Datasheet

NCP5612
http://onsemi.com
9
DIMMING
The built−in Single Wire Serial Link interface provides
a simple way to accurately control the output current
flowing in the two LED. Provision have been made, at
silicon level, to provide a full dimming of the backlight
(NORMAL mode of operation), the ICON current being
adjustable in four steps when it is activated.
Table 1. LED Dimming Configuration
Pulse Count LED activity
Pulse 1 LED#2 = 100 mA, LED#1 de−activated
Pulse 2 LED#2 = 150 mA, LED#1 de−activated
Pulse 3 LED#2 = 250 mA, LED#1 de−activated
Pulse 4 LED#2 = 450 mA, LED#1 de−activated
Pulse 5 to Pulse 20 ICON de−activated, NORMAL back-
light takes place
The DC/DC converter is switched OFF and the two LED
are disconnected when LED−REG=$00.
When the ICON mode is activated, the DC/DC converter
is switched OFF, LED#1 is deactivated from the LED
current sense and the programmed bias current (powered
from the V
bat
source) is forced into LED#2.
Bit Clock I−LED(mA) Bit Clock I−LED(mA)
1 1
9 12
2 2 10 14
3 3 11 16
4 4 12 19
5 5 13 22
6 6 14 25
7 8 15 28
8 10 16 31
Figure 9. Typical Output Current Slope
I
OUT
(mA)
2
0
15105.00
35
30
25
20
15
10
5.0
0
I
OUT
= F(Bit Clock)
(linear scale)
BIT CLOCK
Figure 10. Typical Efficiency