Application Note AN-1019 IR21571: Dual Lamp Ballast: Parallel Configuration By T. Ribarich, E. Thompson, A. Mathur, International Rectifier Table of Contents Page Introduction ..........................................................................................1 Functional Description (Variation I) ......................................................1 Schematic Diagram (Variation I) ..........................................................3 Measurements (Variation I) ..................................................................4 Bill of Materials (Variation I) .................................................................6 Functional Description (Variation II) .....................................................7 Schematic Diagram (Variation II) .........................................................8 Bill of Materials (Variation II) ................................................................9 Driving two lamps in parallel results in lower voltage stress on the ballast output stage components, the wiring, and the fixture sockets. Additionally, the resonant L and C associated with the lamps will be less sensitive to component tolerances due to the lower running lamp voltages compared to the series configuration. For these reasons, the parallel configuration is becoming more popular. The IR21571 can be used in a ballast to control parallel lamp configurations. 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, and ramp failure during normal operation. Two variations of this circuit are included in this application note. The first one switches off both lamps when one is taken out, and automatically restarts when both lamps are in place. The second variation allows one lamp to remain running when the other is removed. When the lamp is reinserted, the ballast restarts in the pre-heat mode. www.irf.com AN-1019 cover APPLICATION NOTE AN-1019 International Rectifier • 233 Kansas Street El Segundo CA 90245 USA IR21571: Dual Lamp Ballast: Parallel Configuration By T. Ribarich, E. Thompson, A. Mathur, International Rectifier TOPICS COVERED Introduction Functional Description Schematic Diagrams Measurements Bill of Materials INTRODUCTION Driving two lamps in parallel results in lower voltage stress on the ballast output stage components, the wiring, and the fixture sockets. Additionally, the resonant L and C associated with the lamps will be less sensitive to component tolerances due to the lower running lamp voltages compared to the series configuration. For these reasons, the parallel configuration is becoming more popular. The IR21571 can be used in a ballast to control parallel lamp configurations. 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, and ramp failure during normal operation. Two variations of this circuit are included in this application note. The first one switches off both lamps when one is taken out, and automatically restarts when both lamps are in place. The second variation allows one lamp to remain running when the other is removed. When the lamp is reinserted, the ballast restarts in the pre-heat mode. FUNCTIONAL DESCRIPTION (Variation I: Both lamps turn off when one is removed) The output stage circuitry for a dual lamp configuration is shown in Figure 1. This is the portion of the ballast that is controlled by the IR21571. The design is similar to that for a single lamp; with the addition of a second lamp resonant circuit connected in parallel. The second lamp in parallel is connected in a manner that mirrors the immediate circuitry surrounding the first bulb. This provides the exact same resonant L and C, and basic protective circuitry for both bulbs due to their parallel setting. Protective