Abstract:
Disclosed is a semiconductor device capable of detecting levels of an external supply voltage, which includes a plurality of signal receivers for simultaneously receiving external input signals, wherein a driving voltage is applied to only one of the signal receivers according to the levels of the external supply voltage.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to reduction of power consumption in a semiconductor device capable of selecting an external supply voltage.  
         [0003]     2. Description of the Prior Art  
         [0004]     One of the characteristics in most semiconductor devices having been recently designed is that various functions are provided to the semiconductor device for harmonization with an external system. The aforementioned semiconductor device is generally called a multifunctional semiconductor device. The reason for manufacturing the multifunctional semiconductor device as described above is because it is necessary to consider the situations of a market requiring a semiconductor device or a relation with a peripheral circuit of a system using a semiconductor device. For example, in a memory device, an option is provided so that a data width can be selected among X32, X16 and X8 or an external supply power can be selected between 1.8V and 2.5V.  
         [0005]     However, in contrast with other options, when one of different external supply powers is selected and used in a semiconductor device, consumption power may become problematic.  
         [0006]     This will be described in detail with reference to  FIG. 1 .  
         [0007]      FIG. 1  is a block diagram schematically showing the general construction of a semiconductor device selecting and using one of different external supply powers.  
         [0008]     As shown in  FIG. 1 , the semiconductor device basically includes a 1.8V dedicated block  11  and a 2.5V dedicated block  12 . The 1.8V dedicated block  11  receives an external input signal and converts the received signal to an internal signal used in the semiconductor device when an external voltage is selected to be 1.8V. The 2.5V dedicated block  12  receives an external input signal and converts the received signal to an internal signal used in the semiconductor device when an external voltage is selected to be 2.5V. Herein,  FIG. 1  shows only an example. Also, the voltage level of the external voltage may change according to the types of semiconductor devices and three or more types of external voltages may be applied to the semiconductor device. A signal selector  13  selects signals outputted from the 1.8V dedicated block  11  and the 2.5V dedicated block  12  and transfers the selected signals to the internal circuit. Further, the signal selector  13  is typically constructed by a circuit having a switching function like a multiplexer.  
         [0009]     Hereinafter, the operation of the internal circuit shown in  FIG. 1  will be described.  
         [0010]     First, when an external supply voltage applied for operating the semiconductor device including the internal circuit shown in  FIG. 1  is selected to be 1.8V, the 1.8V dedicated block  11  is selected. Accordingly, input signals applied to the semiconductor device are transferred to the signal selector  13  via the 1.8V dedicated block  11 .  
         [0011]     In contrast, when the external supply voltage is selected to be 2.5V, the 2.5V dedicated block  12  is selected. Accordingly, the input signals applied to the semiconductor device are transferred to the signal selector  13  via the 2.5V dedicated block  12 .  
         [0012]     However, in the prior art, as shown in  FIG. 1 , the 1.8V dedicated block  11  is operated by the supply power V peri  and the ground voltage V ss  and the 2.5V dedicated block  12  is operated by the external supply power VDD the ground voltage V ss . Herein, the supply power V peri  is an internal voltage generated when the semiconductor device is powered-up and the external supply power VDD is a voltage applied from an external of the semiconductor device.  
         [0013]     By this reason, even after the 1.8V dedicated block  11  has been selected, the external supply power VDD the ground voltage Vs are supplied to the 2.5V dedicated block  12 , thereby causing unnecessary power consumption.  
         [0014]     Similarly, even after the 2.5V dedicated block  12  has been selected, the supply power V peri  the ground voltage V ss  are supplied to the 1.8V dedicated block  11 , thereby causing unnecessary power consumption.  
       SUMMARY OF THE INVENTION  
       [0015]     Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and it is an object of the present invention is to provide a solution for reducing power consumed in a semiconductor device by controlling a supply voltage applied to a 1.8V dedicated block and a supply voltage applied to a 2.5V dedicated block.  
         [0016]     It is another object of the present invention is to provide a solution for reducing power consumed in a semiconductor device by selectively switching a supply voltage applied to a 1.8V dedicated block and a supply voltage applied to a 2.5V dedicated block.  
         [0017]     In order to achieve the above objects, according to one aspect of the present invention, there is provided a semiconductor device capable of detecting levels of an external supply voltage, the semiconductor device comprising: a plurality of signal receivers for simultaneously receiving external input signals, wherein a driving voltage is applied to only one of the signal receivers according to the levels of the external supply voltage.  
