®
RT8471
1.2A/1A, Hysteretic, High Brightness LED Driver with
Internal Switch
General Description
Features
The RT8471 is a high efficiency, continuous mode inductive
step-down converter, designed for driving single or multiple
series connected LEDs from a voltage source higher than
the LED voltage. It operates from an input voltage of 7V to
36V and employs hysteretic control with a high side current
sense resistor to set the constant output current.
The RT8471 includes an output switch and a high side
output current sensing circuit, which uses an external
resistor to set the nominal average output current. LED
brightness control is achieved with PWM dimming from
an analog or PWM input signal.
The RT8471 is available in a small TSOT-23-5 package or
a more thermal efficient SOP-8 (Exposed Pad) and MSOP8 (Exposed Pad) packages.
Applications
Ordering Information
RT8471
Package Type
J5 : TSOT-23-5
SP : SOP-8 (Exposed Pad-Option 1)
FP : MSOP-8 (Exposed Pad)
Lead Plating System
G : Green (Halogen Free and Pb Free)
(for MSOP-8 (Exposed Pad) and
TSOT-23-5 )
Z : ECO (Ecological Element with
Halogen Free and Pb free)
(for SOP-8 (Exposed Pad) Only)
Automotive LED Lighting
High Power LED Lighting
Indicator and Emergency Lighting
Architectural Lighting
Low Voltage Industrial Lighting
Signage and Decorative LED Lighting
Marking Information
RT8471GJ5
01= : Product Code
01=DNN
DNN : Date Code
RT8471ZSP
Note :
Richtek products are :
7V to 36V Input Voltage Range
Hysteretic Control with High Side Current Sensing
Internal N-MOSFET with 350mΩ
Ω Low RDS(ON)
1A Output Current (For TSOT-23-5 Only)
1.2A Output Current (For SOP-8 (Exposed Pad) and
MSOP-8 (Exposed Pad) Only)
Up to 97% Efficiency
Typical ±5% LED Current Accuracy
Analog or PWM Control Signal for LED Dimming
300Hz On-Board Ramp Generator
Input Under Voltage Lockout
Thermal Shutdown Protection
RoHS Compliant and Halogen Free
RoHS compliant and compatible with the current require-
RT8471ZSP : Product Number
RT8471
ZSPYMDNN
YMDNN : Date Code
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
RT8471GFP
0D= : Product Code
0D=YM
DNN
Copyright © 2013 Richtek Technology Corporation. All rights reserved.
DS8471-02
December 2013
YMDNN : Date Code
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1
RT8471
Pin Configurations
(TOP VIEW)
VIN
SENSE
5
4
2
VIN
SENSE
2
GND
3
ADJ
4
3
GND
9
8
GND
7
LX
6
NC
5
NC
SENSE
GND
GND
ADJ
VIN
NC
LX
LX
8
2
3
GND
9
4
7
6
5
LX GND ADJ
TSOT-23-5
MSOP-8 (Exposed Pad)
SOP-8 (Exposed Pad)
Typical Application Circuit
VIN
7V to 36V
CIN
RS
RT8471
VIN
optional
SENSE
D
ADJ
GND
L
LX
Functional Pin Description
Pin No.
TSO T-23-5
SOP-8
(Exposed Pad)
MSOP-8
(Exposed Pad)
1
7
5, 6
2
Pin Name
LX
3, 8,
2, 3,
GND
9 (Exposed Pad) 9 (Exposed Pad)
Pin Function
Switch O utput Terminal. Dr ai n of inter nal N-MOSFET.
Ground. The exposed pad must be soldered to a
large PCB and connected to GND for maximum
power dissipation.
3
4
4
ADJ
4
2
1
SENSE
5
1
8
VIN
Dimming Control Input :
--- Analog signal input for analog PWM dimming.
--- PWM signal input for digital PWM dimming.
Output Current Sense. Sense LED string current with
an external resistor connected between VIN and
SENSE.
Supply Input Voltage.
--
5, 6
7
NC
No Internal Connection.
Copyright © 2013 Richtek Technology Corporation. All rights reserved.
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is a registered trademark of Richtek Technology Corporation.
DS8471-02
December 2013
RT8471
Function Block Diagram
VIN
Regulator
Bandgap
SENSE
+
-
UVLO
UVLO
VCC
1.25V
+
-
UVLO
Dimming
Ramp Gen.
