307C Lighting Thermistors Vishay Cera-Mite PTC Thermistors For Electronic Fluorescent Ballasts FEATURES • Electrode preheat thermistors for use in compact fluorescent lamps (CFL) and electronic ballasts. • Current limiting, time-delayed start-up extends lamp life. • Quiet, flicker-free operation. • Developed in cooperation with leading ballast designers. • Both standard and custom parts are available. • Economical, reliable and proven in millions of lamps throughout the world. APPLICATION CONSIDERATIONS • Ignition time can be optimized to increase life of lamp. • PTC resistance (R25) is chosen, along with filament resistance and application voltage, to control desired electrode preheat current. • Lamp preheat time is determined by time required for thermistor to switch from low to high resistance state. Preheat currents shown result in switch times of approximately 1 second at 25°C. Lower currents result in longer switch times. PTC THERMISTORS FOR ELECTRONIC FLUORESCENT BALLASTS FLUORESCENT LAMP C PTC Tinned Copper Clad Steel Wire 24 AWG when D ≤ 8.5mm 22 AWG when D ≥ 10mm 5mm max 32mm min 4.5mm max. D LS = 5mm Options: • High Temperature Coating • Short Clipped Leads • Other Wire Forms and Lead Spacings RESISTANCE INSTANTANEOUS CONTINUOUS PREHEAT R25 VOLTAGE VOLTAGE CURRENT (OHMS) (VRMS) (VRMS) (mA) 4 1 2 3 150 265 80 215 150 280 200 200 50 175 50 430 70 265 150 350 100 260 95 370 125 230 80 280 150 235 90 260 200 320 145 300 240 350 150 260 300 400 165 225 380 410 170 205 600 420 120 185 600 460 200 170 850 450 340 140 100 340 265 390 150 340 150 400 180 350 165 380 200 355 265 300 300 370 75 270 300 420 320 230 500 480 400 190 800 530 450 155 850 520 175 190 70 210 50 750 70 300 140 725 85 210 50 670 150 400 100 550 85 280 60 820 100 310 90 750 400 430 120 420 D MAX. (mm) 4.5 4.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 7 7 7 7 7 7 7 7 7 8.5 8.5 8.5 8.5 10 10 10 5 PART NUMBER 307C1407 307C1414 307C1230 307C1654 307C1364 307C1259 307C1253 307C1223 307C1171 307C1225 307C1390 307C1252 307C1224 307C1622 307C1403 307C1306 307C1569 307C1375 307C1242 307C1360 307C1361 307C1362 307C1260 307C1367 307C1366 307C1363 307C1287 307C1258 307C1365 307C1422 6 R25 - Nominal zero power resistance ± 25% at 25°C. For given diameter, higher resistance thermistors offer higher maximum voltages. Instantaneous Voltage - Maximum rms voltage permitted across thermistor during fluorescent lamp start-up cycle. Continuous Voltage - Maximum rms voltage continuously applied across thermistor during normal lamp operation. Preheat Current - rms current (60Hz) which switches thermistor to high resistance in approximately 1 second at 25°C ambient. Size (mass) of PTC influences rate of I2R temperature increase. For given resistance, larger thermistors have longer switch times. Optional coating slightly increases switch time. Note 6: P/N suffix (not shown) describes wire lead forms and other options. Note 1: Note 2: Note 3: Note 4: Note 5: www.vishay.com 10 [email protected] Document Number: 23088 Revision 14-May-02