The LMD18400 is a fully protected quad high side driver. It contains four common-drain DMOS N-channel power switches, each capable of switching a continuous 1 Amp load (>3 Amps transient) to a common positive power supply. The switches are fully protected from excessive voltage, current and temperature. An instantaneous power sensing circuit calculates the product of the voltage across and the current through each DMOS switch and limits the power to a safe level. The device can be disabled to produce a “sleep” condition reducing the supply current to less than 10 µA. Separate ON/OFF control of each switch is provided through standard LSTLL/CMOS logic compatible inputs.

A MICROWIRE compatible serial data interface is built in to provide extensive diagnostic information. This information includes switch status readback, output load fault conditions and thermal and overvoltage shutdown status. There are also two direct-output error flags to provide an immediate indication of a general system fault and an indication of excessive operating temperature.

The LMD18400 is packaged in a special power dissipating leadframe that reduces the junction to case thermal resistance to approximately 20°C/W.

• Four Independent Outputs with >3A Peak, 1A Continuous Current Capability
• 1.3? Maximum ON Resistance Over Temperature
• True Instantaneous Power Limit for Each Switch
• High Survival Voltage (60 VDC, 80V Transient)
• Shorted Load (to Ground and Supply) Protection
• Overvoltage Shutdown at VCC > 35V
• LS TTL/CMOS Compatible Logic Inputs and Outputs
• <10 µA Supply Current in “Sleep” Mode
• −5V Output Clamp for Discharging Inductive Loads
• Serial Data Interface for 11 Diagnostic Checks:
  • Switch ON/OFF Status
  • Open or Shorted Load
  • Operating Temperature
  • Excessive Supply Voltage
• Two Direct-output Error Flags