LX
GND
+
ADJ
Dimming
-
Copyright © 2013 Richtek Technology Corporation. All rights reserved.
DS8471-02
December 2013
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
3
RT8471
Absolute Maximum Ratings
(Note 1)
Supply Input Voltage, VIN ------------------------------------------------------------------------------------Switch Voltage, LX -------------------------------------------------------------------------------------------- Sense Voltage, SENSE ------------------------------------------------------------------------------------- All Other Pins ---------------------------------------------------------------------------------------------------- Power Dissipation, PD @ TA = 25°C
TSOT-23-5 (Two-layer PCB) ---------------------------------------------------------------------------------TSOT-23-5 (Four-layer PCB) --------------------------------------------------------------------------------SOP-8 (Exposed pad, Two-layer PCB) -------------------------------------------------------------------SOP-8 (Exposed pad, Four-layer PCB) ------------------------------------------------------------------MSOP-8 (Exposed pad, Two-layer PCB) ----------------------------------------------------------------MSOP-8 (Exposed pad, Four-layer PCB) --------------------------------------------------------------- Package Thermal Resistance (Note 2)
TSOT-23-5, θJA (Two-layer PCB) ---------------------------------------------------------------------------TSOT-23-5, θJC (Two-layer PCB) ---------------------------------------------------------------------------TSOT-23-5, θJA (Four-layer PCB) --------------------------------------------------------------------------TSOT-23-5, θJC (Four-layer PCB) --------------------------------------------------------------------------SOP-8 (Exposed pad, Two-layer PCB), θJA -------------------------------------------------------------SOP-8 (Exposed pad, Two-layer PCB), θJC -------------------------------------------------------------SOP-8 (Exposed pad, Four-layer PCB), θJA ------------------------------------------------------------SOP-8 (Exposed pad, Four-layer PCB), θJC ------------------------------------------------------------MSOP-8 (Exposed pad, Two-layer PCB), θJA ----------------------------------------------------------MSOP-8 (Exposed pad, Two-layer PCB), θJC ----------------------------------------------------------MSOP-8 (Exposed pad, Four-layer PCB), θJA ---------------------------------------------------------MSOP-8 (Exposed pad, Four-layer PCB), θJC --------------------------------------------------------- Junction Temperature ----------------------------------------------------------------------------------------- Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------- Storage Temperature Range -------------------------------------------------------------------------------- ESD Susceptibility (Note 3)
HBM (Human Body Model) ----------------------------------------------------------------------------------MM (Machine Model) -----------------------------------------------------------------------------------------
Recommended Operating Conditions
−0.3V to 40V
−0.3V to (VIN + 0.7V)
(VIN − 5V) to (VIN + 0.3V)
−0.3V to 6V
0.37W
0.43W
2.35W
3.26W
1.38W
2.1W
264.4°C/W
21.8°C/W
230.6°C/W
21.8°C/W
42.5°C/W
3.4°C/W
30.6°C/W
3.4°C/W
72°C/W
11.9°C/W
47.4°C/W
11.9°C/W
150°C
260°C
−65°C to 150°C
2kV
200V
(Note 4)
Supply Input Voltage, VIN ------------------------------------------------------------------------------------- 7V to 36V
Junction Temperature Range --------------------------------------------------------------------------------- −40°C to 125°C
Copyright © 2013 Richtek Technology Corporation. All rights reserved.
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is a registered trademark of Richtek Technology Corporation.
DS8471-02
December 2013
RT8471
Electrical Characteristics
(VIN = 12V, TA = 25°C, unless otherwise specified)
Parameter
Symbol
Mean Current Sense Threshold
Voltage
V SENSE
Sense Threshold Hysteresis
V SENSE
Test Conditions
Measure on SENSE Pin with
Respecting to V IN. ADJ is
Floating.
