RT8479C [RICHTEK]
Two-Stage Hysteretic LED Driver;
| 型号： | RT8479C |
| 厂家： | 
RICHTEK TECHNOLOGY CORPORATION |
| 描述： | Two-Stage Hysteretic LED Driver |
| 文件： | 总15页 (文件大小：148K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
®
RT8479C
Two-Stage Hysteretic LED Driver with Internal MOSFETs
General Description
Features
Two-Stage Topology (Boost + Buck)
The RT8479C is a two-stage controller with dual
MOSFETs and consists of a Boost converter (first stage)
and a Buck converter (second stage). The advantage of
two-stage topology is highly compatible with ET (Electronic
Transformer) and extremely high Power Factor
performance in MR16 / AR111 lighting market fields
applications.
Dual MOSFETs Inside
Wide Input Voltage Range : 4.5V to 36V
Excellent Power Factor
Programmable Boost Output Voltage
Independent Dual Stage Function
Programmable LED Current with 5% LED Current
Accuracy
The first stage is a Boost converter for constant voltage
output with inductor peak current over-current protection.
The second stage is a Buck converter for constant output
current by typical constant peak current regulation.
Input Under-Voltage Lockout Detection
Thermal Shutdown Protection
Ordering Information
RT8479C
The RT8479C is equipped with dual output gate drivers
for internal power MOSFETs.
Package Type
SP : SOP-8 (Exposed Pad-Option 2)
The RT8479C is available in the SOP-8 (Exposed Pad)
package.
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Applications
Richtek products are :
MR16 Lighting
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.
Signage andDecorative LEDLighting
Architectural Lighting
High Power LED Lighting
Low Voltage Industrial Lighting
Indicator and Emergency Lighting
Automotive LED Lighting
Simplified Application Circuit
D5
L1
VCC
C
OUT
R1
R2
RT8479C
D1
D2
R
SENSE
OVP
VCC
LED+
LED-
VL
AC 12V
VN
ISN
D6
C
IN
C3
CREG
LX1
C2
VCOMP
ACTL
D3
D4
L2
To
Dimming
C1
LX2
GND
Copyright 2014 Richtek Technology Corporation. All rights reserved.
©
is a registered trademark of Richtek Technology Corporation.
DS8479C-04 August 2014
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RT8479C
Marking Information
Pin Configurations
RT8479CGSP : Product Number
(TOP VIEW)
RT8479C
YMDNN : Date Code
8
7
6
5
GSPYMDNN
LX1
OVP
LX2
2
3
4
CREG
VCC
ISN
GND
ACTL
9
VCOMP
SOP-8 (Exposed Pad)
Functional Pin Description
Pin No.
Pin Name
Pin Function
1
2
3
LX1
Switch Node. The first stage internal MOSFET Drain.
Over-Voltage Protection Sense Input.
OVP
ACTL
Analog / PWM Dimming Control Input. Connect to CREG if not used.
Compensation Node. A compensation network between VCOMP and GND is
needed.
4
5
6
VCOMP
ISN
LED Negative Current Sense Input.
Supply Voltage Input. For good bypass, place a ceramic capacitor near the
VCC pin.
VCC
Internal Regulator Output. Place an 1F capacitor between the CREG and
GND pins.
7
CREG
LX2
8
Switch Node. The second stage internal MOSFET Drain.
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
9 (Exposed Pad)
GND
Function Block Diagram
ISN VCC
-130mV
ACTL
Logic
ACTL
V
Regulator
CREG
LX2
VCC
UV/OV
EN2
EN1
EN2
EN1
Core
Logic
OVP
LX1
VCOMP
+
GND
-
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DS8479C-04 August 2014
RT8479C
Operation
The RT8479C VCC is supplied from the first stage Boost
output.
The first stage is a constant output voltage Boost topology
and senses the peak inductor current for over-current
protection with excellent Power Factor.
The second stage is a constant output current Buck
topology. The current sense voltage threshold between
the VCC and ISN pins is only 130mV to reduce power
loss.
