Abstract:
Disclosed are examples of apparatuses including memory devices and systems comprising memories sharing a common enable signal, wherein the memories may be put into different power modes. Example methods for setting the different power modes of the memories are disclosed. In some examples, different power modes may be set by issuing memory group-level commands, memory-level commands, or combinations thereof.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 14/319,302, filed Jun. 30, 2014, This application is incorporated by reference herein in its entirety and for all purposes. 
     
    
     BACKGROUND 
       [0002]    Memory systems may include a plurality of discrete memory devices. Each memory device may include multiple memories. In some systems, the individual memories may be referred to as logical units (LUNs). The LUNs may be organized into memory groups, where each LUN belonging to a memory group receives a common chip enable CE signal. Each memory group may contain one or more LUNs. The common CE signal may be utilized to save layout area and reduce circuit complexity in the memory system by avoiding the need for providing (as used herein, “providing” refers to, for example, generating, issuing, passing, sending, transmitting and the like) separate CE signals to each of the LUNs of a memory group. 
         [0003]    A memory controller in the memory system (which may be external to or internal to the memory device) may use command and address signals provided to the memory devices to command the discrete memories to perform memory operations. Memory operations may include read operations for reading stored data from the memories, as well as write operations for writing data to the memories to be stored. The memory controller typically selects a desired LUN in a desired memory group to perform a memory operation, such as reading or writing data to a selected LUN. The memory controller may provide a logic level low CE signal to the desired memory group to activate the LUNs of the memory group. The LUNs may enter an elevated power mode that readies the LUNs to perform a memory operation. Although one of the LUNs will typically be commanded to perform the memory operation, the shared CE signal results in all LUNs in the memory group entering an elevated power mode that draws an increased current compared to a low power mode. 
         [0004]    While the unselected LUNs in the memory group may not be performing memory operations, the current drawn by the memory group is nonetheless additive across all of the unselected LUNs, which results in significant power consumption by a memory group. In configurations having memory groups with a high number of LUNs, the power consumption for activating all of the LUNs of the memory group for a memory operation relative to merely one of the LUNs may be significant. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a block diagram of a memory device according to an embodiment of the invention. 
           [0006]      FIG. 2  is a block diagram of a logical unit according to an embodiment of the invention. 
           [0007]      FIG. 3  is a block diagram of a memory system according to an embodiment of the invention. 
           [0008]      FIG. 4A  is a block diagram of a method performed by a memory controller according to an embodiment of the invention. 
           [0009]      FIG. 4B  is a block diagram of a method performed by a memory group according to an embodiment of the invention. 
           [0010]      FIG. 4C  is a block diagram of power modes of a logical units in different states according to an embodiment of the invention. 
           [0011]      FIG. 5A  is a block diagram of an additional method performed by a memory controller according to an embodiment of the invention. 
           [0012]      FIG. 5B  is a block diagram of an additional method performed by a memory group according to an embodiment of the invention. 
           [0013]      FIG. 5C  is a block diagram of power modes of a logical unit according to an embodiment of the invention. 
           [0014]      FIG. 6A  is a block diagram of a further method performed by a memory controller according to an embodiment of the invention. 
           [0015]      FIG. 6B  is a block diagram of a further method performed by a memory group according to an embodiment of the invention. 
           [0016]      FIG. 7  is a block diagram of a set feature command according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Certain details are set forth below to provide a sufficient understanding of embodiments of the disclosure. However, it will be clear to one having skill in the art that embodiments of the disclosure may be practiced without these particular details. Moreover, the particular embodiments of the present disclosure described herein are provided by way of example and should not be used to limit the scope of the disclosure to these particular embodiments. In other instances, well-known circuits, control signals, timing protocols, and software operations have not been shown in detail in order to avoid unnecessarily obscuring the disclosure. As used herein, apparatus may refer to, for example, an integrated circuit, a memory, a memory device, a memory system, an electronic device or system, a smart phone, a tablet, a computer, a server, etc. 
         [0018]      FIG. 1  illustrates a memory device  100  that includes a memory group  105 . The memory group  105  includes four memories  110   a - d , labeled as logical units (LUN 0 - 3 ). Although four LUNs are shown, more or fewer may be included in the memory group. The memory group  105  receives a chip enable CE signal  115  labeled as CE 0 _n. The CE signal is provided to all of the LUN&#39;s  110   a - d  in the memory group  105 . In other words, it is a common CE signal. The memory group  105  further includes a communication channel  120 , labeled as Channel n. The communication channel  120  may be a data bus, which may be used for receiving commands and addresses, receiving data, and sending data. Other signals may also be provided or received by the memory group  105  through the communication channel  120 . In some embodiments, the memory group  105  may include additional communication channels. Although the memory device  100  is shown with one memory group  105 , the memory device  100  may include a plurality of memory groups. If the memory device  100  comprises a plurality of memory groups, the memory device  100  may receive a different CE signal for each memory group, and each memory group may have a corresponding communication channel. 
