c o p y r igh t @ w i n s em i microelectronics c o . , lt d . , a l l ri g h t r e s er v ed . rev. a mar .20 10 WS21351 WS21351 WS21351 WS21351 t11 -1 half-bridge half-bridge half-bridge half-bridge power power power power ic ic ic ic for for for for cfl cfl cfl cfl lamps lamps lamps lamps features features features features integrated 600v half-bridge gate driver lower power level-shifting circuit adjustable oscillator frequency and preheat time maximum voltage of 600 v internal clamping zener diode soft start functionality g g g g erneral erneral erneral erneral d d d d escription escription escription escription the WS21351 is a high-voltage monolithic integrated circuit which is designed for driving compact fluorescent lamps (cfl) in a half-bridge configuration. WS21351 features a soft start function, an adjustable oscillator and an internal drive function with a high-voltage level shifter for driving the half bridge. typical typical typical typical application application application application product product product product summary summary summary summary p p p p ackages ackages ackages ackages v offset 600v max. duty cycle 50% t r /t p 80/40ns v clamp 15.6v typ. d eadtime (typ.) 2 s 8 lead pdip
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 2 / 7 w w w w s21351 s21351 s21351 s21351 general general general general information information information information pin pin pin pin configuration configuration configuration configuration terminal terminal terminal terminal assignments assignments assignments assignments pin pin pin pin # # # # name name name name description description description description 1 1 1 1 p gnd power ground 2 2 2 2 out half bridge output 3 3 3 3 v dc high-voltage supply 4 4 4 4 v b high-side floating supply 5 5 5 5 v dd supply voltage 6 6 6 6 gnd signal ground 7 7 7 7 r min oscillator frequency set resistor 8 8 8 8 c ph preheating time set capacitor block block block block diagram diagram diagram diagram WS21351 WS21351 WS21351 WS21351 WS21351 WS21351 WS21351 WS21351
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 3 / 7 w w w w s21351 s21351 s21351 s21351 a a a a bsolute bsolute bsolute bsolute maximum maximum maximum maximum ratings ratings ratings ratings symbol symbol symbol symbol parameter parameter parameter parameter min. min. min. min. typ. typ. typ. typ. max. max. max. max. unit unit unit unit v b high-side floating supply -0.3 600 v v out half bridge output -0.3 575 v in rmin, cph pins input voltage -0.3 7 i cl clamping current level -25 25 ma dv out /dt allowable offset voltage slew rate -50 50 v/ns t a operating temperature range -25 125 c t stg storage temperature range -65 150 t l lead temperature (soldering,10 seconds) 300 note: more than the limit specified in the table parameters will result in permanent damage to the device. the device is not recommended in these extreme conditions of work, working conditions in the limit above which may affect device reliability. electrical electrical electrical electrical characteristics characteristics characteristics characteristics ( v bias (v dd , v b -vout)=14.0v, t a =25 c, unless otherwise specified. ) symbol symbol symbol symbol parameter parameter parameter parameter condition condition condition condition min. min. min. min. typ. typ. typ. typ. max. max. max. max. unit unit unit unit supply supply supply supply characteristics characteristics characteristics characteristics vddth(st+) vdd uvlo positive going threshold vdd rising from 0v 11.2 12.8 14 v vddth(st-) vdd uvlo negative going threshold vdd decreasing 9 10 11 vddhy(st) vdd-side uvlo hysteresis 2 8 vcl supply clamping voltage idd =20ma 14 4 15 6 ist start-up supply current vdd = 10v 50 80 a idd dynamic operating supply current running freq=85khz 4 5 ma floating floating floating floating supply supply supply supply characteristics characteristics characteristics characteristics ( ( ( ( vb-vout vb-vout vb-vout vb-vout ) ) ) ) vhsth(st+) high-side uvlo positive going threshold vb C vout increasing 7 5 9 10 5 v vhsth(st-) high-side uvlo negative going threshold vb C vout decreasing 7 8 8 9 2 vhshy(st) high-side uvlo hysteresis 1 ihst high-side quiescent supply current vb C vout = 14v 60 ua oscillator oscillator oscillator oscillator characteristics characteristics characteristics characteristics fpre preheating frequency rmin = 82k , vcph =0v 66 86 96 khz fosc running frequency rmin = 82k , vcph =6v 29 34 39 khz duty oscillator duty cycle 50 % dt output dead time 2 0 us vcph maximum cph voltage 6 v mosfet mosfet mosfet mosfet characteristics characteristics characteristics characteristics ilkmos mosfet leakage current vds = 500v 10 a ron on resistance (dynamic) vgs = 12v, id = 100ma 8 vgs = 12v, id = 500ma 10
