Increasing the Performance of PFC and LED Driver Applications

Increasing the Performance of PFC and LED Driver Applications Tad Keeley Sr. Marketing Director Class ID: AC04B Renesas Electronics America Inc.

Tad Keeley : Sr. Marketing Director Renesas Electronics America Senior Marketing Director for Analog and Power 12 years with Renesas in Marketing roles for non-mcu products 7 prior years in Semiconductor Process Engineering BA Physics from Reed College MBA Stanford GSB 2

Renesas Technology & Solution Portfolio 3

Discrete and Integrated Power Products 30V-1500V in Application Optimized Processes Low voltage family optimized for LED Qgd Backlight x Rds(on) LCDs Separate family optimized for pure Rds(on) performance 600V Super Junction MOSFETs for SMPS 300V-1350V Discrete Devices Class-leading turn-off loss High-speed, short-circuit rated, and low Vce(on) optimized using thin wafers Multiple package options and bare die option available Broad Line-up of Packages and Devices SiC, Fast Recovery, SBD and Others SiC Schottky barrier diodes for very high switching speeds 3A to 30A, 600V parts available SBD optimized for high switching speeds Optimized for Highest Efficiency & Compactness Dr MOS solutions for > 93% peak efficiency, up to 1.5MHz PFC ICs for solutions up to 98% peak efficiency Smallest CSP packages for POL, Battery Charger and Fuel Gauge Applications Current ratings from 0.8A to 30A rms Voltage ratings from 600V to 1500V Junction temperature to 150 C 4

Enabling The Smart Society Challenge: Enable LED s to reduce energy consumption towards lighting. The US has an installed base of 5 billion bulbs. These are primarily either incandescent or compact fluorescent Together, these consume 18% of total US electricity! LED retrofitting should reduce the energy requirement by half.* * DOE Estimates by 2030 5

Enabling The Smart Society Challenge: Designing efficient LED supplies presents circuit challenges: Compact conversion of AC line power to DC Efficiency > 85% PF > 0.9 Stringent harmonics, ripple, dimming, reliability and cost requirements. Example from Lamp-wallpaper.com (vendor unknown) 6

Enabling The Smart Society Solution: Renesas extends PFC product family for LED applications to develop single stage PFC buck circuit using a hi-side switch to replace incumbent low side switch topologies to improve performance across the requirement spectrum 7

Agenda LED retrofit opportunity and requirements Pertinent terms and definitions Single stage PFC buck circuit with high side switch improves upon incumbent topologies Results and data Summary Q & A 8

What is the Retrofit Market? & Replace this And this With these The US has 5 billion light bulbs installed, and about 2 billion light bulbs are sold in the US each year! 9

Why Replace Incandescent and CFL Bulbs? Efficiency LED 2007-2010 CFL 27 40 W CFL 5 26 W Standard Incandescent LED in Development 10 IESNA Lighting Handbook, Ninth Edition p 26-3 and Wikipedia 10

Why Replace Incandescent and CFL Bulbs? Efficiency Lifetime 25K hours per LED How many incandescent and CFL bulbs to reach 25K hours? Incandescents CFLs LED 1K hours per 10K hours per 25K hours per OSRAM Online Study 4.08.2009 11

Why Replace Incandescent and CFL Bulbs? Efficiency Lifetime Maintenance Costs Online e-conolight.com brochure 12

Why Replace Incandescent and CFL Bulbs? Efficiency Lifetime Maintenance Costs From EDN Joke Contest 13

Why Replace Incandescent and CFL Bulbs? Efficiency Lifetime Maintenance costs Regulatory compliance Energy Independence and Security Act of 2007 Requires ~ 25 percent more efficiency for household light bulbs. Effectively phases out household incandescent bulbs (but not CFL s and specialty lamps). Was signed by then President Bush in 2007. 14

Why Replace Incandescent and CFL Bulbs? 15

Why Replace Incandescent and CFL Bulbs? Question: Why regulate power factor for LED lighting down to 25W, when other equipment less than 75W is exempted from Power Factor regulations? Answer: Related to the 5B Bulbs installed in the US, 18% of US electricity consumption; each US households averages 40 active bulbs, so in aggregate low PF LEDs will contribute a lot of harmonic current to the AC lines in even residential buildings. 16

Efficiency Efficiency = Useful Power Output / Total Power consumed Often and herein denoted by Greek symbol h 18

Linear Loads Linear load: A load in which a sinusoidal voltage draws a sinusoidal current with the same frequency. Examples Resistor: V= I*R Resistive Loads Incandescent Bulb Electric Heater 19

Linear Loads Question: Resistive loads, defined by Ohm s law, are clearly, linear. How about purely inductive or capacitive load, is it linear as well? 20