Min
Typ
Max
Unit
95
100
105
mV
--
±15
--
%
Low Side Switch On-Resistance
RDS(ON)
Low Side Switch Leakage Current
V LX = 12V, VADJ = 0V
---
350
0.01
500
10
m
A
Under Voltage Lockout Threshold
V UVLO
VIN Rising
--
5.2
--
V
Under Voltage Lockout Threshold
Hysteresis
V UVLO
--
400
--
mV
Ramp Frequency
fRAMP
--
300
--
Hz
Logic-High
V ADJ, H
1.4
--
--
Logic-Low
V ADJ, L
--
--
0.2
0.3
--
1.3
Logic-High
--
1.2
1.3
Logic-Low
0.3
0.4
--
ADJ Input Threshold
Voltage
Analog Dimming Range
Analog Dimming
Threshold Voltage
V
V
V
Minimum Switch On-Time
tON(MIN)
LX Switch On
--
210
--
ns
Minimum Switch Off-Time
Quiescent Input Current with
Output Off
Quiescent Input Current with
Output Switching
Internal Propagation Delay
tOFF(MIN)
LX Switch Off
--
170
--
ns
IVIN, Off
V ADJ = 0V
--
450
--
A
IVIN, On
ADJ is Floating, fSW = 250kHz,
V IN = 8V
--
1000
--
A
tPD
--
25
--
ns
Sense Pin Input Current
ISENSE
--
300
--
nA
Thermal Shutdown
Thermal Shutdown Hysteresis
TSD
T SD
---
150
30
---
C
C
V SENSE = VIN 0.1V
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 in natural convection at TA = 25°C on a two-layer and four-layer test board of JEDEC 51 thermal
measurement standard. For SOP-8 (Exposed Pad) and MSOP-8 (Exposed Pad) the measurement case position of θJC
is on the exposed pad of the package. For TSOT-23-5, the measurement case position of θJC is on the lead 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 © 2013 Richtek Technology Corporation. All rights reserved.
DS8471-02
December 2013
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
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RT8471
Typical Operating Characteristics
Output Current vs. Input Voltage
1 LED
2 LED
3 LED
4 LED
5 LED
6 LED
7 LED
8 LED
9 LED
10 LED
1.03
Output Current (A)
Output Current Deviation vs. Input Voltage
4%4
1.02
1.01
1.00
0.99
0.98
0.97
ILED = 1A, L = 33μH
Output Current Deviation (%)1
1.04
1 LED
3%3 2 LED
3 LED
2%2 4 LED
5 LED
1%1 6 LED
7 LED
0%0 8 LED
9 LED
10 LED
-1%
-1
-2%
-2
-3%
-3
ILED = 1A, L = 33μH
-4%
-4
0.96
0
10
20
30
0
40
10
Input Voltage (V)
Switching Frequency vs. Input Voltage
40
Duty Cycle vs. Input Voltage
100%
100
10 LED
9 LED
8 LED
7 LED
6 LED
5 LED
4 LED
3 LED
2 LED
1 LED
800
700
600
500
400
300
Duty Cycle (%)
Duty Cycle (%)
Switching Frequency (kHz)1
30
Input Voltage (V)
900
200
90%
90 10 LED
9 LED
80 8 LED
80%
7 LED
70 6 LED
70%
60 5 LED
60%
4 LED
50 3 LED
50%
2 LED
40
40%
1 LED
30
30%
20
20%
100
10
10%
ILED = 1A, L = 33μH
0
0
10
20
30
ILED = 1A, L = 33μH
0%0
0
40
10
Input Voltage (V)
Efficiency vs. Input Voltage
40
LX Switch On-Resistance vs. Temperature
560
(mΩ)
On-Resistance (m
)
3 LED
90
90%
1 LED
85%
85
30
620
9LED
7 LED
95
95%
20
Input Voltage (V)
100
100%
Efficiency (%)
20
80%
80
500
440
380
320
75%
75
ILED = 1A, L = 33μH
260
70%
70
0
10
20
30
Input Voltage (V)
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40
-50
-25
0
25
50
75
100
125
150
Temperature (°C)
is a registered trademark of Richtek Technology Corporation.