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 4 / 7 w w w w s21351 s21351 s21351 s21351 operation operation operation operation description description description description under-voltage under-voltage under-voltage under-voltage lockout lockout lockout lockout (uvlo)function (uvlo)function (uvlo)function (uvlo)function the WS21351 has uvlo circuits for both high-side and low-side circuits. when vdd reaches vddth+, uvlo is released and the WS21351 operates normally. under uvlo condition, WS21351 consumes little current, typically 50ua. after uvlo is released, WS21351 operates normally until vdd goes below vddth-, the uvlo has hysteresis which typically is 2.8v . at uvlo condition, all latches that determine the status of the ic are reset. WS21351 has a high-side gate driver circuit. the supply for the high-side driver is applied between vb and vout. to protect from malfunction of the driver at low supply voltage between vb and vout, WS21351 provides an additional uvlo circuit between this supply rails. if vb-vout is under vhsth+, the driver holds low state to turn off the high-side switch, when vb-vout is higher than vhsth C after vb-vout exceeds vhsth+, operation of the driver continues. oscillator oscillator oscillator oscillator operation operation operation operation the ballast circuit for a fluorescent lamp is based on the lcc resonant tank and a half-bridge inverter circuit, as shown in fig4 . to accomplish zero-voltage switching (zvs) of the half-bridge inverter circuit, the lcc must be driven at a higher frequency than its resonant frequency, which is determined by l, cs, cp, and rl; where rl is the equivalent lamp's impedance. the transfer function of lcc resonant tank is heavily dependent on the lamp impedance, rl, as illustrated in figure 4. the oscillator in WS21351 generates effective driving frequencies to assist lamp ignition and improve lamp life longevity.accordingly, the oscillation frequency is changed in the following sequence : preheating freq > ignition freq > running freq . preheating preheating preheating preheating and and and and ignition ignition ignition ignition mode mode mode mode when vdd exceeds vddth+ threshold, the WS21351 enters preheating mode. an internal current source charges the external capacitor on pin cph, and the voltage on pin cph starts ramping up linearly. the frequency ramps down towards the resonance frequency of the high-q ballast output stage causing the lamp voltage and load current to increase. the voltage on pin cph continues to increase and the frequency keeps decreasing until the lamp ignites. if the WS21351 WS21351 WS21351 WS21351
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 5 / 7 w w w w s21351 s21351 s21351 s21351 lamp ignites successfully, the voltage on pin cph continues to increase until it internally limits at 6v (v cph _ max ). the frequency stops decreasing when v cph reach 5v and stays at the minimum frequency as programmed by an external resistor, on pin rmin (as show in fig 4). the minimum frequency should be set below the high-q resonance frequency o f the ballast output stage to ensure that the frequency ramps through resonance for lamp ignition .the desired preheat time can be set by adjusting the slope of the v cph ramp with the external capacitor on pin cph. the relation of lcc tank frequency and pin cph voltage v cph as show in fig5. run run run run mode mode mode mode the WS21351 enters run mode when the voltage on pin cph exceeds 5v . the lamp has ignited and the ballast output stage becomes a low-q, series-l, parallel-rc circuit. the voltage on the cph pin continues to increase but the frequency don't change as the minimum frequency is reached. the resonant inductor, resonant capacitor, dc bus voltage and minimum frequency determine the running lamp power. the relation of minimum run frequency and the setting resistor r rmin as show in fig 6. the ic stays at this minimum frequency unless vdd decreases below the v ddth C threshold
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 6 / 7 w w w w s21351 s21351 s21351 s21351 WS21351 WS21351 WS21351 WS21351 for for for for 18w 18w 18w 18w cfl cfl cfl cfl application application application application
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 7 / 7 w w w w s21351 s21351 s21351 s21351 dip-8 dip-8 dip-8 dip-8 package package package package dimension dimension dimension dimension
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