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RT8479C
Absolute Maximum Ratings (Note 1)
Supply Voltage, VCC to GND ------------------------------------------------------------------------------------------ −0.3V to 45V
ACTL, CREG, OVP, VCOMP to GND -------------------------------------------------------------------------------- −0.3V to 6V
LX1, LX2 toGND ----------------------------------------------------------------------------------------------------------- −0.3V to 40V
VCC to ISN ----------------------------------------------------------------------------------------------------------------- −0.3V to 3V
Power Dissipation, PD @ TA = 25°C
SOP-8 (Exposed Pad) --------------------------------------------------------------------------------------------------- 3.44W
Package Thermal Resistance (Note 2)
SOP-8 (Exposed Pad), θJA ---------------------------------------------------------------------------------------------- 29°C/W
SOP-8 (Exposed Pad), θJC --------------------------------------------------------------------------------------------- 2°C/W
Junction Temperature ----------------------------------------------------------------------------------------------------- 150°C
Lead Temperature (Soldering, 10 sec.)------------------------------------------------------------------------------- 260°C
Storage Temperature Range -------------------------------------------------------------------------------------------- −65°C to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Model)---------------------------------------------------------------------------------------------- 2kV
MM (Machine Model) ----------------------------------------------------------------------------------------------------- 200V
Recommended Operating Conditions (Note 4)
Supply Input Voltage, VCC---------------------------------------------------------------------------------------------- 4.5V to 40V
Junction Temperature Range-------------------------------------------------------------------------------------------- −40°C to 125°C
Ambient Temperature Range-------------------------------------------------------------------------------------------- −40°C to 85°C
Electrical Characteristics
(VCC = 10VDC, No Load, CLOAD = 1nF, TA = 25°C, unless otherwise specified)
Parameter
Supply Voltage
Symbol
Test Conditions
Min
Typ Max Unit
CREG UVLO_ ON
V
V
OVP = 0V
OVP = 0V
--
--
4.2
3.9
--
--
V
V
UVLO_ ON
CREG UVLO_ OFF
UVLO_ OFF
Supply Current
VCC Shutdown Current
VCC Quiescent Current
Internal Reference Voltage
Internal Reference Voltage
I
V
V
= 3.5V
--
--
--
10
1.5
5
--
--
--
A
mA
V
SHDN
Q
CC
CC
I
= 10V
V
CREG
I
= 20mA
--
--
4.9
5
--
--
V
CREG
(I
CREG
= 20mA)
Stage 1 Max On-Time
High-Level
Low-Level
s
V
V
I
1.85 1.94 2.04
OVP_H
OVP_L
Stage 1 OVP
V
1.52
1.6
1.68
OVP Pin Leakage Current
ACTL Turn On Threshold
ACTL Turn Off Threshold
--
--
--
1
--
--
--
A
mV
mV
OVP
V
240
60
ACTL_ON
V
ACTL_OFF
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DS8479C-04 August 2014
RT8479C
Parameter
Symbol
Test Conditions
Min
94
--
Typ
97
--
Max
100
1
Unit
Sense threshold percentage
at VACTL = 2.7V
ACTL Sense Threshold High
%
ACTL Input Bias Current
ISN Threshold
A
VISN
VACTL = 3V
123.5 130 136.5
mV
Stage 2 Peak to Peak Sense
Voltage
(dV1 + dV2) / 2
Sink = 100mA
--
15
--
%
LX1 Internal Switch RDS(ON) RDS(ON)_1
--
--
0.15
0.2
--
--
LX2 Internal Switch RDS(ON) RDS(ON) _2 Sink = 100mA
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. θJC is
measured at the exposed pad of the package.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
Copyright 2014 Richtek Technology Corporation. All rights reserved.