features include DC Bus Voltage Detection and Half Bridge Current Sensing and Protection. (For additional information on these protective features please see Page 2 of the IR21571 datasheet.) Lamp detection and automatic restart work similarly to a single lamp configuration. Both lower filament sensing networks are OR-ed into the SD pin through resistors R17A and R17B. If either lamp is removed, the SD pin is pulled above the internal turn-off threshold of 2V, and the half-bridge is disabled. When both lamps are in place, the shutdown pin falls below the internal 1.7V threshold and the IC re-initiates the preheat sequence www.irf.com 1 AC Rectified Line VBUS (+) R12 R14 R11 R13 CRAMP VDC HO 16 2 CPH VS 15 3 RPH VB 14 RT 5 RUN 6 CT RSTART IR21571 4 CSTART CT C16 C10 RPH RT R21 M2 L3A D3 VCC 13 COM 12 LO 11 R15 R16 C11 L3B C15 C12 C14 R17 D6 M3 D4 RDT R18 7 DT CS 10 R20A D5 C17B CPH 1 C17A C9 R19A ROC 8 OC SD 9 C13 COC CCS RCS R20B R19B VBUS (-) Figure 1: Ballast output stage circuitry for the dual lamp parallel configuration (Variation I). 2 www.irf.com Schematic Diagram (Variation 1) www.irf.com L2 D2 R8 R12 R1 L1 R14 L R4 R11 BR1 R13 C9 R5 GND 1 8 2 7 C8 CPH 1 VDC HO 16 2 CPH VS 15 3 RPH VB 14 C1 R7 3 MC34262 CRAMP M1 C7 6 4 RT 5 RUN CSTART C5 4 5 R6 R3 RSTART 6 C4 CT CT VCC 13 COM 12 R15 C15 R16 C11 C12 C14 R17 LO D6 11 M3 D4 R18 7 DT CS 10 8 OC SD 9 R20A R19A ROC C13 COC L3B L3A D3 RDT R10 C16 C10 RPH RT IR21571 C3 R9 C6 R21 M2 CCS RCS R20B R19B Note: Thick traces represent high-frequency, high-current paths. Lead lengths should be minimized to avoid high-frequency noise problems D5 C17B D1 R2 N C17A RV1 C2 3 MEASUREMENTS (VARIATION I: Both lamps turn off when one is removed) The waveforms shown in Figures 2 and 3 were captured during the ignition mode. They are similar for either lamp in the parallel configuration. Dummy filament resistors have been inserted to simulate a lamp non-strike fault condition. This forces the over-current threshold of the IR21571 to be exceeded during igntion mode and the half bridge is disabled. It is at this time that maximum inductor current and lamp voltage are measured. Figures 4 and 5 show the filament current and lamp voltage during preheat and igntion modes. Figures 6 and 7 show the filament current and lamp voltage during preheat, ignition and run modes. Figure 8 shows a typical lamp filament voltage during preheat mode. Figure 2: Upper and lower filament currents during ignition mode (1A/Div). Figure 4: Upper and lower filament current during preheat and ignition (1A/Div). 4 Figure 3: Lamp ignition voltage during ignition mode. Figure 5: Lamp voltage during preheat and ignition www.irf.com Figure 6: Upper and lower filament current during preheat, ignition and run modes (1A/Div). Figure 7: Lamp voltage during preheat, ignition and run modes. Figure 8: Preheat filament voltage www.irf.com 5 Bill o f Materials ( VARIATION I) 6 Item # Q ty 1 1 Int’l R ectifier M anufacturer 2 1 3 1 4 P art N um ber D escription R eference D F 10S B ridge R ectifier, 1A 1000V BR1 R oederstein W Y 0222M C M BF 0K C apacitor, 2.2nF 275 V AC Y C ap C1 R G Allen 275MK P 334K C apacitor, 0.33uF 275 VA C C2 2 R G Allen 400MP S 104K06A C apacitor, 0.1uF 400 V D C C 3, C 16 5 2 R G Allen S 1206Z103K 1H R N C apacitor, 0.01uF S MT 1206 C 4, C S TA R T 6 3 R G Allen S 1206Z 474K1H R N C apacitor, 0.47uF S MT 1206 C 5, C 6, C 13 7 1 R G Allen 1H 2R 2M 50T B15X11 C apacitor, 2.2uF 50VD C 105C C7 8 1 R G Allen 2W 10M 450TB 113X21 C apacitor, 10uF 450VD C 105C C8 9 4 R G Allen S 1206Z 104K1H R N C apacitor, 0.1uF SM T 1206 C 9,C 10, C 11, C O C 10 2 R G Allen S 1206Z 334K1H R N C apacitor, 0.33uF S MT 1206 CPH, CRAMP 11 1 