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  Richtek Technology Electronic Components Datasheet  

RT9278 Datasheet

High Efficiency Boost LDO Converter & High Power White LED Driver

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®
RT9278
High Efficiency Boost LDO Converter & High Power White
LED Driver
General Description
Features
The RT9278 is a compact, high efficiency, synchronous
step-up converter, it provides a power supply solution for
products powered by either two-cell, three-cell Alkaline/
NiMH or one-cell Li-Ion/Li-polymer battery.
The RT9278 is boost converter with PWM control loop,
provide up to 95% efficiency by using a synchronous
rectifier. The maximum peak current in the internal switch
is limited to up to 2A.
It keeps the output voltage regulated when the input
voltage exceeds the setting output voltage. The output
voltage can be set by an external resister divider, or be
fixed to reduce external components. It integrates a linear
controller for linear regulator.
RT9278 is available in VDFN-10L 3x3 package.
Ordering Information
RT9278
Package Type
QV : VDFN-10L 3x3 (V-Type)
Lead Plating System
P : Pb Free
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
` RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
` Suitable for use in SnPb or Pb-free soldering processes.
95% Efficiency Synchronous Boost Converter
High Supply Capability
2A Current Limit
Input Voltage Range : 1.5V to 5.5V
600kHz Fixed Switching Rate
Adjustable Output Voltage Options Up to 5.5V
Output Voltage Keep Regulated when Input Voltage
Exceed Setting Output Voltage
1uA Supply Current in Shutdown Mode
External Compensation Network
Build in Linear Controller for Linear Regulator
Over Temperature Protection
Small 10-Lead VDFN Package
RoHS Compliant and 100% Lead (Pb)-Free
Applications
Digital Still Camera
Camera White LED Flash Light
PDAs
Portable Device
Marking Information
RT9278PQV
AC- : Product Code
AC-YM
DNN
YMDNN : Date Code
Pin Configurations
(TOP VIEW)
FB
COMP
GND
EN
LX
1
2
3
4
5
GND
11
10 LFB
9 LDRI
8 PGND
7 VDD
VOUT
RT9278QQV
AC=YM
DNN
AC= : Product Code
YMDNN : Date Code
VDFN-10L 3x3
Copyright ©2012 Richtek Technology Corporation. All rights reserved.
DS9278-07 January 2012
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1


  Richtek Technology Electronic Components Datasheet  

RT9278 Datasheet

High Efficiency Boost LDO Converter & High Power White LED Driver

No Preview Available !

RT9278
Typical Application Circuit
Chip Enable
VIN
L1 Chip
1 to 10µH Shutdown 100ms
C1
4.7µF
R1 2.2k
4 EN
VDD 7
RT9278
5 LX
8 VOUT 6
PGND
FB 1
2 COMP LDRI 9
C3
1µF
C2
12nF
3 GND
LFB 10
C4
2.2µF
Q1
AO7401
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
L1
4 EN
VDD 7
VIN
1 to 10µH Chip Shutdown
C1
4.7µF
R1 2.2k
RT9278
5 LX
8 VOUT 6
PGND
FB 1
2 COMP LDRI 9
C3
1µF
Q1
AO3403
C4
2.2µF R2
300k
Istrobe
700mA
IMovie 100ms 200mA
GPIO
2.8V
D1 0V
Power LED
C2
3 GND
LFB 10
12nF
R4 1k
R3 R4 = 1k
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 :
Patent Pending.
The GPIO Signal has to pull high before enable IC.
Chip Enable
VIN
L1
4.7uH
C1
10µF
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
1µF
C4
10µF
Q1
AO3403
R2
510k
C5
100pF
VOUT
3.3V
R3
470k
R4
150k
Figure 3. Synchronous Boost Converter with Load Disconnect in Shutdown
Copyright ©2012 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS9278-07 January 2012


Part Number RT9278
Description High Efficiency Boost LDO Converter & High Power White LED Driver
Maker Richtek
PDF Download

RT9278 Datasheet PDF






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