Features for the LM5161

• Wide 4.5-V to 100-V Input Voltage Range
• Integrated High-Side and Low-Side Switches
  • No Schottky Diode Required
• 1-A Maximum Load Current
• Constant ON-Time Control
  • No External Loop Compensation
  • Fast Transient Response
• Selectable DCM Buck Operation at Light Load
• CCM Option Supports Multi-Output Fly-Buck™
• No External Ripple circuit needed (at FPWM = 0)
• Nearly Constant Switching Frequency
• Frequency Adjustable Up to 1 MHz
• Programmable Soft-Start Time
• Prebias Start-Up
• Peak Current Limiting Protection
• Adjustable Input UVLO and Hysteresis
• ±1% Feedback Voltage Reference
• Thermal Shutdown Protection

Description for the LM5161

The LM5161 is a 100-V, 1-A synchronous step-down converter with integrated high-side andlow-side MOSFETs. The constant-ON-time control scheme requires no loop compensation and supportshigh step-down ratios with fast transient response. An internal feedback amplifier maintains ±1%output voltage regulation over the entire operating temperature range. The ON-time varies inverselywith input voltage resulting in nearly constant switching frequency. Peak and valley current limitcircuits protect against overload conditions. The under-voltage lockout (EN/UVLO) circuit providesindependently adjustable input undervoltage threshold and hysteresis. The FPWM input pin in LM5161selects either the forced continuous conduction mode (CCM) under all load levels or thediscontinuous conduction mode (DCM) under light or no load conditions. When operating in forcedCCM, the LM5161 supports the multiple output and isolated Fly-Buck applications. When programmedfor the DCM operation, the LM5161 provides a tightly regulated buck output without any additionalexternal feedback ripple injection circuit.