DS8471-02
December 2013
RT8471
Quiescent Input Current vs. Input Voltage
Quiescent Input Current vs. Input Voltage
500
1000
800
600
400
200
VADJ = 2V
0
0
10
20
30
Quiescent Input Current (μA)1
Quiescent Input Current (μA)
1200
495
490
485
480
475
VADJ = 0V
470
40
0
10
Input Voltage (V)
1200
1000
1000
Output Current (mA)
Output Current (mA)
40
Output Current vs. PWM Duty Cycle
Output Current vs. PWM Duty Cycle
800
600
400
800
600
400
200
200
RS = 0.1Ω, fDimming = 10kHz
0
0%
20
20%
40
40%
60
60%
80
80%
RS = 0.1Ω, fDimming = 500Hz
0
0
0%
100
100%
20
20%
40
40%
60
60%
80
80%
100
100%
PWM Duty Cycle (%)
PWM Duty Cycle (%)
Output Current vs. ADJ Voltage
Ramp Frequency vs. Temperature
1200
330
R = 100mΩ
325
800
Ramp Frequency (Hz)1
1000
Output Current (mA)
30
Input Voltage (V)
1200
0
20
R = 150mΩ
600
400
R = 350mΩ
200
320
315
310
305
300
295
VIN = 12V, 1LED
0
290
0.2
0.5
0.8
1.1
1.4
ADJ Voltage (V)
Copyright © 2013 Richtek Technology Corporation. All rights reserved.
DS8471-02
December 2013
1.7
-50
-25
0
25
50
75
100
125
150
Temperature (C)
is a registered trademark of Richtek Technology Corporation.
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7
RT8471
Digital Dimming from ADJ On
VADJ
(2V/Div)
Digital Dimming from ADJ Off
VADJ
(2V/Div)
IOUT
(500mA/Div)
IOUT
(500mA/Div)
VIN = 12V, RS = 0.1Ω, fDimming = 500Hz, 1 LED
VIN = 12V, RS = 0.1Ω, fDimming = 500Hz, 1 LED
Time (5μs/Div)
Time (5μs/Div)
Power On from VIN
Power Off from VIN
VIN
(5V/Div)
VIN
(5V/Div)
IOUT
(500mA/Div)
IOUT
(500mA/Div)
RS = 0.1Ω, 1 LED
Time (1ms/Div)
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RS = 0.1Ω, 1 LED
Time (1ms/Div)
is a registered trademark of Richtek Technology Corporation.
DS8471-02
December 2013
RT8471
Application Information
The RT8471 is a simple high efficiency, continuous mode
inductive step-down converter. The device operates with
an input voltage range from 7V to 36V and delivers up to
1.2A of output current. A high side current sense resistor
sets the output current. A dedicated PWM dimming input
enables pulsed LED dimming over a wide range of
brightness levels. A high side current sensing scheme
and an onboard current setting circuitry minimize the
number of external components. A 1% sense resistor
performs a ±5% LED current accuracy for the best
performance.
Under Voltage Lockout (UVLO)
The RT8471 includes a UVLO feature with 400mV
hysteresis. The internal MOSFET turns off when VIN falls
below 4.8V (typ.).
Setting Average Output Current
The RT8471 output current which flows through the LEDs
is set by an external resistor (RS) connected between the
VIN and SENSE terminal. The relationship between output
current (IOUT) and RS is shown as below :
IOUTavg = 0.1V
RS
(A)
Analog Dimming Control
The ADJ terminal can be driven by an external voltage
(VADJ) to adjust the average output current. The average
output current is given by :
V
0.4
IOUTavg = 0.1V ADJ
0.8
RS
where VADJ is ranged from 0.4V to 1.2V. When VADJ is
larger than 1.2V, the output current value will only depend
on the external resistor (RS).
Digital Dimming Control
A Pulse Width Modulated (PWM) signal can drive the ADJ
terminal directly. Notice that the PWM signal logic high
level must be above 1.4V and the logic low level must be
below 0.2V at the ADJ terminal. It's recommended to
maintain the PWM dimming at low frequency (ex. 500Hz
) in order to obtain a linear dimming curve.
PWM Soft-Start Behavior
The RT8471 features an optional PWM soft-start behavior
that allows for gradual brightness transition. This is
achieved by simply connecting an external capacitor
between the ADJ pin and GND. An internal current source
will then charge this capacitor for soft-start behavior,
resulting in steady LED current increase and decrease
during power on and power off, as shown in Figure 1.
1.2V
Internal
VRAMP
0.4V
VADJ 0V
1.2A
ILED
0A
Figure 1. PWM Soft-Start Behavior Mechanism
Copyright © 2013 Richtek Technology Corporation. All rights reserved.
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December 2013
is a registered trademark of Richtek Technology Corporation.
