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Design
LM3414, LM3414HV
SNVS678F – JUNE 2010 – REVISED NOVEMBER 2015
LM3414/HV 1-A, 60-W Common Anode-Capable Constant Current Buck LED Driver
Requires No External Current Sensing Resistor
1 Features
•
1
•
•
•
•
•
•
•
•
•
•
•
3 Description
(1)
Supports LED Power up to 60 W : 18x 3-W
HBLEDs
Requires No External Current Sensing Resistor
±3% LED Current Accuracy
Up to 96% Efficiency
High Contrast Ratio (Minimum Dimming Current
Pulse Width 0.
D1
LM3414 / LM3414HV
CVCC
VCC
R1
PGND
IADJ
GND
GND
Q1
Analog
temperature
sensor
GND
VIN
U1
GND
CIN
GND
LX
PWM
dimming signal
DIM
FS
* DAP connect to GND
R2
L1
High power LED Array
Vin
VCC
RFS
GND
RIADJ
GND
Figure 19. Application Circuit of LM3414/HV With Temperature Fold-Back Circuitry and PWM Dimming
14
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SNVS678F – JUNE 2010 – REVISED NOVEMBER 2015
Feature Description (continued)
7.3.6 Internal VCC Regulator
The LM3414/HV features a 5.4-V internal voltage regulator that connects between the VIN and VCC pins for
powering internal circuitry and provide biases to external components. The VCC pin must be bypassed to the
GND pin with a 1-µF ceramic capacitor, CVCC that connected to the pins as close as possible. When the input
voltage falls to less than 6 V, the VCC voltage will drop to less than 5.4 V and decrease proportionally as Vin
decreases. The device will shutdown as the VCC voltage falls to less than 3.9 V. When the internal regulator is
used to provide bias to external circuitry, it is essential to ensure the current sinks from VCC pin does not exceed
2 mA to maintain correct voltage regulation.
7.4 Device Functional Modes
There are no additional functional modes for this device.
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LM3414, LM3414HV
SNVS678F – JUNE 2010 – REVISED NOVEMBER 2015
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8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
8.1.1 Setting the Switching Frequency
Both the LM3414 and LM3414HV are PWM LED drivers that contain a clock generator to generate constant
switching frequency for the device. The switching frequency is determined by the resistance of an external
resistor RFS in the range of 250 kHz to 1 MHz. Lower resistance of RFS results in higher switching frequency. The
switching frequency of the LM3414/HV is governed using Equation 5.
fSW =
20 x 106
kHz
RFS
(5)
1000
ƒSW (kHz)
800
600
400
200
20
40
RFS (kΩ)
60
80
Figure 20. Switching Frequency vs RFS
Table 1. Examples for fSW Settings
fSW (kHz)
RFS (kΩ)
250
80
500
40
1000
20
To ensure accurate current regulation, the LM3414/HV should be operated in continuous conduction mode
(CCM) and the ON time should not be shorter than 400 ns under all operation condition.
8.1.2 Setting LED Current
The LM3414/HV requires no external current sensing resistor for LED current regulation. The average output
current of the LM3414/HV is adjustable by varying the resistance of the resistor, RIADJ that connects across the
IADJ and GND pins. The IADJ pin is internally biased to 1.255 V. The LED current is then governed by
Equation 6.
ILED =
3125 x 103
mA
RIADJ
where
•
16
350 mA < ILED < 1A
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SNVS678F – JUNE 2010 – REVISED NOVEMBER 2015
1.4
1.2
ILED(A)
1.0
0.8
0.6
0.4
0.2
0.0
0
1
2
3 4 5 6
RIADJ(k )
7
8
9
Figure 21. LED Current vs RIADJ
Table 2. Examples for IOUT Settings
IOUT (mA)
RIADJ (kΩ)
350
8.93
500
6.25
700
4.46
1000
3.13
The LED current can be set to any level in the range from 350 mA to 1A. To provide accurate LED current, RIADJ
should be a resistor with no more than 0.5% tolerance. If the IADJ pin is accidentally shorted to GND (RIADJ = 0),
the output current is limited to avoid damaging the circuit. When the overcurrent protection is activated, current
regulation cannot be maintained until the overcurrent condition is cleared.
8.1.3 Inductor Selection
To ensure proper output current regulation, the LM3414/HV must operate in Continuous Conduction Mode
(CCM). With the incorporation of PLM, the peak-to-peak inductor current ripple can be set as high as ±60% of
the defined average output current. The minimum inductance of the inductor is decided by the defined average
LED current and allowable inductor current ripple. The minimum inductance can be found by the equations
shown in Equation 7 through Equation 8.