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RT8479C
Typical Application Circuit
L1
10µH
D5
VCC
R
R1
130k
C
4.7µF
C
OUT_EC
220µF
OUT
SENSE
RT8479C
D1
D3
D2
D4
250m
2
6
OVP
VCC
LED+
VL
AC 12V
VN
R2
10k
C5
5
7
ISN
C
1µF
D6
IN
C3
4.7µF
4LED
LED-
1
4
3
CREG
LX1
C2
4.7µF
VCOMP
ACTL
L2
68µH
For
Dimming
Signal
C1
0.47µF
8
LX2
GND
9 (Exposed Pad)
D1,D2, D3, D4, D5, D6 = PMEG4020
ACTL can be connected to CREG if not used.
C5 depends on PCB layout and noise immunity.
Figure 1. Typical MR16 LED Lamp for 5W Application
Sense Threshold vs. ACTL Voltage
150
135
120
105
90
75
60
45
30
15
VCC = 20V, Temp = 25°C
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
ACTL Voltage(V)
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DS8479C-04 August 2014
RT8479C
Typical Operating Characteristics
Quiescent Current vs. Temperature
Quiescent Current vs.VCC
1.7
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
1.6
1.5
1.4
1.3
1.2
OVP = 5V
VCC = 4.5V to 30V, OVP = 5V
1.1
4
9.2
14.4
19.6
24.8
30
-50
-50
-50
-25
0
25
50
75
100
125
Temperature (°C)
VCC (V)
Operating Current vs. VCC
Operating Current vs. Temperature
4.0
3.5
3.0
2.5
2.0
1.5
1.0
3.6
3.2
2.8
2.4
2.0
1.6
VCC = 10V,
VCC = 4.5V to 30V,
LX1/LX2 Capacitor = 1nF, OVP = 0V
LX1/LX2 Capacitor = 1nF, OVP = 0V
-25
0
25
50
75
100
125
4
9.2
14.4
19.6
24.8
30
VCC (V)
Temperature (°C)
CREG Voltage vs. VCC
CREG Voltage vs. Temperature
7
5.4
5.3
5.2
5.1
5.0
4.9
4.8
6
5
4
3
2
ICREG = 0mA
ICREG = 0mA
ICREG = −20mA
ICREG = −20mA
VCC = 4.5V to 30V
19.8 24.9 30
VCC = 10V
100 125
4.5
9.6
14.7
-25
0
25
50
75
VCC (V)
Temperature (°C)
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RT8479C
ISN Threshold vs. Temperature
ISN Threshold vs. VCC
150
140
130
120
110
100
150
140
130
120
110
100
90
VCC = 4.5V to 30V
19.6 24.8 30
VCC = 10V
100 125
4
9.2
14.4
-50
-25
0
25
50
75
Temperature (°C)
VCC (V)
OVP Hi/Low Level Voltage vs. VCC
OVP Hi/Low Level Voltage vs. Temperature
2.2
2.1
2.0
1.9
1.8
1.7
1.6
1.5
1.4
2.1
2.0
1.9
1.8
1.7
1.6
1.5
1.4
1.3
Hi
Hi
Low
Low
VCC = 10V
100 125
VCC = 4.5V to 30V
4.5
9.6
14.7
19.8
24.9
30
-50
-25
0
25
50
75
VCC (V)
Temperature (°C)
LX2_RDS(ON) vs. Temperature
LX1_RDS(ON) vs. Temperature
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0.25
0.20
0.15
0.10
0.05
0.00
VCC = 10V
100 125
VCC = 10V
100 125
-50
-25
0
25
50
75
-50
-25
0
25
50
75
Temperature (°C)
Temperature (°C)
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DS8479C-04 August 2014
RT8479C
ACTL Threshold Voltage vs. VCC
ACTL Threshold Voltage vs. Temperature
270
240
210
180
150
120
90
270
On
240
210
180
150
120
90
On
Off
Off
60
60
30
30
4
8
12
16
20
24
28
32
-50
-25
0
25
50
75
100
125
VCC (V)
Temperature (°C)
LED Current vs. Input Voltage
LED Current vs. ACTL Voltage
800
700
600
500
400
300
200
100
0
450
440
430
420
410
400
390
380
IOUT = 756mA
IOUT = 382mA
IOUT = 185mA
VCC = 7V to 20V, IOUT = 420mA, Load = 4LED
10 12 14 16 18 20
0
0.5
1
1.5
2
2.5
3
6
8
Input Voltage (V)
ACTL Voltage (V)
LED Current vs. Output Voltage
PK-Current vs. Temperature
440
435
430
425
420
415
410
2500
2000
1500
1000
500
VC = 5V
VC = 0V
VCC = 10V
100 125
Load = 1LED to 6LED
0
4.5
7.6
10.7
13.8
16.9
20
-50
-25
0
25
50
75
Output Voltage (V)
Temperature (°C)
Copyright 2014 Richtek Technology Corporation. All rights reserved.
