Application Note AN-1013 IR21571: Dual Lamp Series Configuration By T. Ribarich, E. Thompson, A. Mathur Table of Contents Page Functional Description..........................................................................1 Measurements .....................................................................................4 Schematic Diagram ..............................................................................7 Bill of Materials.....................................................................................8 Dual lamps connected in series is the popular conventional magnetic ballast retrofit configuration for the U.S. lighting market. The center lamp filaments are connected in parallel which results in six connections to the lamps from the output of the ballast. This retrofit configuration is accomplished using the IR21571 and some modifications to the ballast output stage. Through externally programmable components, the IR21571 affords flexibility of various features such as preheat time and frequency, ignition ramp characteristics, and running mode operating frequency. Comprehensive protection features protect the circuit against conditions such as lamp strike failures, filament failures, low DC bus, thermal overload, or ramp failure during normal operation. This circuit switches off both lamps when one is taken out, and automatically restarts when both lamps are in place. www.irf.com AN-1013 cover APPLICATION NOTE AN-1013-A International Rectifier • 233 Kansas Street El Segundo CA 90245 USA IR21571: Dual Lamp Series Configuration By T. Ribarich, E. Thompson, A. Mathur TOPICS COVERED Introduction Functional Description Schematic Diagrams Waveforms Bill of Materials Dual lamps connected in series is the popular conventional magnetic ballast retrofit configuration for the U.S. lighting market. The center lamp filaments are connected in parallel which results in six connections to the lamps from the output of the ballast. This retrofit configuration is accomplished using the IR21571 and some modifications to the ballast output stage. Through externally programmable components, the IR21571 affords flexibility of various features such as preheat time and frequency, ignition ramp characteristics, and running mode operating frequency. Comprehensive protection features protect the circuit against conditions such as lamp strike failures, filament failures, low DC bus, thermal overload, or ramp failure during normal operation. This circuit switches off both lamps when one is taken out, and automatically restarts when both lamps are in place. FUNCTIONAL DESCRIPTION The output stage circuitry for the series configuration is shown in Figures 1 and 2. The configuration is similar to that for a single lamp except the middle filaments must be heated as well. The configuration in Fig. 2a shows the middle filaments connected in parallel. The primary to secondary turns ratio for transformer L4 is 1:2, which doubles the current for the two middle filaments. As filament current flows during preheat, the filament with the smaller resistance draws more current. However, as the filament heats up the resistance also increases which causes more current to flow through the second filament. As the second filament heats up then current flows again through the first filament. This positive temperature coefficient effect keeps the currents balanced in the filaments continuously such that they are heated equally during the preheat mode. The configuration in Fig. 2b shows the filaments connected in series which may be a desirable configuration as well. The same current flows through each filament resulting in a turns ratio for L4 of 1:1. For either configuration, if one of the middle