1. Power Design Engineer for Lighting
Bringing light to life
Najmi Kamal
Power Design Engineer for Lighting
March 2012

2. TI Solid State Lighting (SSL) Core Competencies
Applications
General Illumination
Retrofit
Commercial
Professional
Back Lighting
Portable
Monitor
Digital TV
Automotive
Exterior Lighting
Full System Solutions
Power Management
Multi-String
Single-String
Multi-Stage
Single-Stage
Monitoring
Communication
High Performance Solution
Expertise
AC/DC
Analog
Digital
DC/DC
Linear
Wireless & PLC
Light Measurement
Resources
EVMs
Cook Book
Ref. designs
Sample software
Application reports
Local design services
Lighting training support
Lighting Know-How

3. High Power Wide Area LM340x
Market Segment Focus
Downlighting LM3464,LM3466
High Power Wide Area LM340x
Street Lights
Parking Lights
Ext. Building
Energy Saving
intelligent Lights
Public Buildings
Commercial
Energy Saving
LED Lamp LM3445,TPS92310
Cost driven
High Light quality
Cost driven
Fast growth
Automotive LM342x, LM3409

4. TI Lighting System Solution
NSC + TI = strong system level know-how

5. Lighting Summary
Lighting Portfolio LED driver Architecture Dimming techniques LED driver MR16 LED bulb design Controller, Ref design High brightness LEDs driver Off line LED Bulb/T8 Ref design Multi Channel LED driver System solutions ( Triac, DALI, 0 to 10V) WEBENCH Architect

6. Texas Instrument’s Current LED Driver Solutions
Quick Selection guide

7. DC/DC Buck Converters for LED Lighting2A
1.5A 1A
0.5A
0.35A 10 20 30 40 50 60 70 80 90
TPS92510 (RTM:10/2011)
LM3406
LM3406HV
LM3414
LM3414HV
MAX LED Current
LM3404
LM3404HV
LM3405 A
LM3402
LM3402HV
TPS92501 (RTM:12/2011)
LM3407
Input Voltage (V)

8. With current (high end system)
How to drive LEDs?
With current (high end system)
Light output is proportional to forward current
Brightness AND color can change with current
With power(low end system)
Bulb

9. N or P FET

10. Duty Cycle Limits Max VO in Bucks
High Side N-MOSFETs (internal or external FETs)
Must turn off for ~200 ns each cycle to recharge CBOOT
The max number of LEDs is then:
This section of a block diagram is from the LM3404, but it applies to the LM3402 and LM3406 as well.
Do you have an idea why we didn’t use in the past P mosfet but N mosfte driver?
The lower the switching frequency, fSW, the closer VO-MAX is to VIN

11. PFET Bucks Can Provide 100% Duty Cycle
Gate is driven below source to turn the PFET ON
Gate can drive to VCC indefinitely
PFET can stay on indefinitely
True 100% duty cycle capability
Buck is better than buck-boost
Better efficiency
Less parts
Faster dimming
High Side P-MOSFETs
The LM3401 and LM3409/09HV are all PFET bucks

12. Dimming

13. Various dimming techniques
4/14/2017
Various dimming techniques
Dimming using PWM signal
White LEDs change Colour over Current!
Solution:
Maintain Current and Change ON-Time = PWM

14. Two different PWM dimming methods
4/14/2017
Two different PWM dimming methods
First method: Dim 1: Continuous inductor current (Good EMC, extra Mosfet )
Second method: Dim 2: more efficient (2khz dim max)

15. Output capacitor for a Buck topology

16. Buck (step-down) DCM or CCM
Vo Limited by VIN
Cout not needed
Continuous output current, low EMI
Easy to stabilize, if needed
Inherent protections against failure L I o Δ I + L Δ I V C F + -
VIN C O + D Vo -
Do we need an output cap for driving LEDs ?
Since we need a current source and not voltage source.
In CCM mode you can leave without cap but big inductor and EMI PB
In DCM mode small inductor and big cap.
The best is in between. + R FB V FB -

