L6585D Combo IC for PFC and ballast control Features ■ Pre-heating and ignition phases independently programmable ■ Ignition voltage control ■ Transition mode PFC with over-current protection SO-20 ■ Programmable and precise End-of-life protection compliant with all ballast configurations ■ Auto-adjusting half-bridge over-current control Applications ■ Automatic re-lamp ■ ■ 3% oscillator precision ■ 1.2µs dead time ■ PFC over-voltage protection and feedback disconnection ■ Under voltage lock-out Block diagram COMP 2.5V + _ INV MULT E/A PFCS 1.7V BOOT and THD 17V OPTIMIZER _ OL + 1.2V Vcc LEB MULTIPLIER + Figure 1. Electronic ballast _ S 0.7V Q SYNCHRONOUS BOOTSTRAP DIODE DEAD TIME LEVEL SHIFTER DRIVING R LATCH Vcc HSD OUT CHOKE SAT. ZCD STARTER HVG DRIVER UV DETECTION PWM COMP. Vcc LVG DRIVER LOGIC LSD OVP PFG COMPARATOR CTR PFSTOP DIS WINDOW PFSTOP & REF. OL CONTROL 1.6V GND HB STOP LOGIC EOL HBCS OVP 1.9V 3.4V DIS 2V 2V 0.75V RELAMP EOLP May 2007 Vcc 4.6 1.5 VCO EOLR 4.63V 0.9V TIMING MANAGEMENT RF OSC EOI Rev 5 Tch 1/25 www.st.com 25 Contents L6585D Contents 1 Device description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 2.1 Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2 Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.1 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 5.1 Start-up sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 5.1.1 Pre-heating (time interval A Figure 5) . . . . . . . . . . . . . . . . . . . . . . . . . . 12 5.1.2 Ignition (time interval B Figure 5) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 5.1.3 Run mode (time interval C Figure 5) . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 6 End of life – window comparator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 7 Half-bridge current control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 8 CTR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 9 Re–lamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 10 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 11 Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 12 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2/25 L6585D 1 Device description Device description Designed in High-voltage BCD Off-line technology, the L6585D embeds a PFC controller, a half-bridge controller, the relevant drivers and the logic necessary to build an electronic ballast. The advanced and precise logic circuitry, combined with the programmability of the End-ofLife windows comparator threshold, makes the L6585D compliant with either "lamp-toground" or "block capacitor-to ground" configurations. Another outstanding feature is the possibility of controlling and limiting the lamp voltage during the ignition phase. The pre-heating and ignition durations are independently settable as well as the half-bridge switching frequencies for each operating phases (pre-heating, ignition and normal mode). Other features (half-bridge over-current with frequency increase, PFC over-voltage) allow building a reliable and flexible solution with a reduced part count. The PFC section achieves current mode control operating in Transition Mode; the highly linear multiplier includes a special circuit, able to reduce AC input current distortion, that allows wide-range-mains operation with an extremely low THD, even over a large load range. The PFC output voltage is controlled by means of a voltage-mode error amplifier and a precise internal voltage reference. The driver of the PFC is able to provide 300mA (source) and 600mA (sink) and the drivers of the half-bridge provide 290mA source and 480mA sink. Figure 2. Typical system block diagram LPFC HV BUS R5 R7 R1 Charge pump CBULK R6 R4 R2 AC MAINS ZCD PFG CBOOT CTR COMP INV 11 10 9 Vcc 7 BOOT 17 20 13 CIN PFCS R8 CCOMP L6585D 12 18 16 8 MULT 15 GND R3 19 1 OSC RSNSPF 2 3 RF EOI RPRE COSC 4 RRUN CIGN RD Tch 5 6 EOLP CD 14 EOL-R RP HSD LB OUT LSD CRES LAMP HBCS RSNSHB