UC2845AN(XBLW)

UC2845 is a fixed-frequency current-mode PWM controller designed for off-line and DC-DC converter applications. This IC integrates an oscillator, temperature-compensated reference voltage source, high-gain error amplifier, current-sensing comparator, and a high-current totem-pole output suitable for driving power MOSFETs. Protection features include input and reference undervoltage lockout with hysteresis, cycle-by-cycle current limiting, a latch for single-pulse metering, and a flip-flop that alternately inhibits the output each oscillator cycle, allowing the output dead time to be programmed between 50% and 70%. The UC2845 is optimized for lower-voltage applications, with UVLO thresholds of 8.2V (turn-on) and 7.6V (turn-off).

Applications

• Switching regulators of any polarity
• Transformer-coupled DC-DC converters

Key features

• Current-mode operation, output switching frequency up to 500 kHz
• Output dead time adjustable from 50% to 70%
• Automatic feed-forward compensation
• Latching PWM for cycle-by-cycle current limiting
• Internal trimmed reference voltage with undervoltage lockout
• High-current push-pull output (drive current up to 1A)
• Undervoltage lockout with hysteresis
• Low startup and operating current (< 0.5 mA)