17. BUCK - To Cap or Not to Cap
No Output Capacitor
No output cap provides high output impedance
Saves a component
Leads to higher LED ripple current
May generate more electromagnetic interference (EMI)
With Output Capacitor
Adding an output cap reduces ripple current
Small cap + small inductor is smaller than one large inductor
Slows pulse-width modulation (PWM) dimming
Must be rated to VIN in case of output open circuit

18. BUCK - To Cap or Not to Cap
No Output Cap
With Output Cap
Note inductor height as well
4.5mm
1.4mm

19. Three Pieces of the Puzzle
Optical – Just as critical, must be integrated into the mechanical design of the lamp
Thermal – Critical. Good designs integrate heat sinking into the design of the lamp
LED Driver – Critical.
Must be good designs.
(Efficient, small size,
EMI/Safety proved)

20. LED Drivers

21. LM3409/09HV: High-Side PFET Buck Controller
VIN 6V to 42V (LM3409)
VIN 6V to 75V (LM3409HV)
External power PFET
100% Duty Cycle Capable
Output Currents up to 4A
Differential, high-side current sense
Simplifies system wiring
PWM dimming and analog dimming at 1000:1
Thermally enhanced eMSOP-10 package
No control-loop compensation
The LM3409 and LM3409HV are buck PFET controllers that extend the input voltage range of the LM3401 and provide several new features at the same time. These controllers use a constant off-time control scheme which naturally combines the safety current limit with peak current control. Like the LM3401 the LM3409 is capable of a true 100% duty cycle, but it adds two important features.
First, the current sensing is done on the high side. Within National, “high-side” current sensing means that the current sense resistor is placed before the anode of the first LED. The principal advantage of this is the simplification of the wiring. LED current returns through system ground, and this eases the design of systems with wiring harnesses, especially those where the LEDs are placed on a separate PCB or are physically distant from the drive electronics.
The second addition to the LM3409 is the IADJ pin, which is designed for linear adjustment of the LED current. A 5 μA current source flows from IADJ, allowing the user to set the current sense voltage by placing a resistor from IADJ to ground. The user can also apply a control voltage to IADJ, which then directly sets the current sense voltage. Both methods allow the user to make the tradeoff between power dissipation in the current sense resistor and the accuracy of the LED current. Linear dimming also opens the door to simple temperature or ambient light feedback loops.

22. LM3401 Hysteretic PFET controller HB LED Driver
Key Features
VIN Range: 4.5V – 35V
Output range: 0.2V (Vfb) to VIN, adjusts to deliver constant current to up to 9 HB LEDs in series with scalable LED current > 2A
No output cap, no compensation components
Logic level dimming 1% to 100%, 70nS delay
Controlled start up allows PWM at Vin for dimming
PFET driver 100% duty cycle capable
Adjustable Dual Side Hysteresis
Adjustable ripple current
Flexible inductor selection
Fine tuning of switching frequency up to 1.5MHz
MSOP-8 package
VIN can also be used for PWM dimming when a logic signal is not available. In this mode of operation DIM should be connected to VIN through a 10 kΩ resistor. There is typically 10 us of startup delay time when using VIN for dimming.
Depending on the application, this de-lay limits the maximum dimming frequency to typically several hundred Hz.
When 100% duty, Vo=Vin, I_LED is fixed to I_LED_MAX (L is a short).
HYST control  Vo goes between Vref – HYS and Vref + HYS
Rsns ADJUST THE OUTPUT CURRENT
Hyst adjust the hysterisys
CS detect the max peak current and switch off the mosfet
I lim adjust the peak current
Applications:
Automotive Lighting, General Illumination, MR16 replacement, Industrial Lighting, Gaming, High-end LCD Backlighting

23. Hysteretic Control (LM3401)
4/14/2017
Fast load Transient / no compensation required
Fsw changes with VIN and VOUT
ILED Ripple constant 23

24. Ref design: LM3401 - 20 Cent-Sized PCB
Runs from 6V to 35V
Drives one white LED in at 800 mA
High-side PFET topology can do 100% duty cycle