CBLOCK 3/25 Pin settings L6585D 2 Pin settings 2.1 Connection Figure 3. Pin sonnection (Top view) OSC RF HSD EOI OUT TCH VCC EOLP LSD EOL-R GND CTR HBCS MULT PFG COMP PFCS INV 4/25 BOOT ZCD L6585D 2.2 Pin settings Functions Table 1. Pin functions Pin num. Name 1 2 3 4 OSC Function An external capacitor to GND fixes the half-bridge switching frequency with a ±3% precision. RF Voltage reference able to source up to 240µA; the current sunk from this pin fixes the switching frequency of the half-bridge for each operating state. A resistor (RRUN) connected to ground sets the half-bridge operating frequency combined with the capacitor connected to the pin OSC. A resistor connected to EOI (RPRE) – in parallel with RRUN – sets the maximum half-bridge switching frequency during pre-heating. EOI Connected to ground by a capacitor that, combined with RPRE, determines the ignition duration Pre-heating: low impedance to set high switching frequency Ignition and run mode: high impedance with controlled current sink in case of HBCS threshold triggering. Tch Pin for setting the pre-heating time and the protection intervention. Connect a RC parallel network (RD and CD) to ground Pre-heating: the CD is charged by an internal current generator. When the pin voltage reaches 4.63V the generator is disabled and the capacitor discharges because of RD; once the voltage drops below 1.52V, the preheating finishes, the ignition phase starts and the RDCD is discharged to ground. Run mode: according to the kind of fault (either over-current or EOL) the internal generator charges the RC parallel network and appropriate actions are taken to stop the application. During proper behavior of the IC, this pin is low impedance. 5 Pin to program the EOL comparator. EOLP It is possible to select both the EOL sensing method and the window comparator amplitude by connecting a resistor (REOLP) to ground. 6 Input for the window comparator and re-lamp function. It can be used to detect the lamp ageing for either “lamp to ground” and “block capacitor to ground” configurations. According to the EOLP pin setting, it is possible to program: – the window amplitude (VW) EOL-R – the center of the window (VSET) either fixed or in tracking with the PFC output bus. This function is blanked during the ignition phase. In case of either lamp disconnection or removal, a second threshold (VSL-UP) crossing latches the IC and drives the chip in “ready-mode” so that when the voltage at EOL-R pin is brought below VSL-DOWN (re-lamp) a new preheating/ignition sequence is repeated. 7 CTR Input pin for: – PFC over-voltage detection: the PFC driver is stopped until the voltage returns in the proper operating range – Feedback disconnection detection – reference for End-of-life in case tracking reference; – shut-down: forcing the pin to a voltage lower than 0.75V, the IC shuts down in unlatched condition. 8 MULT Main input to the multiplier. This pin is connected to the rectified mains voltage via a resistor divider and provides the sinusoidal reference to the PFC current loop. 5/25 Pin settings L6585D Table 1. Pin functions (continued) Pin num. Name 9 10 11 Output of the error amplifier. A compensation network is placed between this pin COMP and INV to achieve stability of the PFC voltage control loop and ensure high power factor and low THD. INV Inverting input of the error amplifier. The information on the output voltage of the PFC pre-regulator is fed into the pin through a resistor divider. Input for the feedback disconnection comparator ZCD Boost inductor’s demagnetization sensing input for PFC transition-mode operation. A negative-going edge triggers PFC MOSFET turn-on. During start-up or when the voltage is not high enough to arm the internal comparator (e.g. AC Mains peak), the PFC driver is triggered by means of an internal starter. 