VK05

VK05CFL STMICROELECTRONICS | Alldatasheet

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Technical content

® VK05CFL ELECTRONIC DRIVER FOR CFL APPLICATION ■ EMITTER SWITCH POWER OUTPUT STAGE ■ INTEGRATED ANTIPARALLEL COLLECTOR SOURCE DIODE ■ INTEGRATED DIAC FUNCTION ■ NOMINAL WORKING FREQUENCY SETTABLE BY EXTERNAL CAPACITOR ■ IGNITION FREQUENCY SET BY LOAD

DESCRIPTION

The VK05CFL is a monolithic device housed in a standard SO-8 package, made by using STMicroelectronics proprietary VIPower M3 Technology. This device is intended both for the low side and the high side driver in half bridge CFL applications. This means that it is possible to realize a complete H-bridge by using two VK05CFL devices: one connected in HSD configuration and the other connected in LSD configuration. In the VK05CFL used in HSD configuration, the diac pin must be connected to source pin. Both diac functionality and discharge circuit for external diac capacitor are integrated. By an external capacitor it is possible to choose the nominal working frequency without influence on the ignition one. TYPE B V ICrms IPeak VK05CFL 520 V 0.25A 1.5A SO-8 BLOCK DIAGRAM osc 2Vref Diac sec diac Source Collector 5Vref R

(*) When mounted on a standard single-sided FR-4 board with 100mm2 of Cu (at least 35µm thick). CONNECTION DIAGRAM PIN FUNCTIONS Symbol Parameter Min Typ Max Unit VCS Collector-Source Voltage 520 V Isec Input Current (secondary) -100 140 mA Vsec Input Voltage (secondary) Internally limited V ICM Collector Peak Current -1.8 1.8 A IOSC Osc Pin Current 100 mA VOSC Osc Pin Voltage Internally limited V Tj Max Operating Junction Temperature -40 150 °C Tstg Storage Temperature Range -55 150 °C Symbol Parameter Value Unit R thj-lead Thermal Resistance Junction - lead Max 15 °C/W R thj-amb Thermal Resistance Junction - ambient Max 52 (*) °C/W Pin Name Pin Function Collector Collector of the NPN high voltage transistor in the cascode configuration. Source Low voltage Power MOSFET source in the cascode configuration and GROUND reference. diac Input of the diac block to start the system up at the beginning. sec Connection with secondary winding of the voltage transformer, in order to trigger and to supply the device. osc Output via to charge external capacitor necessary to set the steady state working frequency. SO-8 Collector Collector Collector Collector sec Source osc diac

ELECTRICAL CHARACTERISTICS (Tcase=25°C unless otherwise specified) FORWARD REVERSE OSC DIAC SEC Symbol Parameter Test Conditions Min Typ Max Unit VCS(sat) Collector-Source Saturation Voltage Vsec=10V; IC =300mA 1.4 2.8 V Symbol Parameter Test Conditions Min Typ Max Unit VCSr Collector-Source Reverse Voltage IC = -300mA -1 -1.5 V Symbol Parameter Test Conditions Min Typ Max Unit IOSC Osc Output Current V sec=10V; VOSC =0V 300 µA VOSC(th) Osc Turn-off Voltage V sec=10V 1.6 2 V Symbol Parameter Test Conditions Min Typ Max Unit Vdiac(thH) Diac On Threshold 28 31 35 V Vdiac(thL) Diac Off Threshold 18 V Symbol Parameter Test Conditions Min Typ Max Unit Vsec(clH) Sec Clamp High I sec=20mA; VOSC =0V 22 V Vsec(clL) Sec Clamp Low I sec= -10mA 25 V Vsec(on) Sec Turn-on Voltage I C =10mA; VOSC =0V 3.5 4.5 5.5 V Isec(on) Sec On Current Vsec=10V; VOSC =0V; IC =300mA 4 mA

The VK05CFL is made by using STMicroelectronics proprietary VIPower M3-3 technology. This technology allows the integration in the same chip both of the control part and the power stage. The power stage is the “Emitter Switching”. It is made by putting in cascode configuration a bipolar high voltage darlington with a low voltage MOSFET. This configuration provides a good trade-off between the bipolars low ON drop with high breakdown voltage in OFF state, and the MOSFETS high switching speed. The maximum theoretical working frequency is in the range of 300KHz. Circuit description The electrical scheme of the VK05CFL used as a self-oscillating converter to drive fluorescent tubes is shown in Fig. 1. Figure 1: Application schematic This topology does not require the saturable transformer to set the working frequency. Two secondary windings are wound on the main ballast choke Lp. These windings have two functions:1) to trigger the ON state and 2) to provide the power supply to the device. A good trade-off for the ratio between the primary winding Lp and the two secondary windings is 10:1; in order to minimize the power dissipated on the resistors R4 - R5 and to guarantee sufficient voltage to supply the device. The steady-state working frequency is set by the two capacitor C5 and C6. They are charged by a current I cap≈300µA. When the voltage on the capacitor reaches an internal fixed value the power stage is turned OFF. By choosing the same value for C5 and C6 the circuit will work with a duty-cycle of 50%. During the start-up, as the resonance frequency is higher than the steady-state frequency, the secondary voltage falls lower than the device sustain voltage before the capacitor C5-6 is charged, switching OFF the device. For this reason the circuit can work at different frequencies during the start-up and steady-state phases. The resistor R2 and the capacitor C8 are needed to bias the internal diac in the low side device in order to start-up the system. In the high side device the diac pin must be connected to the midpoint. R1 is the pull-up resistor and C7 is the snubber capacitor. Input filtering is realized by R4-C10 and R5-C11. It is necessary to have a proper supply voltage on the input pin. L1s L2s VK05CFL TubeLp C7 C3 C10 C11 VK05CFL Bridge Input Filter C4 C13 PTC diac sec osc Source Collector diac sec osc Source Collector

