Datasheet

APPLICATION CIRCUITS
C1-
C2+
C2-
C1+
DM1
DM5
DS2
DS1
DM3DM4 DM2GND
SDATSCLKVIN
C1
4.7
mF
C2
1
mF
C3
1
mF
MainDisplay
C4
4.7
mF
SubDisplay
I
2
CInterface
On/Off, DigitalDimming
VOUT
h
Light
+
I
O
V
F
V
in
ǒ
I
O
) I
op
Ǔ
(1)
TPS60250
TPS60252
SLVS769C – APRIL 2007 – REVISED APRIL 2008 ............................................................................................................................................................ www.ti.com
Figure 20. The Typical Application Circuit for Sub and Main Display
As shown in Figure 20 , typical application circuit for a clam shell phone has 5 main LEDs and 2 sub LEDs.
Recently, the LCD panel makers have developed a new panel that has an improved transparency rate which
makes system efficiency with 100 µ A LED current a critical load point. To meet system efficiency requirements
with the light load conditions for the new LCD operating panels, the TPS60250/2 have a maximum 55 µ A
operating current with 100 µ A output load condition. In this application, the controller always operates in 1 × mode
due to the WLED's low forward voltage drop (about 2.6 V
F
with a 100 µ A WLED current). Thus, the total
efficiency at the light load condition is determined using Equation 1 :
Where:
I
O
: Output Load (WLED) Current
V
F
: Forward Voltage Drop of WLED
V
in
: Input Voltage
I
op
: Operating Current of LED Driver
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Product Folder Link(s): TPS60250 TPS60252