Overview

The LB11851M provides an interface between a microcontroller motor control signal and external MOS transistors. This device can implement a microprocessor fan driver with a minimal number of external components. The LB11851M is optimal for server and personal computer microprocessor fan drive in response to temperature or other external signals when high precision and high air flow are required.

Features

• Fan motor interface driver function (FGIN)

⇒ This IC accepts a signal from a microcontroller and interfaces to external power transistors (PMOS and NMOS) to provide high-efficiency low-power single-phase full-wave drive.

• Variable speed input pin (PWMIN)

⇒ PMOS side PWM control

NMOS side current regeneration using slow decay is used to achieve quite high-speed control.

• Built-in kickback absorption circuit (OUT1P/2P)

⇒ This circuit absorbs the kickback current that is generated at phase switching or power on/off to achieve smooth

current regeneration and protect the external transistors against destruction or degradation.

• Built-in current limiter circuit (SENSE)

⇒ This circuit implements a chopper-type current limiting control that operates at startup and during lock protection mode.

The current detection voltage is set to a fixed 0.2V internally.

• Built-in microcontroller power supply (5VREG)