RT9278

®
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.
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
RT9278 is available in VDFN-10L 3x3 package.
Applications
Ordering Information
RT9278
Package Type
QV : VDFN-10L 3x3 (V-Type)
Lead Plating System
P : Pb Free
G : Green (Halogen Free and Pb Free)
Digital Still Camera
Camera White LED Flash Light
PDAs
Portable Device
Marking Information
RT9278PQV
Note :
AC- : Product Code
Richtek products are :
`
RoHS compliant and compatible with the current require-
`
Suitable for use in SnPb or Pb-free soldering processes.
AC-YM
DNN
YMDNN : Date Code
ments of IPC/JEDEC J-STD-020.
RT9278QQV
Pin Configurations
AC= : Product Code
AC=YM
DNN
(TOP VIEW)
1
10
2
9
3
GND
5
8
7
4
11
9
FB
COMP
GND
EN
LX
YMDNN : Date Code
LFB
LDRI
PGND
VDD
VOUT
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
RT9278
Typical Application Circuit
Chip Enable
L1
1 to 10µH
VIN
4 EN
Chip
Shutdown 100ms
5 LX
8
C1
4.7µF
R1 2.2k
VDD 7
RT9278
PGND
2 COMP
3 GND
C2
12nF
C3
1µF
Q1
AO7401
VOUT 6
C4
2.2µF
FB 1
LDRI 9
LFB 10
700mA
100ms
D1
Power LED
R2
300k
R3
0.28
Figure 1. Novel Up-Down Driver for Power LED with Strobe Mode
Note : Patent Pending.
VIN
Chip Enable
4 EN
VDD 7
L1
RT9278
Chip
Shutdown
1 to 10µH
5 LX
VOUT 6
8
C1
PGND
4.7µF
FB 1
R1 2.2k 2
COMP LDRI 9
3 GND
LFB 10
C2
12nF
Istrobe
C3
1µF
Q1
AO3403
C4
2.2µF
IMovie
700mA
2.8V
GPIO
R2
300k
200mA
100ms
0V
D1
Power LED
R4 1k
R3
0.28
R5
18.2k
R4 = 1kΩ
R3 =
0.2
IStrobe
(GPIO_HI − 0.2) x R4
R5 =
0.2 − (IMovie x R3)
GPIO
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
L1
4.7uH
4
Chip Shutdown
VIN
R1 2.5k
C1
10µF
C2
2.2nF
VDD 7
EN
RT9278
5 LX
6
2 COMP VOUT
8
PGND
9
10 LFB
LDRI
1
3 GND
FB
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
RT9278
VIN
1.6V to 5V
L1
4.7µH
4 EN
GPIO
5 LX
8
C1
10µF
R1 51k
VDD 7
RT9278
PGND
2 COMP
3 GND
C2
3.3nF
C3
1µF
VOUT 6
Q1
AO3403
C4
10pF
FB 1
R2
732k
C5
20µF
R5
620k
R4
510k
R3
226k
VOUT
3.3V
LDRI 9
10
LFB
C6
22pF
C7
1µF
R6
40.2k
Figure 4. Boost-LDO Application for Constant Output Voltage
VIN
1.6V to 3.0V
L1
4.7µH
GPIO
4 EN
5 LX
8
C1
20µF
R1 3.9k
C2
1.5nF
VDD 7
RT9278
PGND
2 COMP
3 GND
VOUT 6
FB 1
VOUT1
3.3V/300mA
C3
1µF
C4
10pF
Q1
AO3403
R2
470k
C5
40µF
R3
150k
R5
887k
R4
510k
LDRI 9
10
LFB
C6
22pF
VOUT2
1.8V/150mA
C7
30µF
R6
110k
Figure 5. Synchronous Boost Converter Driver for Dual Output Voltage
Chip Enable
L
VIN
Chip Shutdown
C1
10µF
RCOMP
CCOMP
4 EN
VDD 7
RT9278
5 LX
9
LDRI
10 LFB
2 COMP
3 GND
C3
1µF
VOUT
PVD
CFF
FB 1
PGND 8
R2
COUT
40µF
R1
Figure 6. Synchronous Boost Converter
Copyright © 2012 Richtek Technology Corporation. All rights reserved.
