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Infineon ICL8001G, Design Manuallines

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ICL8001G / ICLS8082G

Design Guidelines

Design Optimizations

Application Note

22

Version 2.0, 2011-04-14

5.3

Optimized Power Factor Correction Performance

Driver  optimization  for  high  power  factor  correction  can  deliver  very  high  PF > 99 %  and  THD ≈ 10 %.

Corresponding measurements for a 100 V / 10 W LED driver result in the timing diagrams for the setpoint voltage
VR(t) and driver input current Iin(t).

Figure 17

Optimized power factor correction

Figure 18

Bill of Materials (BOM) for 100 V / 10 W LED driver with high PF

Summary of Contents for ICL8001G

Page 1: ... Multimarket Application Note Version 2 0 2011 04 14 ICL8001G ICLS8082G Design Guidelines Phase Cut Dimmable Single Stage LED Driver with PFC using Quasi Resonant Primary Power Control Version 2 0 LED Driver ICs ...

Page 2: ...ery terms and conditions and prices please contact the nearest Infineon Technologies Office www infineon com Warnings Due to technical requirements components may contain dangerous substances For information on the types in question please contact the nearest Infineon Technologies Office Infineon Technologies components may be used in life support devices or systems only with the express written a...

Page 3: ...elines Application Note 3 Version 2 0 2011 04 14 ICL8001G ICLS8082G Design Guidelines werner ludorf infineon com Revision History 2011 04 14 Version 2 0 Previous Revision Page Subjects major changes since last revision First edition ...

Page 4: ...eration 13 4 6 Power Factor Correction 14 4 7 VCC for Dimming 14 5 Design Optimizations 15 5 1 Dimming 15 5 1 1 Dimming Principle 15 5 1 2 Dimmer Compatibility 17 5 1 3 Dimmer List 18 5 1 4 Dimmer Selection 19 5 2 Power Stabilization for Line Voltage Variations 19 5 2 1 Stabilization using IC Foldback Correction 19 5 2 2 Discrete Power Stabilization Circuit for ICL8001G 20 5 3 Optimized Power Fact...

Page 5: ... cell for VCC precharging with a constant current Built in digital soft start Foldback correction and cycle by cycle peak current limitation VCC over undervoltage lockout Auto restart mode for short circuit protection Adjustable latch off mode for output overvoltage protection OVP Description The ICL8001G ICLS8082G employs a quasi resonant QR operation mode and due to the availability of outstandi...

Page 6: ...1 Pin Configuration with PG DSO 8 Table 1 Pin Configuration for PG DSO 8 Pin Symbol Function 1 ZCV Zero Crossing 2 VR Voltage Sense 3 CS Current Sense 4 GD Gate Drive Output 5 HV High Voltage Input 6 n c Not connected 7 VCC Controller Supply Voltage 8 GND Controller Ground Cx Cin Rn Cn Dn Cvcc Dvcc Rs Do Co L1 Rvcc VCC GND T1 np na ns Rzc1 Rzc2 ZCV ICL8001G Vo Vac BR Czc VR PWM Control Protection ...

Page 7: ...se cut dimming functionality CS Current Sense This pin is connected to the shunt resistor for the primary current sensing externally and to the PWM signal generator for switch off determination together with the feedback voltage internally Moreover short winding protection is realized by monitoring the voltage Vcs during on time of the main power switch GD Gate Drive Output This output signal driv...

Page 8: ... compared to the voltage VR which is derived from the input voltage divider Ro Ru This means that the peak current through the power switch Q1 and the primary inductance L varies according to the instant input voltage Vin t as expressed by 2 Depl CoolMOS Startup Cell Power Managment Zero Crossing PWM Control Gate Drive Protection HV GND GD Gate Control Voltage Reference Biasing Over Under Voltage ...

Page 9: ...ation results 4 1 Transformer Parameters For QR operation a sufficiently large reflected voltage from the secondary to the primary side present during the flyback time tf has to be provided After discharge of the transformer by means of the secondary winding current the energy coupled to the reflected voltage is needed to reduce the input voltage at switch on instantly in the VDS valley to Vdsmin ...

Page 10: ...s 14 and the centered IC supply voltage Vccc Vccmax Vccmin 2 19 the auxiliary winding number will be na 10 according to 14 4 2 Power Switch The maximum voltage VDSmax along the drain source path of the MOSFET arises during the line phase with Vin Vinp at the instant just subsequent to switching off the primary current In this phase the high frequency oscillation amplitude 15 adds to the superposit...

Page 11: ...ts maximum value at the input voltage Vinp By choosing the maximum threshold Vcsmax 0 75 V for the shunt voltage generated at the instant of Vinp the shunt resistance is Rs 2 7 Ω based on 17 The upper resistor Ro in the input voltage divider is dimensioned in consideration of losses and PFC For efficiency optimization high ohmic values are preferred A low ohmic input voltage divider enables a maxi...

Page 12: ... 19 The characteristic curve Vcsmax Izc implemented in the IC shows the following steps Figure 4 Vcsmax lzc characteristic curve For the adjusted setting Vinth Vinp and selection of the foldback operation point Vcs max 0 75 V Icz 1 mA using the characteristic curve the detection resistance is calculated to be Rzc1 15 kΩ according to 20 From the characterisitic curve it can be seen that the Vin dep...