Non-Linear Loads Non-linear load: The current flow is non-proportional to the applied voltage. 21

Linear Loads Question: Resistive loads, defined by Ohm s law, are clearly, linear. How about purely inductive or capacitive load, is it linear as well? Answer: Yes! 22

Real Power V(t) R P AC (Watts) = V rms * I rms = I 2 rms*r 23

Reactive Power V(t) L R = Zero Ohms. So real power transfer is zero, instead the circuit has a reactive power. Q = I 2 rms* Z Units = Volt * Amperes Reactive Common Reactive Components Q 24

Apparent Power Apparent Power (S) = volt*amperes = I 2 Z Reactive Power (Q) = volt*amperes reactive = I 2 (X L -X C ) Q Real Power (P) = Watts = I 2 R 25

Power Factor: Incomplete Definition Power factor = Real Power / Apparent Power = COS (Q) Apparent Power (S) Reactive Power (Q) Q Real Power (W) 26

Power Factor: Incomplete Definition Non-linear load example: SMPS. The angle between V & I is zero, so PF = COS ( 0 ) = 1? Wrong: In fact we need another term, THD, to the PF equation 27

Harmonic Current Harmonic current: Harmonic currents are integer multiples of the fundamental frequency (e.g. 60 Hz in the US). Harmonic currents are created by non-linear loads. by converting the signal on the fundamental supply frequency. 120 Hz (2 nd harmonic), 180 Hz (3 rd harmonic), 240 Hz (4 th harmonic) 28

Total Harmonic Distortion Harmonic current: Total harmonic distortion quantifies the magnitude of the harmonics: THD 39 3 I 1 I 2 n I1: RMS value of AC current fundamental In: RMS value of AC current nth harmonic 29

Harmonic current [A] Waveform Distortion by Harmonic Currents AC voltage (sinusoidal) AC current This current wave is distorted by odd order (3 rd, 5 th, 7 th ) harmonic current PF << 1 6 5 4 3 2 1 0 Fundamental = 50 Hz 3 rd 5 th 7 th 9 th (150 Hz) (250 Hz) (350 Hz) (450 Hz) Order of harmonic current 30

A Complete Power Factor Definition Power factor, a complete definition: Power Factor (PF) = Real Power / Apparent Power = COS (Q) * Irms(fundamental) / Irms = COS (Q) * 1/(1+THD) 2 31

Example: Incandescent Light Bulb +100 V AC voltage (AC 100 V) -100 V +0.5 A AC current (AC 0.5 A) -0.5 A In phase & Proportional Power Factor = 1 32

Example: Incandescent Light Bulb with Dimmer AC current controlled With a dimmer, even an incandescent by dimmer bulb PF << 1 33

LED Characteristics I*V curve for a diode: For bright LED s On voltage will be ~ 3.3V Intensity will be ~ 60 lm/watt Compare to ~ 20lm/W for an incandescent bulb Intensity will, approximately, scale linearly with current Drawing from Wikipedia 34

Agenda LED retrofit opportunity and requirements Pertinent terms and definitions Single stage PFC buck circuit with high side switch Results and data Summary Q & A 35

LED Drive Requirements for Retrofit Market h > 85% PF > 0.9 THD < 20% Leading Edge Dimming Compatibility Trailing Edge Dimming Compatibility Maintenance Costs Regulatory Compliance 36

LED Driver Circuit Background Common LED drive circuits combine CRM PFC function With a low-side MOS Gate Drive circuit filter Driver IC Buck-boost low side 37

LED Driver Circuit Background PFC operation is CRM filter di(t)= v(t) L dt Vac Iac IL Ton Toff IC GD Buck-boost low side COMP RAMP Ramp level shift Gate off timing 38

LED Driver Circuit Background An alternate is high side gate drive (High side driver IC will float versus ground, and be more susceptible to noise.) Gate R2A20135 di(t)= v(t) L dt Vac Iac IL Ton Toff GD Gate Gate Drive ramp Amplifier COMP RAMP Gate off timing Ramp level shift Phase compensation Smoothing Peak current 39

Hi-Side Drive Merits are Efficiency and Cost di(t)= v(t) L dt Vac Iac IL Ton Toff GD COMP RAMP Ramp level shift Gate off timing V L = L* (di/dt) 40

Hi-Side Drive Merits are Efficiency and Cost 41

f Hi-Side Drive Merit includes Current Precision High side drive has more precise current accuracy MOS low-side drive MOS high-side drive MOS Current Driver IC MOS Current Driver IC Diode Current Diode Current Only MOS current Controlled by CS resistor!!! Diode current I[A] 10% I[A] Both MOS current and Diode current Controlled by CS resistor!!! MOS current Diode current 6% As inductor value changes, LED current changes t[s] As inductor value changes, LED current isn t pronounced t[s] 42