R G Allen 1H 4R 7M 50T B15X11 C apacitor, 4.7uF 50VD C 105C C 12 12 1 R G Allen S 1812N 152K 3A R N C apacitor, 1.5nF 1K V S MT 1812 C 14 13 1 R G Allen S 1812N 102K 3A R N C apacitor, 1nF 1K V SM T 1812 C 15 14 2 R G Allen 1600P P SB 103K09A C apacitor, 10nF,1600V C 17A , C 17B 15 1 R G Allen S 1206N 471K 2A R N C apacitor, 470pF SM T 1206 CT 16 1 R G Allen S 1206N 101K 2A R N C apacitor, 100pF SM T 1206 CCS 17 2 D iodes LL4148D IC T-N D D iode, 1N 4148 S M T D L35 D 1, D 4 18 2 Int’l R ectifier 10B F60 D iode, SM T S MB D 2, D 3 19 2 D iodes Z MM 5250B C T D iode, Zener 20V S MT D L35 D 5, D 6 20 1 ST L6560 IC , Pow er F actor C ontroller IC 1 21 1 Int’l R ectifier IR 21571 IC , Ballast D river IC 2 22 1 P anas onic E LF -15N 007A E MI Inductor, 1X10m H 0.7Apk L1 23 1 R G Allen R G A -K 86960 P FC Inductor, 2.0m H 2.0Apk L2 24 2 R G Allen R G A 97408C Inductor, 2.0m H , 3.0A pk L3A ,L3B 25 3 Int’l R ectifier IR F840 T ransistor, M O SF E T M 1, M 2, M3 26 6 R G Allen C R 32C 684J T R esistor, 680K ohm S M T 1206 27 2 R G Allen C R 32C 103J T R esistor, 10K ohm SM T 1206 R 1, R 2, R 4, R 5, R 19A , R 19B R 3, R S TA R T 28 1 R G Allen C R 32C 822J T R esistor, 8.2K ohm S M T 1206 R6 29 2 R G Allen R 25G 104JT R esistor, 100K ohm ¼ w att R 7, R 21 30 1 R G Allen C R 32C 223J T R esistor, 22K ohm SM T 1206 R8 31 3 R G Allen C R 32C 220J T R esistor, 22 ohm S MT 1206 R 9, R 13, R 17 32 1 R G Allen R S MF 1/2W 0R 5F T R esistor, 0.5 ohm ½ w att R 10 R 11 33 1 R G Allen C R 32C 563J T R esistor, 56K ohm SM T 1206 34 1 R G Allen R 25G 225JT R esistor, 2.2Mohm ¼ w att R 12 35 1 R G Allen R 25G 394JT R esistor, 390K ohm ¼ w att R 14 36 2 R G Allen C R 32C 100J T R esistor, 10 ohm S MT 1206 R 15, R 16 37 1 R G Allen C R 32C 102J T R esistor, 1K ohm S MT 1206 R 18 38 2 R G Allen C R 32C 105J T R esistor, 1.0M ohm S M T 1206 R 20A , R 20B 39 1 R G Allen R S MF 1/2W 0R 7F T R esistor, 0.7 ohm ½ w att RCS 40 1 R G Allen C R 32C 562J T R esistor, 5.6K ohm S M T 1206 RDT 41 1 R G Allen C R 32C 513J T R esistor, 51K ohm SM T 1206 ROC 42 1 R G Allen C R 32C 823J T R esistor, 82K ohm SM T 1206 RPH 43 1 R G Allen C R 32C 203J T R esistor, 20K ohm SM T 1206 RT 44 1 R G Allen R V 05K 300 T ransient S uppressor RV1 Total 69 www.irf.com FUNCTIONAL DESCRIPTION (VARIATION II: One lamp remains running when the other is removed) Figure 10 shows the output stage for the parallel lamp configuration with the additional control circuitry for lamp presence detection and automatic restart. When one of the lamps is removed, the base of Q1 is pulled high. This turns Q1 on but does not affect SD. The other lamp will therefore remain running. When the lamp is re-inserted, Q1 is turned off and a momentary voltage pulse appears at the SD pin due to C18, R20 and R21. This pulse momentarily pulls SD above the 2V threshold and resets the IR21571. As SD falls below 1.8V, the IR21571 is restarted in the preheat mode. This assures proper heating of the filaments before the lamp is re-ignited. If both lamps are removed, hard-switching will occur at the half-bridge and the resulting currents will cause the voltage across the current sensing resistor, RCS, to exceed the over-current threshold programmed by resistor ROC. This will disable the half-bridge driver outputs HO and LO. AC Rectified Line VBUS (+) R12 R13 R11 R14 C9 CPH 1 VDC HO 16 2 CPH VS 15 3 RPH VB 14 R19 M2 C10 CRAMP RT 4 RT 5 RUN 6 CT CSTART RSTART IR21571 RPH VCC 13 COM 12 LO 11 C16 L3A D3 C11 L3B C15 R15 R16 C14 C12 R17 M3 D6 D4 7 DT CS 10 8 OC SD 9 ROC C17B R18 RDT C17A CT D5 RCS COC CCS C13 VBUS (-) R23 R20 R25 Q1 R22 C18 R24 C19 R21 Figure 10: Ballast output stage with additional circuitry for Variation II. www.irf.com 