25. LM3402/4/6 and LM3402HV/4HV/6HV 0.5A/1.0A/1.5A HB LED Driver
Key Features: COT
VIN Range:
LM340X: 6V – 42V, Buck
LM340XHV: 6V – 75V, Buck
True average current control
Two PWM LED dimming options:
Fast logic pin PWM dimming
LM3406: 2-wire dimming by VIN pin-70%
Feedback Voltage = 200mV
Internal NFET for reduced parts count
Switching Frequency up to 1MHz
Exposed pad eTSSOP-14 package
Drives 1W, 3W, and higher powered LEDs
Fast PWM Dim
2-Wire Dim
LM COT: in CCM, fsw costant enough with the Vin - ton inv. Proportionally to Vin - 1W
LM COT: in CCM, fsw costant enough with the Vin - ton inv. Proportionally to Vin W
LM COT: in CCM, fsw costant enough with the Vin - ton inv. Proportionally to Vin -5W
Adding an external input diode and using the internal VINS comparator allows the LM3406/06HV to sense and respond
to dimming that is done by PWM of the input voltage.
If the VINS pin voltage falls 70% below the VIN pin voltage, the LM3406/06HV disables the internal power FET and shuts off the current to the LED array. The support circuitry (driver, bandgap, VCC) remains active in order to minimize the time needed to the turn the LED back on when the VINS pin voltage rises and exceeds 70% of VIN. This minimizes the response time needed to turn the LeD array back on.
he LM3402, 04 and 06 all feature internal power MOSFETs, giving them the advantage of reduced component count, smaller solution footprint, and built in safety features such as current limit and thermal shutdown. Because power LED currents have coalesced around several discrete points, each member of the LM340x family specifies a minimum current limit over the full temperature range that takes into account both the average current and gives headroom for a wide LED ripple current. These minimum current limit thresholds have been set to allow the ripple currents to be 30% or more peak to peak. All the members of the LM340x family operate over National´s industrial temperature range of minus 40 to plus 125 degrees celsius, which means that the lighting designer can count on getting the full drive current plus ripple even in harsh thermal conditions.
This is a constant on time ARCHITECTURE ,which means that Ton TIME IS FIXED BY rON, ton time is inversly prportional to vin and vout.
Comp pin make the systeme stable for high dimming. High transient
Applications:
Automotive Lighting, General Illumination, Industrial Lighting, Arcitectual

26. Fsw is constant with VIN
COT Control (LM3402/4/6)
4/14/2017
Fast load Transient / no compensation required
Ton is inversely proportional to VIN
Fsw is constant with VIN
ILED Ripple is variable
TON 26

27. COT Control Revised: LM3406
4/14/2017
The LM3406 has the switching frequency constant not only with respect to the input voltage but also to the output voltage
Instead of having a fixed reference, this timer references VOUT so that frequency is truly fixed. 27

28. LM3405A 1A LED Driver Key Features SOT23-6 eMSOP-8
VIN Range from 3V to 22V
Low 205mV Feedback Voltage
Self-Adjusting Output to deliver Constant 1A Current
PWM Dim Pin
Low Side Current Sense With External Resistor
Low 30nA Shutdown Current
Internal NFET for reduced parts count
1.6 MHz Switching Frequency
Tiny 6 Lead TSOT package
Current Mode Control with internal compensation
SOT23-6
Existing SOT-23 pkg (LM3405AXMK) can drive ~ 600mA for an MR16 application
eMSOP8 version of the LM3405A can drive ~ 1A in an MR16 application
eMSOP-8

29. LM3414/14HV Low Side Converter for High Power LED Drives
4/14/2017
Support LED power up to 60W*: 18x 3W HBLEDs
Patented True Average Current Control Provides ±3% Accuracy to Average LED Current
Requires NO external current sensing resistor
Up to 96% efficiency ,1 active component
High contrast ratio
(Minimum dimming current pulse width <10 µS)
Adjustable Constant LED current from 350mA to 1000mA
±3% LED current accuracy
Support PWM /analog dimming and thermal fold-back
Wide input voltage range:
4.5V to 42V (LM3414)
4.5V to 65V (LM3414HV)
Constant Switching Frequency
adjustable from 250 kHz to 1000 kHz
Thermal shutdown protection
ePSOP-8 or LLP-8 package
Internal mosfet
The mosfet is a N MOSF,we do not need a Boost cap.
No Rseens resitor.
Few external componentrs