         [0019]    In some embodiments, when the CE signal  115  is set to a logic level high (e.g., the CE signal is inactive), the memory group  105  may be disabled, that is, all LUNs  110   a - d  may be in a first (e.g., low power) mode, referred to as Mode  0 . In Mode  0 , the LUNs are not at the ready to perform a memory operation, for example, the LUNs may not be able to receive a signal on the communication channel  120 . During the first power mode, circuits of the LUNs may be disabled, for example, various input and output circuits, timing circuits, memory array circuits, etc. The first power mode Mode  0  may correspond to a standby mode of operation in some embodiments. When the CE signal  115  is set to a logic level low (e.g., the CE signal is active), the memory group  105  may be enabled and are at the ready to perform a memory operation, for example, receive commands and address signals on communication channel  120  indicating the desired LUN to be selected for a memory operation. For example, say LUN 2   110   c  is selected. LUN 2   110   c  transitions to second (e.g., increased power) mode, referred to as Mode  1 . In Mode  1 , LUN 2   110   c  is capable of receiving commands on communication channel  120 . During the second power mode, circuits of the LUNs are enabled and at the ready for operation, for example, input and output circuits, timing circuits, memory array circuits, etc. are all enabled. The second power mode Mode  1  may correspond to an active mode of operation in some embodiments. 
         [0020]    The unselected LUNs (LUN 0 , LUN 1 , LUN 3 ) may be transitioned into a third (e.g., an intermediate or low power) mode, referred to as Mode  2 . Although the third power mode could be a different power mode than, for example, the first power mode, in at least some embodiments. The first and third power modes might be the same power mode (e.g., a standby mode). In one example of a third power mode, a certain subset of circuits may be enabled on the LUN. For example, various ones of the input and output circuits, timing circuits, memory array circuits, etc. are enabled, but the LUN may not be capable of executing all commands. During the third power mode, a portion of the circuits enabled during the second power mode, are not enabled, thereby consuming less power during the third power mode relative to the second power mode, The third power mode Mode  2  may correspond to an intermediate mode of operation in some embodiments. For example, in some embodiments, Mode  2  draws more current than Mode  0 , but less than Mode  1 . An advantage or the unselected LUNs transitioning to a third power mode may be a lower current requirement for the memory group  105  than if all of the LUNs in the enabled memory group entered Mode  1 . Furthermore, the time latency of re-enabling unselected LUNs may be less in Mode  2  than in the first power mode, Mode  0 . This may improve performance when various LUN on the same memory group are selected sequentially while the CE signal remains low. Methods of transitioning the LUNs into the desired power modes will be described in more detail below. 
         [0021]      FIG. 2  illustrates a LUN  200  that may be included in a memory group such as memory group  105  illustrated in  FIG. 1 . The LUN  200  may include an input-output controller  215 . The input-output controller  215  may be coupled to a data (DQ) bus  210 . The input-output controller  215  may receive data, address, and command signals via the DQ bus  210 . The DQ bus  210  may correspond to the communication channel  120  in  FIG. 1 . The input-output controller  215  may provide memory address signals to a memory array  225  via an address bus  235 . The memory address signals are decoded to identify the memory location of the memory array  225  for the memory operation. The memory array  225  may provide data to and receive data from the input-output controller  215  via a data bus  230 . The input-output controller  215  may provide command signals to control logic  220  via a command bus  240 . The control logic  220  may provide internal control signals to the circuits of the LUN  200  to perform the memory operation. The control logic  220  may further provide status signals to the input-output controller  215  via a status bus  245 . The control logic  220  may receive a chip enable signal  205  to control activation of the LUN  200 . The chip enable signal  205  may correspond to the common enable signal  115  in  FIG. 1 . Although not shown, the control logic  220  may also receive command latch enable signals, read enable signals, write enable signals, and/or additional signals. These signals may or may not be shared with other LUNS that are included in the memory group that contains LUN  200 . In some embodiments, the I/O controller  215  may be disabled from receiving input from DQ bus  210  and/or the control logic  220  may be disabled from receiving commands from the input-output controller  215  when the LUN in certain power modes, for example, the first power mode, Mode  0 . 
