Integrated circuit comprising a unit for controlling a load of an inductive nature which unit limits parasitic effects in the integrated circuit caused by voltage transients

An integrated circuit for controlling a load of an inductive nature, said circuit comprising:

• first and second supply terminals for receiving a first and a second supply voltage, respectively;
• an output terminal for connection to the inductive load;
• a first output transistor having (i) a first main current path coupled between said first supply terminal and said output terminal and (ii) a first control electrode for closing and opening said first main current path;
• a second output transistor having (i) a second main current path coupled between said second supply terminal and said output terminal and (ii) a second control electrode for closing and opening said second main current path;
• control means coupled to the first and second control electrodes for selectively switching said main current paths of said first and second transistors to control the flow of current from said supply terminals to said inductive load, said circuit being constructed such that, during said switching to control the current to said load, said output terminal is subject to voltage transients of sufficient magnitude to cause parasitic effects therein when both of said main current paths are open,
• wherein the improvement comprises:
• said control means includes means for temporarily closing said main current path of at least one of said first and second output transistors to reduce the voltage transients at the output terminal to a level where parasitic effects in the integrated circuit are avoided.

An integrated circuit for controlling a load of an inductive nature, comprising:

• first and second supply terminals for receiving a first and a second supply voltage, respectively;
• an output terminal for connection to the inductive load;
• a first output transistor having (i) a first main current path coupled between said first supply terminal and said output terminal and (ii) a first control electrode for closing and opening said first main current path;
• a second output transistor having (i) a second main current path coupled between said second supply terminal and said output terminal and (ii) a second control electrode for closing and opening said second main current path;
• a parallel element connected electrically in parallel with one of said output transistors, between said one output transistor's respective supply terminal and said output terminal, said parallel element exhibiting a voltage drop greater than said one output transistor when an equivalent current flows therethrough;
• control means coupled to the first and second control electrodes for controlling said first and second output transistors, said control means including
• (i) first means for selectively opening and closing said first and second main current paths for controlling the current flow from said first and second supply terminals through said output terminal into said inductive load;
• (ii) first detecting means for detecting a first voltage transient occurring at said output terminal caused by continued current flow in said inductive load after both of said first and second current paths are open;
• (iii) means for closing said main current path of said one transistor in response to detection of the first voltage transient to shunt current, flowing between said output terminal and the respective supply terminal of said one transistor as a result of the first voltage transient, through said one transistor, thereby preventing a voltage drop across said parallel element;
• (iv) second detecting means for detecting at said output terminal a second voltage transient subsequent to and opposed to the first voltage transient;
• and
• (v) means for opening said main current path of said one transistor in response to detection of the second voltage transient.