Is PCA9955A and PCU9955 respectively capable of driving the LEDs with 100% PWM, that is without any OFF periods?

[zbynekjerie]

Is PCA9955A and PCU9955 respectively capable of driving the LEDs with 100% PWM, that is without any OFF periods? In other words can it be configured to deliver constant uninterrupted current for the LEDs being constantly ON?
The PCA9955A datasheet states

"duty cycle that is adjustable from 0 % to 100 %"

on one place and

"00h (0 % duty cycle = LED output off) to FFh (99.6 % duty cycle = maximum brightness)"

on another. So is 100% or 99.6% the maximal duty cycle ?
We specifically need 100% = no OFF time, just to controll the LED current over I2C.

If PCA9955A/PCU9955 are not capable of such a continuous mode, is there another nxp part that is ?

Thank you,
Zbynek

[TomasVaverka · Accepted solution]

Hello Zbynek,

Thank you for your interest in NXP LED drivers.

First of all, please disregard PCU9955 & PCU9955A. These parts were 5Mbsec I2C but only write mode access and they have been End of Life.

For the PCA the right reference is PCA9955B.

Please have a look page 19 from the data sheet and you will see that by programing the LDR0 to LDR15 registers to 01 the LED outputs are always fully on.

I hope it answers your question. If you need any other information, please let us know or submit a standard technical request and provide us with more information on your application.

Best regards,

Tomas

PS: If this answer helps to solve your question, please mark it as "Correct". Thank you.

[zbynekjerie]

Thank you very much Tomas,

this saved us a lot of research.

Best regards,

Zbynek