UBA2021T

INTEGRATED CIRCUITS DATA SHEET UBA2021 630 V driver IC for CFL and TL lamps Product specification Supersedes data of 2000 Jul 24 File under Integrated Circuits, IC11 2001 Jan 30 Philips Semiconductors Product specification 630 V driver IC for CFL and TL lamps FEATURES • Adjustable preheat and ignition time • Adjustable preheat current • Adjustable lamp power • Lamp temperature stress protection at higher mains voltages • Capacitive mode protection • Protection against a too-low drive voltage for the power MOSFETs. QUICK REFERENCE DATA SYMBOL High voltage supply VFS Start-up state VVS(start) VVS(stop) IVS(standby) Preheat mode fstart tph VRS(ctrl) fB tign fB tno Itot start frequency preheat time control voltage at pin RS CCP = 100 nF − − − − − − − fB = 43 kHz − − − IRHV = 0.75 mA IRHV = 1.0 mA Ii(RHV) operating range of input current at pin RHV − − 0 108 666 −600 42.9 625 oscillator start voltage oscillator stop voltage standby current VVS = 11 V − − − 11.95 10.15 200 high side supply voltage IFS < 15 µA; t < 0.5 s − − PARAMETER CONDITIONS MIN. TYP. GENERAL DESCRIPTION UBA2021 The UBA2021 is a high-voltage IC intended to drive and control Compact Fluorescent Lamps (CFL) or fluorescent TL-lamps. It contains a driver circuit for an external half-bridge, an oscillator and a control circuit for starting up, preheating, ignition, lamp burning and protection. MAX. UNIT 630 − − − − − − − − − − − − − − − 1000 V V V µA kHz ms mV Frequency sweep to ignition bottom frequency ignition time kHz ms Normal operation bottom frequency non-overlap time total supply current 42.9 1.4 1 126 75 kHz µs mA Ω Ω kHz kHz µA RG1(on), RG2(on) high and low side on resistance RG1(off), RG2(off) high and low side off resistance Feed-forward fff feed-forward frequency 63.6 84.5 − 2001 Jan 30 2 Philips Semiconductors Product specification 630 V driver IC for CFL and TL lamps ORDERING INFORMATION PACKAGE TYPE NUMBER NAME UBA2021T UBA2021P BLOCK DIAGRAM SO14 DIP14 DESCRIPTION plastic small outline package; 14 leads; body width 3.9 mm plastic dual in-line package; 14 leads (300 mil) UBA2021 VERSION SOT108-1 SOT27-1 handbook, full pagewidth VS 5 RHV 13 RREF CF 10 12 CI 14 bootstrap charging circuit SB SUPPLY n.c. 4 BAND GAP REFERENCE 8 NON OVERLAP OSCILLATOR LEVEL SHIFTER HIGH SIDE DRIVER 1 2 3 FS G1 S1 CP TIMING LOW SIDE DRIVER 6 G2 RS 9 RS MONITOR CONTROL 7 UBA2021 11 MGS988 PGND SGND Fig.1 Block diagram. 2001 Jan 30 3 Philips Semiconductors Product specification 630 V driver IC for CFL and TL lamps PINNING UBA2021 SYMBOL FS G1 S1 n.c. VS G2 PGND CP RS RREF SGND CF RHV CI PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 gate high transistor (T1) source high transistor (T1) DESCRIPTION high side floating supply voltage high-voltage spacer, not to be connected low voltage supply gate low transistor (T2) power ground timing/averaging capacitor current monitoring input reference resistor signal ground oscillator capacitor start-up resistor/feed-forward resistor integrating capacitor handbook, halfpage handbook, halfpage FS G1 S1 n.c. VS G2 PGND 1 2 3 4 5 6 7 MGS989 14 CI 13 RHV 12 CF FS G1 S1 n.c. VS G2 PGND 1 2 3 4 5 6 7 MGS990 14 CI 13 RHV 12 CF UBA2021T 11 SGND 10 RREF 9 RS UBA2021P 11 SGND 10 RREF 9 RS 8 CP 8 CP Fig.2 Pin configuration (SO14). Fig.3 Pin configuration (DIP14). 2001 Jan 30 4 Philips Semiconductors Product specification 630 V driver IC for CFL and TL lamps FUNCTIONAL DESCRIPTION Introduction handbook, halfpage UBA2021 MGS991 The UBA2021 is an integrated circuit for electronically ballasted compact fluorescent lamps and their derivatives operating with mains voltages up to 240 V (RMS). It provides all the necessary functions for preheat, ignition and on-state operation of the lamp. In addition to the control function, the IC provides level shift and drive functions for the two discrete power MOSFETs, T1 and T2 (see Fig.7). Initial start-up Initial start-up is achieved by charging capacitor CS9 with the current applied to pin RHV. At start-up, MOSFET T2 conducts and T1 is non-conducting, ensuring Cboot becomes charged. This start-up state is reached for a supply voltage VVS(reset) (this is the voltage level at pin VS at which the circuit will be reset to the initial state) and maintained until the low voltage supply (VVS) reaches a value of VVS(start). The circuit is reset in the start-up state. Oscillation When the low voltage supply (VVS) has reached the value of VVS(start) the circuit starts oscillating in the preheat state. The internal oscillator is a current-controlled circuit which generates a sawtooth waveform. The frequency of the sawtooth is determined by the capacitor CCF and the current out of pin CF (mainly set by RRREF). The sawtooth frequency is twice the frequency of the signal across the load. The IC brings MOSFETs T1 and T2 alternately into conduction with a duty factor of approximately 50%. Figure 4 represents the timing of the IC. The circuit block 'non-overlap' generates a non-overlap time tno that ensures conduction periods of exclusively T1 or T2. Time tno is dependent on the reference current IRREF. start-up VCF 0 internal clock 0 V(G1-S1) 0 V(G2) 0 time t no t no Fig.4 Oscillator timing. Operation in the preheat mode The circuit starts oscillating at approximately 2.5 × fB (108 kHz). The frequency gradually decreases until a defined value of current Ishunt is reached (see Fig.5). The slope of the decrease in frequency is determined by capacitor CCI. The frequency during preheating is approximately 90 kHz. This frequency is well above the resonant frequency of the load, which means that the lamp is off; the load consists of L2, C5 and the electrode resistance only. The preheat time is determined by capacitor CCP. The circuit can be locked in the preheat state by connecting pin CP to ground. During preheating, the circuit monitors the load current by measuring the voltage drop over external resistor Rshunt at the end of conduction of T2 with decision level VRS(ctrl). The frequency is decreased as long as VRS > VRS(ctrl). The frequency is increased for VRS < VRS(ctrl). 