         [0018]     In the present invention, the driving voltage is a supply voltage or a ground voltage. Further, in the present invention, levels of the supply voltage applied to each of the signal receivers are different from each other.  
         [0019]     In order to achieve the above objects, according to one aspect of the present invention, there is provided a semiconductor device capable of detecting levels of an external supply voltage, the semiconductor device comprising: an external power detector for detecting the levels of the external supply voltage; a plurality of switches controlled by the external power detector and connected to a plurality of driving voltages; and a plurality of signal receivers connected to the switches, for simultaneously receiving external input signals.  
         [0020]     In the present invention, only some of the switches are turned on according to the voltage levels of the external supply voltage, and the driving voltages are applied to only some of the signal receivers connected to the switches having been turned on. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]     The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:  
         [0022]      FIG. 1  is a block diagram schematically showing the general construction of a semiconductor device selecting and using one of different external supply powers;  
         [0023]      FIG. 2  is a block diagram showing a semiconductor device with reduced power consumption according to a first embodiment of the present invention;  
         [0024]      FIG. 3  is a block diagram showing a semiconductor device with reduced power consumption according to a second embodiment of the present invention; and  
         [0025]      FIG. 4  is a block diagram showing a semiconductor device with reduced power consumption according to a third embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]     Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.  
         [0027]      FIG. 2  is a block diagram showing a semiconductor device according to a first embodiment of the present invention.  
         [0028]     The semiconductor device shown in  FIG. 2  includes a 1.8V dedicated block  21 , a 2.5V dedicated block  22 , an external power detector  24 , and switches a and b. A signal selector  23  selects signals outputted from the 1.8V dedicated block  21  or the 2.5V dedicated block  22  and transfers the selected signals to the internal circuit. Further, the signal selector  23  is equal to the signal selector  13  of  FIG. 1 .  
         [0029]     The 1.8V dedicated block  21  is a circuit element for receiving signals applied from an exterior after an external supply voltage supplied to the semiconductor device has been selected to be 1.8V, and uses the supply voltage V peri  and the ground voltage V ss  as a driving voltage. Herein, the supply voltage V peri  represents a voltage generated in the semiconductor device when the external supply voltage has been supplied to the semiconductor device, that is, the semiconductor device is powered up.  
         [0030]     The 2.5V dedicated block  22  is a circuit element for receiving signals applied from the exterior after the external supply voltage supplied to the semiconductor device has been selected to be 2.5V, and uses the supply voltage VDD and the ground voltage V ss  as a driving voltage. Herein, the supply voltage VDD represents the external supply voltage applied to the semiconductor device. For example, when the external supply voltage is 1.8V, the supply voltage VDD is 1.8V. Further, when the external supply voltage is 2.5V, the supply voltage VDD is 2.5V.  
         [0031]     In Principle, the 1.8V dedicated block  21  and the 2.5V dedicated block  22  described above have functions of a signal receiver for receiving the signals applied from the exterior and a buffer.  
         [0032]     The external power detector  24  is a circuit element for determining whether the external supply power is 1.8V or 2.5V.  
         [0033]     First, when the external supply power is 1.8V, the switch a is turned on by the output signal BD_ 18  of the external power detector  24  and the switch b maintains an off state. When the switch a is turned on, the supply voltage V peri  connected to the switch a is supplied to the 1.8V dedicated block  21 . Since the 1.8V dedicated block  21  is connected to the ground voltage V ss  when the semiconductor device is powered up, the 1.8V dedicated block  21  normally operates after the supply of the supply voltage V peri . In such a case, the switch b is turned off, the supply voltage VDD necessary for operating the 2.5V dedicated block  22  is not applied to the 2.5V dedicated block  22 . Therefore, it is possible to block power consumed in the 2.5V dedicated block  22 .  
         [0034]     Next, when the external supply power is 2.5V, the switch b is turned on by the output signal BD_ 25  of the external power detector  24  and the switch a maintains an off state. When the switch b is turned on, the supply voltage VDD connected to the switch b is supplied to the 2.5V dedicated block  22 . Since the 2.5V dedicated block  22  is connected to the ground voltage V ss  when the semiconductor device is powered up, the 2.5V dedicated block  22  normally operates after the supply of the supply voltage VDD. In such a case, the switch a is turned off, the supply voltage V peri  necessary for operating the 1.8V dedicated block  21  is not applied to the 1.8V dedicated block  21 . Therefore, it is possible to block power consumed in the 1.8V dedicated block  21 .  
