TMDXSK437X: LCD - Backlight drive

prem kumar1

Part Number: TMDXSK437X
Other Parts Discussed in Thread: TPS61081

Hi,

Why TPS61081 SS pin already pulled down . In EVM board schematic additionally control option available SS pin is for the backlight signal (refer below)? Is the same followed in design.

Kindly clarify the above point.

Regards,

Premkumar V

over 3 years ago

0 melissaw over 3 years ago

TI__Genius 15180 points

Hi Premkumar,

The AM437x SK implementation appears to be similar to the “30 WLEDs Driver in Media Factor Form Display” system example in section 10.3.3. of the TPS61081 datasheet.

Regards,

Melissa

0 Amarnath Murugadass over 3 years ago in reply to melissaw

Intellectual 480 points

Hi Melissa,

In the system example as stated in section 10.3.3 of the TPS61081 datasheet what will happen if the PWM signal is always On or always Off?

What will be the state of the output power to the backlight during those conditions?

Also for R1 and R2 in this configuration is there any calculation need to follow to choose the values along with PWM duty cycle

Regards,

M Amarnath

0 Jasper Li over 3 years ago in reply to Amarnath Murugadass

TI__Mastermind 46905 points

HI M Amarnath,

The voltage crossing the Rset is controlled to by Iss*(R1/R2). For example, if R1=R2 = 80Kohm, the Rset voltage will be 200mV.

if the Rset = 1ohm, the current through the LED is 200mA.

Processors

Processors forum

TMDXSK437X: LCD - Backlight drive