IRPLLNR7 Universal Input Linear Fluorescent Ballast Using the IRS2166D Features • • • • • • • • • Drives one 35 W TL5 Lamp Input Voltage: 80 VAC to 260 VAC High Power Factor/Low THD High Frequency Operation Lamp Filament Preheating Lamp Fault Protection with Auto-Restart Low AC Line Protection End of Lamp Life Shutdown IRS2166D(S)PbF HVIC Ballast Controller Table of Contents Page 1. Description......................................................................................2 2. Ballast Block Diagram....................................................................2 3. Electrical Characteristics................................................................3 4. Fault Protection Characteristics......................................................3 5. Overview.........................................................................................3 6. Schematic Diagram.........................................................................4 7. PCB Layout and Component Placement Diagram..........................5 8. Bill of Materials..............................................................................6 9. Inductor Specifications (PFC Inductor) .........................................7 10. Inductor Specifications (Resonant Inductor) ...............................8 11. Demo Board Overview.................................................................9 12. Power Factor Correction Section..................................................9 13. Ballast Control Section.................................................................9 14. Startup Mode.................................................................................9 15. Preheat Mode..............................................................................10 16. Ignition Ramp Mode...................................................................12 17. Run Mode....................................................................................13 18. Normal Power Down and Brown-Out Reset..............................14 19. Lamp Removal and Auto-Restart...............................................14 20. Fault Mode..................................................................................14 21. Current Mode Configuration.......................................................17 22. Design Procedure for Different Lamp Types..............................18 www.irf.com 1 1. Description The IRPLLNR7 Demo Board is a high efficiency, high power factor, fixed output electronic ballast designed for driving rapid start fluorescent lamp types. The design contains an EMI filter, active power factor correction and a ballast control circuit using the IRS2166D(S)PbF Ballast Control IC1. This demo board is intended to ease the evaluation of the IRS2166D, demonstrate PCB layout techniques and serve as an aid in the development of a production ballast using International Rectifier’s IRS2166D. 2. Ballast Block Diagram EMI Filter Rectifier Boost PFC Output Stage Line Input Lamp UVLO PFC Control IRS2166D Control IC Half-Bridge Driver Lamp Fault 1 For convenience, the “(S)PbF” extension of IRS2166D(S)PbF will be removed in the rest of this document www.irf.com RD-0609 2 3. Electrical Characteristics Parameter Lamp Type Input Power Lamp running voltage Run Mode Frequency Preheat Mode Frequency Preheat Time Lamp Preheat Voltage Ignition Voltage Input AC Voltage Range Power Factor Total Harmonic Distortion Units [W] [Vpp] [kHz] [kHz] [s] [Vpp] [Vpp] [VACrms] [%] Value 35 W TL5 38 690 45 60 1 600 1600 80-260 VAC 0.995 at 120 VAC (rms) 0.971at 220 VAC (rms) <10 at 120 VAC (rms) <15 at 220 VAC (rms) 4. Fault Protection Characteristics Fault Line voltage low Upper filament broken Lower filament broken Failure to ignite Open circuit (no lamp) End of life Ballast Deactivates Deactivates Deactivates Deactivates Deactivates