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LED Drivers/LCD Bias
TLC59xx for low current LCD drive
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Q: TLC59xx for low current LCD drive by 8947
I want to use the TLC59xx family for driving LCD panels or LCD 7 segment displays.
These use much lower current than LED displays.
So the question that arises is this:
Which of these TLC59xx parts can have accurate current control at currents below 1mA?
I can find no graphs or data in the datasheets to support this operating area.
Specific case today: would like to set up TLC5947 to drive a low current 30 uA to 200 uA LCD
A: Re: TLC59xx for low current LCD drive by 10449
Using Riref to set the current to less than the minimum current specified in the datasheet (2mA for the TLC5947) can make the output unstable. We can not recommend operating the IC with IOLC less than 2mA.
You can effectively reduce the current by using dot correction or PWM dimming. For the request above, set IOLC to 2mA with a 24.6kohm resistor. Then use PWM dimming to set the duty cycle to 10% to achieve 200uA (200uA/2mA) and set the duty cycle to 1.5% to achieve 30uA (30uA/2mA=0.015). The TLC5947 has 12 bit PWM dimming, so you can effectively run a duty cycle of 1/(2^12) = 1/4096 = 0.000244 = 0.0244%.
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