Application Note AN-1020 IR21571: T5 Lamp Ballast Using Voltage-Mode Filament Heating By T. Ribarich, E. Thompson Table of Contents Page Introduction ..........................................................................................1 Functional Description..........................................................................1 Schematic Diagram ..............................................................................3 Bill of Materials.....................................................................................4 Ballast Input/Output Measurements .....................................................6 T5 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 stage using current-mode filament heating (filaments placed inside L-C tank) will result in excessive lamp voltage during preheat and excessive filament current during running. The output stage has therefore been modified for voltage-mode filament heating using secondary windings off of the resonant inductor. The result is a more flexible ballast output stage necessary for fulfilling the lamp requirements. The IR21571 Ballast Control IC is used to program the ballast operating points and protect the ballast against conditions such as lamp strike failures, filament failures, low DC bus, thermal overload or lamp failure during normal operation. www.irf.com AN-1020 cover APPLICATION NOTE AN-1020 International Rectifier • 233 Kansas Street El Segundo CA 90245 USA IR21571: T5 Lamp Ballast Using Voltage-Mode Filament Heating By T. Ribarich, E. Thompson TOPICS COVERED Introduction Functional Description Schematic Diagrams Bill of Materials INTRODUCTION T5 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 stage using current-mode filament heating (filaments placed inside L-C tank) will result in excessive lamp voltage during preheat and excessive filament current during running. The output stage has therefore been modified for voltage-mode filament heating using secondary windings off of the resonant inductor. The result is a more flexible ballast output stage necessary for fulfilling the lamp requirements. The IR21571 Ballast Control IC is used to program the ballast operating points and protect the ballast against conditions such as lamp strike failures, filament failures, low DC bus, thermal overload or lamp failure during normal operation. FUNCTIONAL DESCRIPTION The output stage has been modified for voltage-mode filament heating (Figure 1). The lamp has been placed outside the under-damped resonant circuit loop which consists of L3 and C15. The filament heating during preheat and dimming is achieved using voltage-mode filament heating with secondary windings off of the resonant inductor (L3A, L3B). The filament heating during preheat (see figure 4) can be adjusted with capacitors C18 and C19. The DC blocking capacitor, C16, is also placed outside the under-damped resonant circuit loop such that it does not influence the natural resonance frequency of L3 and C15. The snubber capacitor, C14, also serves as a charge-pump for supplying the IR21571 and PFC IC. www.irf.com 1 AC Rectified Line L3 (+) C17 L3A (4T) R11 R12 C18 R10 C9 R13 1 VDC HO 16 2 CPH VS 15 M2 C16 CPH C10 3 RPH RPH 4 RT RRUN CSTART 14 VB C14 D3 VCC 13 COM 12 LO 11 R14 R15 C11 5 RUN 6 CT 7 DT CS 10 8 OC SD 9 RSTART CT IR2157-1 CRAMP RT R16 RDT D4 C12 M3 L3B R19 (4T) R17 ROC C19 R18 COC C13 CCS RCS D5 (-) Figure 1. Ballast Output Stage with Voltage Mode Heating 2 www.irf.com Schematic Diagram www.irf.com D6 L3 L2 C17 R7 (4T) R11 R1 L1 L3A D2 R12 L C18 RV1 R4 C2 R10 D1 R2 N BR1 C9 R13 R5 1 VDC HO 16 2 CPH VS 15 M2 C8 C16 CPH GND 1 8 C1 C10 2 3 7 L6560 C6 CRAMP R8 RT 4 6 RT RRUN 5 5 RUN RSTART R6 6 R3 RPH RPH CSTART 4 3 M1 CT IR2157-1 