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RT8479C
Power On from VIN
CREG UVLO vs. Temperature
5.0
4.5
4.0
3.5
3.0
2.5
2.0
IOUT
(500mA/Div)
UVLO-H
UVLO-L
LX2
(50V/Div)
VOUT
(10V/Div)
VIN
(10V/Div)
VIN = 10V, 4LEDs
Time (25ms/Div)
-50
-25
0
25
50
75
100
125
Temperature (°C)
Power Off from VIN
Power On from AC-IN
IOUT
(500mA/Div)
IOUT
(200mA/Div)
LX2
(50V/Div)
VOUT
(10V/Div)
VOUT
(10V/Div)
VCC
(20V/Div)
VIN
(10V/Div)
AC-IN
(50V/Div)
VIN = 10V, 4LEDs
Time (25ms/Div)
Time (10ms/Div)
Power Off from AC-IN
IOUT
(200mA/Div)
VOUT
(10V/Div)
VCC
(20V/Div)
AC-IN
(50V/Div)
Time (10ms/Div)
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DS8479C-04 August 2014
RT8479C
Application Information
Average Output Current Setting
The RT8479C consists of a constant output current Buck
controller and a fixed off-time controlled Boost controller.
The output current that flows through the LED string is
set by an external resistor, RSENSE, which is connected
between the VCC and ISN terminal. The relationship
between output current, IOUT, and RSENSE is shown below:
The Boost controller is based on a peak current, fixed off-
time control architecture and designed to operate up to
1MHz to use a very small inductor for space constrained
applications. A high-side current sense resistor is used
to set the output current of the Buck controller. A 1%
sense resistor performs a 5% LED current accuracy for
the best performance.
IOUT = 130mV / RSENSE
LED Current Ripple Reduction
Higher LED current ripple will shorten the LED life time
and increase heat accumulation of LED. To reduce the
LEDcurrent ripple, an output capacitor in parallel with the
LEDshould be added. The typical value of output capacitor
is 4.7μF.
Under-Voltage Lockout (UVLO)
The RT8479C includes an under-voltage lockout function
with 100mV hysteresis. The internal MOSFET turns off
when VCC falls below 4.2V (typ.).
VCC Voltage Setting
The VCC voltage setting is equipped with an Over-Voltage
Protection (OVP) function. When the voltage at the OVP
pin exceeds threshold approximately 1.9V, the power
switch is turned off. The power switch can be turned on
again once the voltage at the OVP pin drops below 1.6V.
CREG Regulator
The CREG pin requires a capacitor for stable operation
and to store the charge for the large GATE switching
currents. Choose a 10V rated low ESR, X7R or X5R,
ceramic capacitor for best performance. A4.7μF capacitor
will be adequate for many applications. Place the capacitor
close to the IC to minimize the trace length to the CREG
pin and to the IC ground.
For Boost applications, the output voltage can be set by
the following equation :
VCC(MAX) = 1.9 x (1 + R4 / R5)
An internal current limit on the CREG output protects the
RT8479C from excessive on-chip power dissipation.
R4 and R5 are the voltage divider resistors from VOUT to
GND with the divider center node connected to the OVP
pin. For MR16 LEDlamp application, the minimum voltage
of VCC should maintain above 25V for stable operation.