12 PFCS 13 PFG Input to the PFC PWM comparator. The current flowing in the PFC mosfet is sensed by a resistor; the resulting voltage is applied to this pin and compared with an internal sinusoidal-shaped reference, generated by the multiplier, to determine the PFC MOSFET’ s turn-off. A second comparison level detects abnormal currents (e.g. due to boost inductor saturation) and, on this occurrence, shuts down and latches the IC reducing its consumption to the start-up. An internal LEB prevents undesired function triggering. PFC gate driver output. The totem pole output stage is able to drive power MOSFET’S with a peak current of 300mA source and 600mA sink. 14 2-levels half-bridge current monitor for current control. The current flowing in the HB mosfet is sensed by a resistor; the resulting voltage is applied to this pin. Low threshold (active during run mode): in case of thresholds crossing, the IC reacts with self-adjusting frequency increase in order to limit the half-bridge HBCS (lamp) current. High threshold: – ignition: in case of thresholds crossing during the frequency shift, the IC reacts with self-adjusting frequency increase in order to limit the lamp voltage and preventing operation below resonance. – run mode: in case of thresholds crossing because of current spikes (due e. g. to capacitive mode / cross-conduction), the L6585D latches to avoid MOSFETs damaging, 15 GND Ground. Current return for both the signal part of the IC and the gate driver. 16 LSD Low side driver output: the output stage can deliver 290mA source and 480mA sink (typ. values). 17 VCC Supply Voltage of both the signal part of the IC and the gate driver. Clamped with a Zener inside. 18 OUT High Side Driver Floating Reference. This pin must be connected close to the source of the high side power MOS. 19 HSD High side driver output: the output stage can deliver 290mA source and 480mA (typ. values). 20 6/25 Function Bootstrapped Supply Voltage. Between this pin and VCC, the bootstrap capacitor must be connected. BOOT A patented integrated circuitry replaces the external bootstrap diode, by means of a high voltage DMOS, synchronously driven with the low side power MOSFET. L6585D Electrical data 3 Electrical data 3.1 Maximum ratings Table 2. Absolute maximum ratings Symbol Pin VBOOT 20 VOUT dVOUT /dt VCC Value Unit Floating supply voltage -1 to 618 V 18 Floating ground voltage -3 to VBOOT – 18 V 18 Floating ground max. slew rate 50 V/ns Self-limited V -0.3 to 5 V 2, 5 -0.3 to 2.7 V 6 Vcc 7 -0.3 to 7 14 -5 to 5 17 1, 3, 4, 8, 10, 12 9, 11 Parameter (1) IC Supply voltage (ICC = 20mA) Analog input and outputs ZCD clamp (IZCD < 4mA) V Self-limited IRF 2 Current capability 240 µA IEOLP 5 Current capability 100 µA FOSC(MAX) Maximum operating frequency 250 KHz PTOT Power dissipation @TA = 70°C 0.83 W 1. The device has an internal Clamping Zener between GND and the VCC pin, it must not be supplied by a Low Impedance Voltage Source. Note: ESD immunity for pins 18, 19 and 20 is guaranteed up to 900V (Human Body Model) 3.2 Thermal data Table 3. Thermal data Symbol RthJA TJ TSTG Description Value Unit 120 °C/W Junction operating temperature range -40 to 150 °C Storage temperature -55 to 150 °C Max. thermal resistance junction to ambient 7/25 Electrical characteristics 4 L6585D Electrical characteristics VCC = 15V, TA = 25°C, CL = 1nF, COSC = 470pF, RRUN = 47K, unless otherwise specified Table 4. Electrical characteristics Symbol Pin Parameter Test condition Min Typ Max Unit 16 V Supply voltage Vcc VCC(on) VCC VCC Operating range After turn-on Turn-on threshold (1) 13.6 14.3 15 V 9.6 10.3 11 V 16.2 17.2 17.7 V 250 370 µA VCC(OFF) VCC Turn-off threshold (1) VZ VCC Zener Voltage Icc = 20mA IST-UP VCC Start-up current Before turn-on @ 13V ICC VCC Operating supply current Iq VCC Residual current 11 Supply current 7 mA IC latched 370 µA -1 µA PFC section – multiplier input IMULT MULT Input bias current VMULT = 0 VMULT MULT Linear operation range VCOMP = 3V MULT Output max. slope VMULT = 