C5 C3 14 VB C14 D3 VCC 13 COM 12 R14 R15 C11 LO D4 C12 R16 M3 L3B 11 R19 C4 CT (4T) RDT R9 R17 7 DT CS 10 8 OC SD 9 ROC C19 R18 COC C13 CCS RCS D5 Note: Thick traces represent high-frequency, high-current paths. Lead lengths should be minimized to avoid high-frequency noise problems 3 Bill of Materials Lamp type: T5/35W/28W/14W Line Input Voltage: 180..255 VAC/50..60 Hz Item # 1 2 3 4 5 Qt 1 1 1 1 2 Manufacturer International Rectifier Roederstein RG Allen RG Allen RG Allen Part Number DF10S WY0222MCMBF0K 275MKP334K 400MPS104K06A S1206Z103K1HRN Description Bridge Rectifier, 1A 1000V Capacitor, 2.2nF 275 VAC Y Cap Capacitor, 0.33uF 275 VAC Capacitor, 0.1uF 400 VDC Capacitor, 0.01uF SMT 1206 BR1 C1 C2 C3 C4, CSTART 6 7 8 9 10 11 12 13 2 1 3 3 1 1 1 1 RG Allen RG Allen RG Allen RG Allen RG Allen RG Allen RG Allen RG Allen S1206Z474K1HRN 2V10M350TB110X20 S1206Z104K1HRN S1206Z224K1HRN 1H4R7M50TB15X11 S1812N152K3ARN 1600PPSA472K09A 400MEF224K08A Capacitor, 0.47uF SMT 1206 Capacitor, 10uF 350VDC 105C Capacitor, 0.1uF SMT 1206 Capacitor, 0.22uF SMT 1206 Capacitor, 4.7uF 50VDC 105C Capacitor, 1.5nF 1KV SMT 1812 Capacitor, 4.7nF,1600V Capacitor, 0.22uF, 400V C5,C6 C8 C10, C11, COC CPH, C9, CRAMP C12 C14 C16 C17 14 15 2 1 RG Allen RG Allen R15W334M1HA5R S1206N471K2ARN Capacitor, 0.33uF, 50V Capacitor, 470pF SMT 1206 C18, C19 CT 16 17 18 1 2 3 RG Allen Diodes International Rectifier S1206N101K2ARN LL4148DICT-ND 10BF60 Capacitor, 100pF SMT 1206 Diode, 1N4148 SMT DL35 Diode, SMT SMB CCS D1, D4 D2, D3, D6 19 20 1 1 Diodes ST ZMM5247BCT L6560 Diode, Zener 17V SMT DL35 IC, Power Factor Controller D5 IC1 21 22 23 24 1 1 1 1 International Rectifier Panasonic RG Allen RG Allen IR21571 ELF-15N007A RGA-K86960 To be determined IC2 L1 L2 L3, L3A,L3B 25 26 27 28 29 30 31 32 33 34 35 36 37 3 2 1 2 1 2 3 2 1 1 1 2 1 International Rectifier RG Allen RG Allen RG Allen RG Allen RG Allen RG Allen RG Allen RG Allen RG Allen RG Allen RG Allen RG Allen IRFBC30 CR32C684JT CR32C752JT CR32C824JT CR32C103JT CR32C223JT CR32C220JT RSMF1/2W1R2FT CR32C563JT R25G225JT CR32C102JT R25G394JT R25G105JT IC, Ballast Driver EMI Inductor, 1X10mH 0.7Apk PFC Inductor, 2.0mH 2.0Apk Inductor, 4.0mH, 1.5Apk with 2 secondary windings of 4 turns Transistor, MOSFET Resistor, 680K ohm SMT 1206 Resistor, 7.5K ohm SMT 1206 Resistor, 820K ohm SMT 1206 Resistor, 10K ohm SMT 1206 Resistor, 22K ohm SMT 1206 Resistor, 22 ohm SMT 1206 Resistor, 1.2 ohm ½ watt Resistor, 56K ohm SMT 1206 Resistor, 2.2M ohm ¼ watt Resistor, 1K ohm SMT 1206 Resistor, 390K ohm ¼ watt Resistor, 1.0M ohm ¼ watt M1, M2, M3 R1, R2 R3 R4, R5 R6 R7, RSTART R8, R13, R16 R9, RCS R10 R11 R17 R12, R18 R19 38 39 40 41 42 1 1 1 1 1 RG Allen RG Allen RG Allen RG Allen RG Allen CR32C243JT CR32C273JT CR32C104JT CR32C103JT CR32C203JT Resistor, 24K ohm SMT 1206 Resistor, 27K ohm SMT 1206 Resistor, 100K ohm SMT 1206 Resistor, 10K ohm SMT 1206 Resistor, 20K ohm SMT 1206 ROC RPH RRUN RDT RT 43 44 Total 1 2 64 RG Allen RG Allen RV05K300 CR32C103JT Transient Suppressor Resistor, 10 ohm SMT 1206 RV1 R14, R15 4 Reference www.irf.com Figure 2, Inductor Current During Ignition (500mA/div) Figure 3, Lamp Voltage During Ignition (500V/div) Figure 4, Filament current during Preheat (T5/35W) Figure 5, VS & CS during preheat (T5/35W) www.irf.com Figure 6, VS & CS during running (T5/35W) 5 Parameter T5/35W T5/28W T5/14W Preheat Frequency 60 kHz 60 kHz 60 kHz Lamp Preheat Voltage 350 Vpp 350 Vpp 350 Vpp Lamp Ignition Voltage 2KVpp 2KVpp 2KVpp Run Frequency 42 kHz 42 kHz 42 kHz Ballast PF 0.99 0.99 0.95 Lamp Running Voltage 720 Vpp 575 Vpp 265 Vpp Ballast Input Power 35W 28W 14W Table 1. Ballast Input / Output Measurements 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 6 www.irf.com