The CREG pin has set the output to 4.3V (typ.) to protect
the internal FETs from excessive power dissipation
caused by not being fully enhanced. If the CREG pin is
used to drive extra circuits beside RT8479C, the extra
loads should be limited to less than 10mA.
Step-Down Converter Inductor Selection
The RT8479C implemented a simple high efficiency,
continuous mode inductive step-down converter. The
inductance L2 in Buck converter is determined by the
following factors : inductor ripple current, switching
frequency, VOUT/VIN ratio, internal MOSFET, topology
specifications, and component parameter. The inductance
L2 is calculated according to the following equation :
Internal MOSFET
There are two drivers, LX1 and LX2, in the RT8479C.
The driver consists of a CMOS buffer designed to drive
the internal power MOSFET.
It features great sink capabilities to optimize switch on
and off performance without additional external
components. Whenever the IC supply voltage is lower than
the under voltage threshold, the internal MOSFET is turned
off.
L2 ≥ [VCC(MAX) − VOUT − VISN − (RDS2(ON) x IOUT)] x D / [fSW
x ΔIOUT
]
where
fsw is switching frequency (Hz).
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RT8479C
RDS2(ON) is the low-side switch on-resistance of external
Check the ILIM setting satisfied the output LED current
request by the following equation :
MOSFET (M2). The typical value is 0.35Ω.
D is the duty cycle = VOUT / VIN
(IOUT + ΔIOUT) < [2 x L1 x ILIM + tOFF x (VIN − VOUT − VF)] x
VIN / [2 x L1 x (VCC)]
IOUT is the required LED current (A)
ΔIOUT is the inductor peak-peak ripple current (internally
Diode Selection
set to 0.3 x IOUT
)
To obtain better efficiency, the Schottky diode is
recommended for its low reverse leakage current, low
recovery time and low forward voltage. With its low power
dissipation, the Schottky diode outperforms other silicon
diodes and increases overall efficiency.
VCC is the supply input voltage (V)
VOUT is the total LED forward voltage (V)
VISN is the voltage cross current sense resistor (V)
L2 is the inductance (H)
Input Capacitor selection
The selected inductor must have saturation current higher
than the peak output LEDcurrent and continuous current
rating above the required average output LED current. In
general, the inductor saturation current should be 1.5
times the LED current. In order to minimize output current
ripple, higher values of inductance are recommended at
higher supply voltages. Because high values of inductance
has high line resistance, it will cause lower efficiency.
Input capacitor has to supply peak current to the inductor
and flatten the current ripple on the input. The low ESR
condition is required to avoid increasing power loss. The
ceramic capacitor is recommended due to its excellent
high frequency characteristic and low ESR, which is
suitable for the RT8479C. For maximum stability over the
entire operating temperature range, capacitors with better
dielectric are suggested.
Step-Up Converter Inductor Selection
Thermal Protection
The RT8479C uses a constant off-time control to provide
high efficiency step-up converter.
A thermal protection feature is to protect the RT8479C
from excessive heat damage. When the junction
temperature exceeds 150°C, the thermal protection will
turn off the LX terminal. When the junction temperature
drops below 125°C, the RT8479C will turn on the LX
terminal and return to normal operation.
Following the constant off-time mechanism, the inductance
L1 is calculated according to the following equation :
L1 > tOFF x (VCC(MAX) − VIN(MIN) + VF) / ILIM
where
tOFF is Off-Time. The typical value is 1.5μs.
Analog Dimming Control
ILIM is the input current. The typical value is 2A for MR16
application.
TheACTL terminal is driven by an external voltage, VACTL
,
to adjust the output current to an average value set by
RSENSE. The voltage range for VACTL to adjust the output
current is from 0.24V to 2.5V. If VACTL becomes larger
than 2.5V, the output current value will just be determined
VCC is the supply input voltage (V)
VIN is the input voltage after bridge diodes (V)
VF is the forward voltage (V)
by the external/resistor, RSENSE
.
