TPS61165: 3x7LEDs surrounding parts value

Kevin Huang8

Genius 3625 points

Part Number: TPS61165

Hi Team,

Panel Back Light Spec is Vf=16.8V~19.2V; If=140mA,

Back Light LED is 21 Pcs (3 in Series X 7 in Parallel),

please suggest the surrounding parts value.

R1:

R2:

Rset:

C1:

C2:

0 Patrick Yao over 1 year ago

Hi Kevin,

Is the If=140mA the total current of the 7 paralleled LED strings?

Patrick

0 Kevin Huang8 over 1 year ago in reply to Patrick Yao

Genius 3625 points

Yes

0 Patrick Yao over 1 year ago in reply to Kevin Huang8

Hi Kevin,

What's your PWM voltage and duty cycle? These will all determine the output current.

C1 and C2 you can refer to our datasheet "9.2 Typical Applications" as 4.7uF and 1uF.

Patrick

0 Kevin Huang8 over 1 year ago

Genius 3625 points

Hi Team,

When the PWM is set to the maximum bandwidth, If=140mA, is the value of the Rest resistor VFB(200mV)/If(140mA)=1.42Ω?

0 Kevin Huang8 over 1 year ago

Genius 3625 points

Hi Patrick,

When the PWM is set to the maximum bandwidth, If=140mA, is the value of the Rest resistor VFB(200mV)/If(140mA)=1.42Ω?

0 Patrick Yao over 1 year ago in reply to Kevin Huang8

Hi Kevin,

Yes, you are right. If you want to use PWM to adjust the current, you can refer to below equation:

LED current = Vpwm x (1 - duty cycle) / (R1 / R2 x Rset)

Patrick

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