Deactivates Restart Operation Increase line voltage Lamp exchange Lamp exchange Lamp exchange Lamp exchange Lamp exchange 5. Overview The IRPLLNR7 Demo Board consists of an EMI filter, an active power factor correction section, a ballast control section and a resonant lamp output stage. The active power factor correction section is a boost converter operating in critical conduction mode, free-running frequency mode. The ballast control section provides frequency modulation control of a traditional RCL lamp resonant output circuit and is easily adaptable to a wide variety of lamp types. The ballast control section also provides the necessary circuitry to perform lamp fault detection, shutdown and auto-restart. www.irf.com RD-0609 3 6. Schematic Diagram: IRS2166D, Single Lamp, Voltage Mode Heating L N GND F1 L1 CY RV1 C1 BR1 C2 LPFC MPFC DPFC CBUS RPFC RZX RVDC RBUS1 PFC ZX COMP CT RPH RT CPH VBUS RBUS2 CCOMP RPH RT CPH CVDC CT DCOMP 1 2 3 4 5 6 7 8 IRS2166D IC BALLAST 16 15 14 13 12 11 10 9 HO VS RHO RLIM2 CCS RLIM1 CSD1 DSD RLIM RLO CVCC2 CBOOT VCC CVCC1 VB COM LO CS SD CSD Note: Thick traces represent high-frequency, high-current paths. Lead lengths should be minimized to avoid high-frequency noise problems MHS MLS RSD RCS RSUPPLY DCP2 RPU CSNUB DCP1 CRES LRES:A DEOL1 DEOL2 RDC CDC LRES:B CH1 CH2 LRES:C 4 RD-0609 www.irf.com REOL1 REOL2 REOL3 CEOL REOL4 7. PCB Layout and Component Placement Diagram www.irf.com RD-0609 5 8. Bill Of Materials Note: Different lamp types require different frequency programming components. Item # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Qty 1 1 1 1 1 2 1 1 1 2 1 2 1 1 1 1 1 1 1 2 1 1 3 1 1 1 3 3 1 30 1 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 Total 2 1 1 2 1 1 1 1 1 3 1 1 1 1 1 4 1 1 65 Manufacturer International Rectifier Roederstein Dale Roederstein Panasonic Wima Panasonic Panasonic B.I. Technologies Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Johanson Dielectrics WIMA Panasonic HM00-01761 ECJ-2VB1HC104K ECU-V1H473KBM ECU-V1H102JCH ECU-V1H333KBM ECU-V1H103KBM ECE-A1HGE02R2 ECJ-3YB1E105K 102R29W821KV4E FKP1-3300/2000/5 ECU-V1H221KBM Panasonic Panasonic Digi-key Diodes ECQB1104JFW ECU-V1H821KBN MURS160DICT-ND LL4148DICT-ND International Rectifier B.I. Technologies International Rectifier Panasonic Panasonic Phoenix Passive Components Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic Panasonic IRS2166D HM00-01762 IRF830 ERJ-8GEYJ22 ERJ-6ENF5902V 5033ED220K0F12AF 5 ERJ-8GEYJ680K ERJ-6ENF2202V ERJ-8GEYJ1K ERJ-8GEYJ10 ERJ-12RQF1R5U ERJ-8GEYJ223V ERJ-6ENF1302V Panasonic Panasonic Panasonic ERJ-8GEYJ104V ERJ-8GEYJ224V ERJ-8GEYJ333V Panasonic Panasonic ERJ-8GEYJ105V ERJ-8GEYJR00V WAGO WAGO 235-203 235-207 www.irf.com Part Number DF10S WY0222MCMBF0K CW-1/2 F1772433-2200 ELF-15N007A MKP10 ERZ-V05D471 Description Bridge Rectifier, 1A 1000V Capacitor, 2.2nF 275 VAC Y Cap Resistor, 0.5 ohm, 1/2W Capacitor, 0.33uF 275 VAC EMI Inductor, 1X10mH 0.7Apk Capacitor, 0.1uF 400 VDC Transient Suppressor Capacitor, 10uF 450VDC 105C PFC Inductor, 1.0mH 3Apk Capacitor, 0.1uF SMT 1206 Capacitor, 0.47uF SMT 1206 Capacitor, 1nF SMT 1206 Capacitor, 0.33uF SMT 1206 Capacitor, 0.01uF SMT 1206 Capacitor, 2.2uF 50VDC 105C Capacitor, 1.0uF SMT 1206 Capacitor, 820pF 1KV SMT 1812 Capacitor, 3.3nF 2KV Capacitor, 220pF SMT 1206 Capacitor, 0.1uF 100V Capacitor, 820pF SMT 1206 Diode, 1A 600V, SMT SMB Diode, 1N4148 SMT DL35 Diode, 11V Zener, SMT 1206 IC, Ballast + PFC Control Inductor, 4.0mH 3Apk Transistor, MOSFET Resistor, 22 ohm SMT 1206 Resistor, 59K ohm 1% SMT1206 Reference BR1 CY F1 C1 L1 C2, CDC, RV1 CBUS LPFC CBOOT, CVCC2 CPH CSD, CEOL CSD1 CVDC CVCC1 CCOMP CSNUB CRES CCS CH1, CH2 CT DPFC DCP1, DCP2, DSD DCOMP IC BALLAST LRES MPFC, MHS, MLS RPFC, RLO, RHO RPH Resistor, 220K ohm 1/2W RSUPPLY Resistor, 680K ohm SMT 1206 Resistor, 22K