Medium and High Power LED Drivers

Medium and High Power Drivers

1

Medium/High Power LED Lighting
• Broad power range (20 – 400 W)
• Replace HID or Fluorescent
• Power architecture based on:
– End product and application needs
– Many LED configurations
– 1-3 power conversion stages

Large Array LEDs, 2 Independent Drivers
2 • Template • Nov-12

Modular Strips of LEDs
Confidential Proprietary

Trends in High Power Lighting
• Decision to use LEDs is based on total cost of operation
– Upfront Purchase Cost
– Maintenance Cost
– Energy Cost

• Controls that allow dimming, reduce energy cost and improve
payback time
• Drivers + Sensors + Communication = “Intelligent Control”
–
–
–
–

Occupancy and activity sensors
Ambient Light Sensors
Constant Light output
Autonomous (µC/Sensor) or Networked (wired/wireless)



Example: Intelligent Bi-level Lighting
• LEDs are easy to dim in
discrete levels of light tied to
motion or activity
• Typical dimming step can be
at 20-30% which give
significant energy savings
• Many different uses
–
–
–
–
–
–

Outdoor Parks
Petrol station canopies
Parking structures
Stairways
Refrigerator case lighting
Security Lights



High Lumen Lighting Considerations
Dimming
Control

PWM
LED
Module
w/ CCR

Power Supply

AC

PFC

Isolated
DC-DC

DC
Output
(48-60V)

3 Loss producing stages
PFC + DC/DC + LED Driver
Overall Efficiency may be 85-88%

PWM
LED
Lamp
w/CCR

PWM

Courtesy:

LED
Lamp
w/CCR

•

For large area lighting, many LEDs are
required (40-100+ 1W LEDs) to get lumen
output

•

New high power LEDs are simplifying drivers
by only needed to drive single string
CREE XP-G2 Series
450 lumens @ 1.5 A (Vf = 3.1V)



ON has a Broad Range of Power Solutions
• Power Factor Correction Controllers

• Flyback Controllers and Switchers
– Quasi-resonant
– Fixed Frequency

• Buck Controllers and Switchers
• Half Bridge Drivers and Resonant LLC Controllers

• Secondary Side Controllers (Linear and Sync Rectification)
• Application Specific Products Combos


Wide Range of Topologies Used
Isolated Flyback

Constant Current
Fixed Voltage*

Single Stage PFC
Non-isolated Buck-boost,
Buck or Boost

Constant Current

Isolated Flyback or LLC

Constant Current
Fixed Voltage*

Non-isolated buck

Constant Current

PFC (CrM/CCFF/CCM)

Multi-Stage

* Fixed voltage drivers typically have 24-55 V output and need DC-DC Buck
LED Driver like NCL30160/1, NCL30105, or CAT4201


Hi-PF Drivers – Single versus Two Stage
Flyback
or
LLC
or
Buck

• Advantages

• Advantages

– Direct current drive
– Single switch and magnetic

– Primary energy storage
means low output ripple
– Easy to scale in power/size
– Easy to provide secondary
bias power

• Disadvantages
– 100 / 120 Hz ripple
– Higher MOSFET Stress
– Wider Duty Cycle

• Disadvantages
– Two magnetics, at least 2
power switches

– Limited to ~ 100-150 W


25 W Hi-PF Single Stage Design
•NCL30000 Constant On Time CrM
Flyback Control
– 90 – 305 Vac Input
– Efficiency > 87%
– Input current THD: <15%/PF > 0.97
– LED power: 25 W (Vf = 36 Vdc)
– LED current: 700 mA +/- 4%
– Maximum LED voltage: 44 Vdc

230 Vac 50 Hz:
447 mA pk-pk
2 470 uF Caps

DN05031 Design Note


NCL30001 100 W Single Stage LED Driver
HV
Startup
Multiplier
Input

Adjustable
Constant
Frequency

Demo Board

• Constant Current Output up to 3 A
• > 2:1 VF range from 90-265 Vac
• CCM Avg Current Control Flyback

• EMI Frequency Jittering

AND8427 App Note


NCL300001 Efficiency Versus Pout
Iout = 1A
90%

Efficiency (%)

88%

86%

84%

120 Vac
230 Vac

82%

80%
20

25

30

35
Pout (W)



40

45

50

PFC Solutions for 2 Stage Architectures
Power Factor Controllers

Fixed Frequency

Variable Frequency

Discontinuous
Mode

CCFF

NCP1605

NCP1611
NCP1612
NCP1615

PFC Handbook

Interleaved
PFC

CrM

Continuous
Mode

Single Stage
PFC

NCP1631

MC33262
NCP1607
NCP1608

NCP1653/4

NCP1652A
NCL30001

“Patent Pending” Current Controlled Frequency Foldback (CCFF) control improves efficiency
across line /load. Ideal for Dimmable LED Drivers



