Abstract:
A method of protecting an integrated circuit that includes sensing a temperature of an integrated circuit that has a data pin, generating a temperature data signal based on the sensing, implementing a temperature sensing protocol and supplying the temperature data signal to the data pin based on the temperature sensing protocol.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to the field of memory chips.  
           [0003]    2. Discussion of Related Art  
           [0004]    A known integrated memory IC  100  that is a writeable memory of the DRAM type is shown in FIG. 1. Such a dynamic random access memory (DRAM) chip  100  includes a plurality of memory storage cells  102  in which each cell  102  has a transistor  104  and an intrinsic capacitor  106 . As shown in FIGS. 2 and 3, the memory storage cells  102  are arranged in arrays  108 , wherein memory storage cells  102  in each array  108  are interconnected to one another via columns of conductors  110  and rows of conductors  112 . The transistors  104  are used to charge and discharge the capacitors  106  to certain voltage levels. The capacitors  106  then store the voltages as binary bits, 1 or 0, representative of the voltage levels. The binary 1 is referred to as a “high” and the binary 0 is referred to as a “low.” The voltage value of the information stored in the capacitor  106  of a memory storage cell  102  is called the logic state of the memory storage cell  102 .  
           [0005]    As shown in FIGS. 1 and 2, the memory chip  100  includes six address input contact pins A 0 , A 1 , A 2 , A 3 , A 4 , A 5  along its edges that are used for both the row and column addresses of the memory storage cells  102 . The row address strobe (RAS) input pin receives a signal RAS that clocks the address present on the DRAM address pins A 0  to A 5  into the row address latches  114 . Similarly, a column address strobe (CAS) input pin receives a signal CAS that clocks the address present on the DRAM address pins A 0  to A 5  into the column address latches  116 . The memory chip  100  has data pin Din that receives data and data pin Dout that sends data out of the memory chip  100 . The modes of operation of the memory chip  100 , such as Read, Write and Refresh, are well known and so there is no need to discuss them for the purpose of describing the present invention.  
           [0006]    A variation of a DRAM chip is shown in FIGS. 5 and 6. In particular, by adding a synchronous interface between the basic core DRAM operation/circuitry of a second generation DRAM and the control coming from off-chip a synchronous dynamic random access memory (SDRAM) chip  200  is formed. The SDRAM chip  200  includes a bank of memory arrays  208  wherein each array  208  includes memory storage cells  210  interconnected to one another via columns and rows of conductors.  
           [0007]    As shown in FIGS. 5 and 6, the memory chip  200  includes twelve address input contact pins A 0 -A 11  that are used for both the row and column addresses of the memory storage cells of the bank of memory arrays  208 . The row address strobe (RAS) input pin receives a signal RAS that clocks the address present on the DRAM address pins A 0  to A 11  into the bank of row address latches  214 . Similarly, a column address strobe (CAS) input pin receives a signal CAS that clocks the address present on the DRAM address pins A 0  to A 11  into the bank of column address latches  216 . The memory chip  200  has data input/output pins DQ 0 - 15  that receive and send input signals and output signals. The input signals are relayed from the pins DQ 0 - 15  to a data input register  218  and then to a DQM processing component  220  that includes DQM mask logic and write drivers for storing the input data in the bank of memory arrays  208 . The output signals are received from a data output register  222  that received the signals from the DQM processing component  220  that includes read data latches for reading the output data out of the bank of memory arrays  208 . The modes of operation of the memory chip  200 , such as Read, Write and Refresh, are well known and so there is no need to discuss them for the purpose of describing the present invention.  
           [0008]    It is noted that new generations of SDRAM chips are being optimized for bandwidth. The most common method of accomplishing such optimization is to increase the clocking rate of SDRAM chips. By increasing the clocking rate and shortening operation cycles for normal operations, the consumption of current and power during operations increases. Since the internal temperature of the chip is proportional to the power consumption, increasing the clocking rate will result in an increase in the internal temperature of the chip.  
           [0009]    It is known that there are circumstances where the heat generated in SDRAM chips optimized for bandwidth exceeds the maximum amount of heat that the chip package can dissipate. In most cases, the extent of time at which the generated heat exceeds the maximum amount of heat that can be dissipated is so short that the thermal constant of the chip package is sufficiently high in value so as to prevent destruction of the SDRAM chip.  