cathodes is removed, an over-current condition is sensed at the current sense pin. This causes a fault condition and the IC shuts down. The micro-power current supply resistor is connected to VCC from the AC rectified line through the upper filament. When the upper filament is removed, the micro-power current is no longer supplied to the IC and VCC falls below under voltage lockout (UVLO). When the lamp is re-inserted, VCC increases again above the UVLO+ threshold and the IC returns to the preheat mode. When the lower cathode is in place, the Shutdown Pin (SD) is kept low through resistor R17. When the lower filament is removed, VCC pulls SD high through resistor R18. At this point, both IR21751 half-bridge outputs are pulled low, and the IC enters micro-power mode. When the lower filament is reinserted, SD is pulled low again and the IC returns to the preheat mode. Additional protection features such as low-line conditions, over-temperature and near-resonance detection are also provided by the IC. (For additional information on these protection features please see the IR21571 datasheet.) www.irf.com 1 R14A R14B VRECT(+) VBUS(+) R14C R14D R12 C17 C17 R11 R13 C9 1 CPH CRAMP 16 L3 M2 C15 2 CPH VS 15 3 RPH VB 14 4 RT VCC 13 5 RUN COM 12 6 CT LO 11 7 DT RPH RSTART (2) D4 C11 (1) (1) C16 C12 M3 D5 R16 CS D6 10 ROC R18 R17 OC L4 (1) R15 RDT 8 L4 R19 C10 CSTART CT HO IR21571 RT VDC SD 9 CCS C13 RCS COC VBUS(-) Note: Thick traces represent high-frequency, high-current paths. Lead lengths should be minimized to avoid high-frequency noise problems. The above configuration shows the middle filaments connected in parallel. The configuration at the right shows the middle filaments connected in series with the secondary windings of L4. Figure 1, Ballast output stage for dual lamp series connection (both parallel and series middle filament configurations). 2 www.irf.com R14A R14A R14B VRECT(+) R14B VRECT(+) L3 L3 C17 C17 R14D R14D R14C R14C L4 L4 (2) VCC (1) (1) VCC R18 SD (1) R18 R17 SD VBUS(-) R17 VBUS(-) Fig. 2a Fig. 2b Figure 2, Series lamp connection showing both parallel and series filament configurations. www.irf.com 3 MEASUREMENTS Figures 3 and 4 show the lamp filament currents during preheat mode for the parallel center filament configuration. The middle filament current is twice the upper and lower filaments due to the 2:1 winding ratio of transformer L4. Figures 5 and 6 show equal heating in all filaments. Figure 3. Upper and Lower Filament Currents (1A/Div) Figure 5. Upper and Lower Filament Voltages 4 Figure 4. Middle Filament Currents (1A/div) Figure 6. Middle Filament Voltages www.irf.com MEASUREMENTS (Cont.) Figure 7 and 8 show the lamp filament currents during ignition for the parallel center filament configuration. The middle filament current is twice the upper and lower filaments due to the 2:1 winding ratio of transformer L4. Figure 9 shows the ignition voltage across both lamps. For dual lamps in series, this voltage is usually set at least 1.5 times the required ignition voltage for a single lamp. Figure 7. Upper and Lower Filament Ignition Currents (1A/Div) Figure 8. Middle Filament Ignition Current (1A/Div) Figure 9, Lamp Ignition Voltage www.irf.com 5 MEASUREMENTS (Cont.) Figures 10 and 11 show the lamp filament currents during preheat, ignition and running modes for the parallel center filament configuration. The middle filament current is twice the upper and lower filament currents due to the 2:1 winding ratio of transformer L4. Figure 12 shows the total lamp voltage over both lamps during normal preheat, ignition and running modes Figure 10. Upper and Lower Filament Current (1A/Div) Figure 11. Middle Filament Current (1A/div). Figure 12. Lamp Voltage 