Semiconductor integrated circuit device

Abstract

A semiconductor integrated circuit device enhanced in design efficiency while achieving multi-functionalization and power saving is to be provided. The semiconductor integrated circuit device has first through third circuit blocks, and is placed in a first power supply state in which the operation of internal circuits in the first circuit block is guaranteed in accordance with an instruction from the third circuit block or a second power supply state in which the operation of the internal circuits is not guaranteed. The second circuit block has an input unit which receives signals supplied from the first circuit block, and the input unit of the second circuit block has an input circuit which, in accordance with a control signal sent from said third circuit block to said second circuit block, causes a specific signal level to be maintained in compliance with the operating voltage of the second circuit block irrespective of the signal supplied from the first circuit block when the third circuit block instructs the second power supply state to the first circuit block.

1 . A semiconductor integrated circuit device comprising:
 a circuit block;   a power supply switch which is capable of supplying or cutting off a power supply to the circuit block; and   a power supply switch controller which controls the power supply switch,   wherein the power supply switch controller includes:
 a first output circuit and a second output circuit coupled to the power supply switch and outputting a power supply switch control signal which controls the power supply switch; 
 a first driving circuit which drives the first output circuit; 
 a second driving circuit which drives the second output circuit; 
 a voltage decision circuit for determining a level of the power supply switch control signal; and 
 a timer circuit coupled to the voltage decision circuit and the second driving circuit, 
   wherein the second output circuit has a larger current supply capacity than the first output circuit, and   wherein the timer circuit actuates the second output circuit via the second driving circuit after the voltage decision circuit determines that the power supply switch control signal reaches a predetermined level.   
     
     
         2 . A semiconductor integrated circuit device according to  claim 1 ,
 wherein the semiconductor integrated circuit device includes a power supply line and an internal power supply line,   wherein the internal power supply line is coupled to the circuit block, and   wherein the power supply switch is coupled to the power supply line and the internal power supply line.   
     
     
         3 . A semiconductor integrated circuit device according to  claim 2 ,
 wherein a current flows between the power supply line and the internal power supply line through the power supply switch after the first output circuit outputs the power supply switch control signal, and   wherein an amount of the current increases after the voltage decision circuit determines that the power supply switch control signal reaches the predetermined level.   
     
     
         4 . A semiconductor integrated circuit device according to  claim 1 ,
 wherein the second output circuit does not output the power supply switch control signal before the voltage decision circuit determines that the power supply switch control signal reaches the predetermined level.   
     
     
         5 . A semiconductor integrated circuit device according to  claim 1 ,
 wherein the semiconductor integrated circuit device includes another circuit block, and   wherein, after the voltage decision circuit determines that the power supply switch control signal reaches the predetermined level, the timer circuit outputs an indicating signal to inform said another circuit block that an operation of the circuit block is valid.   
     
     
         6 . A semiconductor integrated circuit device according to  claim 1 ,
 wherein the power supply switch is comprised of a MOSFET,   wherein the first and second output circuits are coupled to a gate of the MOSFET, and   wherein the power supply switch control signal controls the gate of the MOSFET.   
     
     
         7 . A semiconductor integrated circuit device according to  claim 1 ,
 wherein the voltage decision circuit has a hysteresis characteristic.   
     
     
         8 . A semiconductor integrated circuit device according to  claim 1 ,
 wherein the power supply is a ground potential.   
     
     
         9 . A semiconductor integrated circuit device comprising:
 a power supply line;   an internal power supply line;   a circuit block coupled to the internal power supply line;   a power supply switch coupled to the power supply line and the internal power supply line; and   a power supply switch controller which generates a switch control signal for the power supply switch,   wherein an amount of a current flow between the power supply line and the internal power supply line through the power supply switch increases after the power supply switch control signal reaches a predetermined level.   
     
     
         10 . A semiconductor integrated circuit device comprising:
 a power supply line;   an internal power supply line;   a circuit block coupled to the internal power supply line;   a power supply switch coupled to the power supply line and the internal power supply line; and   a power supply switch controller which is capable of generating a switch control signal to drive the power supply switch in two stages,   wherein amounts of a current flow between the power supply line and the internal power supply line through the power supply switch are different in the two stages.   
     
     
         11 . A semiconductor integrated circuit device comprising:
 a first line for a first supply voltage;   a second line;   a third line for a second supply voltage;   an internal logic circuit coupled between the first line and the second line;   a switch MOSFET including a drain coupled to the second line, a source coupled to the third line and a gate;   a first circuit including an output coupled to the gate of the switch MOSFET; and   a second circuit including an output coupled to the gate of the switch MOSFET, wherein a current supply capacity of the second circuit is larger than a current supply capacity of the first circuit.   
     
     
         12 . A semiconductor integrated circuit device according to  claim 11 ,
 wherein the second circuit drives the gate of the switch MOSFET after the first circuit drives the gate of the switch MOSFET.   
     
     
         13 . A semiconductor integrated circuit device according to  claim 11 , further comprising:
 a third circuit coupled to the gate of the switch MOSFET and capable of outputting a signal to the second circuit when a level of the gate of the switch transistor reaches a predetermined level.   
     
     
         14 . A semiconductor integrated circuit device comprising:
 a first line for a first supply voltage;   a second line;   a third line for a second supply voltage;   an internal logic circuit coupled between the first line and the second line;   a switch MOSFET including a drain coupled to the second line, a source coupled to the third line and a gate;   a first circuit including an output coupled to the gate of the switch MOSFET and including a first MOSFET to drive the gate of the switch MOSFET; and   a second circuit including an output coupled to the gate of the switch MOSFET and including a second MOSFET to drive the gate of the switch MOSFET, wherein a current supply capacity of the second MOSFET is larger than a current supply capacity of the first MOSFET.