0

10

20

30

40

50

60

70

80

90

100

0

10 20 30 40 50 60 70 80 90 100

DIMMING DUTY CYCLE (%)

VIN = 3.0 V

VIN = 3.6 V

VIN = 4.2 V

VIN = 5.0 V

C002

FLTR

FLTR

1

RC

1

C

=

2 (R

// R ) f

p

RC

r

0.35

=

t

f

24

TPS61160, TPS61161

SLVS791E – NOVEMBER 2007 – REVISED JULY 2016

www.ti.com

Product Folder Links: TPS61160 TPS61161

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Copyright © 2007–2016, Texas Instruments Incorporated

To provide gradual dimming, a large capacitor must be chosen to provide a long transient time when changing

the PWM duty cycle. Equation 14 shows how to calculate the recommended corner frequency of the RC filter

based on the 10% to 90% rise time. Once the corner frequency is known, it can be used to calculate the required

capacitor using Equation 15.

(14)

(15)

frequency of 0.7 Hz and a capacitor of 47 μF.

8.2.2.3 Application Curves

Figure 20. Efficiency vs Dimming Duty Cycle

Figure 21. Start-Up with 6 Series LEDs (External PWM,