When the circuit is supplied, the capacitor C8 is charged by the resistor R2 till the voltage across it reaches the internal diac threshold value (~ 30V). The low side switch is turned ON and consequently current will flow from the HV rail to ground through the path formed by C3//C2, C4 and Lp (in case that the pre-heating network is not present: PTC and C13 are not connected). The voltage drop on Lp is “transferred” to the two secondary windings (wound in opposition) in order to confirm the ON state for the low side device and the OFF state for the high side device. As soon as the low side device switches ON, the capacitor C8 is discharged to ground by an internal HV diode to avoid diac restart. In this preliminary phase the tube is OFF and the circuit will oscillate at the Lp-C4 series with (C3//C2) resonance frequency we can neglect C3//C2 As this frequency is higher than the steady-state one, the two devices will switch ON-OFF at this frequency, as the voltage on the two secondary windings falls below the voltage needed to keep the device on. As soon as the tube is ignited the resonance frequency is reduced ≈(Lp-C3//C2) and the circuit will work at the steady-state frequency fixed by the two capacitors C5 and C6. It is possible to calculate the steady-state frequency by these formulae: (R = internal impedance) Considering the VK05CFL board: R=12KΩ ; C5=C6=1.2nF; tstorage≈400nsec; C7=680pF⇒ t(dv)/(dt)≈800nsec; the working frequency will be: f≈35KHz. In figure 2 and figure 3, the start-up phase without preheating is reported, while in figure 4 the main waveforms in steady-state are shown. Figure 2: Start-up phase fst up– 2π L c C 4⋅ T on RC 5 2---ln⋅⋅= 2---TT on tstorage tdv() dt()⁄++= f 1 T---= midpoint Idevice

Waveforms below was obtained by using the application demoboard mounted for european market: COMPONENT LIST 5W to 15W lamp Reference Value T1 Lp=3,1mH, N1/N2=N1/N3=10 L 0 820µH D0,D1,D2,D3 1N4007 C1, C12 22µF/200V electrolytic (for Europe to replace C1, C12 with Cx=3,3µF/400V) C2, C3 100nF/250V C4 2,4nF/400V C5, C6 1.2nF/63V C7 470pF/400V C8 22nF/100V C10, C11 1.5nF/100V R0 10 Ω 1/2W R1, R2 1M Ω 1/4W R4, R5 2.2K Ω 1/4W U1, U2 VK05CFL >15W to 23W lamp Reference Value T1 Lp=2,1mH, N1/N2=N1/N3=10 L 0 820µH D0,D1,D2,D3 1N4007 C1, C12 22µF/200V electrolytic (for Europe Cx=6.8µF/400V) C2, C3 100nF/250V C4 2,4nF/400V C5, C6 1nF/63V C7 470pF/400V C8 22nF/100V C10, C11 1.5nF/100V R0 10 Ω 1/2W R1, R2 1M Ω 1/4W R4, R5 1K Ω 1/2W U1, U2 VK05CFL Device power dissipation Vs. power lampDevice ΔT (Tamb =25 °C) for different power lamps

Figure 6: Board electrical scheme VK05CFL D0 D1 D2 D3 C11 C10 R1C7 12 34 13 42 8765 87 5 6 220V ~ C12 110V ~ VK05CFL

Freewheeling diode If=f(Vf) characteristic at Freewheeling diode If=f(Vf) characteristic at Collector current Vs. collector-source saturation voltage at Tamb =125ºC Vsec = 6V Vsec = 10V Vsec = 15V Vsec = 6V Vsec = 10V Vsec = 15V Collector current Vs. collector-source saturation voltage at T amb =25ºC T = 25°C T = 125°C Tamb =25ºC Tamb =125ºC Test circuitBipolar storage time Vs. collector current

DIM. mm. inch A 1.75 0.068 a1 0.1 0.25 0.003 0.009 a2 1.65 0.064 a3 0.65 0.85 0.025 0.033 b 0.35 0.48 0.013 0.018 b1 0.19 0.25 0.007 0.010 C 0.25 0.5 0.010 0.019 c1 45 (typ.) D 4.8 5 0.188 0.196 E 5.8 6.2 0.228 0.244 e 1.27 0.050 e3 3.81 0.150 F 3.8 4 0.14 0.157 L 0.4 1.27 0.015 0.050 M 0.6 0.023 S 8 (max.) L1 0.8 1.2 0.031 0.047 SO-8 MECHANICAL DATA

SO-8 TUBE SHIPMENT (no suffix) All dimensions are in mm. Base Q.ty 100 Bulk Q.ty 2000 Tube length (± 0.5) 532 A 3.2 B 6 C (± 0.1) 0.6 TAPE AND REEL SHIPMENT (suffix “13TR”) All dimensions are in mm. Base Q.ty 2500 Bulk Q.ty 2500 A (max) 330 B (min) 1.5 C (± 0.2) 13 F 20.2 G (+ 2 / -0) 12.4 N (min) 60 T (max) 18.4 TAPE DIMENSIONS According to Electronic Industries Association (EIA) Standard 481 rev. A, Feb. 1986 All dimensions are in mm. Tape width W 12 Tape Hole Spacing P0 (± 0.1) 4 Component Spacing P 8 Hole Diameter D (± 0.1/-0) 1.5 Hole Diameter D1 (min) 1.5 Hole Position F (± 0.05) 5.5 Compartment Depth K (max) 4.5 Hole Spacing P1 (± 0.1) 2 Top cover tape End Start No componentsNo components Components 500mm min 500mm minEmpty components pockets saled with cover tape. User direction of feed REEL DIMENSIONS C B A

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