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RT8471
The capacitor can be selected according to below
equation :
t OFF
C = 1.5 x 10-6 x tSS
VOUT
L IL
VD VSEN IOUT RL
tOFF(MIN) (170ns typ.)
where tss is the soft-start period.
where
LED Current Ripple Reduction
VD is the rectifier diode forward voltage (V)
Higher LED current ripple will shorten the LED life time
and increase heat accumulation of LED. There are two
ways to reduce the LED current ripple. One way is by
increasing the inductance to lower LED current ripple in
absence of an output capacitor. The other way is by adding
an output capacitor in parallel with the LED. This will then
allow the use of a smaller inductor.
VSEN is the voltage cross current sense resistor (V)
Inductor Selection
The inductance is determined by inductor current ripple,
switching frequency, duty ratio, circuit specifications and
component parameters, as expressed in the following
equation :
D
L > VIN VOUT VSEN RDS(ON) IOUT
f
SW IL
where
fSW is the switching frequency (Hz)
RDS(ON) is the low side switch on-resistance of internal
MOSFET ( = 0.35Ω typical)
RL is the inductor DC resistance (Ω)
L is the inductance (H)
The saturation current of the selected inductor must be
higher than the peak output LED current, and the
continuous current rating must be above the average output
LED current. In general, the inductor saturation current
should be 1.5 times the LED current. In order to reduce
the output current ripple, a higher inductance is
recommended at higher supply voltages. However, it could
also cause a higher line resistance and result in a lower
efficiency.
Diode selection
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 increase overall efficiency.
D is the duty cycle determined by VOUT/VIN
IOUT is the required LED current (A)
ΔIL is the inductor peak-peak ripple current (internally set
to 0.3 x IOUT)
VIN is the input supply voltage (V)
VOUT is the total LED forward voltage (V)
Besides, the selected inductance has also to satisfy the
limit of the minimum switch on/off time. The calculated
on time must be greater than 210ns of the minimum on
time, and the off time must be greater than 170ns of the
minimum off time. The following equation can be used to
verify the suitability of the inductor value.
tON
L IL
VIN VOUT IOUT RSEN RL RDS(ON)
tON(MIN) (210ns typ.)
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Input Capacitor selection
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 are
suitable for the RT8471. For maximum stability over the
entire operating temperature range, capacitors with better
dielectric are suggested.
Thermal Protection
A thermal protection feature is included to protect the
RT8471 from excessive heat damage. When the junction
temperature exceeds a threshold of 150°C, the thermal
protection will turn off the LX terminal. When the junction
temperature drops below 120°C, the RT8471 will turn back
on the LX terminal and return to normal operations.
is a registered trademark of Richtek Technology Corporation.
DS8471-02
December 2013
RT8471
Thermal Considerations
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
TSOT-23-5 packages, the thermal resistance, θJA, is
264.4°C/W on a standard JEDEC 51-3 two-layer thermal
test board and 230.6°C/W on a standard JEDEC 51-7 fourlayer thermal test board. For SOP-8 (Exposed pad)
package, the thermal resistance, θJA, is 42.5°C/W on a
standard JEDEC 51-7 two-layer thermal test board, and
30.6°C/W on a standard JEDEC 51-7 four-layer thermal
test board. For MSOP-8 (Exposed pad) package, the
thermal resistance, θJA, is 72°C/W on a standard JEDEC
51-7 two-layer thermal test board, and 47.4°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 formulas :
The maximum power dissipation depends on the operating
ambient temperature for fixed T J(MAX) and thermal
resistance, θJA. The derating curves in Figure 2 allow the
designer to see the effect of rising ambient temperature
on the maximum power dissipation.
4.0
Maximum Power Dissipation (W)1
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 :
SOP-8 (Exposed Pad, Four-Layer PCB)
SOP-8 (Exposed Pad, Two-Layer PCB)
MSOP-8 (Exposed Pad, Four-Layer PCB)
MSOP-8 (Exposed Pad, Two-Layer PCB)
TSOT23-5 (Four-Layer PCB)
TSOT23-5 (Two-Layer PCB)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 2. Derating Curves of Maximum Power
Dissipation
PD(MAX) = (125°C − 25°C) / (264.4°C/W) = 0.37W for
TSOT-23-5 package (Two-Layer PCB)
PD(MAX) = (125°C − 25°C) / (230.6°C/W) = 0.43W for
TSOT-23-5 package (Four-Layer PCB)
PD(MAX) = (125°C − 25°C) / (42.5°C/W) = 2.35W for
SOP-8 (Exposed pad, Two-Layer PCB) package
PD(MAX) = (125°C − 25°C) / (30.6°C/W) = 3.26W for
SOP-8 (Exposed pad, Four-Layer PCB) package
P D(MAX) = (125°C − 25°C) / (72°C/W) = 1.38W for
MSOP-8 (Exposed pad, Two-Layer PCB) package
PD(MAX) = (125°C − 25°C) / (47.4°C/W) = 2.1W for
MSOP-8 (Exposed pad, Four-Layer PCB) package
Copyright © 2013 Richtek Technology Corporation. All rights reserved.
