TPS92360: Efficiency Data vs. Iout

Dice-K

Part Number: TPS92360

Hi support team,

Is there a graph showing the load (Iout) and efficiency when using 6 LEDs?
Figures 8-2 to 8-5 in the datasheet show the efficiency for dimming duty with RSET = 10.2ohm (Iout = 20 mA).
I would like to confirm the efficiency under the following conditions.

Vin: 3.3V
Vout: 18V (Vf=3V, 6 in series)
Iout: 3mA

Regards,
Dice-K

8 months ago

0 Hongjia-Wu 8 months ago

TI__Genius 11710 points

Hi Dice-K,

Our expert will check and come back to you next week.

Regards,

Emma Wu

0 Young Zhao 8 months ago

TI__Genius 14910 points

Hi Dice-k,

the eff would be around 85% per figure8-5 dimming duty 15%

0 Dice-K 8 months ago in reply to Young Zhao

Mastermind 8141 points

Hi Young,
Thank you for your reply.

The average output current under the two conditions below is 3mA for both, but is the efficiency similar?

Iout Setting = 20mA, Dimming Duty = 15%
Iout Setting = 3mA, Dimming Duty = 100%

Best regards,
Dice-K

+1 Young Zhao 8 months ago in reply to Dice-K

TI__Genius 14910 points

The full scale loading is per the Rest resistor, you need to fix it first and change the PWM dimming duty per system needs.

The PWM switching would make slightly eff loss if CCM.

0 Dice-K 8 months ago in reply to Young Zhao

Mastermind 8141 points

Hi Young,
Thank you for your support.

Does this mean that Case 2 is slightly more efficient because there is no power loss due to PWM Dimming operation ?

Case 1: Iout Setting = 20mA, Dimming Duty = 15%
Case 2: Iout Setting = 3mA, Dimming Duty = 100%

Best regards,
Dice-K

0 Young Zhao 8 months ago in reply to Dice-K

TI__Genius 14910 points

Another thing needs to consider is that the BOOST eff would be lower at light load, which would make the total eff worse here. The different Iout set would bring different inductor and the inductor would affect the eff too. Suggest to set the full scale loading/Rset first, and change the dimming duty per system needs.

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TPS92360: Efficiency Data vs. Iout