led lighting driver ic introduction
DESCRIPTION
LED Lighting Driver IC IntroductionTRANSCRIPT
LED Lighting Driver IC Introduction
Robin LiaoJanuary 2011
http://www.richtek.com/LED
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Contents
LED Lighting Driver IC Overview
AC input to constant current LED driver -- Isolated
AC input to constant current LED driver -- Non-isolated
DC to CC Solution
Applications
Selection Guide
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LED Lighting Driver IC Overview
4
LED Lighting Driver IC Overview
LED Lighting
AC/CC
DC/CC
Isolated
Non-isolated
With ET
Without ET
E26/E27/E17, T5/T8 Par30/Par38, Street light
GU10, E26/E27/E17 T5/T8, Par30/Par38
MR16, AR111
Street light, car light, desk light, freeze light, projector Emergency light
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AC input to constant current LED driver -- Isolated
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AC Input Solution -- Isolated
• Application• E27, GU10 …. Bulb, Par 30, Par 38
• T5, T8 …. Light bar, Freeze light
• Street light, Desk light…
• Richtek advantage• High-precision constant current control to limit current accuracy in +/-
5% range on mass production.
• Small package and high integrated solution with less external components to fit into a small bulb or light bar
• Very low quiescent current
• Dimming on secondary side to provide better accuracy
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Secondary side CC/CV controller
AC to CC – Isolated – secondary side CC/CV controller & dimming
RT8456
RT8454
RT8457
Single channel CC/CV controller
Single channel CC/CV controller with dimming
Multi-channel CC/CV controller with dimming
Easily work with any kind of primary side topology.
Provide high precision LED current.
LED current accuracy does not vary with the accuracy of transformer.
OVP support
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RT8456 Secondary-side constant Current Controller
Secondary side LED current regulation
Support LED voltage up to 45V
High accuracy LED current threshold control over wide input voltage and temperature range
0.6mA operation current
Programmable LED current through 60mV sense resister
Programmable OVP
Easily connected to different kinds of primary side solutions
TSOT 23-6
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RT8457: Dimmable secondary side constant current controller
LED voltage up to 45V
Support Triac dimming, PWM dimming, analog dimming
High accuracy LED current threshold control over wide input voltage and temperature range
Programmable LED current through 60mV sense resister
Programmable OVP
Easily connected to different kinds of primary side solutions
SOP-8
Dimming Input
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RT8454 AC-CC 6-Ch Current Regulators
Vcc up to 50V
Programmable channel current
3% current sense amplifier input offset
Easy dimming
Programmable soft start and OVP
Automatic detecting unconnected AND/OR broken channel to avoid output over voltage
Vcc under voltage lockout and Thermal shutdown
One LDO controller embedded
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RT8454 AC-CC One-Stage Driving Scheme
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Application Tip: RT8454Channel Number Extension
Vaux
AC
to DC
Prim
ary Side C
ircuit
Opto-Coupler
AC
Pow
er Lines
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Applications: Isolated E26/27, T5/T8, PAR30/38…..
• Primary side solution example1. Flyback: R7912 (MOS inside) R7732(MOS ext.)
Low PF, small output current ripple, good efficiency, good for no-PF requirement condition.
2. Valley-fill PFC+Flyback For small power (<10W), PF at 0.7~0.9 range. Small output current ripple, good for small
power and PF>0.7 application.
3. Active PFC+Flyback High PF (>0.9), lower efficiency, small output current ripple, good for high power design.
4. PFC single stage High PF (>0.9), low cost, need big output cap to reduce current ripple. Good for small power,
low cost design.
5. LLC High efficiency, high cost. Good for high power, high performance design.
6. Primary side constant current : R7710 Current accuracy is suffered from transformer accuracy. Good for current accuracy <+/-10%
application
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Applications: Isolated E26/27, T5/T8, PAR30/38…..
• Secondary side solution• RT8456, RT8457, RT8454 can work with any kind of primary side
topologies and become constant current LED drivers except (6)
• Maintain current accuracy at +/-5% independent of the variation of transformer
Non-dimmable: Primary side + RT8456 Dimmable: (bleeder)+ Primary side + RT8457
• Support Triac dimming with external bleeder added
• Support PWM, analog, wireless… dimming on secondary side with accurate current control.
• Using MCU for Traic dimming can provide the best compatibility of dimmer.