Hi-Side Drive Merit includes Current Precision High side drive has more precise current accuracy Question: What typical circumstance may change the inductance value? Answer : Temperature change. L = m 0 m r N 2 A / l m 0 permeability of free space m r rel permeability of core N = number of turns A = cross section of coil l = length of coil 43

Hi-Side Drive Merit includes Current Precision High side drive has more precise current accuracy MOS low-side drive MOS high-side drive MOS Current Driver IC MOS Current Driver IC Diode Current Diode Current Only MOS current Controlled by CS resistor!!! Diode current I[A] 10% I[A] Better! 6% Both MOS current and Diode current Controlled by CS resistor!!! MOS current Diode current As inductor value changes, LED current changes t[s] As inductor value changes, LED current isn t pronounced t[s] 44

Complete Circuit Implementation 45

Power Factor Tradeoff Considerations Power Factor improvement options Reduce input capacitor to decrease charge current pulse Reduce V F (load) to decrease zero conduction period length. 46

PF Circuit Performance: Power Factor Higher than 0.9 over a 90Vac to 132Vac input range 1.00 0.95 Vac vs PF 0.90 0.85 PF>0.9 0.80 0.75 0.70 0.65 0.60 0.55 0.50 80 90 100 110 120 130 140 Input voltage[vac] 48

η[%] Circuit Performance : Efficiency Higher than 85% over a 90Vac to 132Vac input range Vac vs Efficiency(η) R13=12kΩ R13=100kΩ 100 95 90 85 80 75 70 65 60 55 50 η>85% 80 90 100 110 120 130 140 Input voltage[vac] 49

THD[%] Circuit Performance: THD Under 20% over a 90V to 132Vac input range Vac vs THD 50 45 40 35 30 25 20 THD<20% 15 10 5 0 80 90 100 110 120 130 140 Input voltage[vac] 50

Iout [A] Circuit Performance : Leading Edge Dimming Dimming from nearly 0% to 100% with 100 to 120 Vac Dimmer type WN575159(Panasonic denko 500VA) Leading dimmer AC100V AC110V AC120V 0.25 Bridge Voltage 0.20 T1 T2 time ratio[%] = 100 (T2/T1) 0.15 0.10 0.05 0.00 0 10 20 30 40 50 60 70 80 90 time ratio [%] 51

Iout [A] Circuit Performance : Trailing Edge Dimming Dimming from 4% to 100% with 100 to 120 Vac Dimmer type DVELV-300P(LUTRON 300W) Min-Max of time ratio is the operation range of dimmer control 調光特性 AC100V AC110V AC120V Bridge Voltage 0.25 0.20 T2 T1 time ratio[%] = 100 (T2/T1) 0.15 0.10 0.05 0.00 10% - 100% area 4% 0 10 20 30 40 50 60 70 80 90 time ratio [%] 52

Iout [A] Demo Board Line-up 調光特性 AC100V AC110V AC120V Bridge Voltage 0.25 0.20 T2 T1 time ratio[%] = 100 (T2/T1) 0.15 0.10 10% - 100% area Improvement in design efficiency, inventory management cost reduction. *Input range : 90 to264v *PF>0.9 within 90 to264v *efficiency>85% within 90 to264v *Iout ripple<30% within 90 to264v *THD<30% within 90 to264v 0.05 High efficiency 4% dimmable solution. *Input range : 90 to132v 0.00 *PF>0.9 *efficiency>85% *Iout ripple<30% *THD<30% 0 10 20 30 40 50 60 70 80 90 time ratio [%] Improvement in design efficiency, inventory management cost reduction. *Input range : 90 to264v *PF>0.97 within 90 to264v *efficiency>81% within 90 to264v *Iout ripple<30% within 90 to264v *THD<30% within 90 to264v 53

Summary Potential benefits of LED retrofit lighting include Halving US energy consumption for lighting Reducing maintenance costs by 80%+ Design challenges of LED retrofit lighting include Meeting PF regulatory requirements Meeting size and efficiency constraints Achieving compatibility with existing dimmers PFC with driver for high side switch is an excellent solution Has inherent efficiency and cost advantages Enables excellent dimming performance Meets PF requirements 55

Questions? 58

Enabling The Smart Society Challenge: Enable LED s to reduce energy consumption towards lighting by meeting circuit challenges. Today lighting consumes 18% of total US electricity! LED retrofitting should reduce the energy requirement by half. Design challenges for size, efficiency, PF, cost must be overcome. Solution: Renesas extends PFC product family for LED applications to develop single stage PFC buck circuit using a hi-side switch to replace incumbent low side switch topologies to improve performance across the requirement spectrum 59

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