ohm 1% SMT 1206 Resistor, 1K ohm SMT 1206 Resistor, 10 ohm SMT 1206 Resistor, 1.5 ohm 1% SMT 2010 Resistor, 22K ohm SMT 1206 Resistor, 13K ohm 1% SMT 1206 Resistor, 100K ohm 1/2W Resistor, 100K ohm SMT 1206 Resistor, 220K ohm SMT 1206 Resistor, 20K ohm SMT 1206 Diode, 10V Zener SMT 1206 Diode, 5.6V Zener SMT 1206 Resistor, 1meg ohm SMT 1206 Resistor, 0 ohm SMT 1206 Wire Jumper Connector, 3 terminal Connector, 4 terminal RBUS1, RBUS2 RT RLIM RLIM1, RLIM2 RCS RZX RVDC RDC RSD REOL1, REOL2, REOL3 REOL4 DEOL1 DEOL2 RPU RJ1 J1, J2, JV1, JV2 X1 X2 RD-0609 6 9. Inductor Specifications (PFC Inductor) INDUCTOR SPECIFICATION TYPE : LPFC CORE SIZE E25/13/7 (EF25) GAP LENGTH 1 PINS 8 HORIZONTAL BOBBIN mm Philips 3C85, Siemens N27 or equivalent CORE MATERIAL NOMINAL INDUCTANCE 1 mH MAXIMUM CURRENT 2 Apk MAXIMUM CORE TEMPERATURE 100 ºC WINDING START PIN FINISH PIN TURNS WIRE DIAMETER (mm) MAIN 1 6 125 4 strands of AWG 32 ZX 3 8 10 4 strands of AWG 32 ELECTRICAL LAYOUT PHYSICAL LAYOUT 20.05mm TOP VIEW 5mm 25mm TEST 1 8 2 7 5mm 3 6 4 5 (TEST FREQUENCY = 50kHz) MAIN WINDING INDUCTANCE MIN 0.9 mH MAIN WINDING RESISTANCE Ohms MAX 1.5 MAX 1.1 mH NOTE : Inductor must not saturate at maximum current and maximum core temperature at given test frequency. www.irf.com RD-0609 7 10. Inductor Specifications (Resonant Inductor) INDUCTOR SPECIFICATION TYPE : LRES(VOLTAGE MODE) CORE SIZE E25/13/7 (EF25) GAP LENGTH 1 HORIZONTAL PINS 8 BOBBIN mm Philips 3C85, Siemens N27 or equivalent CORE MATERIAL NOMINAL INDUCTANCE 4 mH MAXIMUM CURRENT 2 Apk MAXIMUM CORE TEMPERATURE 100 ºC WINDING START PIN FINISH PIN TURNS WIRE DIAMETER (mm) MAIN 1 8 250 4 strands of AWG 32 CATHODE (1) 6 7 10 4 strands of AWG 32 CATHODE (2) 4 5 10 4 strands of AWG 32 ELECTRICAL LAYOUT PHYSICAL LAYOUT 20.05mm TOP VIEW 5mm 25mm TEST 1 8 2 7 5mm 3 6 4 5 (TEST FREQUENCY = 50kHz) MAIN WINDING INDUCTANCE MIN 3.9 mH MAIN WINDING RESISTANCE Ohms MAX 2 MAX 4.1 mH NOTE : Inductor must not saturate at maximum current and maximum core temperature at given test frequency. www.irf.com RD-0609 8 11. Demo Board Overview This demo-board is designed for single TL5/35W Lamp, voltage mode heating (JV1 and JV2 mounted, JC1 and JC2 not mounted). TL5 lamps are becoming more popular due to their lower profile and higher lumen/ watt output. These lamps, however, can be more difficult to control due to their higher ignition and running voltages. A typical ballast output stage using current-mode filament heating (filament placed inside L-C tank) will result in excessive filament current during running. The output stage has therefore been configured for voltage-mode filament heating using secondary windings off of the resonant inductor LRES. The lamp has been placed outside the under-damped resonant circuit loop, which consist of LRES and CRES. The filament heating during preheat can be adjusted with the capacitors CH1 and CH2. The result is a more flexible ballast output stage necessary for fulfilling the lamp requirements. The DC blocking capacitor, CDC, is also placed outside the under-damped resonant circuit loop such that it does not influence the natural resonance frequency of LRES and CRES. The snubber capacitor, CSNUB, serves as charge pump for supplying the IRS2166D. The IRS2166D Ballast Control IC is used to program the ballast operating points and protect the ballast against conditions such as lamp strike failures, low DC bus, thermal overload or lamp failure during normal operations. It is also used to regulate the DC bus and for power factor control allowing high power factor and low harmonic distortion. 12. Power Factor Correction Section The power factor correction section contained in the IRS2166D forms the control for a boost topology circuit operating in critical conduction mode. This topology is designed to step-up and regulate the output DC bus voltage while drawing sinusoidal current from the line (low THD) which is “in phase” with the AC input line voltage (HPF). 