ST L6567 handbook
Contents
1. OSCILLATOR SECTION Minimum Oscillator frequency IRHv OMA CI 5V 44 29 Feed Forward Frequency IRHV 600mA 47 88 ICIP charge CI Charging Current During Preheat ICII charge CI Charging Current During Ignition ICI disch CI Discharge Current CI Low Voltage Threshold RS THRESHOLD SECTION kHz kHz KHz uA V sec mA mA mA mV VcMTH Capacitive Mode Voltage Threshold Preheat Voltage Threshold G1 G2 DELAY TIMES SECTION 4 15 SI L6567 ELECTRICAL CHARACTERISTCS Continued EE e a Ratio between Delay Time IRHv 1mA Cl Conduction Time of G1 and G2 an LOW SIDE DRIVER SECTION HIGH SIDE DRIVER SECTION IFSLK Leakage Current of FS PINto Ves 568V G1 GND Ves 568V G1 Ist LK ag Current of S1 PINto Vsi GND Vsi BOOTSTRAP SECTION Boot Th BOOTSTRAP Threshold Vs 10 6V before turn on 50 Vj AVERAGE RESISTOR Before starting the first commutation when switching 6V is guaranteed General operation The L6567 uses a small amount of current from a supply resistor s to start the operation of the IC Once start up condition is achieved the IC turns on the lower MOS transistor of the half bridge which allows the bootstrap capacitor to charge Once this is achieved the oscillator begins to turn on the upper and lower MOS transistors at high frequency and immediately ramps down to a preheat frequency During this stage the IC preheats the lamp an2. 0 Lee 0 L AI L6567 HIGH VOLTAGE DRIVER FOR CFL MULTIPOWER BCD TECHNOLOGY BCD OFF LINE TECHNOLOGY FLOATING SUPPLY VOLTAGE UP TO 570V GND REFERRED SUPPLY VOLTAGE UP TO 18V n UNDER VOLTAGE LOCK OUT n CLAMPING ON Vs n DRIVER CURRENT CAPABILITY 30mA SOURCE 70mA SINK n PREHEAT AND FREQUENCY SHIFT TIMING 5 5 5 DESCRIPTION The device is a monolithic high voltage integrated cir cuit designed to drive CFL and small TL lamps with a minimum part count It provides all the necessary functions for proper pre heat ignition and steady state operation of the lamp variable frequency oscillator BLOCK DIAGRAM PREHEATING VCO FREQ SHIFTING d BIAS VOLTAGE CURRENT REFEHENGE GENERATOR S014 ORDERING NUMBERS D Li L6567 6567 settable preheating and ignition time capacitive mode protection lamp power independent from mains voltage variation Besides the control functions the IC provides the lev el shift and drive function for two external power MOS FETs in a half bridge topology C HIGH B SIDE O DRIVER S1 o IDE O LOW G2 S s LOGIC DRIVER PGND O SGND R d 4 January 2000 D96IN441B 1 15 This is preliminary information on a new product now in development Details are subject to change without notice L6567 PIN FUNCTION 5 5 E E E CP First timing TPRE TIGN then averaging the ripple in the representation of the HVB derived
3. 20 00 10 00 0 00 LC pis d oa aca r pos L LL 40 00 60 00 80 00 100 00 120 00 140 00 160 00 180 00 200 00 220 00 240 00 Cf pF Figure 7 Tpr vs RREF O Cr 100pF Tdt calculated data Tdt us 2 40 Tdt measured data 2 00 1 60 1 20 0 80 20 00 30 00 40 00 50 00 60 00 Rref Kohm Cf 68pF Ct 82pF 90 00 Cf 100pF 80 00 70 00 L6567 Figure 8 Frequency vs kHv Cr 82pF frequency kHz 120 00 100 00 80 00 Rref 20Kt Rref 22 Rref 24 60 00 Rrefz27l Rref 30 Rref 33 40 00 Rref 36 Rref 39K 43K 47K 51K 0 20 0 40 0 60 0 80 1 00 1 20 Irhv m A Figure 9 Frequency vs kHv O Crz100pF frequency kHz 100 00 80 00 Rret 20 60 00 L Rret 22K Rref 24K F Rret 27K Rret 30K 40 00 L Rret 33K Rret 36K Rref 3 9K 43K Irhv mA Figure 10 Frequency vs kHv O Crz120pF frequency kHz 80 00 60 00 Rref 20 Rref 22 Rref 24 40 00 Rref 27 Rref 30 Rret 33 Rref 36 Rref 39 Rret 43K 47K 51K 20 00 0 20 0 40 0 60 0 80 1 00 1 20 Irhv mA 11 15 L6567 Figure 11 Frequency vs huy O Crz 150pF Figure 13 FFEED FORWARD measurements and 80 00 120000 00 r calculations 1 121 Irhv Cf 110000 00 resp measurements 100000 00 B Ct 100pF 90000 00 60 00 No 80000 00 Cf 120pF N E 70000 00 x E S Cf 150pF gt 60000 00 a UP s E Rret 20 50000 00 40 00 5 o Rref 22 g 40000 00 Rref 24 le Rref 27 30000 00 Rref 30 L Rref 33 20