30. TPS92550 (LML416504) LED Driver Module
Wide Input Voltage Range : 4.5V - 65V
Can drive up to 18 LEDs in series with 65V input
LED current accurately trimmed to +/-3%
450mA LED current + fine tuning by external resistor (= analog dimming!)
Integrated shielded inductor and power components
Efficiency up to 95%
Input Under-Voltage Lock-Out (UVLO)
Stable with ceramic and low ESR capacitors
Low radiated and conducted emissions
LED open and short circuit protection
Thermal Shutdown
Only 3 external passive components needed
Simple PCB layout and high Power Density
RoHS Compliant
Actual LML Module

31. An Evolution of Simple 350mA LED Buck Driver Solution (TO-MOD-7 Module)
10.16mm
8.64mm
14.35mm
LED+
IADJ
GND
LED-
DIM
4th Gen LED Buck DC-DC Driver SMT Module+1Cs
3rd Gen LED Buck DC-DC Driver (Higher Integration) IC+L+D+2Rs+2Cs
National 3.0 Conference
[insert presenter’s name(s)]

32. Retrofit MR16

33. LED MR16 Replacement Solutions
AC Transformer for MR16 Reference Designs
LED MR16 Replacement Solutions
Issue:
Resistive load = PF
Doesn’t switch off at 0v input
Small form factor
mr16 HALOGENE are driven by two kind of transformer.electronic and 50hz transformer
To make an LED bulb working with 50 hz is easy bridge cap and driver , to make it run with ELECTRONIC TRANSFORMER is more complexe that why you will find in the market MR16 WORKING ONLY WITH 50HZ transformer and some with 50 hz and not all electronic transformer.
If you go to shop and buY led MR16 you should know what you have in your selling.
A good MR16 design has the following criteria:
Cost effective
Fits into a standard MR16 enclosure
No electrolytic
Operates well (no flicker) with most of the common electronic transformers (non-dimming)
Good efficiency (system > 80%)
Mitigation of high input current spikes to reduce failure of electronic transformer or MR16 diode bridge

34. Automotive Lighting, General Illumination, Industrial Lighting
LM A HB LED Driver
Key Features: floating buck
VIN Range: 4.5V to 30V
Less than ±10% load current variation
Adjustable switching frequency from 150 kHz to 1 MHz
Internal low side NFET for reduced parts count
Feedback Voltage = 200mV
Fast PWM dimming enabled
Exposed pad eMSOP-8 package
Drives 1W LEDs
One of our solution for low current.
Standard LED Driver with pulse width modulation
No loop compensation
Internal mosfet
Fs:FHZ
ISNS: I SENSE PIN
ANODE OF LED TO PLUS VIN
Applications:
Automotive Lighting, General Illumination, Industrial Lighting

35. Architecture of the LM3407

36. LM MR-16 Retrofit
Runs from low voltage: 11VAC to 20VAC or 14V to 30VDC
Magnetic transformers only
Nominal 12VAC or 24VDC inputs
Drive three white LEDs in series at 350 mA ±10%
1 MHz switching frequency for minimum inductor size
Low-side buck topology uses small, efficient N-MOSFET
Complete solution including a diode bridge and holdup capacitor fits in standard MR-16 bulb housing

37. Halogen MR16 vs. SSL MR16 waveforms
Issue #1 - The two scope captures above illustrate the SSL MR16 technical challenges. Figure one shows typical Halogen MR16 waveforms, and figure two is common MR16 replacement bulbs waveforms. The SSL replacement bulb looks capacitive to the ELVT; therefore large current spikes charge the energy storage device within the SSL MR16 bulb. The switching converter within the bulb then processes the input power from the energy storage element to the LED load. At this time the minimum load requirement of the ELVT is not satisfied, and the ELVT turns off. Once the energy is depleted within the MR16 converter, the ELVT will start up, and the process cycles. The turning off/on of the ELVT will manifest itself as visible flicker.
Issue #2 – The maximum input current to the Halogen bulb is approximately 4.25A. The maximum input current to the SSL bulb is approximately 12A. The large magnitude spike associated with charging the SSL MR16 input capacitor can cause premature failures within the SSL bulb, or even the ELVT.