13. Ballast Control Section The ballast control section of the IRS2166D Ballast Control IC contains an oscillator, a high voltage half-bridge gate driver and lamp fault protection circuitry. Please, refer to the datasheet of this IC for the block diagram and the state diagram. The following is a breakdown of the operation of the ballast in all of the different modes of operation. 14. Startup Mode When power is initially applied to the ballast, the voltage on the VCC pin of the IRS2166D begins to charge up. The voltage for the IRS2166D is derived from the current supplied from the rectified AC line through startup resistor RSUPPLY. During this initial startup when the VCC voltage of the IRS2166D is below its rising under-voltage lock-out threshold, it is in UVLO mode and draws micropower current from VCC. The micro-power current of the IRS2166D allows the use of a large value, low wattage startup resistor (RSUPPLY). When the voltage on the IRS2166D reaches the rising undervoltage lockout threshold (12.5V), the gate driver oscillator is enabled (this assumes that there are no fault conditions) and drives the half-bridge output MOSFETs (MHS and MLS). When the half-bridge is oscillating, capacitor CSNUB, diodes DCP1 and DCP2 form a snubber /charge pump circuit which limits the rise and fall time at the half-bridge output and also supplies the current to charge capacitor CVCC2 to the VCC clamp voltage (approx. 15.6V) of IRS2166D. When the rising under-voltage lockout threshold of the IRS2166D is reached, the power factor control oscillator starts to oscillate and drive MOSFET MPFC to boost and regulate the bus voltage to 400 VDC. www.irf.com RD-0609 9 15. Preheat Mode When the ballast reaches the end of the UVLO mode, the Preheat mode is entered. At this point the ballast control oscillator of the IRS2166D has begun to operate and the half-bridge output is driving the resonant load (lamp) circuit. There is an initial startup frequency that is much higher than the steady state Preheat mode frequency that lasts for only a short duration. This is done to ensure that the initial voltage appearing across the lamp at the startup of oscillation does not exceed the minimum lamp ignition voltage. If, at the initiation of oscillation of the half-bridge, the voltage across the lamp is large enough, a visible flash of the lamp occurs which should be avoided. This in effect is a cold strike of the lamp, which could shorten the life of the lamp. The ballast control section oscillator of the IRS2166D is similar to oscillators found in many popular PWM voltage regulator ICs and consists of a timing capacitor and resistor connected to ground. Resistors RT and RPH program a current that determines the ramp up time of capacitor CT. The downward ramping time of CT is the deadtime between the switching off of the LO (HO) and the switching on of the HO (LO) pins on the IRS2166D. The Preheat mode frequency of oscillation is determined from the parallel resistance of RT and RPH. It is selected such that the voltage appearing across the lamp is below the minimum lamp ignition voltage while supplying enough current to preheat the lamp filaments to the correct emission temperature within the Preheat mode period. The preheating of the lamp filaments is performed with a constant voltage during the Preheat mode. The waveform in Figure 2 shows the lamp filament current while Figure 3 shows lamp filament voltage during the normal Startup, Preheat, and Ignition Ramp modes of the ballast. Figure 2: Lamp filament current during Preheat and Ignition Ramp (500mA / div) (Crossed lamps) www.irf.com RD-0609 10 Figure 3: Lamp filament voltage during preheat and Ignition Ramp (Crossed lamps) Figure 