RT9278 Datasheet, PDF (2/13 Pages) Richtek Technology Corporation – High Efficiency Boost LDO Converter & High Power White LED Driver

RT9278
Typical Application Circuit
Preliminary
Chip Enable
V_IN
L1
Chip
1 to 10uH Shutdown _100ms
4 _EN
VDD ⁷
RT9278
5 _LX
C3
1uF
C1
8
VOUT ⁶
4.7uF
PGND
FB ¹
R1 2.2k _{2 COMP LDRI 9}
C2
12nF
3 _{GND LFB} 10
Q1
AO7401
C4
2.2uF
R2
300k
700mA
D1 ^100ms
Power LED
R3
0.28
Note : Patent Pending.
Figure 1. Novel Up-Down Driver for Power LED with Strobe Mode
Chip Enable
V_IN
L1
1 to 10uH ^{Chip Shutdown}
C1
4 _EN
VDD ⁷
RT9278
5 _LX
8
VOUT ⁶
C3
1uF
4.7uF
PGND
FB ¹
R1 2.2k _{2 COMP LDRI 9}
C2
3 _{GND LFB} 10
Q1
AO3403
C4
2.2uF R2
300k
I_strobe
700mA
I_{Movie 100ms} 200mA
GPIO
2.8V
D1
0V
Power LED
12nF
R4 1k
R3 ^{R4 = 1kΩ}
R5
18.2k
0.28 _{R3 = 0.2}
IStrobe
GPIO
R5 = ^{(GPIO_HI − 0.2) x R4}
0.2 − (IMovie x R3)
Figure 2. Novel Up-Down Driver for Power LED with Strobe Mode and Movie Mode
Note :
l Patent Pending.
l The GPIO Signal has to pull high before enable IC.
Chip Enable
V_IN
L1
4.7uH
C1
10uF
Chip Shutdown
R1 2.5k
4
EN
VDD ⁷
5
RT9278
LX
2 _COMP ^{VOUT 6}
C2
2.2nF
8 _PGND
10 _LFB
3 _GND
LDRI ⁹
FB ¹
C3
1uF
C4
10uF
Q1
AO3403
R2
510k
C5
100pF
V_OUT
3.3V
R3
470k
R4
150k
www.richtek.com
2
Figure 3. Synchronous Boost Converter with Load Disconnect in Shutdown
DS9278-04 August 2007