How the NCP1611/12 CCFF Approach Works
With classic CrM / BCM control
– As the load is reduced, the switching
frequency increases
– At light loads the controller may enter
“burst mode” resulting in noise

With CCFF control:
– As the load is reduced, the switching
frequency decreases reducing losses
– At light loads the controller’s lower
frequency can be clamped above
audible frequency band
– Skip mode operation at very light load
(can be disabled for better THD)
Operating in “Skip”


Valley turn on further improves efficiency
and reduces EMI


NCP1611 Typical Application Schematic
Brownout

Frequency Foldback/Skip Control

Output Feedback Sense

 Skip can be easily disabled

Two Versions:

ZCD and Current sense (CS) are multiplexed
onto one pin with low cost 1N4148 diode

Loop
Compensation

A - Startup at 10.5 Vdc (typ) with soft start for auxiliary biased applications
B - Higher startup of 17 Vdc (typ) with normal startup for self-biased applications allowing smaller Vcc capacitor


Frequency Fold-back Operation
•

Current flow from FFcontrol is proportional
to the input line current

•

The voltage on FFcontrol pin determines
the operating condition
–
–
–

VFF > 2.50 V
VFF < 0.65 V
Otherwise

…. CrM
…. Skip mode
…. Frequency fold-foldback

•

RFF selection determines the point where
frequency foldback is initiated

•

Normally, a small capacitor is placed in
parallel with RFF to filter noise on the pin
but not distort the waveform

•

See 5 Step Design Application Note for
details
–
–

NCP1611EVB – Full load, 115 Vac Input


AND9062 – NCP1611
AND9065 – NCP1612

NCP1611/2 CCFF Comparison
• Improved efficiency in light load over traditional CrM PFC as switching
frequency is reduced at light load
• Significant efficiency gain for wide mains starting at ~ 50% load
• Improved reliability and safety without extra components
Efficiency vs Load@ 230Vac

Efficiency vs Load @ 115Vac
99

98

98

97

97

96

96

95

95

94

94

Efficiency (%)

100

99

Efficiency (%)

100

93
92
91

93
92
91
90

90
CCFF with Skip

88

CCFF with Skip

89

CCFF with Skip Off

89

88

CCFF with Skip Off
CRM

CRM

87

87

86

86

Vin= 230 Vac, Pout(max) = 160 W

Vin= 115 Vac, Pout(max) = 160 W

85

85
0

10

20

30

40

50

60

70

80

90

100

0

10

20

30

40

50

60

70

Relative Output Power (%)

Relative Output Power (%)

By forcing VFF, efficiency gain can be easily evaluated


80

90

100

Optimizing the FFcontrol Filter for Best THD
VFF > 2.50 V …. CrM
VFF < 0.65 V …. Skip mode
Otherwise …. Frequency fold-foldback



Harmonic Content at Light Load
JIS/EN61000-3-2 Class C > 25 W Pout Limits
With skip inhibited, even at <20% of full load
harmonics and THD are excellent
230 Vac Nominal
100 Vac Nominal

Note: For 230 Vac, a 8.2 MΩ between from VCC to FFcontrol
ensures that the NCP1611 does not enter skip mode



US Line Voltage Performance
THD < 20% across wide load range

115 Vac Nominal, Full Load

115 Vac Nominal, 20% of Full Load

277 Vac Nominal, Full Load

277 Vac Nominal, 16% of Full Load



Other Key Features of NCP1611/12
• Performance
–
–
–
–
–
–

Dynamic Response Enhancer for fast line/load transient response
Wide Vcc Range to 35 V with Gate Voltage Clamp
20 µA typical startup, 50 µA maximum
Vcc startup at 10.5V (A version) or 17 V (B Version)
Line Range Detection to adjust optimize loop gain
NCP1612 has PFC Okay and Independent bulk monitoring

• Safety
–
–
–
–

Over-current protection for saturated inductor or shorted bypass diode
Output over-voltage (soft and fast) and under-voltage protection
Input line brownout protection
Open feedback disable and open ground fault monitoring



NCP1611/2 Collateral
• The following items are available to allow easy evaluation
and simplify the design process:
– NCP1612GEVB – 160 W Demo Board:
• Schematic and BOM
• Gerber Files
• Evaluation Board Manual

– Safety Evaluation App Note
– Step-by-Step Design Guide
– NCP1612 Excel® based Design Tool

< 13 mm height



HV DC/DC Second Stage
Resonant Half Bridge

Flyback

• Single switch architecture, good • Soft switching needed for highest
efficiency and lowest EMI generation
efficiency, typically < 100 W

• ON is a leader in fixed frequency
and quasi-resonant control
–
–
–
–

HV Startup
QR Valley locking
Robust fault protection
Wide range of product offering down
to 6 pin controllers