DS8471-02
December 2013
is a registered trademark of Richtek Technology Corporation.
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11
RT8471
Layout Considerations
For best performance of the RT8471, please abide the
following layout guide.
The capacitor CIN, CADJ and external resistor, RS, must
be placed as close as possible to the VIN and SENSE
pins of the device respectively.
The GND should be connected to a strong ground plane.
Keep the main current traces as short and wide as
possible.
The inductor (L) should be mounted as close to the
device with low resistance connections.
The ADJ pin trace need to be kept far away from LX
terminal.
Place the resistor RS as close as
possible to VIN and SENSE pins.
RS
VIN
CIN
GND
D
Place the capacitor
CIN as close as
possible to VIN pin.
LED+
VIN
SENSE
5
4
1
2
Place the capacitor
CADJ as close as
possible to the ADJ
pin.
3
LX GND ADJ
L
CADJ
LED-
Figure 3. PCB Layout Guide
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is a registered trademark of Richtek Technology Corporation.
DS8471-02
December 2013
RT8471
Outline Dimension
H
D
L
B
C
b
A
A1
e
Symbol
Dimensions In Millimeters
Dimensions In Inches
Min
Max
Min
Max
A
0.700
1.000
0.028
0.039
A1
0.000
0.100
0.000
0.004
B
1.397
1.803
0.055
0.071
b
0.300
0.559
0.012
0.022
C
2.591
3.000
0.102
0.118
D
2.692
3.099
0.106
0.122
e
0.838
1.041
0.033
0.041
H
0.080
0.254
0.003
0.010
L
0.300
0.610
0.012
0.024
TSOT-23-5 Surface Mount Package
Copyright © 2013 Richtek Technology Corporation. All rights reserved.
DS8471-02
December 2013
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
13
RT8471
H
A
M
EXPOSED THERMAL PAD
(Bottom of Package)
Y
J
X
B
F
C
I
D
Dimensions In Millimeters
Symbol
Dimensions In Inches
Min
Max
Min
Max
A
4.801
5.004
0.189
0.197
B
3.810
4.000
0.150
0.157
C
1.346
1.753
0.053
0.069
D
0.330
0.510
0.013
0.020
F
1.194
1.346
0.047
0.053
H
0.170
0.254
0.007
0.010
I
0.000
0.152
0.000
0.006
J
5.791
6.200
0.228
0.244
M
0.406
1.270
0.016
0.050
X
2.000
2.300
0.079
0.091
Y
2.000
2.300
0.079
0.091
X
2.100
2.500
0.083
0.098
Y
3.000
3.500
0.118
0.138
Option 1
Option 2
8-Lead SOP (Exposed Pad) Plastic Package
Copyright © 2013 Richtek Technology Corporation. All rights reserved.
www.richtek.com
14
is a registered trademark of Richtek Technology Corporation.
DS8471-02
December 2013
RT8471
D
L
EXPOSED THERMAL PAD
(Bottom of Package)
U
E
V
E1
e
A2
A
A1
b
Symbol
Dimensions In Millimeters
Dimensions In Inches
Min
Max
Min
Max
A
0.810
1.100
0.032
0.043
A1
0.000
0.150
0.000
0.006
A2
0.750
0.950
0.030
0.037
b
0.220
0.380
0.009
0.015
D
2.900
3.100
0.114
0.122
e
0.650
0.026
E
4.800
5.000
0.189
0.197
E1
2.900
3.100
0.114
0.122
L
0.400
0.800
0.016
0.031
U
1.300
1.700
0.051
0.067
V
1.500
1.900
0.059
0.075
8-Lead MSOP (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.
DS8471-02
December 2013
www.richtek.com
15
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