0 to 1V, VCOMP = Upper clamp 0.75 V/V MULT Gain VMULT = 1V, VCOMP= 3V 0.52 1/V ∆VCS ∆VMULT KM 0 to 3 V PFC section – error amplifier VINV IINV Gv INV Voltage feedback input threshold INV Line regulation INV Input bias current INV Gain-bandwidth product (2) Source current 60 mV -1 µA VCOMP = 4V, VINV = 2.4 V -2.6 mA Sink current VCOMP = 4V, VINV = 2.6 V 4 mA Upper clamp voltage ISOURCE = 0.5 mA 4.2 V Lower clamp voltage ISINK = 0.5 mA 2.25 V INV Open loop detection threshold CTR > 3.4 1.2 V COMP Static OVP threshold COMP Open loop 50 MHz COMP Voltage gain (2) V 1 ICOMP 8/25 VCC = 10.3V to 16V 2.55 dB INV VDIS 2.5 80 GB VCOMP 2.45 2.1 2.25 2.4 V L6585D Table 4. Symbol Electrical characteristics Electrical characteristics (continued) Pin Parameter Test condition Min Typ Max Unit CTR pin DIS CTR PFOV CTR Disable threshold Falling edge 0.75 V 120 mV 3.4 V 140 mV Lower threshold (falling) 1.7 V Hysteresys 0.12 Higher threshold (rising) 3.4 Hysteresys 0.14 Hysteresys Dynamic PFC overvoltage Rising edge Hysteresys Available range as tracking reference CTR V PFC section – current sense comparator ICS PFCS Input bias current VCS = 0 (2) tLEB PFCS Leading edge blanking VCSdis PFCS IC disable level td(H-L) PFCS Delay to output VCSclamp PFCS Current sense reference clamp -1 µA 100 200 300 ns 1.65 1.75 1.85 V 120 VCOMP = Upper clamp 1.0 1.08 ns 1.16 V PFC section – zero current detector VZCDH ZCD Upper clamp voltage IZCD = 2.5 mA 5 VZCDL ZCD Lower clamp voltage IZCD = -2.5 mA -0.3 VZCDA ZCD Arming voltage (positive-going edge) (2) 1.4 V VZCDT ZCD Triggering voltage (negative-going edge) (2) 0.7 V IZCDb ZCD Input bias current VZCD = 1 to 4.5 V IZCDsrc ZCD Source current capability -4 mA IZCDsnk ZCD Sink current capability 4 mA V 0 0.3 1 V µA PFC section – gate driver ISINK = 10mA 0.2 V PFG Output high/low tf PFG Fall time 40 90 ns tr PFG Rise time 90 140 ns ISINK PFG Peak sink current 475 600 mA ISOURCE PFG Peak source current 200 300 mA PFG Pull-down resistor 10 kΩ ISOURCE = 10mA 14.5 V 9/25 Electrical characteristics Table 4. Symbol L6585D Electrical characteristics (continued) Pin Parameter Test condition Min Typ Max Unit Half bridge section – Timing & oscillator ICH TCH Charge current VTCH = 2.2V VCHP TCH Charge threshold (positive going-edge) VCHN TCH RTCH REOI IEOI 30 µA (1) 4.63 V Discharge threshold (negative going edge) (1) 1.50 V TCH Leakage current 1.5V < VTCH < 4.5V, falling TCH Internal impedance Run mode EOI Open state current VEOI = 2V EOI EOI impedance During pre-heating EOI EOI current generator during ignition and run mode 150 Tspike = 200ns (3) 20 Tspike = 400ns (3) 100 Tspike = 600ns (3) 200 Tspike = 1µs (3) VEOI EOI 0.1 µA 200 Ω 0.15 µA 150 Ω µA 270 EOI threshold (1) 1.83 1.9 1.98 V (1) 1.92 2 2.08 V VREF RF Reference voltage IRF RF Max current capability µA 240 Rising threshold (1) 3.7 V OSC Falling threshold (1) 0.9 V D OSC Output duty cycle TDEAD OSC fRUN fPRE OSC 48 50 52 % Dead time 0.96 1.2 1.44 µs OSC Half-bridge oscillation frequency (run mode) 58.4 60.2 62 KHz OSC Half-bridge oscillation frequency (pre heating) 113.2 116.7 120.2 KHz RPRE=50K Half bridge section – End Of Life FUNCTION and re-lamp comparator VS VW 10/25 EOLP Current capability 100 EOLP Reference voltage 1.92 EOL-R Operating range EOL-R Window comparator reference Half window amplitude EOLP=27K 220K = REOLP = 270K or 22K = REOLP = 27K µA 2 0.95 2.08 V 4.15 V tracking with CTR V REOLP > 620K or 75K = REOLP = 91K 2.5 220K = REOLP = 270K or 75K = REOLP = 91K 220 mV REOLP > 620K or 22K = REOLP = 27K 720 mV L6585D Table 4. Symbol Electrical characteristics Electrical characteristics (continued) Pin Parameter Test condition Min Typ Max Unit EOL-R Sink/source capability 2.5 µA EOL-R Relamp comparator 4.63 V hysteresys 160 mV Half bridge section – Half-bridge current sense HBCSH HBCS HBCSL HBCS HBCS Frequency increase threshold Latched threshold VEOI < 1.9V (ignition) 1.53 1.6 1.66 V VEOI > 1.9V (run mode) 0.85 0.91 0.97 V Run mode 1.53 1.6 1.66 V 0.3 V Half bridge section – Low side gate driver LSD Output low voltage ISINK = 10mA LSD Output high voltage ISOURCE = 10mA LSD Peak source current 200 290 mA LSD Peak sink current 400 480 mA TRISE LSD Rise time 120 ns TFALL LSD Fall time 80 ns LSD Pull-down resistor 45 KΩ 14.5 ; V Half bridge section – High side gate driver (voltages referred to OUT) VOUT + 0.3 HSD Output low voltage ISINK = 10mA HSD Output high voltage ISOURCE = 10mA HSD Peak source current 200 290 mA HSD Peak sink current 400 480 mA TRISE HSD Rise time 120 ns TFALL HSD Fall time 80 ns HSD HSD-OUT pull-down 50 KΩ V VBOOT – 0.5 V High-side floating gate-drive supply BOOT OUT Leakage current VBOOT = 600V (2) Leakage current VOUT = 600V Synchronous bootstrap diode on-resistance VLSD = HIGH (2) 5 µA 5 µA 250 Ω 1. Parameter in tracking 2. Specification over the -40°C to 125°C junction temperature range are ensured by design, characterization and statistical correlation 3. A pulse train has been sent to the HBCS pin with f=6KHz; the pulse duration is the one indicated in the notes as "TON" 11/25 Application information L6585D 5 Application information 5.1 Start-up sequence 5.1.1 Pre-heating (time interval A Figure 5) After IC turn-on, unless a lamp absence is detected, the oscillator starts switching at a frequency (fPRE) set by values of COSC and RRUN and RPRE Figure 4: Equation 1 1.328 f PRE = ----------------------------------------------------------C OSC ⋅ ( R RUN || R PRE ) The pre-heating time is: Equation 2 CD 4.63 T PRE = 4.63 ⋅ -------- + R D ⋅ C D ⋅ ln ----------1.52 I CH where CD and RD are shown in Figure 4 and ICH is typically 34 µA. Figure 4. Oscillator, pre-heating and ignition circuitry IMAX VREF RF RRUN RPRE CIGN EOI RD Tch CD COSC 12/25 LOGIC OSC L6585D 5.1.2 Application information Ignition (time interval B Figure 5) When the voltage at pin TCH drops down to 1.50V (typ.), the pin EOI is driven in high impedance state and CIGN is exponentially charged according to the time constant τ given by CIGN*RPRE that defines the ignition time and the frequency shift starts. The ignition time is the time necessary to EOI voltage to reach 1.9V, so, by means of simple calculation: Equation 3 T IGN = 3 ⋅ C IGN ⋅ R PRE During this phase, the half-bridge current control can limit the maximum voltage applied to the lamp by forcing small frequency increases whenever the half-bridge sense resistor voltage exceeds the HBCSH threshold (see the “Half-Bridge current control” paragraph). Figure 5, centre and right, shows the L6585D behavior as the lamp gets older; if it doesn’t ignite for a time longer than the pre-heating one (counted by a cycle charge/discharge of the TCH pin), the IC is stopped, enters low consumption and waits for either a re-lamp or an UVLO. 13/25 Application information 5.1.3 L6585D Run mode (time interval C Figure 5) As the voltage at EOI exceeds 1.9V and the lamp has ignited, the L6585D enters Run mode and remains in this condition unless one of the protections (all enabled in this mode) is trigged. The switching frequency reaches the FRUN value set by RRUN and COSC: Equation 4 1.328 f RUN = ---------------------------------R RUN ⋅ C OSC Figure 5. Oscillator, pre-heating and ignition sequence VCC(on) VCC(on) VCC VCC VCC(off) τ = RD x CD 4.63V Tch EOI Tch 2V EOI 1.9V fPRE fHB VCC(off) 4.63V Tch 1.5V 2V EOI 1.9V fPRE fHB fRUN fRUN VHBCS VHBCS VLAMP VLAMP VLAMP 14/25 B C A 1.5V 2V 1.9V fPRE fHB VHBCS A VCC(off) 4.63V 1.5V VZ VCC(on) VCC B C fRUN A B C L6585D End of life – window comparator 6 End of life – window comparator To detect the ageing of the lamp with particular attention to the effect appearing as asymmetric rectification, a programmable window comparator has been introduced (centered around “VREF” with amplitude “VW”) that triggers when the EOL-R voltage is higher than VREF+ VW/2 or lower than VREF – VW/2. By