AC-DC Quasi-Resonant Flyback Controller Evolution
2nd Generation
Advance Protection
Features

Features and Efficiency

1st Generation High
Voltage Controllers
Industry first QR AC-DC
controllers with Direct
Connection to High Voltage
Line

4th Generation
Improved No Load
Power Consumption

3rd Generation Major
Leap in Light Load
Efficiency

-Brown Out Protection
-Overpower Compensation

-Frequency Foldback
-NCP1380 Introduces Valley
Lockout

- Active X2 Discharge
- Power Savings Mode

NCP1339
<10 mW No Load

NCP1336
- HV Startup

NCP1385
- No HV

NCP1380
NCP1351 (VF)
NCP1381

NCP1337
NCP1308

-DSS

NCP1338

- OVP on
Vcc

NCP1207

- Better for
Aux SMPS

-Dual OCP for peak
power

-PFC Go To
Standby
-Fault Timer
-Voltage Ref

NCP1379

NCP1937
(Combo)

- UVLO

CrM PFC + QR

NCP1382
-Latch
Threshold

NCP1377
- No DSS
NCP1378
- Lower
UVLO

|

2004

|


2005

|

2006

|

2007

| 2008 | 2009 | 2010 | 2011 |


2012

|

2013

Isolated High Voltage Driver Topology
500 mA

+

• Single string, no current mis-match
• 100 watts example
– 20 LED = 60V (30 W)
– 60 LED = 180V (90 W)

Driver
90-305 Vac
Input

PFC+Flyback

_


• Constant Current Output
• Higher voltage, lower current can
improve efficiency

– DC-DC Stage Eliminated (+)
– Requires UL Class 1 in US >60 V
– Increased fixture safety design

HV DC/DC Second Stage

Flyback

• Single switch architecture, good • Soft switching needed for highest
efficiency and lowest EMI generation
efficiency

• ON is a leader in fixed frequency
and quasi-resonant control
–
–
–
–

HV Startup
QR Valley locking
Robust fault protection
Wide range of product offering down
to 6 pin controllers



Benefits of an LLC series resonant converter
• Type of serial resonant converter that allows operation in relatively
wide input voltage and output load range when compared to the
other resonant topologies
• Limited number of components: resonant tank elements can be
integrated to a single transformer – only one magnetic component
needed
• Zero Voltage Switching (ZVS) condition for the primary switches
under all normal load conditions
• Zero Current Switching (ZCS) for secondary diodes, no reverse
recovery losses

Cost effective, highly efficient and EMI friendly solution
for high and medium output voltage commonly used in
LED Driver topologies


NCP1398 High Performance
Resonant Controller
Value Proposition
An upgraded version of the NCP1397, the NCP1398 offers the same high performance and protection features. In
addition it also improves the Rt pin robustness, open/short pin protection and Brown out feature.

Unique Features



Built-in drivers
Adjustable & accurate
minimum frequency



Fast and slow fault
detection, Broken FB loop
detection

Benefits

Application Data




Compact design
Keeps the converter in
the right region & ease
the design
 Robust and rugged
power supply & help to
be compliant with safety
standards

Others Features





Latch input, brownout
Adjustable dead-time
Adjustable soft start
Easy no-Load operation and low standby power due
to programmable skip cycle
 Enable capability

Market & Applications





Flat TVs
High power AC adapters
Desktop PCs / Servers
High Power LED Drivers

Ordering & Package Information



NCP1398ADR2G (SOIC-16) = Auto-recovery
NCP1398BDR2G (SOIC-16) = Latch


NCP1398 5th Generation LLC Controller
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•

High-frequency operation from 50 kHz up to 750 kHz
Adjustable minimum switching frequency with 3% accuracy
Adjustable dead-time
Externally adjustable soft-start
Precise and high impedance Brown-out protection
Latched input for severe fault conditions, e.g. over temperature or OVP
Timer-based auto-recovery over-current protection
Latched output short circuit protection
Open feedback loop protection for NCP1398B version
Disable input for ON/OFF control
Skip mode with adjustable hysteresis
Vcc operation up to 20 V
Common collector opto-coupler connection for easier ORing
Internal temperature shutdown
600 V Half-Bridge driver with 1 A / 0.5 A sink / source drive capability



Typical Application Schematic



Resonant Mode Topology is a High Efficiency
Solution for LED Drivers
Classical Approach

NCL30051 Approach

• CrM PFC + LLC

• CrM PFC + Fixed Frequency

– Ex: NCP1607 + NCP1397
– 8 pin + 16 pin SOIC

– Single SOIC16

• Power control is based on
changing LLC frequency

• Power control is based on
changing PFC bulk

– Lower frequency = more power

– Higher bulk = more power

• Very flexible to support wide
range of Vin and Vout

• Limitation is dynamic range of
bulk voltage

• Regulates out 100/120 Hz
ripple

• Great to simplify Fixed Voltage
LED Driver Designs



NCL30051 – Resonant Controller with
integrated Fixed On-Time CRM PFC
Value Proposition
NCL30051 is a combination of a PFC and half bridge resonant controller which has all functionality to implement a
high efficiency driver in a small low form factor. Regulation is achieved by varying PFC bulk voltage

