Load Driving Device and Electrical Device Using the Same

Abstract

A load driving device according to the present invention includes: a first current generation section generating a first current in accordance with a driving current of a load; a second current generation section generating a predetermined second current; an integration section charging and discharging a capacitor in accordance with magnitude relation between the first current and the second current; a comparison section comparing a terminal voltage of the capacitor and a predetermined threshold voltage; and an output section generating a protection signal based on output logic of the comparison section. Such configuration permits appropriately preventing load burnout.

1 - 10 . (canceled) 
   
   
       11 . A load driving device comprising:
 a first current generation circuit arranged to generate a first current in accordance with a driving current of a load;   a second current generation circuit arranged to generate a second current in accordance with a predetermined second current;   a first circuit arranged to output a voltage in response to magnitude relation between the first current and the second current; and   an output section arranged to generate a protection signal based on the voltage of the first circuit.   
   
   
       12 . The load driving device according to  claim 11 , further comprising a comparison section arranged to compare the voltage of the first circuit and predetermined threshold voltage. 
   
   
       13 . The load driving device according to  claim 11 , wherein the first circuit comprises:
 a capacitor; and   a charge/discharge circuit arranged to output a current to the capacitor in response to a difference between the first current and the second current.   
   
   
       14 . The load driving device according to  claim 11  further comprising a bias circuit arranged to output a bias voltage to the capacitor. 
   
   
       15 . The load driving device according to  claim 11 , wherein the first current generation circuit is arranged to directly detect a current value of the driving current by using a detector serially connected to a power source side or ground side of the load. 
   
   
       16 . The load driving device according to  claim 11 , wherein the second current generation circuit comprises:
 a constant current source arranged to generate a constant current; and   a current mirror circuit arranged to generate the second current in accordance with the constant current.   
   
   
       17 . An electric device comprising:
 a load driving device;   a load controlled by a driving current from the load driving device; and   a microcomputer arranged to receive an input of a protection signal from the load driving device,   wherein the load driving device comprises:
 a first current generation circuit arranged to generate a first current in accordance with a driving current of a load; 
 a second current generation circuit arranged to generate a second current in accordance with a predetermined second current; 
 a first circuit arranged to output a voltage in response to magnitude relation between the first current and the second current; and 
 an output section arranged to generate a protection signal based on the voltage of the first circuit. 
   
   
   
       18 . The electric device according to  claim 17 , wherein the load driving device comprises a comparison section arranged to compare the voltage of the first circuit and a predetermined threshold voltage. 
   
   
       19 . The electric device according to  claim 17  wherein the first circuit comprises:
 a capacitor; and   a charge/discharge circuit arranged to output a current to the capacitor in response to a difference between the first current and the second current.   
   
   
       20 . The electric device according to  claim 17  further comprising a bias circuit arranged to output a bias voltage to the capacitor. 
   
   
       21 . The electric device according to  claim 18 , wherein the output circuit comprises a protective operation control circuit arranged to mute driving of the load based on the output of the comparison circuit. 
   
   
       22 . The electric device according to  claim 21 , wherein the protective operation control section is arranged to release the mute condition of the load based on a release signal from the microcomputer. 
   
   
       23 . The electric device according to  claim 17  arranged such that the microcomputer, based on the protection signal, mutes or releases the driving of the load. 
   
   
       24 . The electric device according to  claim 17  arranged such that the microcomputer, upon reception of an input of the protection signal, stores error history information of the load driving device into a memory. 
   
   
       25 . The electric device according to  claim 17  arranged such that the microcomputer, upon reception of an input of the protection signal, reports error of the load driving device by using at least one of a display and a speaker.