means of the resistor connected to the EOLP pin, it is possible to select: 1. the sensing mode: 2. Figure 6. – fixed reference: the centre of the window comparator (VREF) is fixed at 2.5V by an internal reference; – tracking reference: the centre of the window comparator is the voltage at pin CTR (that is a signal proportional to the PFC output voltage). the half-window amplitude (VW/2): 220mV or 720mV. End-of-life detection circuitry and waveforms RP2 CTR RP1 HV BUS HV BUS CBOOT CBOOT BOOT INTERNAL FIXED REF. WINDOW COMPARATOR INPUT CTR HSD WINDOW COMPARATOR INPUT OUT AMPLITUDE HSD OUT CBLOCK AMPLITUDE LSD EOLP BOOT INTERNAL FIXED REF. LSD VLAMP EOLR RFL or RFH EOLR EOLP VK VLAMP VK RE1 CBLOCK RE2 RFL or RFH VZ2 VZ1 RE1 RE2 HVBUS (100Hz or 120Hz) PFCOUT PFCOUT/2 VCB VLAMP VREF + W/2 + VZ1 + VR2 CTR VK VREF – W/2 – VZ1 – VR2 VREF + W/2 VEOLR VREF + W/2 VREF VREF – W/2 VREF – W/2 VEOLR 15/25 End of life – window comparator L6585D The four possible configurations are summarized in the following table, together with the value of resistance to be connected to the EOLP pin in order to obtain the desired setting: Table 5. Configuration of the EOLP pin EOLP resistor Symbol Reference Half–window amplitude REOLP > 620K RFH Fixed 2.5V ± 720mV 220K = REOLP = 270K RTL Tracking with CTR ± 220mV 75K = REOLP = 91K RFL Fixed 2.5V ± 220mV 22K = REOLP = 27K RTL Tracking with CTR ± 720mV Tracking reference: this setting is suitable for the block capacitor to ground configuration (Figure 6, left). In this case the window comparator centre is set by the CTR voltage that is internally transferred to the EOL structure. The effect of rectification appears as shifting of the DC voltage component across the block capacitor, which, under normal conditions, equals one half of the PFC output voltage. A signal proportional to the DC block capacitor voltage is sent to the EOL-R pin by means of a resistive divider (RE1 and RE2); the dividers RE1 and RE2 and RP1 and RP2 must be designed to set the EOL-R voltage equal to CTR under nominal condition. Fixed reference: this setting is suitable for the lamp to ground configuration (Figure 6, right). The effect of rectification appears as shifting of the DC lamp voltage. A resistive divider (RE1 and RE2) senses the voltage across the lamp under normal condition, that is an AC signal with zero average value whereas in case of asymmetric rectification the DC value can shift either in positive or negative direction. Two Zener diodes can be connected back-to-back between the EOL-R pin and the centre of the resistive divider. The Zener voltages should differ by an amount as close as possible to the double of the internal reference to have a symmetrical detection, as it can easily obtained from the following equations: ● VUP = VREF + W/2 + VZ1 + VR2 ● VDOWN = VREF – W/2 – VZ2 – VR1 where VUP and VDOWN are the VK values (equal in absolute value) that trigger the window comparator. To avoid an immediate intervention of the EOL protection, a filtering is introduced; as long as the fault condition persists, the Tch internal generator charges the CD up to 4.63V and then it opens. If this fault condition is still present when the Tch voltage decreases down to 1.5V, then the half bridge is stopped, otherwise (if the fault disappears) the counting is stopped and reset. 16/25 L6585D 7 Half-bridge current control Half-bridge current control The information about the lamp current can be obtained by reading the voltage across a sense resistor placed in series to the source of the half-bridge low side MOS. This circuitry is enabled at the end of the pre-heating phase and it enriches the L6585D with two features: ● Controlled lamp voltage/current during ignition (Figure 5): by properly setting the sense resistor (such that the VHBCS level is crossed in correspondence of a lamp voltage higher than the ignition voltage) it is possible to limit the maximum lamp voltage