DS9278-07 January 2012
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
3
RT9278
Table 1. Component Selection for Figure 6 (L=2.2µH)
Input Voltage Output Voltage
(V)
(V)
L
(µH)
COUT
(µF)
R1
(kΩ)
R2
(kΩ)
RCOMP
(kΩ)
CCOMP
(nF)
CFF
(pF)
1.5~3.0
3.3
2.2
40
150
470
43
5.6
18
1.5~3.3
5.0
2.2
40
130
680
24
8.2
12
3.0~4.5
5.0
2.2
40
130
680
24
3.9
12
Table 2. Component Selection for Figure 6 (L=4.7µH)
Input Voltage Output Voltage
(V)
(V)
L
(µH)
COUT
(µF)
R1
(kΩ)
R2
(kΩ)
RCOMP
(kΩ)
CCOMP
(nF)
CFF
(pF)
1.5~3.0
3.3
4.7
40
150
470
24
10
18
1.5~3.3
5.0
4.7
40
130
680
24
15
12
3.0~4.5
5.0
4.7
40
130
680
24
8.2
12
Table 3. Component Selection for Figure 6 (L=6.8µH)
Input Voltage Output Voltage
(V)
(V)
L
(µH)
COUT
(µF)
R1
(kΩ)
R2
(kΩ)
RCOMP
(kΩ)
CCOMP
(nF)
CFF
(pF)
1.5~3.0
3.3
6.8
40
150
470
24
15
18
1.5~3.3
5.0
6.8
40
130
680
24
22
12
3.0~4.5
5.0
6.8
40
130
680
24
12
12
Table 4. Component Selection for Figure 6 (L=10µH)
Input Voltage Output Voltage
(V)
(V)
L
(µH)
COUT
(µF)
R1
(kΩ)
R2
(kΩ)
RCOMP
(kΩ)
CCOMP
(nF)
CFF
(pF)
1.5~3.0
3.3
10
40
150
470
24
22
18
1.5~3.3
5.0
10
40
130
680
24
33
12
3.0~4.5
5.0
10
40
130
680
24
18
12
Copyright ©2012 Richtek Technology Corporation. All rights reserved.
www.richtek.com
4
is a registered trademark of Richtek Technology Corporation.
DS9278-07
January 2012
RT9278
Functional Pin Description
Pin No.
Pin Name
Pin Function
1
FB
Feedback Input Pin.
2
COMP
Feedback Compensation Pin.
3
GND
Ground.
4
EN
Enable Input Pin
5
LX
Switch Node.
6
VOUT
Output Pin
7
VDD
Device Input Power Pin.
8
PGND
Power Ground.
9
LDRI
Linear Controller Driver Output.
10
LFB
Linear Controller Feedback Input.
The exposed pad must be soldered to a large PCB and connected to
11 (Exposed Pad) GND
GND for maximum power dissipation.
Function Block Diagram
COMP
VOUT
Error
AMPLIFIER
-
FB
VREF = 0.8V
Error
Comparator
-
+
+
VDD
Control
and
Driver
Logic
LX
GND
Oscillator
and
Shutdown
Control
EN
Slope
Compensation
Current
Sense
PGND
LDRI
LFB
VREF = 0.2V
+
Copyright © 2012 Richtek Technology Corporation. All rights reserved.
DS9278-07 January 2012
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
5
RT9278
Operation
RT9278 integrates a high-efficiency step-up DC-DC converter and a linear regulator controller. The boost converter is
based on a fixed frequency, pulse-width-modulation (PWM) controller using a synchronous rectifier to obtain maximum
efficiency. Current mode control with external compensation network makes it easy to stabilize the system and keep
maximum flexibility. The linear regulator controller can use to drive the external P-Channel MOSFET switch for load
disconnection. It keeps the output voltage regulated even when the input voltage exceeds the nominal output voltage,
and keeps the output voltage completely disconnected from input voltage (battery) when the chip is in shutdown mode
Soft-start
When the chip is enabled. Soft-start is achieved by ramping up the PWM duty from very small to normal operation. The
ramping up PWM duty is achieved by sourcing 1uA from error amplifier to the compensation capacitor. When the output
voltage is regulated, the PWM duty enters the normal operation, and the error amplifier can sink and source up to 22uA.
The soft-start time is set by the following formula :
TSS =
(1V - 1μA x RCOMP) x CCOMP
1μA
RCOMP and CCOMP are compensation components.
Current limit
The current of NMOS is sensed cycle by cycle to prevent over current. When over current limit, then the NMOS is off.
This state is latched and then reset automatically at next clock cycle.
Over voltage
When the chip voltage is higher than 6.5V, Switch is off. When the Over Voltage Protection is relieved, the chip operates
well again.
Thermal protection
Thermal protection function is integrated in the chip. When the chip temperature is higher than 180°C, the controllers
are shutdown. 20°C is the hysteresis range of temperature to prevent unstable operation when the thermal protection
happens. When the thermal protection is relieved, the chip operates well again.