         [0022]      FIG. 3  illustrates a memory system  300  connected to a host  305 . The host may be a laptop computer, personal computer, digital camera, mobile telephone, or other electronic device. The host  305  may interface with the memory system  300  via a serial advanced technology attachment (SATA), peripheral component interconnect express (PCIe), a universal serial bus (USB), or other interface. The memory system  300  may receive command signals from the host  305 , and the memory, system  300  may provide data signals and/or other signals to the host  305 . The memory system  300  may include a memory controller  310  and a memory device  335 . The controller  310  may be configured to provide signals to the memory device  335  to control its operation based on the command, address, data, and/or other signals received by the memory system  300  from the host  305 . Although depicted in this embodiment as being external to the memory device  335 , in other embodiments the controller  310  might be at least partially internal to the memory device. The memory device may include two memory groups  340 ,  345 . Each memory group  340 ,  345  may include one or more memories (LUN_ 0 -N). Although two memory groups are shown, the memory device  335  may include more or fewer memory groups. Likewise, while the memory system  300  is shown including memory device  335 , additional memory devices may be included in the memory system  300  as well. The controller  310  may control the state of chip enable signals  315 ,  325  received by the memory device  335 . The number of chip enable signals may correspond to the number of memory groups included in the memory device  335 . The controller  310  and memory device  335  may pass address, data, and command signals via data buses  320 ,  330 . Each data bus  320 ,  330  may correspond to a memory group  340 ,  335  included in the memory device  135 . The data buses  320 ,  330  may correspond to respective communication channels for the memory groups  340 ,  345 . In some embodiments, the controller  310  and memory device  335  may pass signals via a single data bus. Although only one memory device  335  is shown, the controller  310  may control multiple memory devices within the memory system  300 . 
         [0023]    The controller may transition the LUNs to the desired power mode responsive to selection of a memory group.  FIG. 4A  illustrates a process  400  performed by a controller, for example, the external controller  310 , according to an embodiment of the invention.  FIG. 4B  illustrates a process  450  performed by the selected memory group, for example, memory group  340  or memory group  345 , according to an embodiment of the invention. The controller may set the common chip enable signal, for example CEO_n  315 , for the selected memory group to a logic level low at step  405 . Once the common CE signal is set to logic level low, the controller selects a desired LUN from the plurality of on the memory group by providing the address of the and a command for selecting the LUN at step  410 . Any appropriate LUN addressing system known in the art may be used. After sending the select command, the controller then issues a memory group-level set feature command at step  415 . A memory group-level command is issued to all LUNs in a memory group, however, the memory group-level command sent at step  415  may designate the power mode for the unselected LUNs. 
         [0024]    With reference to  FIG. 4B , the memory group, such as memory group  340  in  FIG. 3  or memory group  105  in  FIG. 1 , receives the logic level low common chip enable, such as CE 0 _n  315  or CE 0 _n  115 , at step  455 , which puts the LUNs of the memory group into a second power mode, Mode  1 , as illustrated in State  2  in  FIG. 4C . Prior to receiving the logic level low CE signal, the LUNs of the memory group may be in a first power mode Mode  0 , for example. This is illustrated in State  1  in  FIG. 4C . In Mode  1 , the LUNs may be ready to perform a memory operation. The memory group receives the select command and address from the controller and the desired LUN may be selected at step  460 . In some embodiments, the select command may be received by an input-output controller, for example, the input-output controller  215  in  FIG. 2 . The select command may be executed by control logic in the LUN, for example, control logic  220  in  FIG. 2 . This is illustrated in State  3  in  FIG. 4C . In this example, LUN 2  is selected. When the memory group-level command is received, all unselected LUNs may be put into a different power mode, such as a third power mode Mode  2  at step  465 , as illustrated in State  4  in  FIG. 4C . This method may take two address-command sequences to complete: one sequence to select a selected LUN, and another sequence to put the unselected LUNs into a different power mode. When the controller sets the CE signal for the&gt;selected memory group to a logic level high, all LUNs may return to Mode  0 , as illustrated in State  5  in  FIG. 4C . In some embodiments State  1  and State  5  are equivalent. For subsequent Memory operations by the memory group, the controller sets the CE signal to a logic level low for the selected memory group, and select and memory group-level commands may be issued again by the controller to configure the power modes of the LUNs of the selected memory group. 
         [0025]      FIG. 5A  illustrate a process  500  performed by the controller according to another embodiment of the invention. The controller may be external controller  310  in some embodiments.  FIG. 5B  illustrates a process  550  performed by the selected memory group, for example, memory group  340  or memory group  345 , according to another embodiment of the invention. The controller may set the common chip enable signal for the selected memory group to a logic level low at step  505 , the chip enable signal may be CEO_n  315  or CEO_n  115  in some embodiments, Once the common CE signal is set to logic level low, the controller provides sequentially, in other words, one at a time, individual LUN-level (rather than memory group-level) set feature commands and addresses to each unselected LUN at step  515 . In contrast to processes  400  and  450  illustrated by  FIGS. 4A and 4B , the controller may provide sequentially, individual LUN-level set feature commands to each unselected LUN at step  515 . Each LUN-level command may have an associated address designating the particular unselected LUN. 
