1. LED Lighting Driver IC Introduction
封面：分為上下標，且在報告人及部分都有詳細分列
Robin Liao
January 2011

2. 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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3. LED Lighting Driver IC Overview

4. LED Lighting Driver IC Overview
Isolated
E26/E27/E17, T5/T8 Par30/Par38, Street light
AC/CC
Non-isolated
GU10, E26/E27/E17 T5/T8, Par30/Par38
LED Lighting
With ET
MR16, AR111
DC/CC
Street light, car light, desk light, freeze light, projector Emergency light
Without ET

5. AC input to constant current LED driver -- Isolated

6. 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

7. Secondary side CC/CV controller
AC to CC – Isolated – secondary side CC/CV controller & dimming
RT8456
Single channel CC/CV controller
RT8457
Single channel CC/CV controller with dimming
RT8454
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

8. 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

9. 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

10. 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

11. RT8454 AC-CC One-Stage Driving Scheme

12. Application Tip: RT8454Channel Number Extension
Vaux
AC to DC Primary Side Circuit
Opto-Coupler
AC Power Lines

13. Applications: Isolated E26/27, T5/T8, PAR30/38…..
Primary side solution example
Flyback: R7912 (MOS inside) R7732(MOS ext.)
Low PF, small output current ripple, good efficiency, good for no-PF requirement condition.
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.
Active PFC+Flyback
High PF (>0.9), lower efficiency, small output current ripple, good for high power design.
PFC single stage
High PF (>0.9), low cost, need big output cap to reduce current ripple. Good for small power, low cost design.
LLC
High efficiency, high cost. Good for high power, high performance design.
Primary side constant current : R7710
Current accuracy is suffered from transformer accuracy. Good for current accuracy <+/-10% application

14. 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.

15. Valley-fill PFC+R7732+RT8456

16. AC input to constant current LED driver -- Non-isolated

17. AC-CC non-isolated product roadmap
AC to CC – non-isolated
RT8458
High-side buck CC LED driver
RT8459
High-side PFC buck CC LED driver
RT8460
High-side PFC inverting buck-boost CC LED driver
MOS inside
RT8469
RT8468

18. RT8458 floating buck LED driver for non-isolated application
Unique self-biasing floating buck driver topology
True average LED current sense
High efficiency (>90% possible)
Cheap and simple external components
Very wide input voltage range (16V~400V or higher)
Stable LED current over wide input voltage range
Works with standard series drum choke inductors
Support OVP & OCP
Small PCB to to fit GU10, E17…..
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The best way to drive LEDs from AC power input!!

19. Three RT8458 applications Typical application Valley-fill PFC+RT8458
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)
Valley-fill PFC+RT8458
PF at 0.7~0.9 for low power application (<10W)
Good for small power, PF>0.7 design
Big cap for high power or high PF application.
Active PF + RT8458
High PF (>0.95)
Good for high power, high PF design
Higher cost
Lower efficiency

20. RT8458 typical application circuit
OVP option
Vout>31V
EMI improvement

21. 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
9.327
91.26
130
10.29
36.19
9.300
90.38
180
10.19
36.02
9.257
90.85
220
10.21
90.67
260
10.23
36.06
9.267
90.59

22. RT8458 efficiency vs. LEDs
LED current=350mA

23. RT8459 High PF, floating buck LED driver for non-isolated application
Unique self-biasing floating buck driver topology
True average LED current sense for high PF application
Cheap and simple external components
Very wide input voltage range (16V~400V or higher)
Stable LED current over wide input voltage range with high PF support
Works with standard series drum choke inductors
Support OVP & OCP
Small PCB to to fit GU10, E17…..

24. RT8459 typical application circuit

25. RT8459 test result with universal input
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
9.23
0.955
91.14
264
43.41
9.42
8.51
0.932
90.32
** Good line regulation for universal input with high PF support
** NOTED: Higher output current ripple & big output cap. for PFC single stage design

26. How to choose the driving topology?
Need PFC? NO
RT8458 typical application
Small output current ripple? NO
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

27. DC to CC Solution

28. Richtek’s Product -- DC to Constant Current
RT8450B
RT8453B
RT8470
RT8471
Converter
RT8452
RT8482
RT8480
RT8488
Controller
Application
MR16, AR111
Street light, Desk light, Freeze light
Car light, Projector lamp
Solar lighting, Emergency light

29. 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

30. 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 Efficiency (%)
LED String
Topology
RT8450A
4.5~40+Zener drop 50
UP to 1.5A
> 95 1
Buck,Boost,Buck-Boost
RT8450B
RT8452
4.5~36+Zener drop 48
External MOSFET
RT8453
4.5~40 38
Buck
RT8480
Limited by external MOSFET
> 93
Boost, SEPIC
RT8482
RT8470
7~30 28
UP to 1A
>95
RT8488
7~36+Zener drop
>92 6
Boost

31. Applications

32. Applications: MR16 Major solutions Special applications
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

33. Application: MR16 (RT8470 BUCK---a typical low cost design)

34. MR16—RT8470 Buck CH1: Vin CH1: LED voltage CH4: Iin CH4: LED current
Average LED current will be different with different ET connected

35. 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

36. Application: RT8453 MR16 CH1: Vin CH1: LED voltage CH4: Iin
CH4: LED current
Very stable LED current with different ET connected

37. Applications: Street Light (I)
AC Power
Other Control Signals
MCU
NTC
Sense LED Temp.
Gx6
Vbase
Dim
FBx6
Vaux
6 Current Sources
RT8454
CSx6 ….
6 CHs
PFC +
AC2DC
Primary
Side
Circuit
Opto

38. 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
Gbias
Vaux
6 Current Sources
RT8488
CSx6 ….
6 CHs
(Either one or both)

39. 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
Gbias
Vaux
Dimming
RT8480
Up to 40xLEDs (160V)
IFB
Current FB
(Either one or both)

40. Application: Thermal protection

41. Selection guide

42. LED Lighting Selection Guide Sorted by 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
Street Light, Solar Light
Buck, Boost, flyback
RT8450B,RT8482,RT8488,RT8454
Emergency Light
T5, T8 Light Bar
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
Automotive Light

43. Ending 頁