Datasheet
I =
PP
V D
IN
·
L f·
S
¾
I =
OUT(MAX)
V
IN
·
(
I -
LIM
I
PP
2
· h
¾
V
OUT
)
¾
TPS65200
SLVSA48 –APRIL 2010
www.ti.com
3. V
OUT
= Output voltage of the boost converter. It is equal to the sum of VFB and the voltage drop across
LEDs.
(4)
Where:
1. I
PP
= inductor peak to peak ripple
2. L = inductor value
3. f
s
= switching frequency
(5)
Where:
1. I
OUT(MAX)
= maximum output current of the boost converter
2. I
LIM
= over current limit
3. h = efficiency
For instance, for V
IN
= 3 V, 7 LEDs output equivalent to V
OUT
of 23 V, an inductor value of 22 µH, a current limit
of 700 mA, and an efficiency of 85%, the maximum output current is ~65 mA.
CHARGE MODE OPERATION
For current limited power source, such as a USB host or hub, the high efficiency converter is critical in fully
utilizing the input power capacity and quickly charging the battery. Due to the high efficiency in a wide range of
the input voltage and battery voltage, the switching mode charger is a good choice for high speed charging with
less power loss and better thermal management.
The TPS65200 is a highly integrated synchronous switch-mode charger with reverse boost function for USB
OTG support, featuring integrated MOSFETs and small external components, targeted at extremely space-limited
portable applications powered by 1-cell Li-ion or Li-polymer battery pack.
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