7 Schematic Diagram (Variation II) 8 L2 R8 D2 R12 R1 L1 R13 L R4 RV1 C2 R11 D1 R2 N BR1 R14 C9 R5 1 VDC HO 16 2 CPH VS 15 3 RPH VB 14 R19 M2 C8 8 2 7 C1 3 MC34262 R9 C6 CRAMP M1 C7 RT RPH 6 4 RT 5 RUN CSTART C5 4 5 R6 R3 RSTART C4 IR21571 C3 C16 C10 R7 L3A D3 VCC 13 COM 12 C11 L3B C15 R15 R16 C14 C12 R17 6 CT LO 11 7 DT CS 10 8 OC SD 9 M3 D6 D4 CT R18 RDT R10 ROC D5 RCS COC CCS C13 R20 Note: Thick traces represent high-frequency, high-current paths. Lead lengths should be minimized to avoid high-frequency noise problems R23 R25 Q1 R22 C18 www.irf.com R24 C19 R21 C17B 1 CPH C17A GND Bill of Materials (Variation II) Item # Qty Manufacturer 1 1 International Rectifier DF10S Bridge Rectifier, 1A 1000V BR1 2 1 Roederstein WY0222MCMBF0K Capacitor, 2.2nF 275 VAC Y Cap C1 3 1 RG Allen 275MKP334K Capacitor, 0.33uF 275 VAC C2 4 2 RG Allen 400MPS104K06A Capacitor, 0.1uF 400 VDC C3, C16 Part Number Description Reference 5 3 RG Allen S1206Z103K1HRN Capacitor, 0.01uF SMT 1206 C4, CSTART, C18 6 3 RG Allen S1206Z474K1HRN Capacitor, 0.47uF SMT 1206 C5, C6, C13 7 1 RG Allen 1H2R2M50TB15X11 Capacitor, 2.2uF 50VDC 105C C7 8 1 RG Allen 2W10M450TB113X21 Capacitor, 10uF 450VDC 105C C8 9 4 RG Allen S1206Z104K1HRN Capacitor, 0.1uF SMT 1206 C9,C10, C11, COC 10 2 RG Allen S1206Z334K1HRN Capacitor, 0.33uF SMT 1206 CPH, CRAMP 11 1 RG Allen S1206Z474K1HRN Capacitor, 0.47uF SMT 1206 C19 12 1 RG Allen 1H4R7M50TB15X11 Capacitor, 4.7uF 50VDC 105C C12 13 1 RG Allen S1812N152K3ARN Capacitor, 1.5nF 1KV SMT 1812 C14 14 1 RG Allen S1812N102K3ARN Capacitor, 1nF 1KV SMT 1812 C15 15 2 RG Allen 1600PPSB103K09A Capacitor, 10nF,1600V C17A, C17B 16 1 RG Allen S1206N471K2ARN Capacitor, 470pF SMT 1206 CT 17 18 1 2 RG Allen Diodes S1206N101K2ARN LL4148DICT-ND Capacitor, 100pF SMT 1206 Diode, 1N4148 SMT DL35 CCS D1, D4 19 2 International Rectifier 10BF60 Diode, SMT SMB D2, D3 20 2 Diodes ZMM5250BCT Diode, Zener 20V SMT DL35 D5, D6 21 1 ST L6560 IC, Power Factor Controller IC1 22 1 International Rectifier IR21571 IC, Ballast Driver IC2 23 1 Panasonic ELF-15N007A EMI Inductor, 1X10mH 0.7Apk L1 24 1 RG Allen RGA-K86960 PFC Inductor, 2.0mH 2.0Apk L2 25 2 RG Allen RGA97408C Inductor, 2.0mH, 3.0Apk L3A, L3B 26 3 International Rectifier IRF840 Transistor, MOSFET M1, M2, M3 27 4 RG Allen CR32C684JT Resistor, 680K ohm SMT 1206 R1, R2, R4, R5 28 2 RG Allen CR32C103JT Resistor, 10K ohm SMT 1206 R3, RSTART 29 1 RG Allen CR32C822JT Resistor, 8.2K ohm SMT 1206 R6 30 5 RG Allen R25G104JT Resistor, 100K ohm ¼ watt 31 1 RG Allen CR32C223JT Resistor, 22K ohm SMT 1206 R7, R19, R20, R22, R24 R8 32 3 RG Allen CR32C220JT Resistor, 22 ohm SMT 1206 R9, R13, R17 33 1 RG Allen RSMF1/2W0R5FT Resistor, 0.5 ohm ½ watt R10 34 1 RG Allen CR32C563JT Resistor, 56K ohm SMT 1206 R11 35 1 RG Allen R25G225JT Resistor, 2.2Mohm ¼ watt R12 36 1 RG Allen R25G394JT Resistor, 390K ohm ¼ watt R14 37 2 RG Allen CR32C100JT Resistor, 10 ohm SMT 1206 R15, R16 38 1 RG Allen CR32C102JT Resistor, 1K ohm SMT 1206 R18 39 1 RG Allen CR32C514JT Resistor, 510K ohm SMT 1206 R21 www.irf.com 9 Bill of Materials (Variation II) cont. 40 2 RG Allen CR32C105JT Resistor, 1.0M ohm SMT 1206 R23, R25 41 1 RG Allen RSMF1/2W0R7FT Resistor, 0.7 ohm ½ watt RCS 42 1 RG Allen CR32C562JT Resistor, 5.6K ohm SMT 1206 RDT 43 1 RG Allen CR32C513JT Resistor, 51K ohm SMT 1206 ROC 44 1 RG Allen CR32C823JT Resistor, 82K ohm SMT 1206 RPH 45 1 RG Allen CR32C203JT Resistor, 20K ohm SMT 1206 RT 46 1 Zetex FMMT2222ACT Transistor, Bipolar, NPN SMT Q1 47 1 RG Allen RV05K300 Transient Suppressor RV1 Total 75 IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245 Tel: (310) 252-7105 Data and specifications subject to change without notice. 10/21/2000 10 www.irf.com