UC3845AN(XBLW)

The UC3845 is a fixed frequency current mode PwM controllers. It is specifically designed for Off- Line and DC- DC converter applications. These integrated circuits feature an oscillator, a temperature compensated reference, high gain error amplifier, current sensing comparator, and a high current totem pole output ideally suited for driving a power MOSFET. Also included are protective features consisting of input and reference undervoltage lockouts each with hysteresis, cycle- by- cycle current limiting, a latch for single pulse metering, and a flip- flop which blanks the output off every other oscillator cycle, allowing output deadtimes to be programmed from 50% to 70%. The U3845 is tailored for lower voltage applications having UVLO thresholds of 8.2V (on) and 7.6V (off). This device is available in SOP- 8 package and DIP8 package.

Applications

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

Key features

• Current Mode Operation to 500 kHz Output Switching Frequency
• Output Deadtime Adjustable from 50% to 70%
• Automatic Feed Forward Compensation
• Latching PWM for Cycle- By- Cycle Current Limiting
• Internally Trimmed Reference with Undervoltage Lockout
• High current push- pull output (drive current up to 1A)
• Undervoltage Lockout with Hysteresis
• Low Startup and Operating Current (< 0.5mA)