Because:
'IL =
VIN - VLED
xDxT
L
(7)
Thus:
LMIN =
VIN -VLED VLED 1
x
x
1.2 x ILED VIN fSW
(8)
The LM3414/HV can maintain LED current regulation without output filter capacitor. This is because the inductor
of the floating buck structure provides continuous current to the LED throughout the entire switching cycle. When
LEDs are driven without filter capacitor, the LED peak current must not set exceeding the rated current of the
LED. The peak LED current is governed by Equation 9.
'IL =
(VIN -VLED) VLED
+ ILED(AVG)
2L x VIN x fSW
(9)
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SNVS678F – JUNE 2010 – REVISED NOVEMBER 2015
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8.2 Typical Applications
8.2.1 LM3414/HV Design Example
Vin
High power LED Array
D1
LM3414/14HV
CVCC
VCC
VIN
PGND
4.5V ± 42 VDC (LM3414)
Iout = 1A
CIN
4.5V ± 65 VDC (LM3414HV)
GND
L1
LX
IADJ
DIM
GND
FS
PWM dimming signal
GND
RIADJ
* DAP connect to GND
RFS
GND
GND
Figure 22. LM3414/HV Design Example Schematic
8.2.1.1 Design Requirements
• Input Voltage: VIN
• LED String Voltage: VLED
• LED Current: ILED
• Switching Frequency: fSW
• Maximum LED Current Ripple: ΔiL-PP
• Maximum Input Voltage Ripple: ΔVIN
8.2.1.2 Detailed Design Procedure
8.2.1.2.1 Calculate Operating Parameters
To calculate component values the operating duty cycle (D) must be calculated using Equation 10.
D=
VLED
VIN
(10)
8.2.1.2.2 Calculate RIADJ
To get the desired LED current calculate the value for RIADJ using Equation 11.
RIADJ =
3125
ILED
(11)
8.2.1.2.3 Calculate RFS
Calculate the value of RFS for the desired switching frequency using Equation 12.
RFS =
18
20 × 109
fSW
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SNVS678F – JUNE 2010 – REVISED NOVEMBER 2015
Typical Applications (continued)
8.2.1.2.4 Calculate LMIN
Calculate the minimum inductor value required for the desired LED current ripple using Equation 13.
LMIN =
:VIN - VLED; × VLED
fSW × VIN × ¨iL-PP
(13)
8.2.1.2.5 Calculate CIN-MIN
Calculate the minimum input capacitor value for the desired input voltage ripple using Equation 14.
CIN-MIN =
D × :1 -D; × ILED
fSW × ¨VIN
(14)
8.2.2 LM3414/HV Design Example (IOUT = 1 A)
Vin
Iout = 1000 mA (nom.)
100V
2.2 PF
CIN
CVCC
16V 1 PF
LM3414 / LM3414HV
VCC
VIN
PGND
IADJ
100V
2A
LED x 6
D1
24V ± 42 VDC (LM3414)
24V - 65 VDC (LM3414HV)
GND
L1 47 PH
LX
U1
GND
DIM
FS
GND
RIADJ
3.24k
* DAP connect to GND
GND
RFS
40.2k
GND
Figure 23. LM3414/HV Design Example (IOUT = 1 A) Schematic
8.2.2.1 Design Requirements
• Input Voltage: VIN = 48 V ±10%
• LED String Voltage: VLED = 35 V
• LED Current: ILED = 1 A
• Switching Frequency: fSW = 500 kHz
• Maximum LED Current Ripple: ΔiL-PP ≤ 500 mA
• Maximum Input Voltage Ripple: ΔVIN ≤ 200 mV
8.2.2.2 Detailed Design Procedure
8.2.2.2.1 Calculate Operating Parameters
To calculate component values the operating duty cycle (D) for this application can be calculated be calculated
using Equation 15.
D=
VLED
35V
=
= 0.73
48V
VIN
(15)
8.2.2.2.2 Calculate RIADJ
For 1A LED current calculate the value for RIADJ using Equation 16.
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SNVS678F – JUNE 2010 – REVISED NOVEMBER 2015
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Typical Applications (continued)
RIADJ =
3125
3125
=
= 3.125k
ILED
1A
(16)
Choose a standard value of RIADJ = 3.24kΩ.
8.2.2.2.3 Calculate RFS
Calculate the value of RFS for 500-kHz switching frequency using Equation 17.
RFS
20 × 109
20 × 109
=
=
= 40k
fSW
500kHz
(17)
Choose a standard value of RFS = 40.2kΩ.
8.2.2.2.4 Calculate LMIN
Calculate the minimum inductor value required for 500 mA or less peak-to-peak LED current ripple using
Equation 18.