6 www.irf.com SCHEMATIC DIAGRAM www.irf.com R14A R14B L2 D2 R8 R14C R14D R12 R1 L1 L C17 R4 RV1 C2 D1 R2 N D3 R11 C14 BR1 R13 C9 R5 1 VDC HO 16 2 CPH VS 15 3 RPH VB 14 M2 C8 GND 1 8 2 7 C1 R7 3 MC34262 CRAMP M1 C7 RT C10 RPH 6 4 RT 5 RUN 6 CT 7 DT CSTART C5 4 5 R6 R3 RSTART C4 CT R10 IR21571 C3 R9 C6 L3 C15 CPH R19 VCC L4 (2) D4 (1) 13 C11 C16 C12 COM 12 R15 LO 11 CS 10 M3 D5 RDT R16 D6 R18 ROC R17 8 OC SD 9 CCS C13 RCS COC Note: Thick traces represent high-frequency, high-current paths. Lead lengths should be minimized to avoid high-frequency noise problems C17 The schematic above shows the middle filaments connected in parallel. In this configuration, L4 is wound in a 1:2 ratio. The schmatic at the right shows the middle filaments connected in series with the secondary winding of L4. In this configuration, L4 is wound in a 1:1 ratio. L4 (1) (1) 7 BILL OF MATERIALS Item # 1 Qt y 1 Manufacturer Part Number Description Reference International Rectifier DF10S Bridge Rectifier, 1A 1000V 2 1 Roederstein WY0222MCMBF0K Capacitor, 2.2nF 275 VAC Y Cap C1 3 1 Roederstein F1772433-2200 Capacitor, 0.33uF 275 VAC C2 BR1 4 2 Wima MKP10 Capacitor, 0.01uF 400 VDC C3, C15 5 2 Panasonic ECU-V1H103KBM Capacitor, 0.01uF SMT 1206 C4, CSTART 6 3 Panasonic ECJ-3YB1E474K Capacitor, 0.47uF SMT 1206 C5, C6, C13 7 4 Panasonic ECU-V1H104KBM Capacitor, 0.1uF SMT 1206 C9, COC, C10, C11 8 1 Panasonic EEU-EB2V100 Capacitor, 10uF 350VDC 105C C8 9 1 Panasonic ECU-V1H471KBM Capacitor, 470pF SMT 1206 CT 10 1 Panasonic ECJ-3VB1E334K Capacitor, 0.33uF SMT 1206 CRAMP 11 1 Panasonic ECJ-3VB1E274K Capacitor, 0.27uF SMT 1206 CPH 12 1 Panasonic ECE-A1HGE010 Capacitor, 1uF 50VDC 105C C12 13 1 Vitramon 1812A152KXE Capacitor, 1.5nF 1KV SMT 1812 C14 14 1 Vitramon 1812A102KXE Capacitor, 1nF 1KV SMT 1812 C16 15 1 Panasonic ECW-H16682JV Capacitor, 6.8nF 1.6KV C17 16 1 Panasonic ECU-V1H101KBM Capacitor, 100pF SMT 1206 CCS D1, D5, D6 17 3 Diodes LL4148DICT-ND Diode, 1N4148 SMT DL35 18 2 International Rectifier 10BF60 Diode, SMT SMB D2, D4 19 1 Diodes ZMM5250BCT Diode, Zener 20V SMT DL35 D3 20 1 Motorola MC34262 IC, Power Factor Controller IC1 21 1 International Rectifier IR21571 IC, Ballast Driver IC2 22 1 Panasonic ELF-15N007A EMI Inductor, 1X10mH 0.7Apk L1 23 1 R.G. Allen RGA-K86960 PFC Inductor, 2.0mH 2.0Apk L2 24 1 Inductor, 2mH 3.0Apk L3 25 1 Inductor, 1:2, EF20, no gap L4 50 Turns:100 Turns, AWG 28 Inductor, 1:1, EF20, no gap 100 Turns:100 Turns, AWG 28 26 3 International Rectifier IRF840 Transistor, MOSFET M1, M2, M3 27 5 Panasonic ERJ-8GEYJ680K Resistor, 680K ohm SMT 1206 R1, R2, R4, R5, R17 28 2 Panasonic ERJ-8GEYJ10K Resistor, 10K ohm SMT 1206 R3, RSTART 29 1 Panasonic ERJ-8GEYJ8.2K Resistor, 8.2K ohm SMT 1206 R6 30 1 Panasonic ERJ-8GEYJ100K Resistor, 100K ohm SMT 1206 R7 31 1 Panasonic ERJ-8GEYJ22K Resistor, 22K ohm SMT 1206 R8 32 3 Panasonic ERJ-8GEYJ22 Resistor, 22 ohm SMT 1206 R9, R13, R15 33 1 Dale CW-1/2 Resistor, 0.5 ohm ½ watt R10 34 1 Panasonic ERJ-8GEYJ56K Resistor, 56K ohm SMT 1206 R11 35 1 Yageo 2.2MQBK-ND Resistor, 2.2megohm ¼ watt R12 36 1 Dale CW-1/2 Resistor, 0.68 ohm ½ watt RCS 37 1 Panasonic ERJ-8GEYJ6.8K Resistor, 6.8K ohm SMT 1206 RDT 38 1 Panasonic ERJ-8GEYJ30K Resistor, 30K ohm SMT 1206 ROC 39 1 Panasonic ERJ-8GEYJ68K Resistor, 68K ohm SMT 1206 RPH 40 1 Panasonic ERJ-8GEYJ20K Resistor, 20K ohm SMT 1206 RT 41 4 Yageo 110KQBK-ND Resistor, 110K ohm ¼ watt R14A, R14B, R14C, R14D 42 1 Panasonic ERJ-8GEYJ1K Resistor, 1K ohm SMT 1206 R16 43 1 Panasonic ERJ-8GEYJ1.0M Resistor, 1.0megohm SMT 1206 R18 44 1 Yageo 100KQBK-ND Resistor, 100K ohm ¼ watt R19 45 1 Panasonic ERZ-V05D471 Transient Suppressor RV1 Total 67 Data and specifications subject to change without notice. 8 10/30/2000 www.irf.com