TPS92391: Programmatic Selection of PWM and current mode transition threshold

Sheldon Rubin

Part Number: TPS92391

Section 7.3.8.5 Hybrid Mode of the TPS92391 datasheet, at the bottom of Page 25, states that:

"The PWM and current modes transition threshold can be set at 12.5% or at 0% brightness. The latter selection allows for pure current dimming control mode."

There doesn't appear to be a way to set the transition threshold to these values. Is 12.5% the only value possible when the device is resistor configured to the Hybrid Mode? Similarly, is 0% the only value possible when the device is resistor configured to the Current Dimming Mode?

Am I missing something? It would be desirable to be able to select between these two values programmatically.

Thanks for you help!

over 4 years ago

0 Hardy Wu over 4 years ago

TI__Genius 12915 points

Hi Rubin,

Sorry for late reply. Yes the threshold only can be set as 12.5% or 0.

0 Sheldon Rubin over 4 years ago

Prodigy 50 points

Hello Hardy Wu,

Thank you for the reply. My real question is how to select the two different threshold values? Can this be done programmatically or is it only the result of the resistor selection for the Hybrid Dimming Mode (12.5%) or the the Current Dimming Mode (0%)?

0 Hardy Wu over 4 years ago in reply to Sheldon Rubin

TI__Genius 12915 points

Hi Rubin,

Yes it can be selected through resistor. Another way is set the MODE_SEL value in register 1Eh. 0% hybrid dimming mode is named as current dimming mode.

0 Sheldon Rubin over 4 years ago

Prodigy 50 points

Hi Harry Wu,

It would be great if we could select the mode using MODE_SEL but the datasheet lists the parameter as read-only. Is MODE_SEL a R/W parameter??

0 Hardy Wu over 4 years ago in reply to Sheldon Rubin

TI__Genius 12915 points

Sorry my fault. It is read only register and can not be used to set mode.

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TPS92391: Programmatic Selection of PWM and current mode transition threshold