Page 13: ...e capacitance of the power switch has elapsed Figure 5 Determination of the switch on instant The delay td elapses from the instant of discharging the transformer to when the first VDS valley is reached For initial dimensioning of the delay circuit the relationship 21 can be used For the 230 V 10 W demo board an initial value of td 1 µs is appropriate For output overvoltage protection with final s...

Page 14: ...f the setpoint VR t determines the power flow to the QR operated flyback This is also true if the input voltage is shaped by means of a phase cut dimmer regardless of whether this is a trailing or leading edge wall dimmer Therefore the variation of the effective input voltage determines the power level supplied to the LED load at the driver output The low frequency variation of the input power is ...

Page 15: ...x 2 0 Consequently the light level depends on the RMS input voltage Vrms ts provided by the phase cut dimmer and the dimming range is therefore given by the phase cut limits of the wall dimmer For the example of a trailing edge dimmer the following diagrams show the time dependence of the modified input voltage V t ts with the fixed parameter switching instant ts T 4 and the RMS input voltage Vrms...

Page 16: ...r Figure 10 Output power versus input trail edge Vrms Effective for the application is the dependence of the LED driver power on the switching instant ts switching angle The following experimental diagram obtained with an Ehmann trailing edge dimmer shows the dependence of the switching instant ts on the driver input power upper curve and LED power lower curve respectively Figure 11 Relationship b...

Page 17: ...lel to the input voltage divider In the circuit diagram further below an R C circuit is implemented Dimensioning of R8 220 Ω and C8 68 nF not integrated in the standard demo board layout provides stabilization for leading edge dimmer operation The non dimming driver efficiency is reduced by only typically 1 Figure 12 Extended application circuit for dimming Especially for applications with low inp...

Page 18: ... will lead to a reduction in driver efficiency 5 1 3 Dimmer List Table 2 Input voltage 230 V 10 W Manufacturer Type designation Power limit Dimming range PDL Leading Edge CAT634LM 450 W 20 100 Busch Leading Edge 2200 400 W 16 100 Ehmann Leading Edge T10 300 W 3 100 Ehmann Trailing Edge T46 315 W 23 100 HPM Trailing Edge Cat400T 400 W 6 100 PDL Trailing Edge CAT624TM 450 W 10 100 Table 3 Input volt...

Page 19: ...ly on a resistive load for sufficient digital IC supply should not be selected for LED driver control 5 2 Power Stabilization for Line Voltage Variations For stable lumen output and limitation of LED power during mains voltage variations it may be useful to consider power stabilization for the LED driver design This can be achieved by appropriate use of IC foldback correction without additional ex...

Page 20: ...te differential amplifier can be proposed Here the Vin signal is sensed by means of a voltage divider consisting of R21 and R22 and smoothed by C21 The Zener diode D21 is used for the reference voltage When the smoothed voltage is much smaller than the reference voltage the current though R23 will flow only through R24 and there is no influence on the output power of the demo board When the value ...

Page 21: ...he same slope as Vin t the input current will not change significantly but still enable designs with a high power factor and low harmonic distortion Careful optimization of the discrete stabilization circuit containing the components stated in the BOM below when connected to the 230 V 10 W driver delivers variations of ILED 0 3 and ILED 1 3 at Vac 10 and Vac 10 respectively There is no influence o...

Page 22: ...Driver optimization for high power factor correction can deliver very high PF 99 and THD 10 Corresponding measurements for a 100 V 10 W LED driver result in the timing diagrams for the setpoint voltage VR t and driver input current Iin t Figure 17 Optimized power factor correction Figure 18 Bill of Materials BOM for 100 V 10 W LED driver with high PF ...

Page 23: ... OV threshold Voovpth 35 V the Rzc2 resistance value is increased to Rzc2 2 7 kΩ based on the equation 25 6 2 Output Short Circuit Protection In the case of an output short circuit the IC will switch to Auto Restart Mode by means of VCC undervoltage detection No special dimensioning is required for this purpose 6 3 Input Overvoltage Protection OVP Upon input overvoltage the foldback point correcti...

Page 24: ...lication For details see the Application Note AN186 What will happen under no load conditions The application circuits based on ICL8001G ICLS8082G are designed to work with LEDs only Under no load conditions it will go to either the auto restart mode due to Vcc OVP or latched off mode due to output OVP 7 2 Control Principle How does ICL8001G ICLS8082G realize dimming control and power factor corre...

Page 25: ...onsidered The ICL8001G ICLS8082G PWM parameter GPWM and offset voltage needed for low driver tolerances possess especially high precision as stated in the ICL8001G ICLS8082G data sheet 8 References Data Sheet ICL8001G ICLS8082G AN EVAL LED ICL8001G Bulb02 for LED Drivers 230 V 10 W AN EVAL LED ICL8082G Bulb01 for LED Drivers 230 V 10 W AN186 40 W LED Street and Indoor Lighting Reference Design ...

Page 26: ...Published by Infineon Technologies AG w w w i n f i n e o n c o m ...

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