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Valley-fill PFC+R7732+RT8456
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AC input to constant current LED driver -- Non-isolated
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AC-CC non-isolated product roadmap
RT8458
AC to CC – non-isolated
RT8459
High-side buck CC LED driver
High-side PFC buck CC LED driver
RT8460High-side PFC inverting buck-boost CC LED driver
RT8469
RT8468
MOS inside
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RT8458 floating buck LED driver for non-isolated application
The best way to drive LEDs from AC power input!!
Unique self-biasing floating buck driver topologyTrue average LED current senseHigh efficiency (>90% possible)Cheap and simple external componentsVery wide input voltage range (16V~400V or higher)Stable LED current over wide input voltage rangeWorks with standard series drum choke inductorsSupport OVP & OCPSmall PCB to to fit GU10, E17…..
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Three RT8458 applications1. Typical application
Advantage Very good line regulation. LED current variation between 110V/220V AC input is
minor. (<+/-2%) Small input/Output cap Simple external components Good for application do not need PFC.
Disadvantage Low PF (About 0.6)
2. Valley-fill PFC+RT8458 Advantage
PF at 0.7~0.9 for low power application (<10W) Good for small power, PF>0.7 design
Disadvantage Big cap for high power or high PF application.
3. Active PF + RT8458 Advantage
High PF (>0.95) Good for high power, high PF design
Disadvantage Higher cost Lower efficiency
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RT8458 typical application circuit
OVP option
Vout>31V
EMI improvement
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High-efficiency universal input design
Vin.ac (V) Pin(W) V-LED (V) I-LED (A) Pout (W) Eff. (%)
90 10.25 36.20 0.257 9.303 90.76
110 10.22 36.29 0.257 9.327 91.26
130 10.29 36.19 0.257 9.300 90.38
180 10.19 36.02 0.257 9.257 90.85
220 10.21 36.02 0.257 9.257 90.67
260 10.23 36.06 0.257 9.267 90.59
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RT8458 efficiency vs. LEDs
LED current=350mA
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RT8459 High PF, floating buck LED driver for non-isolated application
Unique self-biasing floating buck driver topologyTrue average LED current sense for high PF applicationCheap and simple external componentsVery wide input voltage range (16V~400V or higher)Stable LED current over wide input voltage range with high PF supportWorks with standard series drum choke inductorsSupport OVP & OCPSmall PCB to to fit GU10, E17…..
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RT8459 typical application circuit
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RT8459 test result with universal input
** Good line regulation for universal input with high PF support
** NOTED: Higher output current ripple & big output cap. for PFC single stage design
8459 Vout=44V//200mA/15LEDs
Vin.ac (V) Vo (V) Io (mA) Pin (W) Po (W) PF Eff. (%) current offset (%)
90 43.33 194 9.3 8.41 0.980 90.39 -1.02%
110 43.37 196 9.26 8.50 0.981 91.80 0.00%
130 43.35 195 9.19 8.45 0.985 91.98 -0.51%
180 43.31 191 9.03 8.27 0.972 91.61 -2.55%
220 43.36 194 9.23 8.41 0.955 91.14 -1.02%
264 43.41 196 9.42 8.51 0.932 90.32 0.00%
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How to choose the driving topology?
Need PFC? RT8458 typical applicationNO
Small output current ripple?