L1 is the inductance (H)
V
0.24
2.5
0.13V
ACTL
I
=
OUT avg
R
D = 1 - (VIN / VOUT
)
SENSE
fsw = (1 - D) / tOFF
ACTL Control
where
The ACTL pin is the dimming function pin with the DC
level proportional to the output LED current until ACTL
clamp voltage that is the max output current (100%).
D is the operation duty
fsw is the switching frequency of Boost controller.
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DS8479C-04 August 2014
RT8479C
Thermal Considerations
For 5W MR16 LED Lamp application in Figure 1, the
typical PCB size is 2x2 mm2 with two-layer layout plane.
For continuous operation, do not exceed absolute
maximum junction temperature. The maximum power
dissipation depends on the thermal resistance of the IC
package, PCB layout, rate of surrounding airflow, and
difference between junction and ambient temperature. The
maximum power dissipation can be calculated by the
following formula :
Under 25°C room temperature, the case temperature of
RT8479C is around 65°C. If RT8479C is operated in higher
output power or smaller PCB size, the thermal plane for
heat dissipation should be concerned seriously.
PD(MAX) = (TJ(MAX) − TA) / θJA
where TJ(MAX) is the maximum junction temperature, TA is
the ambient temperature, and θJA is the junction to ambient
thermal resistance.
For recommended operating condition specifications, the
maximum junction temperature is 125°C. The junction to
ambient thermal resistance, θJA, is layout dependent. For
SOP-8 (Exposed Pad) package, the thermal resistance,
θJA, is 29°C/W on a standard JEDEC 51-7 four-layer
thermal test board. The maximum power dissipation at TA
= 25°C can be calculated by the following formula :
PD(MAX) = (125°C − 25°C) / (29°C/W) = 3.44W for
SOP-8 (Exposed Pad) package
The maximum power dissipation depends on the operating
ambient temperature for fixed TJ(MAX) and thermal
resistance, θJA. The derating curve in Figure 2 allows the
designer to see the effect of rising ambient temperature
on the maximum power dissipation.
3.6
Four-Layer PCB
3.0
2.4
1.8
1.2
0.6
0.0
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 2. Derating Curve of Maximum PowerDissipation
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RT8479C
Layout Consideration
Locate input capacitor as
close to the VCC as
possible.
D5
L1
VCC
R1
R2
R
OVP
C15
SENSE
C
OUT
ISN
C8
LED+
D6
C3
GND
C
IN
L2
D1
D3
D2
D4
LED-
8
7
6
5
LX1
OVP
LX2
VL
2
3
4
CREG
VCC
ISN
GND
VN
ACTL
9
C5
C2
C7
VCOMP
C5: VCC-ISN bypass capacitor;
noise interference like inductive and
magnetic pick up will be rejected by
C5.
C1
GND
Figure 3. PCB Layout Guide
Copyright 2014 Richtek Technology Corporation. All rights reserved.
©
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
14
DS8479C-04 August 2014
RT8479C
Outline Dimension
H
A
Y
M
EXPOSED THERMAL PAD
(Bottom of Package)
J
B
X
F
C
I
D
Dimensions In Millimeters Dimensions In Inches
Symbol
Min
Max
5.004
4.000
1.753
0.510
1.346
0.254
0.152
6.200
1.270
2.300
2.300
2.500
3.500
Min
Max
A
B
C
D
F
H
I
4.801
3.810
1.346
0.330
1.194
0.170
0.000
5.791
0.406
2.000
2.000
2.100
3.000
0.189
0.150
0.053
0.013
0.047
0.007
0.000
0.228
0.016
0.079
0.079
0.083
0.118
0.197
0.157
0.069
0.020
0.053
0.010
0.006
0.244
0.050
0.091
0.091
0.098
0.138
J
M
X
Y
X
Y
Option 1
Option 2
8-Lead SOP (Exposed Pad) Plastic Package
Richtek Technology Corporation
14F, No. 8, Tai Yuen 1st 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.
DS8479C-04 August 2014
www.richtek.com
15
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