Copyright © 2012 Richtek Technology Corporation. All rights reserved.
www.richtek.com
6
is a registered trademark of Richtek Technology Corporation.
DS9278-07 January 2012
RT9278
Absolute Maximum Ratings
z
z
z
z
z
z
z
z
z
(Note 1)
Supply Voltage, VDD -------------------------------------------------------------------------------------------------- 7V
LX Pin Voltage ---------------------------------------------------------------------------------------------------------- − 0.3V to 7V
The Other pins --------------------------------------------------------------------------------------------------------- − 0.3V to 7V
Power Dissipation, PD @ TA = 25°C
VDFN-10L 3x3 ---------------------------------------------------------------------------------------------------------- 1.43W
Package Thermal Resistance (Note 2)
VDFN-10L 3x3, θJA ---------------------------------------------------------------------------------------------------- 70°C/W
Lead Temperature (Soldering, 10 sec.) --------------------------------------------------------------------------- 260°C
Junction Temperature ------------------------------------------------------------------------------------------------- 150°C
Storage Temperature Range ---------------------------------------------------------------------------------------- − 65°C to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Mode) ------------------------------------------------------------------------------------------ 2kV
Recommended Operating Conditions
z
z
(Note 4)
Ambient Temperature Range ---------------------------------------------------------------------------------------- −40°C to 85°C
Junction Temperature Range ---------------------------------------------------------------------------------------- −40°C to 125°C
Electrical Characteristics
(VBAT = 1.8V, VOUT = 3.3V, TA = 25°C, unless otherwise specified)
Parameter
Min
Typ
Max
Unit
--
1.5
--
V
Operating Voltage Range, After start-up VBAT
1.1
--
5.5
V
VOUT Output Voltage Range
2.4
--
5.5
V
--
6.5
--
V
Start-Up Voltage
Symbol
VST
Test Conditions
IL = 1mA
VOUT_ADJ
VOUT Over Voltage Protection
Switch-off Current I (VBAT)
I SW OFF
VOUT = 3.3V, VFB = 0.9V
--
200
350
μA
Shutdown Current
I OFF
EN Pin = 0V, Open Loop
--
0.01
1
μA
Feedback Reference Voltage
VFB
Close Loop, VOUT = 3.3V
0.784
0.8
0.816
V
Switching Frequency
fS
--
650
--
kHz
Maximum Duty
D(MAX)
--
85
--
%
SWN Switch ON Resistance
VOUT = 3.3V
--
210
--
mΩ
SWP Switch ON Resistance
VOUT = 3.3V
--
240
--
mΩ
VOUT = 3.3V
--
2
--
A
GM
--
0.2
--
ms
Compensation Source Current
--
22
--
μA
Compensation Sink Current
--
22
--
μA
Current Limit Setting
I SW
Error Amplifier
Copyright © 2012 Richtek Technology Corporation. All rights reserved.
DS9278-07 January 2012
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
7
RT9278
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
--
0.2
--
V
EN Input High Level Threshold
--
--
1.3
V
EN Input Low Level Threshold
0.4
--
--
V
Linear Controller
Feedback Voltage for Linear Controller
VLFB
Thermal Shutdown
T SD
--
180
--
°C
Thermal Shutdown Hysteresis
ΔTSD
--
20
--
°C
Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in
the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may
affect device reliability.
Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
Copyright © 2012 Richtek Technology Corporation. All rights reserved.
www.richtek.com
8
is a registered trademark of Richtek Technology Corporation.
DS9278-07 January 2012
RT9278
Typical Operating Characteristics
Frequency vs. Temperature
700
Reference Voltage vs. Temperature
0.804
VDD = 3.3V
VDD = 3.3V
0.803
Reference Voltage (V)
660
640
620
600
0.802
0.801
0.8
0.799
0.798
0.797
580
0.796
-50
-25
0
25
50
75
100
125
-50
-25
Efficiency vs. Output Current
Efficiency (%)
VIN
VIN
VIN
VIN
70
60
=
=
=
=
3.0V
2.5V
2.0V
1.5V
50
40
30
20
10
100
125
VOUT = 5V
70
VIN
VIN
VIN
VIN
VIN
VIN
VIN
60
50
40
30
=
=
=
=
=
=
=
4.5V
4.0V
3.5V
3.0V
2.5V
2.0V
1.5V
20
10
0
1
10
100
1000
1
10
100
1000
Output Current (mA)
Output Current (mA)
Input Voltage vs. Output Voltage
Input Voltage vs. Output Voltage
5.150
VOUT = 3.3V
VOUT = 5V
5.100
Output Voltage (V)
3.325
Output Voltage (V)
75
80
0
3.350
50
90
Efficiency (%)
VOUT = 3.3V
90
80
25
Efficiency vs. Output Current
100
Refer to Application Circuit Figure 3
100
0
Temperature (°C)
Temperature (°C)
Refer to Application Circuit Figure 3
Frequency (kHz)
680
3.300
3.275
3.250
5.050
5.000
4.950
4.900
3.225
4.850
3.200
1.6
1.8
2.0
2.2
2.4
2.6
2.8
Input Voltage (V)
Copyright © 2012 Richtek Technology Corporation. All rights reserved.