         SUMMARY OF THE INVENTION  
         [0010]    One aspect of the present invention regards a method of protecting an integrated circuit that includes sensing a temperature of an integrated circuit that has a data pin, generating a temperature data signal based on the sensing, implementing a temperature sensing protocol and supplying the temperature data signal to the data pin based on the temperature sensing protocol.  
           [0011]    The above aspect of the present invention provides the advantage of preventing the thermal destruction of a memory chip.  
           [0012]    The present invention, together with attendant objects and advantages, will be best understood with reference to the detailed description below in connection with the attached drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 schematically shows a top view of an embodiment of a known memory chip;  
         [0014]    [0014]FIG. 2 shows a block diagram of the memory chip of FIG. 1;  
         [0015]    [0015]FIG. 3 schematically shows an embodiment of a memory array to be used with the memory chip of FIG. 1;  
         [0016]    [0016]FIG. 4 schematically shows an embodiment of a memory cell to be used with the memory array of FIG. 3;  
         [0017]    [0017]FIG. 5 schematically shows a top view of a second embodiment of a known memory chip;  
         [0018]    [0018]FIG. 6 shows a block diagram of the memory chip of FIG. 5;  
         [0019]    [0019]FIG. 7 schematically shows an embodiment of a thermal protection system according to the present invention;  
         [0020]    [0020]FIG. 8 shows a timing diagram for an embodiment of a temperature sensing protocol to be used with the thermal protection system of FIG. 7 according to the present invention;  
         [0021]    [0021]FIG. 9 shows a timing diagram for a second embodiment of a temperature sensing protocol to be used with the thermal protection system of FIG. 7 according to the present invention; and  
         [0022]    [0022]FIG. 10 shows a timing diagram for a third embodiment of a temperature sensing protocol to be used with the thermal protection system of FIG. 7 according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    As shown in FIG. 7, a thermal protection system  301  to be used with the present invention includes an integrated circuit, such as an SDRAM chip  300  that has a structure similar to that of the SDRAM chip  200  described previously with respect to FIGS. 5 and 6. An example of the thermal protection system  301  is disclosed in a U.S. Patent Application to Torsten Partsch et al., filed concurrently with the present application and entitled “Use of an On-Die Temperature Sensing Scheme for Thermal Protection of DRAMS,” (Attorney Docket No. 10808/56), the entire contents of which is incorporated herein by reference.  
         [0024]    In such a thermal protection system  301 , the SDRAM chip  300  includes a bank of memory arrays  308  that include memory storage cells  310  interconnected to one another via columns and rows of conductors in a manner similar to the memory arrays  208  and memory storage cells  210  discussed previously. The memory chip  300  includes twelve address input contact pins A 0 -A 11 , row address strobe (RAS) input pin, column address strobe (CAS) input pin and data input/output pins DQ 0 - 15  that receive and output signals in the same manner as their counterparts in the SDRAM chip  200  discussed previously. It should be noted that the present invention could be used with other types of memory chips, such as other types of semiconductor integrated circuits and other types of memory devices, such as SDRAMS and DDR SDRAMS.  
         [0025]    The signals associated with the input contact pins A 0 -A 11  are fed to a bank of row address latches  314  and a bank of column address latches  316  that correspond to and operate in the same manner as the latches  214  and  216 , respectively. The signals associated with the data input/output pins DQ 0 - 15  are relayed to or from data input register  318 , data output register  322  and DQM processing component  320  that correspond to and operate in the same manner as registers  218 ,  222  and DQM processing component  220 , respectively. Note that the DQM processing component  320  includes read data latches and write data latches.  
         [0026]    As shown in FIG. 7, the thermal protection system  301  further includes a temperature sensor  350  that is attached to the die of the SDRAM chip  300  and centrally positioned on the SDRAM chip  300  and may be connected to a power bus or a temperature sensitive net so as to sense a real time temperature of the SDRAM chip  300 . The sensor  350  can be activated at all times or at distinct times designated by the system. Note that a variety of known sensors, such as a wheatstone bridge, would be acceptable for the temperature sensor  350 . The temperature sensor  350  generates an analog signal T analogreal  representative of the sensed real time temperature and the signal  351 , T analogreal , is sent to an analog-to-digital converter  352  where it is digitized. The digitized signal  353 , T digitalreal , is then sent both to a DQ pin and to a register  354  where its value is stored in a memory  355  thereof. The analog-to-digital converter  352  and the register  354  are run by clock signals sent by a clock  356  that may be a system clock of the memory chip  300 . Note that one advantage of the present invention is that no additional pins for the memory chip  300  are needed  
         [0027]    The value T digitalreal  of the sensed real time temperature is then sent to a comparator  358  that is connected to the register  354 . As shown in FIGS.  810 , the sensed real time temperature T digitalreal  is sent from the DQ pin to the comparator  358  per a temperature sensing protocol generated by protocol component  365  of the control system  364 . By using a temperature sensing protocol, the control system  364  will be able to receive the sensed real time temperature via the DQ bus.  