4. condition L6567 is designed to drive CFL and TL lamps with a minimum part count topology This feature implies that each external component is related to one or more circuit operating state This table is a short summary of these relationships FMIN gt RREF amp CF FFEED FORWARD gt Cr amp IRHV TPRE amp TIGN gt CP amp RREF FPRE gt RSHUNT L CL LAMP Tpr gt RREF df dt gt CI Some useful formulas can well approximate the values MINS g Page Cr If IRHv is greater than Inyy 2 following expression a the feed forward frequency is settled and the frequency value is fitted by the REF F lnuv FEEDFORWARD 121 Ge 8 15 SI L6567 Other easy formulas fit rather well TpT 46 75 10 12 RREF TPRE 224 Cp RREF As far as df dt is concerned there are no easy formulas that fit the relation between Cr Rr and Ci Cj is charged and discharged by three different currents that are derived from different mirroring ratios by the current flowing on Rrer The voltage variations on C are proportional to the current that charges Cr that is to say they are proportional to df dt The values obtained in the testing conditions Cj 100nF are during preheating and working conditions the typical frequency increase is 20KHz ms the typical decrease is 10Khz ms During ignition the frequency variation is 200Hz ms If slower variations are needed CI has to be increased Due to th
5. 000 00 Rre 36 E Rref 39 10000 00 20 00 Rref 43K 47K 51K Ir 0 00 L L 1 1 L L 0 40 0 60 0 80 1 00 1 20 Irhv mA 0 20 0 40 0 60 0 80 1 00 1 20 Irhv m A Figure 12 Fin measurements and calculations 100 00 measuraments Fmin 1 8 Cf Rref 80 00 6000 N I E E u 40 00 Cf 82pF Cf 100pF Cf 120pF 20 00 Cf 150pF 20 00 30 00 40 00 50 00 Rref Kohm 12 15 SI L6567 Domo om a Tech Toe T MECHANICAL DATA e e e 165 0068 ee pe of tats 5 typ Bin e T Tes ose fosa E 58 ee loz 024 Pe oo es fre oso re sa 4 osso 0157 a 46 sos 0209 o4 127 cos 0 050 M d doel door S cem 1 D andF donotinclude mold flash or protiusiore Mold flash or potrusions shall not exceed 0 15mm 006inch OUTLINE AND MECHANICAL DATA 14 15 L6567 Information furnished is believed to be accurate and reliable However STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights ofthird parties which may result from its use No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics Specifications mentioned in this publication are subject to change without notice This publication supersedes and replaces all information previously supplied STMicroelectronics pro
6. The circuit is held in the preheating mode when pin 8 Cp is grounded In case FMIN is reached during preheat the IC assumes an open load Consequently the oscillation stops with the low side MOS transistor gate on and the high side gate off This condition is kept until W undershoots Vs Low1 6 15 ISTA L6567 Figure 2 Preheating and ignition state FREQUENCY preheating ignition burning state state state TIME Ignition mode At the end of the preheat phase the frequency decreses to the minimum frequency Fyin causing an increased coil current and a high voltage appearing across the lamp That is because the circuit works near resonance This high voltage normally ignites the lamp There is no protection to avoid high ignition currents through the MOS transistors when the lamp doesn t ignite This only occurs in an end of lamp life situation in which the circuit may break Now the lowest frequency is the resonance frequency of L and Cj the capacitor across the lamp The ignition phase finishes when the frequency reaches FMIN or at maximum when the ignition time has elapsed The ignition time is related to Tene TiGN 15 16 TpRE The Cp capacitor is charged 15 times with the same current used to charge it during TPRE The frequency shifting slope is determined by Ci During the ignition time the VRs monitoring function changes in the capacitive mode protection Steady state operation feed forward frequency The lamp s