DS9278-07 January 2012
3.0
1.6
1.925
1.93 2.25 2.575
2.58
2.9
3.225
3.23 3.55 3.875
3.88
4.2
Input Voltage (V)
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
9
RT9278
Output Voltage vs. Output Current
Output Voltage vs. Output Current
3.310
4.98
4.97
4.96
3.305
3.295
Output Voltage (V)
Output Voltage (V)
3.300
3.290
3.285
3.280
3.275
3.270
VIN
VIN
VIN
VIN
3.265
3.260
3.255
=
=
=
=
3.0V
2.5V
2.0V
1.5V
VOUT = 3.3V
1
10
100
4.88
4.87
4.86
VIN
VIN
VIN
VIN
VIN
VIN
VIN
VOUT = 5V
1
1000
=
=
=
=
=
=
=
4.2V
4.0V
3.5V
3.0V
2.5V
2.0V
1.5V
10
100
Output Current (mA)
Power LED Efficiency vs. Input Voltage
Normal Operation
90
80
70
60
50
40
30
20
Vf = 3.5V, ILED = 200mA, L = 4.7μH
Refer to Application Circuit Figure 1
Output Current (mA)
100
Power LED Efficiency (%)
4.92
4.91
4.90
4.89
4.85
3.250
10
4.95
4.94
4.93
1000
VOUT
(10mV/Div)
(5V/Div)
VLX
(1V/Div)
VIN
I IN
(500mA/Div)
VIN = 1.5V, VOUT = 5V, ILOAD = 100mA
0
3 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4 4.1 4.2 4.3
Time (1μs/Div)
Input Voltage (V)
Normal Operation
Normal Operation
VOUT
VOUT
(10mV/Div)
(10mV/Div)
(5V/Div)
VIN
(1V/Div)
VLX
VLX
(1V/Div)
VIN
I IN
(1A/Div)
I IN
VIN = 1.5V, VOUT = 5V, ILOAD = 300mA
Time (1μs/Div)
Copyright © 2012 Richtek Technology Corporation. All rights reserved.
www.richtek.com
10
(5V/Div)
(500mA/Div)
VIN = 4.2V, VOUT = 5V, ILOAD = 100mA
Time (1μs/Div)
is a registered trademark of Richtek Technology Corporation.
DS9278-07 January 2012
RT9278
Normal Operation
Load Transient Regulation
VIN = 1.5V, VOUT = 5V, ILOAD = 100mA to 300mA
Load Current
(mA)
(10mV/Div)
VOUT
VIN
(1V/Div)
VLX
400
200
0
I IN
(500mA/Div)
VIN = 4.2V, VOUT = 5V, ILOAD = 300mA
Output Voltage
Deviation (mV)
(5V/Div)
50
0
-50
Time (1μs/Div)
Time (1ms/Div)
Load Transient Regulation
Flash LED
Load Current
(mA)
VIN = 4.2V, VOUT = 5V, ILOAD = 100mA to 400mA
VIN = 3.0V, Power LED = 200mA to 700mA
VIN
400
200
(100mV/Div)
0
(2V/Div)
Output Voltage
Deviation (mV)
GPIO
(500mA
/Div)
100
0
I LED
-100
I IN
(500mA/Div)
Time (1ms/Div)
Time (10ms/Div)
Flash LED
Flash LED
VIN = 3.77V, Power LED = 200mA to 700mA
VIN
VIN = 4.3V, Power LED = 200mA to 700mA
VIN
(100mV/Div)
(100mV/Div)
(2V/Div)
(2V/Div)
GPIO
GPIO
(500mA
/Div)
(500mA/Div)
I LED
I LED
I IN
(500mA/Div)
Mode Transition
Time (10ms/Div)
Copyright © 2012 Richtek Technology Corporation. All rights reserved.