38. First schematic draft for MR 16
4/14/2017

39. Final schematic of the MR16
4/14/2017
Final schematic of the MR16

40. Plots of the LM3409 BUCK BOOST
4/14/2017
CH4: Inductor current
CH2: Rectified input voltage
CH3: Input current
CH3: LED current   

41. MR16 in design with electronic transformer
4/14/2017

42. LM3401 MR16 Reference Design Vin: 12VAC Vout: 6.2V (2 series LEDs)
4/14/2017
LM3401 MR16 Reference Design
Vin: 12VAC
Vout: 6.2V (2 series LEDs)
Iout: 1A
Pout: 6.2W
Efficiency: 81%
PF: 0.85
Dimmable with electronic low voltage dimmers/electronic transformers
LED Agnostic
Demo board, reference design, CAD design files available online (RD-188)

43. LM3401 MR16 Reference Design

44. TPS40211 Sepic Reference Design

45. LM3444 Boost Reference Design

46. LM3444 BUCK BOOST Reference Design

47. Controller/ Regulator/ Ref design

48. Why Not More Internal FET Boosts?
Boost and Buck-boost
The buck is the only switching converter where average output current (LED current) is equal to average inductor current. In every other converter the average inductor current is different from LED current. Any time the circuit is boosting, be it the boost topology or one of the buck-boost topologies, the inductor current will be higher than the output current. How much higher depends upon the topology and upon both input and output voltage. Internal FET regulators are very limiting because their current limits are almost always fixed. Even within the very few internal FET boosts or buck-boosts that have adjustable current limits, power dissipation and self heating limit the true maximum current. To make matters worse, current limits detect peak current, not average current. This means that output current, input and output voltage, and also inductance must all be taken into account when designing a circuit.
Exemple 10v out 1a out
Vin 5v 2A average on the coil.
SEPIC and Flyback

49. LM3410 Boost and SEPIC LED Driver
Key Features
Input voltage range of 2.75 to 5.5V
Output voltage range of 3 to 24V
Switch current up to 2.1A guaranteed over temperature
Low, 190mV feedback voltage
Option of 520 or 1600 kHz switching frequency
PWM Dim pin
160mΩ switch resistance
Current Mode control with internal compensation
Applications:
Portable Illumination/Flashlight, Personal Navigation Device, Portable Measurement Equipment, Automotive Control/Entertainment Console, Portable DVD Player
LLP-6
eMSOP-8
SOT23-5

50. TPS61500 3A, Boost High Brightness LED Driver
Features
Benefits
Operating Voltage Ranges:
VIN: V
VOUT: VIN to 38V
Suitable for Use in Battery,12V, or 15V Systems
3A Peak Switch Current
Can be Used to Drive High Current LEDs
Adjustable Switching Frequency: 200k-2.2MHz with up to 93% Efficiency
Allows Designed to be Optimized for Efficiency or Size
Dimming: PWM or PWM-to-Analog
Use PWM for No LED Color Shift. Use Analog to Eliminate Audible Noise from Pulsed Currents.
UVLO, Over-Voltage, Current Limit and Thermal Shutdown
Protects Against Abnormal and Fault Conditions
Applications
LED General Illumination
LED Flashlights
LED Backlighting
TPS61500EVM-369
TOOLS

51. TPS40211 4.5V to 52V Current Mode N-Ch Controller
Features
Benefits
Supports Boost, Flyback and SEPIC Topologies
Suitable for a Wide Variety of LED Lighting Applications
4.5 to 52V Input Voltage Range
Can Drive Up To 14 Series HB LEDs
Programmable Switching Frequency (35kHz to 1MHz)
Flexible Filter Design
Frequency Synchronization (with External Components)
Can Operate with an External Clock
260mV Internal Voltage Reference
Reduces Power Dissipation in Sense Resistor
Integrated Low-Side Driver
Reduces Component Count
Programmable Over-Current Limit and Internal UVLO
Protects Against Fault and Abnormal Operating Conditions
Applications
High Current LED Drivers (Street Lighting, High Bay)
LED Based MR-16 Light Bulb Replacement
LED Backlighting
TPS40211EVM-352
TOOLS