Unique Features

Benefits

Block Diagram

 Half bridge driver with 600  No need for external level
shifter or transformer
V high side gate drive
 Resonant controller with  Increases efficiency at
light load. Reduces EMI
fixed frequency and soft-skip
 PFC with constant on-time  Excellent PF at mains with
low ripple
controller & error amp

Others Features





Disable Input to half bridge
50 ns max rise and fall time on the high and low side gate
drive
500 ns min fixed crossover dead time between drives
No electrolytic outputs needed for output filtering

Market & Applications



Ordering & Package Information

LED Drivers and Supplies
Applications include Wall packs, street lights, outdoor
area lights, low and high bay lighting



NCL30051DR2G: SOIC-16


Pb

Simplified Application Schematic
PFC Stage

C


A
High Voltage Startup
simplifies biasing

B

Simple fixed frequency resonant
half bridge step down operation:
• As output voltage varies at A
•Feedback signal is generated at B
• PFC voltage at point C changes to regulate output


Half Bridge can be disabled
for PWM dimming

NCL30051LEDGEVB Available
95

• Pout Maximum
• Power Factor
• CC Iout Range

90 – 265 Vac

94

>90% Efficient
35 - 45 W (Iout = 1A)

93

60 W (board limited to 120 W) but the NCL30051
is capable of power up to 250 W
PF > 0.9 (50-100% of load with dimming) and
IEC61000-3-2 class C compliance

92

Efficiency (%)

• Universal Input

91

90

89

0.7 - 1.5 A (3 A with component changes)

120 Vac

88

230 Vac

• Vout Range

35 - 50 V

87

86

• Protection Features
• Output Open and Short Circuit Protection
• Over Temperature
• Over Current Protection - auto recovery
• Over Voltage Protection – input (OVP bulk voltage)

85
34

38

42

46

LED Forward Voltage (Vdc)

• Dimming
• Two-step bi-level analog
• PWM dimming
Dimming range > 20:1
• 1-10 V analog voltage input

PWM or
Analog Dimming
Interface


50

Example: Advanced Lighting Application

NCP1607

NCL30105
Buck LED Driver

IR
Control

(2x) …Two
strings to
implement
white LED
color control

MCU for
Dimming and
Control


Whole
Room Light
40-80 W
80 lm/W


Summary
• LED Lighting is evolving requiring new solutions that can
support the latest generations of LEDs on the market

• Topology choices are evolving to improve efficiency and
reduce overall system cost
• Intelligent control can enhance energy saving and extend
operation lifetime even if more complex drivers are needed to
support

• We have only begun to harness what is possible with Solid
State General Lighting


Appendix



CCFF PFC Feature Comparison to NCP1608
Protection and Control Features

NCP1608

NCP1611

NCP1612

o
o

o
o
o
o

o

o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o

Soft Start

A Version

A Version

Reduced component stress at startup

High Vcc Startup Threshold/Low Icc

B Version

B Version

Reduces Vcc capacitor size & startup time

o
o

o
o
o
o

Fast Overvoltage Protection (F-OVP)
Undervoltage Protection
Soft OVP

Bulk Sensing

Dynamic Response Enhancer
Bulk Undervoltage Protection (BUV)
Independent Sensing of FOVP & BUV
Cycle-by-cycle Over Current Protection

Current Sense

o

Shorted Boost or Bypass Diode
Saturated Inductor Detection
Vcc - UVLO
UVLO Gate Driver Pulldown

Monitoring

o
o

Line Range Gain Selection
AC Line Brownout
FB

o

CS/ZCD

Open Pin
Protection

GND

o
o
o
o
o
o
o
o
o
o

FOVP/BUV
Disable

Control

Skip Mode Disable
Thermal Shutdown

o

PFC Okay
Latch Input



Benefit
Protects supply under abnormal operation
Improved transient response when load is reduced
Dramatically improved transient response
Informs downstream controller when Bulk is too low
Enhanced Fault Protection
Fault Protection
System Robustness, Safety Testing
Fault Protection
Ensures proper operation of controller
Ensures FET is off during turn on and turn off
Optimizes control loop for wide mains applications
Improves system robustness to line faults

Simplifies safety testing

Simplifies PFC ON/OFF Sequencing

Eliminates audible noise, improves THD & PF at light load
Enhanced Fault Protection
Sequencing control for downstream converter
Enhanced fault control, easy to implement thermal latchoff

Medium and High Power LED Drivers

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