7. d after a predetermined time ramps down again until it reaches the final operating frequency The IC monitors the current to determine if the circuitis operating in capacitive mode If capacitive switching is detected the IC increases the output frequency until zero voltage switching is resumed Startup and supply in normal operation At start up the L6567 is powered via a resistor connected to the RHy pin pin 13 from the rectified mains The current charges the Cs capacitor connected to the Vs pin pin 5 When the Vs voltage reaches the threshold Vs Low1 max 6V the low side MOS transistor is turned on while the high side one is kept off This condition assures that the bootstrap capacitor is charged When Vs HiGH1 threshold is reached the oscillator starts and the RHv pin does not provide anymore the supply current for the IC see fig 1 4 5 15 L6567 Figure 1 Start up VsuicHt Vstow1 Va low side mosfet Va Vs high side mosfet 0 Cr 0 Oscillator The circuit starts oscillating when the voltage supply Vs has reached the Vs HIGH1 threshold In steady state condition the oscillator capacitor Cr at pin 12 is charged and discharged symmetrically with a current set main ly by the external resistor RREF connected to pin 10 The value of the frequency is determined by capacitor Cr and resistor RREF This fixed value is called FN A dead time Tp7 between the ON phases of the transistors is provided for avoiding cross con
8. duction so the duty cycle for each is less than 5096 The dead time depends on RREF value fig 7 The IC oscillating frequency is between Fmin and Fmax 2 5 FMIN in all conditions Preheating mode The oscillator starts switching at the maximum frequency FMAx Then the frequency decreases at once to reach the programmed preheating frequency fig 2 The rate of decreasing df dt is determined by the external ca pacitor Cj pin 14 The preheat time TprE is adjustable with external components RREF and Cp The preheat current is adjusted by sense resistance RSHUNT During the preheating time the load current is sensed with the sense resistor RSHUNT connected between pin 9 Rs and pin 7 PGND At pin 9 the voltage drop on RSHUNT is sensed at the moment the low side MOS FET is turned off There is an internal comparator with a fixed thresh old VpH if Vas gt VpH the frequency is decreased and if Vrs lt VpHthe frequency is increased If the VpHthresh old is reached the frequency is held constant for the programmed preheating time Tpng TPRE is determined by the external capacitor Cp pin8 and by the resistor RREF Cp is charged 16 times with a current that depends on RREF and these 16 cycles determine the TPRE So the preheat mode is programmable with external components as far as TPRE is concerned RREF amp Cp and as far as the preheating current is concerned choosing properly RsHUNT and the resonant load components L and CL
9. ducts are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics The ST logo is a registered trademark of STMicroelectronics 6 1999 STMicroelectronics All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia Brazil China Finland France Germany Hong Kong India Italy Japan Malaysia Malta Morocco Singapore Spain Sweden Switzerland United Kingdom U S A http www st com 15 15 Lyr
10. ese tight relationships it is recommended to follow a precise procedure first Ryy has to be chosen looking at startup current needs and dissipation problems Then the feed forward frequency range has to be determined and so Cr is set Given a certain Cr RRgr is set in order to fix FMIN Now Cp can be chosed to set the desired TpRE and TIGN The other external parameters RSHUNT and Ci can be chosen at the end because they are just related to a single circuit parameters SI 9 15 L6567 Figure 4 IC Operation NO OSCILLATION LOW SIDE MOS ON HIGH SIDE MOS OFF START OSCILLATION F Fuax T Ta I ee v v a FREQUENCY INCREASE FREQUENCY DECREASE DECREASE FREQUENCY FREQUENCY OPEN LOAD DETECTION STOP LOW SIDE MOS ON AND HIGH SIDE MOS OFF STOP OSCILLATION LOW SIDE MOS ON HIGH SIDE MOS OFF INCREASE FREQUENCY DECREASE RESTARTWITH FREQUENCY F Fuax i FREQUENCY SHIFTS IN T Ticn TOWARDS BURNING STATE CONDITION F MAX Fwmax Freebrorwaro FcapacmveMoDE 10 15 Figure 5 Working frequency vs kHv frequency kHz RREF 30Kohm Cf 47pF Cf 56pF Cf 120pF METE Cf 150pF S600 Cf 180pF 40 00 Cf 220pF 30 00 20 00 10 00 000 L114 rr lu Ilii L 1 0 20 0 40 0 60 0 80 1 00 1 20 Irhv mA Figure 6 Frequency vs Q RREF 30Kohm frequency kHz 160 00 150 00 140 00 Rref 30Kohm 130 00 120 00 110 00 100 00 90 00 80 00 70 00 60 00 50 00 40 00 80 00 I 0 75mA