4 shows a plot of the half-bridge oscillation frequency as a function of time for all of the normal modes of operation: Preheat mode, Ignition Ramp mode and Run mode. fosc fPreheat fRun fIgnition t preheat ignition run Figure 4: Oscillator frequency versus time, Normal operating conditions www.irf.com RD-0609 11 The duration of the Preheat mode as well as the mode of operation of the ballast are determined by the voltage on the CPH pin of the IRS2166D. At the completion of the UVLO mode, Preheat mode is entered and an internal current source is activated at the CPH pin of the IR2166, which begins to charge up capacitor CPH. The ballast remains in the Preheat mode until the voltage on the CPH pin exceeds the Ignition Ramp mode threshold (10 V). 16. Ignition Ramp Mode At the completion of the Preheat mode the ballast switches to the Ignition Ramp mode and the frequency ramps down to the run frequency. Resistor RPH is no longer connected directly in parallel with resistor RT so the run frequency is determined only with RT. During this ramping downward of the frequency, the voltage across the lamp increases in magnitude as the frequency approaches the resonant frequency of the LC load circuit until the lamp ignition voltage is exceeded and the lamp ignites. The maximum ignition voltage that can be generated is determined from the value of RCS, but in any case the ignition frequency must be higher than the run frequency. Figure 5 shows the ramping of voltage appearing across the lamp. Fig. 5: Ignition ramp (crossed lamps) During the Ignition Ramp mode the voltage on the CPH pin of the IRS2166D continues to ramp up until the voltage at the CPH pin of the IRS2166D exceeds the Run mode threshold (13 V). Overcurrent sensing and fault counter are enabled during Preheat and Ignition modes. A full explanation of the functionality of the over-current sensing is in the section on Fault Mode. www.irf.com RD-0609 12 17. Run Mode During the Run mode the frequency is shifted to the run frequency. The run frequency is determined only by RT. The 1 V to 3 V end-of-life window comparator in the SD pin is enabled at the beginning of the Run mode. The full explanation of the functionality of the end-of-life sensing is in the section on Fault Mode. The Run mode frequency is that at which the lamp is driven to the lamp manufacturer’s recommended lamp power rating. The running frequency of the lamp resonant output stage for selected component values is defined as, 1 frun = 2π 2 2 2 ⎡ 1 1 ⎛ PLamp ⎞ ⎛ PLamp ⎞ ⎤ − 2⎜ − 2⎜ ⎟ + ⎢ ⎟ ⎥ −4 ⎝ CV 2 Lamp ⎠ ⎝ CV 2 Lamp ⎠ ⎥⎦ LC ⎣⎢ LC ⎛ 2VDCbus ⎞ 1− ⎜ ⎟ ⎝ VLampπ ⎠ 2 L2 C 2 where, L C PLamp VLamp = = = = Lamp resonant circuit inductor (L3) Lamp resonant circuit capacitor (C14) Lamp running power Lamp running voltage amplitude (H) (F) (W) (V) Figure 6 shows the voltage appearing across the lamp during Startup, Preheat, Ignition Ramp and Run modes. Fig. 6: Preheat, Ignition Ramp and Run Voltage in the lamp www.irf.com RD-0609 13 18. Normal Power Down and Brown-Out Reset A normal power down occurs when the AC line voltage is disconnected from the ballast. A brown-out condition occurs when the AC line is disconnected momentarily. When either of these conditions occurs, the COMP pin voltage gets limited by the zener diode DCOMP causing the PFC on-time to become limited and the voltage on the VBUS pin of the IRS2166D to drop below the undervoltage reset threshold (3 V). VCC will then be discharged below the power down threshold (UVLO-) and the ballast will go into UVLO mode. The ballast control oscillator is stopped, the half-bridge and PFC gate driver outputs (LO, HO and PFC) are turned off and the IRS2166D goes into its UVLO/micro-power mode and the bus voltage collapses. When the AC line returns, VCC will increase again above UVLO+ and the ballast will restart in