         [0028]    One example of a temperature sensing protocol is shown in FIG. 8. In this example, an existing command that does not require DQ bus activity is used to signal that a temperature sensing protocol is to proceed. An example of such a command is a valid command, such as the PRE-CHARGE ALL (PCHA) command. The temperature sensing protocol is engaged when the command is activated at a time when the DQ bus has no activity. In such a case, completion of the command results in temperature data corresponding to the sensed real time temperature T digitalreal  being placed on the DQ bus after a time At as measured from the discontinuation of the command. The temperature data is then fed to the comparator  358  at a rate equal to the clock frequency and continues until a set time in the protocol has elapsed. The elapsed time has a magnitude, such as one or two clock pulse periods, sufficient to ensure that the data is validated, read and stopped. Placing of the temperature data on the DO bus is continued after receipt of another PRE-CHARGE ALL command.  
         [0029]    A second example of a temperature sensing protocol is shown in FIG. 9. Again an existing command that does not require DQ bus activity, such as PRE-CHARGE ALL, is used to signal that a temperature sensing protocol is to proceed. The second temperature sensing protocol is engaged when the command is activated at a time when the DQ bus has no activity. After a time Δt 1  as measured from the discontinuation of the command, a read command R regarding a DQ pin is sent on the DO bus. The combination and timing of the command and the read command R signals is interpreted as a temperature sensing command which results in temperature data corresponding to the sensed real time temperature T digitalreal  being placed on the DO bus after a time Δt 2  as measured from the discontinuation of the read command R. The temperature data is then fed to the comparator  358  at a rate equal to the clock frequency and continues until it is validated, read, and stopped. Placing of the temperature data on the DQ bus is continued after receipt of another PRE-CHARGE ALL command and Read command.  
         [0030]    A third example of a temperature sensing protocol is shown in FIG. 10. In this example, a new temperature sensing command is implemented. The new command is stored in a command registry located in the control system  364 . The new command is implemented when there is no DQ bus activity. After a time At as measured from the discontinuation of the new command, temperature data corresponding to the sensed real time temperature T digitalreal  is placed on the DQ bus. The temperature data is then fed to the comparator  358  at a rate equal to the clock frequency and continues until it is validated, read and stopped. Placing of the temperature data on the DQ bus is continued after receipt of another new temperature sensing command.  
         [0031]    In each of the protocols described above with respect to FIGS.  8 - 10 , the commands are triggered by the system. The widths of the commands and the At&#39;s can have a variety of values ranging from two to sixteen clock cycles.  
         [0032]    The comparator  358  includes a memory  360  that stores a threshold temperature T threshold  that corresponds to a maximum tolerable temperature, such as 55° C., for the memory chip  300 . The maximum tolerable temperature has a value that ranges from 55° C. to 75° C. depending on the heat dissipation properties of the memory chip. The comparator  358  compares the value of T digitalreal  with the value of the threshold temperature T threshold  and generates a comparison signal  362  that indicates whether or not the value of T digitalreal  exceeds the value of T threshold .  
         [0033]    As shown in FIG. 7, the comparison signal  362  is sent to a control system  364  that is connected to the memory chip  300 . The control system  364  controls operation of the memory chip  300  based on the comparison signal  362  by either shutting down the memory chip  300  or reducing power consumption of the memory chip  300  in the manner described in a U.S. Patent Application to Torsten Partsch et al., filed concurrently with the present application and entitled “Use of an On-Die Temperature Sensing Scheme for Thermal Protection of DRAMS,” (Attorney Docket No. 10808/56), the entire contents of which is incorporated herein by reference.  
         [0034]    The foregoing description is provided to illustrate the invention, and is not to be construed as a limitation. Numerous additions, substitutions and other changes can be made to the invention without departing from its scope as set forth in the appended claims.