during ignition. In case of this occurrence, then the L6585D would react with a small frequency increase that allows limiting the lamp voltage (V+IGN). This also prevents the risk of crossing the resonance frequency of the LBALLAST-CRES circuit. If the lamp ignites before TCH reaches 1.50V (Figure 5 left) that is EOI has exceeded 1.9V, then: – EOI internal switch opens and its voltage moves asymptotically to 2V – The switching frequency reaches the operating one; – When TCH reaches 1.52, it will be discharged If instead that the lamp hasn’t ignited after a time equal to the pre-heat time (Figure 5 right) the oscillator stops, the chip enters low consumption mode and this condition is latched until the mains supply voltage is removed or a re-lamp is detected. ● Over-current protection during run mode: if the HBCSL threshold is crossed, the TCH internal generator is turned on as well as the one at pin EOI causing a frequency increase: this implements a current control structure. During run mode another protection is active: a second comparator (HBCSH) on the pin HBCS detects anomalous current flow through the sense resistor such as the spikes generated by the capacitive mode; the crossing of this second threshold latches the IC. 17/25 CTR 8 L6585D CTR This is a multi-function pin, connected to a resistive divider to the PFC output bus: 18/25 ● PFC over-voltage: in case of PFC output overshoot (e.g. at start-up) that causes a threshold crossing, the PFC section stops switching until the pin voltage falls below 3.26V (typ.); this is helpful because the bandwidth of the PFC error amplifier is narrow so the control loop is not fast enough to properly reacts ● Feedback disconnection: The OVP function above described (together with the static one embedded in the PFC error amplifier) is able to handle “normal” over-voltage conditions, i.e. those resulting from an abrupt load/line change or occurring at start-up. In case of over-voltage generated when the upper resistor of the feedback output divider fails open, the control loop can no longer read the information on the output voltage and will force the PFC pre-regulator to work at maximum ON time; if this occurs (i.e. the pin INV falls below 1.2V, typ.) and the CTR detects an OVP, the gate drivers activity is immediately stopped, the device enters low consumption and the condition is latched as long as the IC supply voltage is above the UVLO threshold; ● Reference for EOL in case of tracking reading. ● Disable: by forcing the pin below 0.75V an immediate unlatched shut-down is activated; it can be also used as re-lamp in fact after the pin voltage is above 0.8V a preheating/ignition sequence is repeated. L6585D 9 Re–lamp Re–lamp A second comparator has been introduced on the pin EOL-R; a voltage higher than the internal threshold is read as lamp absence so the chip suddenly stops switching, enters idle mode (low consumption) and is ready for a new pre-heating/ignition sequence as soon as a new lamp is inserted. In this idle mode the consumption of the chip is reduced so that the current flowing through the resistors (connected to the high voltage bus for the start-up) is enough to keep the VCC voltage above the UVLO threshold. After a re-lamp cycle (that is the EOL-R voltage is brought above 4.63V and then released below), a new pre-heating/ignition sequence starts. Table 6. IC configuration Pre-heating Ignition Run mode EOI charge from 0 to 1.9V (typ.); Until a fault appears or It depends on RD and the AC Mains is removed CD Time duration TCH cycle(1); It depends on RD and CD Half-bridge switching frequency 1.328 f PRE = ----------------------------------------------------------C OSC ⋅ ( R RUN || R PRE ) The frequency shifts from fPRE to fRUN with exponential trend 1.328 f RUN = ---------------------------------R RUN ⋅ C OSC RELAMP comparator ENABLED ENABLED ENABLED CTR: PFC overvoltage ENABLED ENABLED ENABLED CTR: disable function ENABLED ENABLED ENABLED ENABLED – low threshold ⇒ disabled – high threshold ⇒ FSW increase ENABLED – low threshold ⇒ FSW increase – high threshold ⇒ latch Half-bridge current sense DISABLED EOL: window comparator DISABLED DISABLED ENABLED PFC choke saturation ENABLED ENABLED ENABLED 1. TCH cycle: charge of the TCH voltage up to 4.63V and discharge down to 1.50V following the RDCD time constant 19/25 Re–lamp Table 7. L6585D Fault conditions Fault Lamp absence (re-lamp comparator) End of life Half-bridge current sense Shut-down Choke saturation Condition IC behavior At turn-on: EOL-R voltage higher than 4.63V – The TCH charge doesn’t start (no ignition) – Drivers stopped – IC low consumption (Vcc clamped) Run mode: EOL-R voltage higher than 4.63V – All drivers stopped – IC low consumption (Vcc clamped) EOL-R voltage outside the limits of window comparator – TCH cycle (1) (reset if the fault disappears) – drivers stopped at the end of TCH cycle – IC low consumption (VCC clamped) Re-lamp cycle (2) Ignition: HBCS threshold – TCH cycle (1) with lamp voltage control – In case of HBCS at the end of the TCH cycle, drivers stopped – IC low consumption (Vcc clamped) Re-lamp cycle (2) Run mode: HBCSL threshold – TCH cycle (1) with lamp voltage control (frequency increase) – In case of HBCS at the end of the TCH cycle, drivers stopped – IC low consumption (Vcc clamped) Re-lamp cycle (2) Run mode: HBCSH threshold – Drivers stopped – IC low consumption (Vcc clamped) Re-lamp cycle (2) CTR voltage lower than 0.8V – Drivers stopped – IC low consumption (Vcc clamped) When the CTR voltage returns above 0.8V, the IC driver restart with a pre-heating sequence PFCS voltage higher than 1.6V – Drivers stopped – IC low consumption (Vcc clamped) Re-lamp cycle (2)(3) Over-voltage of PFC CTR voltage higher than – PFC driver stopped output 3.4V PFC open loop (feedback disconnection) 1. Action required CTR voltage higher than – Drivers stopped 3.4V AND INV voltage – IC low consumption (Vcc clamped) lower than 1.2 Lamp replacement (EOL-R below 4.63V) When the CTR voltage returns below 3.26V (Typ.), the PFC driver restarts Re-lamp cycle (2)(3) TCH cycle: charge of the TCH voltage up to 4.63V and discharge down to 1.50V following the RDCD time constant; 2. Re-lamp cycle: the voltage at EOL-R pin must be first pulled above 4.63V and then released below it; this typically happens in case of lamp replacement. After a re-lamp cycle, a new pre-heating sequence will be repeated. 3. This fault actually is a "board" fault so a lamp replacement is not effective to restart the ballast 20/25 L6585D 10 Package mechanical data Package mechanical data In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. These packages have a Lead-free second level interconnect. The category of second Level Interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com. 21/25 Package mechanical data Table 8. L6585D SO-20 mechanical data Dimensions mm. inch Ref. Min. Typ. A a1 Max. Typ. 2.65 0.1 Max. 0.104 0.2 a2 0.004 0.008 2.45 0.096 b 0.35 0.49 0.014 0.019 b1 0.23 0.32 0.009 0.012 C 0.5 0.020 c1 45° (typ.) D 12.60 13.00 0.496 0.512 E 10.00 10.65 0.393 0.419 e 1.27 0.050 e3 11.43 0.450 F 7.40 7.60 0.291 0.300 L 0.50 1.27 0.020 0.050 M 0.75 S Figure 7. 22/25 Min. 0.029 8° (max.) Package dimensions L6585D 11 Order codes Order codes Table 9. Order codes Part Number Package Packaging L6585D SO-20 Tube L6585DTR SO-20 Tape and Reel 23/25 Revision history 12 L6585D Revision history Table 10. 24/25 Revision history Date Revision Changes 12-Jan-2006 1 Initial release 25-Oct-2006 2 Final datasheet 21-Dec-2006 3 Updated fRUN value on Table 4: Electrical characteristics on page 8 12-Apr-2007 4 Updated electrical values on Table 4 23-May-2007 5 Updated Figure 1: Block diagram on page 1 and Eq.1 and 4 L6585D Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale. 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