RT8459 typical application
Valley-fill PFC+RT8458 good for small power, PF in 0.7~0.9
Active PFC + RT8458, good for high power design or PF>0.9
NO
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DC to CC Solution
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Richtek’s Product -- DC to Constant Current
Converter
Controller RT8480RT8452
RT8450B
RT8482
RT8453B RT8470
RT8488
• Application• MR16, AR111• Street light, Desk light, Freeze light• Car light, Projector lamp• Solar lighting, Emergency light
RT8471
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Richtek’s Product -- DC to Constant Current
• Richtek advantage• Cover wide input/output voltage range and support different
kinds of topology include buck, boost, buck-boost, SEPIC• Accurate output current over wide temperature range• Stable output current vs. input/output voltage change• Easy Dimming : Analog, PWM or PWM Converting to Analog
with One External Capacitor, Triac dimming• Support high-speed PWM dimming up to 50kHz• Better reliability with bipolar process• Cost competitive
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Selection Guide for DC to CC Products
DC Input to Constant Current
Part Number Vin(V) Max Vout(V)LED current per
string (mA)
Max Efficie
ncy(%)
LED String
Topology
RT8450A 4.5~40+Zener drop 50 UP to 1.5A > 95 1Buck,Boost,Buck-
Boost
RT8450B 4.5~40+Zener drop 50 UP to 1.5A > 95 1Buck,Boost,Buck-
Boost
RT8452 4.5~36+Zener drop 48 External MOSFET > 95 1Buck,Boost,Buck-
Boost
RT8453 4.5~40 38 UP to 1.5A > 95 1 Buck
RT8480 4.5~40+Zener dropLimited by
external MOSFET
External MOSFET > 93 1 Boost, SEPIC
RT8482 4.5~36+Zener drop 48 External MOSFET > 95 1Buck,Boost,Buck-
Boost
RT8470 7~30 28 UP to 1A >95 1 Buck
RT8488 7~36+Zener drop Limited by external MOSFET
External MOSFET >92 6 Boost
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Applications
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Applications: MR16
• Major solutions• RT8470 low cost solution
• Lowest cost solution• About 70% Electronic Transformer (ET) compatibility• Different brightness with different ET connected• Very popular in China
• RT8453 high ET compatibility solution• Very high ET compatibility• Keep same brightness with different ET connected
• Special applications• RT8453 dimmable solution
• Dimmable with minor cost added from the previous solution• Same performance as the previous solution without dimmer connected• ET limited• With selected ET, about 50% dimmer can dim pretty well
• RT8453 non electrolytic cap solution• High ET compatibility with square wave output
• RT8453 three-step dimming• Support three-step dimming with three-step dimming controller added• Use ON/OFF break to switch between three steps
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Application: MR16 (RT8470 BUCK---a typical low cost design)
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MR16—RT8470 Buck
CH1: Vin
CH4: Iin
CH1: LED voltage
CH4: LED currentAverage LED current will be different with different ET connected
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Application: RT8453 MR16
Excellent electronic transformer compatibility
High efficiency, stable output LED current
Support Triac dimming with selected ET and Dimmer but no extra cost added
No flicker with most of the ET
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Application: RT8453 MR16
CH1: Vin
CH4: Iin
CH1: LED voltage
CH4: LED currentVery stable LED current with different ET connected
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Applications: Street Light (I)
AC Power
Other Control Signals
MCU
NTC
Sense LED Temp.
Gx6
Vbase
Dim
FBx6Vaux 6 Current
Sources
RT8454
CSx6
….6 CHs
….
PFC +
AC2DCPrimary
SideCircuit
Opto
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Applications : Street Light (II)
PFC AC2DC
Solar Cell
LiFePO3 Batteries
AC Power
Other Control Signals
MCU
NTC
Sense LED
Temp.
Gx6
DC 12V~48V
Gate
Sense
Dim
FBx6
GbiasVaux
6 Current Sources
RT8488
CSx6
….6 CHs
….
(Either one or both)
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Applications : Street Light (III)
PFC AC2DC
Solar Cell
LiFePO3 Batteries
AC Power
Other Control Signals
MCU
NTC
Sense LED Temp.
Thermal Feedback
DC 12V~48V
Gate
Sense
Dim
PWMO
GbiasVaux
Dimming
RT8480
Up to 40xLEDs (160V)
IFB Current FB
(Either one or both)
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Application: Thermal protection
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Selection guide
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LED Lighting Selection Guide Sorted by Application
LED Lighting Selection Guide Sorted by Application
Application Topology Richtek Solution
Solid-State Lighting AC or DC Input
MR16 Buck, Buck-Boost, Boost RT8450B,RT8482,RT8453, RT8470
AR111 Boost RT8450B,RT8482
GU10, E27,PAR30,PAR38 Flyback, non-isolated RT8458, RT8456, RT8457
Office Lamp Boost, Flyback, non-isolated RT8450B,RT8482, RT8456, RT8458
Decoration Light Boost RT8450B,RT8482
Street Light, Solar Light Buck, Boost, flyback RT8450B,RT8482,RT8488,RT8454
Emergency Light Boost RT8450B,RT8482
T5, T8 Light Bar Flyback, non-isolated RT8456, RT8457, RT8458
RGB Light Buck RT8453, RT8470
Freeze Light Buck, Flyback, non-isolated RT8450B,RT8453, RT8456, RT8470, RT8458
Projector Synchronous Buck RT8452
Automotive Application
Interior Light Buck, SEPIC, Buck-Boost RT8450B,RT8482, RT8488, RT8480
Exterior Light Buck, SEPIC, Buck-Boost RT8450B,RT8482, RT8488, RT8480
Automotive Light Buck, SEPIC, Buck-Boost RT8450B,RT8482, RT8488, RT8480
http://www.richtek.com/LED