A2550: Relay Driver with 5 V Regulator for Automotive Applications


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 

Top Features

  • 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 

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check Stock
APEK2550KLP-01-T DEMO BOARD -20°C to 85°C No -- Contact your
local sales rep
Distributor Stock
A2550KLP-T 16-lead TSSOP -40°C to 125°C Yes View Data pre-EOL Contact your
local sales rep
Distributor Stock
A2550KLPTR-T 16-lead TSSOP -40°C to 125°C Yes View Data Contact your
local sales rep
Distributor Stock

Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.


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

Allegro 16-Pin LP package