Preheat mode. 19. Lamp Removal and Auto-Restart When the lamp is removed, the SD pin will pull above the 5 V shutdown threshold via the external pull-up resistor RPU. The ballast will remain in a non-latched shutdown condition with LO, HO, and the PFC gate drive outputs off. When the lamp is re-inserted, the lower filament will pull the SD pin back below 3 V and the ballast will restart in Preheat mode. 20. Fault Mode Fault mode is when the ballast driver is shutdown due to the detection of a lamp fault. Note that when the ballast is in this Fault mode the power factor correction section of the ballast is also shutdown and the bus voltage will drop to the non-boosted/unregulated level. There are several lamp fault conditions that can put the ballast into the Fault mode. The lamp fault conditions detected include: hard-switching detection, over-current detection (CS pin) and end-of-life or no load detection (SD pin). Resistor RCS in the source lead of the low-side MOSFET (MHS) serves as the current sensing point for the halfbridge, which is used to detect these lamp fault conditions. In operation when the half-bridge is oscillating, a voltage appears across RCS whenever the low-side MOSFET, MHS, is turned on or the high-side MOSFET, MLS, is turned off. The magnitude of this voltage directly relates to the current in the lamp resonant circuit. Figure 7 shows the voltage which appears across resistor RCS during normal Run mode conditions. Also shown in Figure 7 are the gate drive signals for the low-side MOSFET (LO pin) and the high-side MOSFET (HO-VS pin). www.irf.com RD-0609 14 Figure 7: Normal Run mode; Upper trace: voltage across RCS, Middle trace: IC2 LO pin voltage, Lower trace: IC2 HO-VS pin voltage During the Preheat and Ignition modes the over-current threshold at the CS pin and internal fault counter are enabled. During Run mode the fault counter is disabled. If at any time thereafter the voltage magnitude across resistor RCS rises above the over-current threshold (1.3 V) for a single event, a lamp fault condition is signaled and the half-bridge output MOSFETs’, (MHS and MLS) are turned off and the ballast goes into Fault mode. During Preheat and Ignition, a lamp fault condition is signaled only after 25 cycles to avoid triggering this protection in the case of a current transient that can happen during normal ignition. An over-current condition can occur if the lamp fails to ignite or the lamp is broken (an open circuit cathode or broken lamp). Figure 8 shows the voltage across resistor RCS and the voltage at the half-bridge (VS pin) when the ballast detects a failure to ignite the lamp and goes into Fault mode. Figure 9 shows the voltage appearing across the lamp during the tail end of the Preheat mode and the Ignition Ramp mode for a failure of the lamp to ignite condition. If a cathode is broken (open circuit) the half-bridge output hard-switches and each time the low-side MOSFET (MHS) is turned on a large current pulse occurs and thus a large voltage pulse occurs across resistor RCS signaling a fault, Figure 10 shows this hard-switching condition. The ballast will remain in Fault mode until either the line voltage is reset or a lamp replacement is performed. www.irf.com RD-0609 15 CS VS Figure 8: Failure of lamp to ignite condition (lamp filaments good): Upper trace: voltage across RCS, Lower trace: voltage at VS pin Figure 9: Failure of lamp to ignite condition (lamp filaments good): Lamp voltage during end of Preheat and Ignition Ramp modes www.irf.com RD-0609 16 Figure 10: Hard-switching condition (upper filament open): Upper trace: voltage across RCS, Middle trace: IC2 LO pin voltage, Lower trace: IC2 HO-VS pin voltage During an end-of-life lamp fault condition, the lamp voltage can increase or decrease asymmetrically. The resulting excessive voltage across