What PWM are needed for each LCD Brightness Level

Ok someone here was so kind to sugest ..."the SSC32 (32 PWM channels, RS232 or TTL control) is $40..." for my LED brake light project.
Someone at the Lynxmotion Support forum said - "Eh, Not really." But then said I could read the manual to see if it would work or not. Well, that just exposes My ignorance!! :) Do all, most all LCD take the same Pulse widfth for certian brightness levels at the apporpriate voltage/amp level per each LED. Or, do each type of LED have their own unique PWM/voltage/amperage ratio for each brightness level? If I had ANY idea along those lines I would have better idea if the SSC-32 can do what I need it to do. The LEDs in question at the moment are 5mm High Flux Red LED (AlGaInP) with 2 each of these on each channel.
Am I being well too simplistic in my questions? I would need at least 3 brightness levels Low/Running, Medium/Braking and High/Attention for several brief flashes not sure if high sure be the rate high or an over drive.. would be Swell if I could have a fuller range of brightness levels, but not nessecary.
The 5mm High Flux Red LEDs have the following specs: http://www.superbrightleds.com/specs/hf5-r5590.htm
absolute maximum ratings: (TA=25C) PARAMETER SYMBOL RATING UNIT DC Forward Current IF 40 mA Pulse Current(1/10 Duty Cycle, 0.1ms PULSE WIDTH) 100 mA Reverse Voltage VR 4 V Operating Temperature TA -40~+85 C Storage Temperature TSTG -40~+100 C Lead Soldering Temperature (3mm from body) 260C for 3 seconds
optoelectric characteristics: PARAMETER SYMBOL MAX TYP UNIT TEST View Angle of Half Power 21/2 90 Degree Forward Voltage VF 2.5 2.2 V IF=20mA Dominant Emission Wavelength D 630 nm Luminous Intensity IV 5500 mcd IF=20mA
Thanks!
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Chull13 wrote:

This may be my fault... The SSC32 User Manual, under "Getting Started", says that the normal operating mode is to emit a 0.5-2.5ms pulse every 20ms.
Compare that to your LED spec: > DC Forward Current IF 40 mA > Pulse Current(1/10 Duty Cycle, 0.1ms PULSE WIDTH) 100 mA
So the LEDs should use 0.01ms pulses every 0.1ms... The SSC32 emits 0.5ms or longer pulses - these qualify for the "DC forward current" rating of 40mA max. Thus the SSC32 probably isn't the best fit for your application. Also, people can see flicker from around 80Hz and below; the SSC32 operates at 50Hz, with a 1/10 duty cycle. Resistors and capacitors could be used to filter this, but you'd probably be happier with another controller -- either one with a faster PWM or one with DAC (digital-to-analog conversion) outputs.

Each LED type (and sometimes even each part) will need tuning to determine the proper PWM/brighness settings.
Sorry for the bad information. Unfortunately, I don't know of a good, cheap solution for your problem.
- Daniel
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Chull13 wrote:

There's enough variation that if you're building a big LED sign intended for video display, you have to calibrate each LED. But for a brake light, don't bother.
Search for "LED dimmer" and lots of useful things for your problem will appear.
                    John Nagle
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Hey Thank you both for getting back! Daniel no problem - such is life - I just appreciate the time you took to help me out! There are still lots of heklpful people out here!!
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