LT8309ES5#TRMPBF

LT8309 is a secondary-side synchronous rectifier driver that replaces the output rectifier diode in a flyback topology. By replacing the diode with an N-channel MOSFET, applications are no longer restricted by the heat constraints of the output diode. The IC replicates the behaviour of a diode by sensing the drain-to-source voltage to determine when the current becomes negative. The LT8309's low minimum on- and off-times help improve noise immunity. The fast propagation delay of 26ns allows applications to operate in discontinuous conduction mode and critical conduction mode. The gate driver features a 0.8ohm pull-down device for fast turn-offs. The 40V VCC rating allows the part to be driven from the output voltage or the rectified drain voltage of the MOSFET. A low quiescent current of 400µA maximizes efficiency at low output currents. Application includes high output current flybacks, high efficiency flybacks.

• Works with DCM and BCM/CrCM conduction mode flyback topologies
• Input voltage range from 4.5 to 40V (TA = 25°C)
• Supports up to 150V MOSFETs
• Turn-off propagation delay is 26ns (typ, RS = 0 ohm, -100mVOD, VDS to VGATE)
• Accurate minimum on and off timers for reliable operation
• Adjustable and accurate trip point range from +5mV to –30mV
• VCC quiescent current is 300µA (typ, not switching, INTVCC = 8V)
• Drain voltage latch reset is 1.21V (typ, RS = 0 ohm, TA = 25°C)
• Drain current is 10µA (typ, out of pin, TA = 25°C)
• 5-lead plastic TSOT-23 package, temperature range from -40°C to 125°C

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