The UC3856 is a high performance version of the popular UC3846 series of current mode controllers, and is intended for both design upgrades and new applications where speed and accuracy are important. All input to output delays have been minimized, and the current sense output is slew rate limited to reduce noise sensitivity. Fast 1.5A peak output stages have been added to allow rapid switching of power FETs.

A low impedance TTL compatible sync output has been implemented with a tri-state function when used as a sync input.

Internal chip grounding has been improved to minimize internal \x93noise\x94 caused when driving large capacitive loads. This, in conjunction with the improved differential current sense amplifier results in enhanced noise immunity.

Other features include a trimmed oscillator current (8%) for accurate frequency and dead time control; a 1V, 5% shutdown threshold; and 4kV minimum ESD protection on all pins.

• Pin-for-Pin Compatible With the UC3846
• 65ns Typical Delay From Shutdown to Outputs, and 50ns Typical Delay From Sync to Outputs
• Improved Current Sense Amplifier With Reduced Noise Sensitivity
• Differential Current Sense with 3V Common Mode Range
• Trimmed Oscillator Discharge Current for Accurate Deadband Control
• Accurate 1V Shutdown Threshold
• High Current Dual Totem Pole Outputs (1.5A peak)
• TTL Compatible Oscillator SYNC Pin Thresholds
• 4kV ESD Protection