LMIN =
:VIN - VLED; × VLED
:48V - 35V; × 35V
=
500kHz × 35V × 500mA
fSW × VIN × ¨iL-PP
H
(18)
Choose a higher standard value of L = 47µH.
8.2.2.2.5 Calculate CIN-MIN
Calculate the minimum input capacitor value for 200 mV or less input voltage ripple using Equation 19.
CIN-MIN =
D × :1 -D; × ILED
0.73 × :1 - 0.73; × 1A
=
fSW × ¨VIN
500kHz × 200mV
F
(19)
Choose a higher standard value of CIN = 2.2µF.
Table 3. Bill of Materials
DESIGNATION
20
DESCRIPTION
PACKAGE
MANUFACTURE PART NO.
VENDOR
U1
LED Driver IC
LM3414 / LM3414HV
SOIC-8
LM3414 / LM3414HV
TI
L1
Inductor 47 µH
8 × 8 × 4.9 (mm)
MMD-08EZ-470M-SI
Mag.Layers
D1
Schottky Diode 100 V, 2 A
SMP
SS2PH10-M3
Vishay
CIN
Cap MLCC 100V 2.2 µF X7R
1210
GRM32ER72A225KA35L
Murata
CVCC
Cap MLCC 16V 1 µF X5R
603
GRM39X5R105K16D52K
Murata
RIADJ
Chip Resistor 3.24 kΩ 1%
603
CRCW06033241F
Vishay
RFS
Chip Resistor 40.2 kΩ 1%
603
CRCW06034022F
Vishay
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SNVS678F – JUNE 2010 – REVISED NOVEMBER 2015
8.2.2.3 Application Curve
Figure 24. PWM Dimming Top = DIM. Bottom = LED Current.
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LM3414, LM3414HV
SNVS678F – JUNE 2010 – REVISED NOVEMBER 2015
www.ti.com
9 Power Supply Recommendations
Use any DC output power supply with a maximum voltage high enough for the application. The power supply
should have a minimum current limit of at least 1 A.
10 Layout
10.1 Layout Guidelines
Discontinuous currents are the most likely to generate EMI; therefore, take care when routing these paths. The
main path for discontinuous current in the LM3414/HV buck converter contains the input capacitor (CIN), the
recirculating diode (D1), and the switch node (LX). This loop should be kept as small as possible and the
connections between all three components should be short and thick to minimize parasitic inductance. In
particular, the switch node (where L1, D1 and LX connect) should be just large enough to connect the
components without excessive heating from the current it carries.
The IADJ, FS, and DIM pins are all high-impedance control inputs which couple external noise easily, therefore
the loops containing these high impedance nodes should be minimized. The frequency setting resistor (RFS) and
current setting resistor (RIADJ) should be placed close to the FS and IADJ pins as possible.
10.2 Layout Example
+
GND
VIN/LED+
CIN
VCC
VIN
D1
CVCC
LED-
RIADJ
LX
IADJ
DIM
GND
FS
L1
-
PGND
RFS
THERMAL/POWER VIA
Figure 25. Layout Recommendation
22
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SNVS678F – JUNE 2010 – REVISED NOVEMBER 2015
11 Device and Documentation Support
11.1 Related Links
The table below lists quick access links. Categories include technical documents, support and community
resources, tools and software, and quick access to sample or buy.
Table 4. Related Links
PARTS
PRODUCT FOLDER
SAMPLE AND BUY
TECHNICAL
DOCUMENTS
TOOLS AND
SOFTWARE
SUPPORT AND
COMMUNITY
LM3414
Click here
Click here
Click here
Click here
Click here
LM3414HV
Click here
Click here
Click here
Click here
Click here
11.2 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.3 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.4 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
11.5 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
LM3414HVMR/NOPB
ACTIVE SO PowerPAD
DDA
8
95
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 125
L3414
HVMR
LM3414HVMRX/NOPB
ACTIVE SO PowerPAD
DDA
8
2500
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 125
L3414
HVMR
LM3414HVSD/NOPB
ACTIVE
WSON
NGQ
8
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L249B
LM3414HVSDX/NOPB
ACTIVE
WSON
NGQ
8
4500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L249B
LM3414MR/NOPB
ACTIVE SO PowerPAD
DDA
8
95
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 125
L3414
MR
LM3414MRX/NOPB
ACTIVE SO PowerPAD
DDA
8
2500
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 125
L3414
MR
LM3414SD/NOPB
ACTIVE
WSON
NGQ
8
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L248B
LM3414SDX/NOPB
ACTIVE
WSON
NGQ
8
4500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L248B
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of