Datasheet

4

Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Overview

Digital Diagnostic Features

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Over temperature

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Over load

•Short circuit

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Clear detection due to a restart delay time

Protection Functions

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Enhanced short circuit protection with time and power limited active current limitation

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Under voltage lock out

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Over temperature with time and temperature controlled auto restart

•

Over load with power and time controlled auto restart

•

ESD protection

Application

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All types of resistive, inductive and capacitive loads

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Suitable for loads with inrush current, such as motors, coils, solenoids or lamps

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Suitable for EMC optimized switching in slow operation mode

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Suitable for higher speed PWM controlled loads in fast operation mode

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Replacement of electromechanical relays, fuses and discrete circuits

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Micro controller compatible low side power switch with digital feedback for 12V loads

Detailed Description

The BTS 3256D is an autorestart single channel low-side power switch in PG-TO-252-5-11 package providing

embedded protective functions. The device is able to switch all kind of resistive, inductive and capacitive loads.

supply voltage is monitored by the under voltage lock out circuit. The Gate driving unit allows the device to operate

in the lowest ohmic range independent of the input signal level, 3.3 V or 5 V . For slow PWM application the device

offers smooth turn-on and off due to the embedded edge shaping function, to reduce EMC noise. Furthermore the

SRP pin can be used to customize the slew rate of the device in a wide range.

The Device is designed for driving automotive loads like motors,valves, coils or bulbs in continous or PWM mode.

The over voltage protection is for protection during load-dump or inductive turn off conditions. The power MOSFET

is limiting the Drain-Source voltage to a specified level. This function is available even without any supply.

The over temperature protection prevents the device from overheating due to overload and/or bad cooling

conditions. In order to reduce the device stress the edge shaping is disabled during thermal shutdown. After

thermal shutdown the device stays off for the specified restart delay time to enable a clear feedback readout on

the microcontroller. After this time the device follows the IN signal state.

At high dynamic overload conditions, such as short circuit, the device will either turn off immediately due to the

implemented over power limitation, or limit the current for a specified time and then switch off for the restart delay

time. Shutdown of the device is triggered if the power dissipation during limitation is above the over power

threshold. The short circuit shutdown is a timed restart function. The device will stay off for the specified time and

afterwards follow the IN signal state. In order to reduce the device stress the edge shaping is disabled during

protective turn off.