2001 Jan 30 5 Philips Semiconductors Product specification 630 V driver IC for CFL and TL lamps Feed-forward frequency UBA2021 handbook, halfpage fstart MGS992 fB preheat state ignition state burn state time Above a defined voltage level the oscillation frequency also depends on the supply voltage of the half-bridge (see Fig.6). The current for the current-controlled oscillator is in the feed-forward range derived from the current through RRHV. The feed-forward frequency is proportional to the average value of the current through RRHV within the operating range of Ii(RHV), given the lower limit set by fB. For currents beyond the operating range (i.e. between 1.0 and 1.6 mA) the feed-forward frequency is clamped. In order to prevent feed-forward of ripple on Vin, the ripple is filtered out. The capacitor connected to pin CP is used for this purpose. This pin is also used in the preheat state and the ignition state for timing (tph and tign). For calculations refer to Chapter “Design equations”. Fig.5 Operation in the preheat mode. handbook, halfpage MGS993 Ignition state The RS monitoring function changes from VRS(ctrl) regulation to capacitive mode protection at the end of the preheat time. Normally this results in a further frequency decrease down to the bottom frequency fB (approximately 43 kHz). The rate of change of frequency in the ignition state is less than that in the preheat mode. During the downward frequency sweep, the circuit sweeps through the resonant frequency of the load. A high voltage then appears across the lamp. This voltage normally ignites the lamp. Failure to ignite Excessive current levels may occur if the lamp fails to ignite. The IC does not limit these currents in any manner. f (kHz) feed-forward range bottom frequency IRHV (mA) For calculations refer to Chapter “Design equations”. Fig.6 Feed-forward frequency. Capacitive mode protection Transition to the burn state Assuming that the lamp has ignited during the downward frequency sweep, the frequency normally decreases to the bottom frequency. The IC can transit to the burn state in two ways: 1. In the event that the bottom frequency is not reached, transition is made after reaching the ignition time tign. 2. As soon as the bottom frequency is reached. The bottom frequency is determined by RRREF and CCF. When the preheat mode is completed, the IC will protect the power circuit against losing the zero voltage switching condition and getting too close to the capacitive mode of operation. This is detected by monitoring voltage VRS at pin RS. If the voltage is below VRS(cap) at the time of turn-on of T2, then capacitive mode operation is assumed. Consequently the frequency increases as long as the capacitive mode is detected. The frequency decreases down to the feed-forward frequency if no capacitive mode is detected. Frequency modulation is achieved via pin CI. 2001 Jan 30 6 Philips Semiconductors Product specification 630 V driver IC for CFL and TL lamps IC supply Initially, the IC is supplied from Vin by the current through RRHV. This current charges the supply capacitor CS9 via an internal diode. As soon as VVS exceeds VVS(start), the circuit starts oscillating. After the preheat phase is finished, pin RHV is connected to an internal resistor Ri(RHV); prior to this, pin RHV is internally connected to pin VS. The voltage level at pin RHV thus drops from VVS + Vdiode to IRHV × Ri(RHV). The capacitor CS9 at pin VS will now be charged via the snubber capacitor CS7. Excess charge is drained by an internal clamp that turns on at voltage VVS(clamp). Minimum gate-source voltage of T1 and T2 The high side driver is supplied via capacitor Cboot. Capacitor Cboot is charged via the bootstrap switch during the on-periods of T2. The IC stops oscillating at a voltage level VVS(stop). Given a maximum charge consumption on the load at pin G1 of 1 nC/V, this safeguards the minimum drive voltages V(G1−S1) for the high side driver; see Table 1. Table 1 Minimum gate-source voltages VOLTAGE 8 V (min.) 7 V (min.) 6 V (min.) Ground pins UBA2021 Pin PGND is the ground reference of the IC with respect to the application. As an exception, pin SGND provides a local ground reference for the components connected to pins CP, CI, RREF and CF. For this purpose pins PGND and SGND are short-circuited internally. External connection of pins PGND and SGND is not preferred. The sum of currents flowing out of the pins CP, CI, RREF, CF and SGND must remain zero at any time. Charge coupling Due to parasitic capacitive coupling to the high voltage circuitry, all pins are burdened with a repetitive charge injection. Given the typical application in Fig.7, pins RREF and CF are sensitive to this charge injection. For the rating Qcouple a safe functional operation of the IC is guaranteed, independent of the current level. Charge coupling at current levels below 50 µA will not interfere with the accuracy of the VRS(cap) and VRS(ctrl) levels. Charge coupling at current levels below 20 µA will not interfere with the accuracy of any parameter. FREQUENCY