Relay Driver with 5 V Regulator for Automotive Applications



Top Features


Large numbers of relay-based applications require the use of a microprocessor which implements complex system control. In these systems, there is the need for microprocessor logic supply voltage, power-on reset circuitry, and watchdog capabilities. The Allegro A2550 combines the functions of voltage regulator, watchdog, and reset, as well as three low-side DMOS relay driver outputs. Primarily targeted at automotive applications, this IC is designed to provide robust performance over extended voltage and temperature ranges. 

Three low-side DMOS drivers can drive inductive loads, such as relay coils. Each driver integrates rugged voltage clamps which survive automotive load dump pulses up to 48 V. The 40 V rating on VBB also ensures adequate survival in harsh automotive environments. 

A 5 V linear regulator provides 40 mA of output current, with a tolerance of 2% over the operating temperature range. To enhance the usefulness of the IC in automotive applications, the 5 V regulator output, as well as the three low-side driver outputs are protected against overcurrent conditions. 

The A2550 also includes power-on reset circuitry (NPOR) as well as an integrated watchdog circuit. Combined, they service the monitoring and reset requirements of a system microprocessor. 

Typical Applications: 

  • Wiper systems 
  • Sunroof controller 
  • Window lift regulator 
  • Three independent low-side DMOS output drivers 
  • Short-circuit protection of drivers 
  • Eliminates need for flyback diodes on relays 
  • Thermal shutdown 
  • Separate precision 5 V regulator (2%) 
  • Current clamp on 5 V regulator 
  • 16-pin TSSOP package with exposed thermal pad 
  • Programmable reset (NPOR) delay time 
  • Programmable watchdog 
  • Automotive voltage and temperature ranges 
  • Active clamps for automotive load dump specifications 
  • Lead (Pb) free 

16-Pin TSSOP with exposed thermal pad (suffix LP) 

Part Number Specifications and Availability

Documentation and Resources


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