52. LM3429: Low Side N-MOSFET Controller for Constant Current LED Drivers
High side current sense.
A “low side” controller is a switching power regulator that uses an external power MOSFET whose source is connected to system ground. The LM3421, 3423 and 3429 are a family of low side N-MOSFET controllers designed specifically to drive LEDs with a constant current. While the boost regulator is the most common circuit built with low side controllers, they are also capable of SEPIC converters and transformer-based flyback converters.
Like the LM3409 buck controller, the LM342X family feature integrated, differential, high-side current sensing. In addition to simplifying the system wiring, this differential current sense allows them to be used in two more topologies. These are the Vin-referenced buck and the Vin-referenced buck-boost. As the names imply, these are converter topologies that perform step-down and step up-and-down functions, respectively. The difference is that the output current flows back to the input voltage as opposed to ground. In the case of a current source driving LEDs, a load that connects between output voltage and input voltage is perfectly OK in many applications.

53. LM342x Controls the Floating Buck-Boost
VO controlled with respect to VIN
Adjustable, precision threshold protection for LEDs that fail open-circuit
Linear IF control
The circuit shown in this slide is possible thanks to differential current sensing. Other names for this topology are “floating buck-boost”, “negative buck-boost” and “Vin referenced flyback”. Current flows from the input, through the inductor and through the external power FET while the FET is on. When the FET turns off, the current commutates through the Schottky diode, through the LEDs, and back to the input. At first glance it appears that this circuit should have a continuous input current, since the inductor is connected to Vin. This is not the case, however. Like the classic buck-boost and the flyback, this circuit has a discontinuous input current and a discontinuous output current. One principal advantage of this topology is the power efficiency. While not as good as the buck or boost, it is higher than the SEPIC or the flyback.
The voltage designated “Vo” on this slide is equal to the input voltage plus the voltage across the LED string, so the user must be aware that the 75V limit for the IS, HSP and HSN pins is reached more easily. This can be alleviated by moving the current sense resistor to between Vin and the cathode of the last LED in the chain, and by using an external peak current sense resistor between ground and the source of the power FET Q1.

54. LM3423: Adds Fault Flag, Powergood Flag, and Input Disconnect
FLT pin is for error signaling or for input disconnect via PFET
TIMR sets the delay between when LED current is out of spec and when FLT flag goes logic HIGH
DPOL selects the polarity of the nDIM pin when PWM dimming
LRDY is a powergood pin for signaling a system microprocessor

55. LM3429: Features VIN range: 4.5V to 75V: runs from 12V, 24V, 48V rails
Adjustable current sense voltage: 50 mV to 1.24V
Allows linear (analog) dimming without changing the current sense resistor
User can make tradeoff between average current accuracy and power dissipation in RSNS
High-side current sense: LED current returns through system GND
Input for PWM (digital) dimming
Precision output over-voltage protection
Disables the regulator if an LED fails open circuit or the LED array is disconnected
Input under-voltage lockout
Switching frequency as high as 2 MHz
Thermally enhanced TSSOP-14 EP package
Runs at high frequency and drives N-FETs with large gate charge
A “low side” controller is a switching power regulator that uses an external power MOSFET whose source is connected to system ground. The LM3421, 3423 and 3429 are a family of low side N-MOSFET controllers designed specifically to drive LEDs with a constant current. While the boost regulator is the most common circuit built with low side controllers, they are also capable of SEPIC converters and transformer-based flyback converters.
Like the LM3409 buck controller, the LM342X family feature integrated, differential, high-side current sensing. In addition to simplifying the system wiring, this differential current sense allows them to be used in two more topologies. These are the Vin-referenced buck and the Vin-referenced buck-boost. As the names imply, these are converter topologies that perform step-down and step up-and-down functions, respectively. The difference is that the output current flows back to the input voltage as opposed to ground. In the case of a current source driving LEDs, a load that connects between output voltage and input voltage is perfectly OK in many applications.