the lamp filaments can cause the lamp ends to reach temperatures high enough to melt the tube glass. The lamp can then fall out of the fixture and cause harm or damage. To protect against this condition, resistors REOL1, REOL2, REOL3, REOL4, and zener diodes DEOL1 and DEOL2, are used for end-of-life protection. The end-of-life window comparator at the SD/EOL pin is enabled in Run Mode. If the voltage on SD/EOL pin falls outside the range of the internal 1 V to 3 V window comparator, the IC will enter Fault Mode. The SD/EOL pin is internally biased at 2 V with an internal +/-10 µA OTA. The value of REOL4, DEOL1 and DEOL2 are selected such that the SD/EOL pin remains at 2 V during normal operation, but increases above 3 V or decreases below 1 V during an end-of-life fault condition. The lamp voltage end-of-life threshold can be adjusted by changing the value of resistor REOL4 and/or zener diodes DEOL1 and DEOL2 (a threshold of 30% higher than the nominal running lamp voltage is typical). 21. Current Mode Configuration The same PCB can be configured for current mode heating. It is needed to remove the Jumpers JV1 and JV2 and to introduce the Jumpers JC1 and JC2. It could be also useful to add a resistor RDC in parallel to CDC because in this configuration striations (visible dark rings) on the lamps can occur particularly when the lamp has been off for some time and is cold. The value should in the order of 100 kΩ 0.5 W. We suggest the use of the Ballast Designer software to determine the values of the components to use in this configuration. www.irf.com RD-0609 17 22. Design Procedure for Different Lamp Types To adapt the design to different types of lamps you need to adjust the values of: LPFC, MPFC, MLO, MHO, CPH, RT, RPH, RCS, CT, REOL4, CRES, and LRES. Do not change any others values! 1) Use the Ballast Designer Software V4.0 (visit IR website to download) to set the values of LRES, CRES, LPFC, MPFC, MLO and MHO, CT, and to set the starting values of CPH, RT, RPH, RCS and LPFC. Cross both lamps (i.e. connect a filament or resistor to each lamp cathode position but not a good lamp) and measure the lamp voltage at ignition using a storage oscilloscope. 1) Set RCS to get the right maximum ignition voltage (decrease RCS to increase the ignition voltage) Cross both lamps (i.e. connect a filament or resistor to each lamp cathode position but not a good lamp) and measure the lamp voltage at ignition using a storage oscilloscope. Connect both lamps correctly and measure the input power 2) Set RT to set the power on the lamp (increase RT to decrease the frequency and increase the power on the lamp) 3) Set RPH to set the right preheat frequency (increase RPH to decrease the preheat frequency and increase the preheat current) In the case of voltage mode heating, increase CH1 and CH2 to increase the preheat voltage (use 6-7 turns in the secondary of LRES). 4) Select CPH to set the preheat time (increase CPH to increase the preheat time) 5) Verify the value of LPFC at each limit of the line/load range: Maximum input voltage: If the COMP pin becomes less than 400 mV the PFC will not operate in a stable manner and it is necessary to increase LPFC. Minimum input voltage: If the PFC does not operate in a stable manner and audible noise can be heard from LPFC, it is necessary to decrease LPFC. 6) Set ROL4 to set the end-of-life protection to a percentage of the lamp voltage. For example, to set the protection threshold to 30% of the lamp voltage: The value of REOL4 is chosen to have the SD pin varying between 2-0.7 V and 2+0.7 V during normal operations and exceeding the window comparator limits (less than 1 V or more than 3 V) with 30% change in the voltage of the lamp. (Fine tuning of this threshold can be done by trying different REOL4 values on the test bench) www.irf.com RD-0609 18