DS9278-07 January 2012
I IN
(500mA/Div)
Time (10ms/Div)
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
11
RT9278
Application Information
RT9278 integrates a high-efficiency synchronous rectifier
step-up DC-DC converter and a linear regulator controller.
To fully utilize its advantages, peripheral components
should be appropriately selected. The following information
provides basic considerations for component selection.
Inductor Selection
For a better efficiency in high switching frequency
converter, the inductor selection has to use a proper core
material such as ferrite core to reduce the core loss and
choose low ESR wire to reduce copper loss. The most
important point is to prevent the core saturated when
handling the maximum peak current. Using a shielded
inductor can minimize radiated noise in sensitive
applications. The maximum peak inductor current is the
maximum input current plus the half of inductor ripple
current. The calculated peak current has to be smaller
than the current limitation in the electrical characteristics.
A typical setting of the inductor ripple current is 20% to
40% of the maximum input current. If the selection is
40%
1
IPK = IIN(MAX) + IRIPPLE = 1.2 × IIN(MAX)
2
⎡ (IOUT(MAX) × VOUT ⎤
= 1.2 × ⎢
⎥
⎣⎢ η × VIN(MIN)
⎦⎥
The minimum inductance value is derived from the following
equation :
L=
η × IIN(MIN)2 × [VOUT - VIN(MIN) ]
0.4 × IOUT(MAX) × VOUT 2 × fOSC
Depending on the application, the recommended inductor
value is between 2.2μH and 10μH.
as well, but the ESR is bigger than ceramic capacitor. The
output voltage ripple consists of two components: one is
the pulsating output ripple current flows through the ESR,
and the other is the capacitive ripple caused by charging
and discharging.
VRIPPLE = VRIPPLE(ESR) + VRIPPLE(C)
≅ IPEAK × ESRC OUT +
Output Voltage Setting
Referring to application circuits (Figure 6), the output
voltage of the switching regulator (VOUT) can be set with
below equation :
R2
) × VFB,
VOUT = (1 +
R1
VFB = 0.8V (typ.)
Linear Regulator
Linear Regular MOSFETs Selection
The linear controller of RT9278 was designed to drive an
external P-Channel MOSFET. The main consideration of
pass MOSFETs of linear regulator is package selection
for efficient removal of heat. The power dissipation of a
linear regulator is
Plinear = (VIN − VOUT) x IOUT
For better input bypassing, low-ESR ceramic capacitors
are recommended for performance. A 10μF input capacitor
is sufficient for most applications. For a lower output power
requirement application, this value can be decreased.
Layout Consideration
`
`
Copyright © 2012 Richtek Technology Corporation. All rights reserved.
www.richtek.com
12
A full GND plane without gap break.
VDD to GND noise bypass − Short and wide connection
for the 1μF MLCC capacitor between Pin7 and Pin3.
VIN to GND noise bypass − Add a capacitor close to L1
inductor, when VIN is not an ideal voltage source.
`
Minimized FB node copper area and keep far away
from noise sources.
`
The MOSFETs of linear regulator should have wide pad
to dissipate the heat.
Output Capacitor Selection
For lower output voltage ripple, low-ESR ceramic capacitors
are recommended. The tantalum capacitors can be used
(W)
The criterion for selection of package is the junction
temperature below the maximum desired temperature with
the maximum expected ambient temperature.
`
Input Capacitor Selection
IPP
2×C× f
is a registered trademark of Richtek Technology Corporation.
DS9278-07 January 2012
RT9278
Outline Dimension
D2
D
L
E
E2
1
e
SEE DETAIL A
b
2
1
2
1
A
A1
A3
DETAIL A
Pin #1 ID and Tie Bar Mark Options
Note : The configuration of the Pin #1 identifier is optional,
but must be located within the zone indicated.
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min
Max
Min
Max
A
0.800
1.000
0.031
0.039
A1
0.000
0.050
0.000
0.002
A3
0.175
0.250
0.007
0.010
b
0.180
0.300
0.007
0.012
D
2.950
3.050
0.116
0.120
D2
2.300
2.650
0.091
0.104
E
2.950
3.050
0.116
0.120
E2
1.500
1.750
0.059
0.069
e
L
0.500
0.350
0.020
0.450
0.014
0.018
V-Type 10L DFN 3x3 Package
Richtek Technology Corporation
5F, No. 20, Taiyuen Street, Chupei City
Hsinchu, Taiwan, R.O.C.
Tel: (8863)5526789
Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should
obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot
assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be
accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third
parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries.
DS9278-07 January 2012
www.richtek.com
13