11. tarts operating at FN determined by RREgr and Cr directly after the ignition phase To prevent too high lamp power at high mains voltages a feed forward correction is implemented At the end of the preheat phase the RHv pin is connected to an internal resistor to sense the High Voltage Bus If the current in this resistor increases and overcomes a value set by RREF the current that charges the oscillator capacitor Cr increases too The effect is an increase in frequency limiting the power in the lamp In order to prevent feed forward of the ripple of the VHv voltage the ripple is filtered with capacitor Cp on pin 8 and an integrated resistor RAVERAGE Figure 3 Burn state FREQUENCY feed forward mode ky ms L6567 Capacitive mode protection During ignition and steady state the operating frequency is higher than the resonance frequency of the load L CL RLAMP and RFILAMENT so the transistors are turned on during the conduction time of the body diode in order to maintain Zero Voltage Switching If the operating frequency undershoots the resonance frequency ZVS doesn t occur and causes hard switching of the MOS transistors The L6567 detects this situation by measuring VRs when the low side MOS FET is turned on At pin 9 there is an internal comparator with threshold Vou TH typ 20mV if Vas lt Vc TH Capacitive mode is assumed and the frequency is increased as long as this situation is present The shift is determined by Cl Steady s
12. tate frequency At any time during steady state the frequency is determined by the maximum on the following three frequencies fSTEADY sTATE MAX FMIN FEED FORWARD CAPACITIVE MODE PROTECTION IC supply At start up the IC is supplied with a current that flows through RHv and an internal diode to the Vs pin which charges the external capacitor Cs In steady state condition RHv is used as a mains voltage sensor so it doesn t provide anymore the supply current The easiest way to charge the Cs capacitor and to supply the IC is to use a charge pump from the middle point of the half bridge To guarantee a minimum gate power MOS drive the IC stops oscillating when Vs is lower than Vs HIGH2 It will restart once the Vs will become higher than Vs HIGH1 A minimum voltage hysteresis is guaranteed The IC re starts operating at f FMax then the frequency shifts towards FwIN The timing of this frequency shifting is TIGN that is CP capacitor is charged and discharged 15 times Now the oscillator frequency is controlled as in stan dard burning condition feed forward and capacitive mode control Excess charge on Cs is drained by an inter nal clamp that turns on at voltage VscL Ground pins Pin 7 PGND is the ground reference of the IC with respect to the application Pin 11 SGND provides a local signal ground reference for the components connected to the pins Cp Cj RREF and Cr Relationship between external components and sistem working
13. through RHV E PIN CONNECTION Top view 1 eo 11 Lp DT pe ENE HER D961N440 3 2 15 L6567 ABSOLUTE MAXIMUM RATINGS Symbol Parameter EK Low Voltage Supply Mains Voltage Sensing VS 2VBE 2 Preheat Averaging e Oscillator Capacitor Voltage Frequency Shift Capacitor Voltage Reference Resistor Voltage Vs CP CF Vol Vrs G2 Vsi GI Vrs Current Sense Input Voltage transient 50ns V Low Side Switch Gate Output High Side Switch Source Output normal operation 1 to 373 0 5sec mains transient 1 to 550 lt V High Side Switch Gate Output normal operation 1 00038 V 0 5sec mains transient 11 000589 V with respect to pin S1 o VetoVs V Floating Supply Voltage normal operation Fst v Nd 0 5sec mains transient r 1 88 1 Do not exceed package thermal dissipation limits 2 For VS lt VShigh 1 3 For VS gt VShigh 1 4 Internally Limited Note ESD immunity for pins 1 2 and 3 is guaranteed up to 900 V Human Body Model lt lt lt lt 4 3 15 L6567 ELECTRICAL CHARACTERISTCS Vs 12V RrEF 30K Cr 100pF Tj 25 C unless otherwise specified sme meme OI ue e we us Vs SUPPLY VOLTAGE SECTION EC COCOS rr AR ECC pem Pe s We prar 7 sis D 1 65 1 8 VS low 1 Vs Voltage to Guarantee 1 Va1 0 and Vez 1 pe Vs Supply Current at Start Up Vs 10 6V Before turn on
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ST L6567 handbook