1 Features

• Qualified for Automotive Applications
• AEC-Q100 Qualified With the Following Results:
  • Device Temperature Grade 1: –40°C to 125°C Ambient Operating Temperature Range
  • Device HBM ESD Classification Level 2
  • Device CDM ESD Classification Level C5
• 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
• Create a Custom Design Using the LM5161-Q1 With the WEBENCH® Power Designer

2 Applications

• Industrial Programmable Logic Controller
• IGBT Gate Drive Bias Supply
• Telecom DC/DC Primary/Secondary Side Bias
• E-Meter Power Line Communication
• Low-Power (<12W), Isolated DC-DC (Fly-Buck)
• Automotive Electronics

3 Description

The LM5161-Q1 is a 100-V, 1-A synchronous step-down converter with integrated high-side and low-side MOSFETs. The constant-ON-time control scheme requires no loop compensation and supports high 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 inversely with input voltage resulting in nearly constant switching frequency. Peak and valley current limit circuits protect against overload conditions. The under-voltage lockout (EN/UVLO) circuit provides independently adjustable input undervoltage threshold and hysteresis. The FPWM input pin in LM5161-Q1 selects either the forced continuous conduction mode (CCM) under all load levels or the discontinuous conduction mode (DCM) under light or no load conditions. When operating in forced CCM, the LM5161-Q1 supports the multiple output and isolated Fly-Buck applications. When programmed for the DCM operation, the LM5161-Q1 provides a tightly regulated buck output without any additional external feedback ripple injection circuit.

1. For all available packages, see the orderable addendum at the end of the datasheet.

 
Typical Buck Application Circuit

Typical Fly-Buck Application Circuit