Bringing light to life
Najmi Kamal
Power Design Engineer for Lighting
March 2012
TI Lighting System Solution
• NSC + TI = strong system level know-how
4
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
Texas Instrument’s Current LED Driver
Solutions
Quick
Selection
guide
6
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
N or P FET
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:
The lower the switching frequency, fSW, the closer
VO-MAX is to VIN
10
PFET Bucks Can Provide 100% Duty Cycle
• High Side P-MOSFETs
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
11
Dimming
Various dimming techniques
• Dimming using PWM signal
– White LEDs change Colour over
Current!
– Solution:
Maintain Current and Change ON-Time =
PWM
13
Two different PWM dimming methods
• First method: Dim 1: Continuous inductor
current (Good EMC, extra Mosfet )
0
1
14
1
D
D
N
G
NMOS
dim2
PWM
2
Q
LED2
3
D
LED1
NMOS
dim1
PWM
Q
LED0
D
Vout
• Second method: Dim 2: more efficient (2khz dim max)
Output capacitor for a Buck topology
Buck (step-down) DCM or CCM
Vo Limited by VIN
L
Io
I L
 IC
CO
VIN
+
-
Cout not needed
+
VF
+
Vo
D
Easy to stabilize, if
needed
R
FB
+
V FB
-
16
Continuous output
current, low EMI
-
Inherent
protections against
failure
LED Drivers
LM3409/09HV: High-Side PFET Buck Controller
– VIN 6V to 42V (LM3409)
RUV2
– VIN 6V to 75V (LM3409HV)
RUV1
– External power PFET
UVLO
• 100% Duty Cycle Capable
CF
• Output Currents up to 4A
LM3409/09HV
EN
• Simplifies system wiring
– Thermally enhanced eMSOP-10
package
– No control-loop compensation
CIN
VCC
IADJ
– Differential, high-side current
sense
– PWM dimming and analog
dimming at 1000:1
VIN
VIN
CSP
RSNS
ROFF
VO
COFF
CSN
COFF
VO
GND
DAP
PGATE
Q1
L1
D1
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IF up to
4A
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
22
Applications:
Automotive Lighting, General Illumination, MR16
replacement, Industrial Lighting, Gaming, High-end
LCD Backlighting
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
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LM3402/4/6 and LM3402HV/4HV/6HV
0.5A/1.0A/1.5A HB LED Driver
Key Features: COT
•
•
•
•
•
•
•
•
CB
VIN
VIN
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 pin70%
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
BOOT
L1
SW
RON
CIN
Fast PWM Dim
D1
RON
IF
LM3406/06HV
VOUT
DIM
CS
RSNS
COMP
VCC
GND
CC
CF
2-Wire Dim
CB
VIN
L1
D1
VIN
BOOT
SW
RON
CIN
D2
RON
IF
LM3406/06HV
VOUT
VINS
CS
RSNS
Applications:
Automotive Lighting, General Illumination, Industrial
Lighting, Arcitectual
25
COMP
CC
GND
VCC
CF
LM3414/14HV Low Side Converter for High
Power LED Drives
•
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
–
Adjustable Constant LED current
from 350mA to 1000mA
–
•
•
Support PWM /analog dimming and
thermal fold-back
Wide input voltage range:
–
–
•
Vin 24VDCnom
4.5V to 42V (LM3414)
4.5V to 65V (LM3414HV)
Iout = 500mA (nom.)
D1
adjustable from 250 kHz to 1000 kHz
Thermal shutdown protection
ePSOP-8 or LLP-8 package
CVCC
X7R
16V 1uF
RIADJ
VCC
VIN
L1 68uH
LX
IADJ
DIM
GND
FS
* DAP connect to GND
5.76k
RFS
40.2k
GND
40V
3A
LM3414
PGND
GND
29
X7R 50V
4.7uF
CIN
Constant Switching Frequency
–
•
•
±3% LED current accuracy
LED x 4
•
(Minimum dimming current pulse width <10 µS)
GND
GND
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 LML416504 Module
30
Retrofit MR16
LED MR16forReplacement
Solutions
AC Transformer
MR16 Reference
Designs
12VACRMS
AC
MAINS
PHASE
DIMMER
MR16
TRANSFORMER
Issue:
•Resistive load = PF
•Doesn’t switch off at 0v input
•Small form factor
MR16
MR16
LM3407 0.35A 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
Applications:
Automotive Lighting, General Illumination, Industrial
Lighting
34
LM3407 - 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
36
Halogen MR16 vs. SSL MR16 waveforms
37
Final schematic of the MR16
39
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)
•
•
http://www.national.com/rd/RDhtml/RD-188.html
42
TPS40211 Sepic Reference Design
44
LM3444 Boost Reference Design
45
LM3444 BUCK BOOST Reference Design
46
Controller/ Regulator/ Ref design
Why Not More Internal FET Boosts?
Inductor Current with
Ripple (ΔiL)
Output Current with
Ripple (ΔiF)
Boost and Buckboost
SEPIC and
Flyback
48
I F  MAX  I LIMIT
 VO  VIN
 1 
VO

