link to page 9 link to page 9 link to page 9 link to page 9 link to page 9 link to page 9 link to page 9 FL7921RELECTRICAL CHARACTERISTICS (VDD = 15 V and TA = −40~105C, unless otherwise noted) (continued) SymbolParameterConditionsMinTypMaxUnitPFC Zero−Current Detection Section tDELAY Maximum Delay from ZCD to Output Turn−On VCOMP = 5 V, fS = 60 kHz 50 − 200 ns tRESTART−PFC Restart Time 300 500 700 ms tINHIB Inhibit Time (Maximum Switching Frequency Limit) VCOMP = 5 V 1.5 2.5 3.5 ms VZCD−DIS PFC Enable / Disable Function Threshold Voltage 0.12 0.19 0.26 V tZCD−DIS PFC Enable / Disable Function Debounce Time VZCD = 100 mV 100 150 200 ms PWM STAGEFeedback Input Section AV Input−Voltage to Current−Sense Attenuation AV = DVCSPWM / DVFB, 1/2.75 1/3.00 1/3.25 V/V (Note 4) 0 < VCSPWM < 0.9 ZFB Input Impedance FB > VG 3 5 7 kW IOZ Bias Current (Note 4) FB = VOZ − 1.2 2.0 mA VOZ Zero Duty−Cycle Input Voltage 0.6 0.85 1.1 V VFB−OLP Open−Loop Protection Threshold Voltage 3.9 4.2 4.5 V tFB−OLP Debounce Time for Open−Loop Protection 40 52.5 65 ms tFB−SS Internal Soft−Start Time (Note 4) VFB = 0 V~3.6 V 8 10 12 ms DET Pin OVP and Valley Detection Section VDET−OVP Comparator Reference Voltage 2.45 2.50 2.55 V Av Open−Loop Gain (Note 4) − 60 − dB BW Gain Bandwidth (Note 4) − 1 − MHz tDET−OVP Output OVP (Auto Recovery) Debounce Time 100 150 200 ms IDET−SOURCE Maximum Source Current VDET = 0 V − − 1 mA VDET−LOW Lower Clamp Voltage IDET = 1 mA −0.5 −0.3 −0.1 V tVALLEY−DELAY Delay from Valley Signal Detected to Output Turn−on (Note 4) 150 200 250 ns tOFF−BNK Leading−Edge Blanking Time for DET−OVP 3 4 5 ms (2.5 V) and Valley Signal when PWM MOSFET Turns Off (Note 4) tTIME−OUT Time−Out After tOFF−MIN 8 9 10 ms PWM Oscillator Section tON−MAX−PWM Maximum On Time 37 46 54 ms tOFF−MIN Minimum Off−Time VFB VN, TA = 25C 7 8 9 ms VFB = VG 32 37 42 VN Beginning of Green−On Mode at FB Voltage Level TA = 25C 1.95 2.10 2.25 V VG Beginning of Green−Off Mode at FB Voltage Level TA = 25C 1.00 1.15 1.30 V DVG Hysteresis for Beginning of Green−Off Mode at FB − 0.1 − V Voltage Level tSTARTER−PWM Start Timer (Time−Out Timer) VFB < VG, TA = 25C 1.85 2.25 2.65 ms VFB > VFB−OLP, 26 32 38 ms TA = 25C PWM Output Section VCLAMP PWM Gate Output Clamping Voltage VDD = 25 V 16.0 17.5 19.0 V VOL PWM Gate Output Voltage Low VDD = 15 V, IO = 100 mA − − 1.5 V VOH PWM Gate Output Voltage High VDD = 15 V, IO = 100 mA 8 − − V www.onsemi.com8