56. Ref design: LM3429 PAR-38 Spotlight
DC Input Voltage 12V to 30V
SEPIC circuit bucks or boosts as needed
ILED up to 1.5A
6 White and one yellow LED for CCT adjustment
All LEDs in series
Yellow LED has separate shunt NFET dimming
250Hz PWM dimming
LM26675 supplies 5V for Nuventix SynJet active cooling
1500 lumens at 50 lm/W
This is a tunable white with high CRI .(Excelent colour rending.)

57. PAR-38 Spot Light – Block Diagram
4/14/2017 57 57

58. Ref Design:LM3429 MR-16 retrofit with active cooling
DC Input Voltage 9V to 36V
Buck-boost circuit runs from 12VDC or 24VDC rails
ILED up to 1A
Powers 1 to 12 LEDs in series
Accepts standard 0-10V linear dimming signals and adjusts LED current down to zero
LM2842 supplies 5V for Nuventix SynJet active cooling
Dimmable using buck boost topology

59. LM3429 MR-16 Buck-boost Schematic

60. - Automotive Backlight
LM Channel Constant Current LED Driver with Integrated Boost Controller
Product Overview:
The LM3492 is a 2-channel linear current controller combined with a boost switching controller ideal for driving LED backlight panels.
Key Features:
VIN Range: 4.5V to 65V
Drive two individual PWM dimmable LED strings up to 65V total 15W (around 230mA)
2 individually dimmable output channel
No Loop compensation required
> 15000:1 contrast ratio for 200Hz dimming frequency
Near constant adjustable switching frequency up to 1 MHz
LED driver Over-Power protection for short to supply scenario
Dynamic Headroom Control
Precision Enable pin
Versatile COMM I/O pin for FAULT reporting (LED rail Power- Good, Short-FAULT, Open-FAULT and Over-Temperature Alert) and Digital Tune for switching frequency
Individual LED string voltage diagnosis mode
eTSSOP-28 package
Applications:
- Automotive Backlight
- 6.5”-10” LCD display backlight applications up to 36 LEDs which requires ultra-high contrast ratio

61. LM3433 HB LED Driver LM3434 Common Anode Capable
real High Brightness LED drivers

62. LM3433 Common Anode Capable HB LED Driver
Key Features:COT
Operating Input voltage Range: -9V to -14V w.r.t. LED Anode
Control inputs are referenced to the LED anode
Output current > 6A
Greater than 30 kHz PWM Dimming frequency
No output capacitor required
Programmable up to 1 MHz switching frequency
Low IQ, 1 mA typical
Soft start
“Intelligent” constant ON time allows for constant ripple current
LLP-24 package
Output configuration allows the anode of the LED to be tied directly to the ground reference chassis for maximum heat sink efficiency
Applications:
LCD Backlighting, Projection Systems, Solid State Lighting, Automotive Lighting

63. Synchronous Buck HB LED Driver with Common Anode Capability
Negative Buck Approach
offers Negative output voltage capability
allows common anode LED modules
LED mounted directly to chassis for Maximum heat sink efficiency!!
Directly mounted on
projector chassis
Here shows the application circuits of LM3433 Buck LED driver, which is designed for driving common anode LED modules in projector application.
If you compared the conventional Buck LED driver shown in previous slides p.9, there are two main differences of LM3433 from conventional Buck LED driver.
First, the LM3433 application circuits, as shown in here, configures as negative buck approach. This offers Negative output voltage capability which allows common anode LED modules to be tied directly to chassis without any insulation layer for maximizing heat sink efficacy!!
As you can see in this block diagram, the reference ground of LED driver is at the same electrical potential as the LED anode. Therefore, this point can be connected to the chassis (earth) without any safety issue.

64. LED Offline products
Retrofit E27
T8 tube non retrofit
High power bay (multi string)