I F  MAX  I LIMIT




VO 


 1 
 VIN  VO 
LM3410 Boost and SEPIC
LED Driver
Key Features
– Input voltage range of 2.75 to 5.5V
– Output voltage range of 3 to 24V
L1
– Switch current up to 2.1A
guaranteed over temperature
D1
Vin
– Low, 190mV feedback voltage
DIMM
4
3
DIM
FB
C2
2
– Option of 520 or 1600 kHz
switching frequency
GND
C1
– PWM Dim pin
5
1
Vin
SW
R1
– 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
49
eMSOP-8
SOT23-5
TPS61500
3A, Boost High Brightness LED Driver
Features
Benefits
• Operating Voltage Ranges:
• VIN: 2.9-18V
• VOUT: VIN to 38V
• 3A Peak Switch Current
• Adjustable Switching Frequency: 200k-2.2MHz with
up to 93% Efficiency
• Dimming: PWM or PWM-to-Analog
• Suitable for Use in Battery,12V, or 15V Systems
• 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
• Can be Used to Drive High Current LEDs
• Allows Designed to be Optimized for Efficiency or Size
• Use PWM for No LED Color Shift. Use Analog to
Eliminate Audible Noise from Pulsed Currents.
LM3429: Low Side N-MOSFET Controller for
Constant Current LED Drivers
52
LM342x Controls the Floating Buck-Boost
IF
RSNS
CO
VO controlled
with respect to
VIN
D1
VIN = 4.5V
to 75V
L1
VIN
IS
CIN
VCC
GATE
Q1
PGND
VO
RCT
Linear IF
control
PWM DIM
SIGNAL
NDIM
LM3421
EN
HSP
Adjustable,
precision
threshold
protection for
LEDs that fail
open-circuit
HSN
CSH
DDRV
COMP
OVP
AGND
53
RPD
VO
LM3423: Adds Fault Flag, Powergood Flag, and
Input Disconnect
VIN = 4.5V
to 75V
VO
L1
D1
RT
CO
IS
RCT
CT
GATE
FLT
PGND
VIN
HSP
QSW
RHSP
CIN
RSENSE
DPOL
RUV2
VCC
CTIMR
TIMR
LM3423
CBYP
HSN
RHSN
+
VSENSE
_
+
VLEDS
-
IF
NDIM
QDIM
DDRV
5V
EN
ON/OFF
RCSH
CSH
To system
microcontroller
LRDY
RUV1
COMP
OVP
CCOMP
AGND
VO
RPD
ROV1
54
ROV2
– 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
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
56
PAR-38 Spot Light – Block Diagram
57
57
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
58
LM3429 MR-16 Buck-boost Schematic
LED
Offline products
•Retrofit E27
•T8 tube non retrofit
•High power bay (multi string)