The LM34923 Step Down Switching Regulator features all of the functions needed to implement a low cost, efficient Buck bias regulator. This high voltage regulator contains an 80V N-Channel MOSFET Switch and a startup regulator. The device is easy to implement and is provided in an 10-pin VSSOP package. The regulator’s control scheme uses an on-time inversely proportional to VIN. This feature results in the operating frequency remaining relatively constant with line and load variations. The control scheme requires no loop compensation, resulting in fast transient response. An intelligent current limit is implemented with a forced off-time which is inversely proportional to VOUT. This scheme ensures short circuit control while providing minimum foldback. Other features include: Thermal Shutdown, VCC Under Voltage Lock-out, Max Duty Cycle Limiter, a Pre-charge Switch, and a programmable Under Voltage Detector with a status flag output.

• Operating Input Voltage Range: 6V to 75V
• Integrated 80V, N-Channel Buck Switch
• Internal Start-up Regulator
• No Loop Compensation Required
• Ultra-Fast Transient Response
• Operating Frequency Remains Constant with Line and Load Variations
• Adjustable Output voltage From 2.5V
• Precision Internal Reference, ±2.5%
• Intelligent Current Limit Reduces Foldback
• Programmable Input UV Detector with Status Flag Output
• Pre-charge Switch Enables Bootstrap Gate Drive with No Load
• Thermal Shutdown
• 10-Pin VSSOP Package