描述

 

The LM5116 is a synchronous buck controller intended for step-down regulator applications from a high-voltage or widely varying input supply. The control method is based upon current mode control utilizing an emulated current ramp. Current mode control provides inherent line feed-forward, cycle-by-cycle current limiting, and ease-of-loop compensation. The use of an emulated control ramp reduces noise sensitivity of the pulse-width modulation circuit, allowing reliable control of very small duty cycles necessary in high-input voltage applications.

 

The operating frequency is programmable from 50 kHz to 1 MHz. The LM5116 drives external high-side and low-side NMOS power switches with adaptive dead-time control. A user-selectable diode emulation mode enables discontinuous mode operation, for improved efficiency at light load conditions. A low quiescent current shutdown disables the controller and consumes less than 10 µA of total input current.

 

Additional features include a high-voltage bias regulator, automatic switch-over to external bias for improved efficiency, thermal shutdown, frequency synchronization, cycle-by-cycle current limit, and adjustable line undervoltage lockout. The device is available in a power enhanced HTSSOP-20 package featuring an exposed die attach pad to aid thermal dissipation.

 

特性

 

Emulated Peak Current Mode

Wide Operating Range Up to 100 V

Low IQ Shutdown (< 10 µA)

Drives Standard or Logic Level MOSFETs

Robust 3.5-A Peak Gate Drive

Free-run or Synchronous Operation to 1 MHz

Optional Diode Emulation Mode

Programmable Output from 1.215 V to 80 V

Precision 1.5% Voltage Reference

Programmable Current Limit

Programmable Soft-Start

Programmable Line Undervoltage Lockout

Automatic Switch to External Bias Supply

HTSSOP-20 Exposed Pad

Thermal Shutdown