         [0035]      FIG. 3  is a block diagram showing a semiconductor device according to a second embodiment of the present invention.  
         [0036]     An external power detector  34 , a 1.8V dedicated block  31 , a 2.5V dedicated block  32 , and a signal selector  33  of  FIG. 3  basically have the same operations and functions as those of the external power detector  24 , the 1.8V dedicated block  21 , the 2.5V dedicated block  22 , and the signal selector  23  of  FIG. 2 .  
         [0037]     First, when the external supply power is 1.8V, a switch a is turned on by the output signal BD_ 18  of the external power detector  34  and a switch b maintains an off state. When the switch a is turned on, the ground voltage V ss  connected to the switch a is supplied to the 1.8V dedicated block  31 . Since the 1.8V dedicated block  31  is connected to the supply voltage V peri  when the semiconductor device is powered up, the 1.8V dedicated block  31  normally operates after the supply of the ground voltage V ss . In such a case, the switch b is turned off, the ground voltage V ss  necessary for operating the 2.5V dedicated block  32  is not applied to the 2.5V dedicated block  32 . Therefore, it is possible to block power consumed in the 2.5V dedicated block  32 .  
         [0038]     Next, when the external supply power is 2.5V, the switch b is turned on by the output signal BD_ 25  of the external power detector  34  and the switch a maintains an off state. When the switch b is turned on, the ground voltage V ss  connected to the switch b is supplied to the 2.5V dedicated block  32 . Since the 2.5V dedicated block  32  is connected to the supply voltage VDD when the semiconductor device is powered up, the 2.5V dedicated block  32  normally operates after the supply of the ground voltage V ss . In such a case, the switch a is turned off, the ground voltage V ss  necessary for operating the 1.8V dedicated block  31  is not applied to the 1.8V dedicated block  31 . Therefore, it is possible to block power consumed in the 1.8V dedicated block  31 .  
         [0039]      FIG. 4  is a block diagram showing a semiconductor device according to a third embodiment of the present invention.  
         [0040]     An external power detector  44 , a 1.8V dedicated block  41 , a 2.5V dedicated block  42 , and a signal selector  43  of  FIG. 4  basically have the same operations and functions as those of the external power detector  24 , the 1.8V dedicated block  21 , the 2.5V dedicated block  22 , and the signal selector  23  of  FIG. 2 .  
         [0041]     First, when the external supply power is 1.8V, switches a and c are turned on by the output signal BD_ 18  of the external power detector  44  and switches b and d maintain off states. When the switches a and c are turned on, the ground voltage V ss  and the supply voltage V peri  respectively connected to the switches a and c are supplied to the 1.8V dedicated block  41 . The 1.8V dedicated block  41  normally operates after the supply of the ground voltage V ss  and the supply voltage V peri . In such a case, the switches b and d are turned off, the ground voltage V ss  and the supply voltage VDD necessary for operating the 2.5V dedicated block  42  are not applied to the 2.5V dedicated block  42 . Therefore, it is possible to block power consumed in the 2.5V dedicated block  42 .  
         [0042]     Next, when the external supply power is 2.5V, the switches b and d are turned on by the output signal BD_ 25  of the external power detector  44  and the switches a and c maintain off states. When the switches b and d are turned on, the ground voltage V ss  and the supply voltage VDD respectively connected to the switches b and d are supplied to the 2.5V dedicated block  42 . The 2.5V dedicated block  42  normally operates after the supply of the ground voltage V ss  and the supply voltage VDD. In such a case, the switches a and c are turned off, the supply voltage V ss  and the supply voltage V peri  necessary for operating the 1.8V dedicated block  41  is not applied to the 1.8V dedicated block  41 . Therefore, it is possible to block power consumed in the 1.8V dedicated block  41 .  
         [0043]     Power consumption of the semiconductor devices can be reduced by employing the semiconductor devices according to the present invention as described above. Accordingly, the semiconductor devices according to the present invention are very proper for mobile products requiring low power.  
         [0044]     The preferred embodiment of the present invention has been described for illustrative purposes, and those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.