PWM Duty Cycle (%)
L
E
D
C
u
rr
e
n
t
(%
)
0
10
20
30
40
50
60
70
80
90
100
0
10
20
30
40
50
60
70
80
90
100
D013
LEDs = 13, I
LED
= 500mA
Analog Adjust Input, V
IADJ
(V)
L
E
D
C
u
rr
e
n
t
(m
A
)
0
0.15
0.3
0.45
0.6
0.75
0.9
1.05
1.2
1.35
1.5
1.65
1.8
1.95
2.1
2.25
2.4
2.55
2.7
2.85
3
0
200
400
600
800
1000
1200
1400
1600
1800
2000
D014
LEDs = 3
Performance Data and Typical Characteristic Curves
Figure 17. Output LED Current vs. IADJ Voltage, V
IADJ
(VIN = 14 V, Number of LEDs in Series = 3)
6.6
PWM Dimming
In order to enable EVM at power-up, the PWM pin of TPS92691-Q1 is tied to VCC through a 100-k
Ω
pullup resistor, R14. The PWM pin can be over-driven by connecting an external digital signal, generated
through a microcontroller or function generator, to PWM test point, TP3. PWM pin can be pulled to ground
to disable switching under fault conditions.
Figure 18. Normalized LED Current vs. PWM Duty Cycle (V
IADJ
= 700 mV, Number of LEDs in series = 13)
13
SLVUAL8 – December 2015
TPS92691 SEPIC LED Driver Evaluation Board
Copyright © 2015, Texas Instruments Incorporated