

16?
http://www.national.com/pf/LP/LP3943.html
http://www.national.com/appinfo/power/lp3943software.html
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.

 

[petrus bitbyter]

16?
http://www.national.com/pf/LP/LP3943.html
http://www.national.com/appinfo/power/lp3943software.html
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.

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

 

[Michael]

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

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.