Overview

The LB11850VA is a single-phase bipolar fan motor driver with speed control function that works with a speed feedback signal. A highly efficient, quiet and low power consumption motor driver circuit, with a high speed accuracy and large variable speed can be implemented by adding a small number of external components.

This pre-driver is optimal for driving large scale fan motors (with large air volume and large current) such as those used in servers and consumer products.

Functions and Features

• Pre-driver for Single-phase Full-wave Drive

♦ PMOS-NMOS is Used as an External Power TR, Enabling High-efficiency and Low-power-consumption Drive by Means of the Low-saturation Output and Single-phase Full-wave Drive

• On-chip Speed Control Circuit

♦ The Speed Control (Closed Loop Control) Using a Speed Feedback Signal Makes it Possible to Achieve Higher Speed Accuracy and Lower Speed Fluctuations when Supply Voltage Fluctuates or Load Fluctuates, Compared with an Open-loop Control System. Separately Excited Upper Direct PWM Control Method is Used as the Variable-speed Control System

• External PWM Input or Analog Voltage Input Enabling Variable Speed Control

♦ The Speed Control Input Signal is Compatible with PWM Duty Ratio or Analog Voltages

• On-chip Soft Start Circuit

• Lowest Speed Setting Pin

♦ The Lowest Speed can be Set with the External Resistor

• Current Limiter Circuit Incorporated

♦ Chopper Type Current Limit at Start or Lock

• Reactive Current Cut Circuit Incorporated

♦ Reactive Current before Phase Change is Cut to Enable Silent and Low-consumption Drive

• Constraint Protection and Automatic Reset Functions Incorporated

• FG (Speed Detection), RD (Lock Detection) Output

• Constant-voltage Output Pin for Hall Bias