WS21351 Half-bridge power IC for CFL lamps FEATURES Product Summary ■ 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 VOFFSET 600V Max. Duty Cycle 50% Tr/Tp 80/40ns Vclamp 15.6V typ. Deadtime (typ.) 2μs GERNERAL DESCRIPTION Packages 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. 8 Lead PDIP TYPICAL APPLICATION Rev. A Mar.2010 Copyright@Winsemi Microelectronics Co., Ltd., All right reserved. T11-1 WS21351 GENERAL INFORMATION Pin Configuration WS21351 TERMINAL ASSIGNMENTS Pin # Name Description 1 PGND Power ground 2 OUT Half bridge output 3 VDC High-voltage supply 4 VB High-side floating supply 5 VDD Supply voltage 6 GND Signal ground 7 RMIN Oscillator frequency set resistor 8 CPH Preheating time set capacitor BLOCK DIAGRAM WS21351 2/7 Steady, keep you advance WS21351 ABSOLUTE MAXIMUM RATINGS Symbol Parameter Min. Typ. Max. Unit VB High-side floating supply -0.3 600 VOUT Half bridge output -0.3 575 VIN RMIN, CPH pins input voltage -0.3 7 ICL Clamping current level -25 25 mA dVOUT/dt Allowable offset voltage slew rate -50 50 V/ns TA Operating temperature range -25 125 TSTG Storage temperature range -65 150 TL Lead temperature (soldering,10 seconds) V °C 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 Characteristics (VBIAS(VDD, VB-Vout)=14.0V, TA=25°C, unless otherwise specified.) Symbol Parameter Condition Min. Typ. Max. Unit Supply characteristics VDDTH(ST+) VDD UVLO positive going threshold VDD rising from 0V 11.2 12.8 14 VDDTH(ST-) VDD UVLO negative going threshold VDD decreasing 9 10 11 VDDHY(ST) VDD-side UVLO hysteresis VCL Supply clamping voltage IDD =20mA IST Start-up supply current VDD = 10V 50 IDD Dynamic operating supply current Running freq=85KHZ 4．5 V 2．8 14．4 15．6 80 μA mA Floating supply characteristics (VB-VOUT) VHSTH(ST+) High-side UVLO positive going threshold VB –VOUT increasing 7．5 9 10．5 VHSTH(ST-) High-side UVLO negative going threshold VB –VOUT decreasing 7．8 8 9．2 V VHSHY(ST) High-side UVLO hysteresis IHST High-side quiescent supply current 60 uA 1 VB –VOUT = 14V Oscillator characteristics fPRE Preheating frequency RMIN = 82kΩ, VCPH =0V 66 86 96 kHz fOSC Running frequency RMIN = 82kΩ, 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 characteristics ILKMOS MOSFET leakage current RON On resistance (dynamic) VDS = 500V 10 VGS = 12V, ID = 100mA 8 VGS = 12V, ID = 500mA 10 μA Ω 3/7 Steady, keep you advance WS21351 OPERATION DESCRIPTION Under-Voltage Lockout (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 ignition and improve lamp life longevity.Accordingly, the oscillation frequency is changed in the following sequence: Preheating freq > Ignition freq > running freq. 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– after VB-VOUT exceeds VHSTH+, operation of the driver continues. WS21351 Oscillator Operation The ballast circuit for a fluorescent lamp is based on the Preheating and ignition Mode LCC resonant tank and a half-bridge inverter circuit, as When VDD exceeds VDDTH+ threshold, theWS21351 shown in Fig4 . To accomplish Zero-Voltage Switching enters preheating mode. An internal current source charges (ZVS) of the half-bridge inverter circuit, the LCC must be the external capacitor on pin CPH, and the voltage on pin driven at a higher frequency than its resonant Frequency, CPH starts ramping up linearly. The frequency ramps down which is determined by L, CS, CP, and RL; where RL is the towards the resonance frequency of the high-Q ballast equivalent lamp's impedance. The transfer function of LCC output stage causing the lamp voltage and load current to resonant tank is heavily dependent on the lamp impedance, Increase. RL, as illustrated in Figure 4. The oscillator inWS21351 generates effective driving frequencies to assist lamp The voltage on pin CPH continues to increase and the frequency keeps decreasing until the lamp ignites. If the 4/7 Steady, keep you advance WS21351 Lamp ignites successfully, the voltage on pin CPH Run Mode continues to increase until it internally limits at 6V TheWS21351 enters RUN mode when the voltage (VCPH_MAX). The frequency stops decreasing when on pin CPH exceeds 5V . The lamp has ignited and VCPH reach 5V and stays at the minimum frequency the ballast output stage becomes a low-Q, series-L, as programmed by an external resistor, on pin RMIN parallel-RC circuit. The voltage on the CPH pin (as show in Fig 4). The minimum frequency should continues to increase but the frequency don't change be set below the High-Q resonance frequency of the as the minimum frequency is reached. The resonant ballast output stage to ensure that the frequency inductor, resonant capacitor, DC bus voltage and ramps through resonance for lamp Ignition minimum frequency determine the running lamp .The desired preheat time can be set by adjusting power. The relation of minimum run frequency and the slope of the VCPH ramp with the external the setting resistor RRMIN as show in Fig 6. The IC capacitor on pin CPH. The relation of LCC tank stays at this minimum frequency unless VDD frequency and Pin CPH voltage VCPH as show in decreases below the VDDTH– threshold Fig5. 5/7 Steady, keep you advance WS21351 WS21351 for 18W CFL Application 6/7 Steady, keep you advance WS21351 DIP-8 Package Dimension 7/7 Steady, keep you advance