Datasheet LT1072 - 3

LT1072
ELECTRICAL CHARACTERISTICS The
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denotes specifications which apply over the full operating temperature range. Unless otherwise specified, VIN = 15V, VC = 0.5V, VFB = VREF, output pin open. SYMBOL PARAMETER CONDITlONS MIN TYP MAX UNITS
VREF Reference Voltage Measured at Feedback Pin 1.224 1.244 1.264 V VC = 0.8V ● 1.214 1.244 1.274 V IB Feedback Input Current VFB = VREF 350 750 nA ● 1100 nA gm Error Amplifier ∆IC = ±25µA 3000 4400 6000 µmho Transconductance ● 2400 7000 µmho Error Amplifier Source or VC = 1.5V 150 200 350 µA Sink Current ● 120 400 µA Error Amplifier Clamp Hi Clamp, VFB = 1V 1.8 2.3 V Voltage Lo Clamp, VFB = 1.5V 0.25 0.38 0.52 V Reference Voltage Line 3V ≤ VIN ≤ VMAX ● 0.03 %/V Regulation VC = 0.8V %/V AV Error Amplifier Voltage Gain 0.9V ≤ VC ≤ 1.4V 500 800 V/V Minimum Input Voltage ● 2.6 3.0 V IQ Supply Current 3V ≤ VIN ≤ VMAX, VC = 0.6V 6 9 mA Control Pin Threshold Duty Cycle = 0 0.8 0.9 1.08 V ● 0.6 1.25 V Normal/Flyback Threshold on Feedback Pin 0.4 0.45 0.54 V VFB Flyback Reference Voltage lFB = 50µA 15 16.3 17.6 V ● 14 18 V Change in Flyback Reference Voltage 0.05 ≤ IFB ≤ 1mA 4.5 6.8 8.5 V Flyback Reference Voltage lFB = 50µA 0.01 0.03 %/V Line Regulation 3V ≤ VIN ≤ VMAX (Note 4) %/V Flyback Amplifier Transconductance (gm) ∆IC = ±10µA 150 300 650 µmho Flyback Amplifier Source VC = 0.6V Source ● 15 32 70 µA and Sink Current IFB = 50µA Sink ● 25 40 70 µA BV Output Switch Breakdown 3V ≤ VIN ≤ VMAX LT1072 ● 65 90 V Voltage ISW = 1.5mA LT1072HV ● 75 90 V LT1072S8 ● 60 80 V VSAT Output Switch ON Resistance (Note 2) ISW = 1.25A ● 0.6 1 Ω Control Voltage to Switch Current Transconductance 2 A/V ILIM Switch Current Limit Duty Cycle = 50% TJ ≥ 25°C ● 1.25 3 A Duty Cycle = 50% TJ < 25°C ● 1.25 3.5 A Duty Cycle = 80% (Note 3) ● 1 2.5 A ∆IIN Supply Current Increase 25 35 mA/A ∆ISW During Switch ON Time f Switching Frequency 35 40 45 kHz ● 33 47 kHz DC (max) Maximum Switch Duty Cycle 90 92 97 % Flyback Sense Delay Time 1.5 µs Shutdown Mode 3V ≤ VIN ≤ VMAX 100 250 µA Supply Current VC = 0.05V Shutdown Mode 3V ≤ VIN ≤ VMAX 100 150 250 mV Threshold Voltage ● 50 300 mV
Note 1:
Absolute Maximum Ratings are those values beyond which the life
Note 3:
For duty cycles (DC) between 50% and 80%, minimum of a device may be impaired. guaranteed switch current is given by ILIM = 0.833 (2 – DC).
Note 2:
Measured with VC in hi clamp, VFB = 0.8V.
Note 4:
VMAX = 55V for LT1072HV to avoid switch breakdown. 1072fc 3