         [0026]    With reference to  FIG. 5B , the memory group receives the logic level low common chip enable at step  555 , which puts the LUNs of the memory group into a second power mode Mode  1 . Prior to receiving the logic level low CE signal, the LUNs of the memory group may be in a first power mode Mode  0 , for example. The memory group then receives the individual LUN-level set feature commands and addresses from the Controller. Each unselected is put into a desired power mode, such as a third power mode Mode  2 , as each individual LUN-level command is received at step  565 . In some embodiments, the individual LUN-level commands ma be received by an input-output controller, for example, the input-output controller  215  in  FIG. 2 . The individual LUN-level commands may be executed by control logic in the LUN, for example, control logic  220  in  FIG. 2 . This method may take a plurality of address-command sequences to complete, based at least in part, on the number of unselected LUNs in the memory group. However, this method may provide flexibility to put each of the unselected LUNs into a respective power mode. For example, rather than putting all unselected LUNs into Mode  2 , it may be desirable for unselected LUNs to be put into Mode  0  and/or Mode  1 , or some other power mode.  FIG. 5C  illustrates an example of a memory group having LUNs in a variety of power modes. In this example, LUN 2  is selected, LUN 0  in Mode  0 , LUN 1  air Mode  1 , and LUN 3  in Mode  2 , When the controller sets the CE signal for the selected memory group to a logic level high, all LUNs may return to Mode  0 . For subsequent memory operations by the memory group, the controller sets the CE signal to a logic level low for the selected memory group, and individual LUN-level commands may be issued again by the controller to configure the power modes of the LUNs of the selected memory group. 
         [0027]      FIG. 6A  illustrates a process  600  performed by the controller for example, the external controller  310 , according to another embodiment of the invention.  FIG. 6B  illustrates a process  650  performed by the selected memory group, for example, memory group  340  or memory group  345 , according to an embodiment of the invention. The controller may set the common chip enable signal for the selected memory group to a logic level low at step  605 . The controller may then provide a memory group-level set feature command and the address of the selected LUN at step  610 . The memory group-level set feature command may designate the desired power modes of ail LUNs in the memory group. The memory group-level set feature command provided by the controller may designate the address of the memory group, an indication that a memory group-level command is being provided, followed by a set of sub-feature parameters. The sub-feature parameters may provide the address of each LUN in the memory group followed by the desired sub-feature setting, for example, selection status, power mode, or other memory operation setting. In some embodiments, the individual LUN addresses may not be provided in the memory group-level set feature command and the order that the sub-feature parameters are provided to the memory group designate which corresponds to the provided sub-feature parameter. 
         [0028]    With reference to  FIG. 6B , the memory group receives the logic level low common chip enable, for example, the chip enable signal may be CE 0 _n  315  or CE 0 _n  115 , in some embodiments at step  655 , which puts the LUNs of the memory group into a second power mode Mode  1 . Prior to receiving the logic level low CE signal, the LUNs of the memory group may be in a ode Mode  0 , for example. The memory group then receives the memory group-level set feature command at step  660  and sets the selected LUN to Mode  1  and the unselected LUNs to the desired power modes, for example, Mode  2 , based, at least in part, on the sub-feature parameter provided by the memory group-level command for each respective LUN. The unselected LUNs may all be set to the same power mode or may be set different power modes, similar to the state illustrated in  FIG. 5C . In some embodiments, the memory group-level command may be received by an input-output controller, for example, the input-output controller  215  in  FIG. 2 . The memory group-level command may be executed by control logic in the for example, control logic  220  in  FIG. 2 . This method may take one address-command sequence to execute. When the controller sets the CE signal for the select memory group to a logic level high, all LUNs may return to Mode  0 . For subsequent memory operations by the memory group, the controller sets the CE signal to a logic level low for the selected memory group, and a group-level command and address of a selected LUN may be issued again by the controller to configure the power modes of the LUNs of the selected memory group. 
         [0029]    The methods described above are exemplary, and other methods of setting the power modes of the LUNs may be possible. Furthermore, additional power modes may also be possible. For example, a power mode that has a current draw between Mode  1  and Mode  2  may be configured. This mode, referred to as Mode  3  may allow, a LUN to sniff a data bus. Mode  3  may be desirable when a LUN is designated as a memory group terminator for on-die termination applications. 
         [0030]      FIG. 7  illustrates various signals during a memory group-level set-feature command according to an embodiment of the invention. The memory group-level set-feature command may be provided by a controller, such as external controller  310  in  FIG. 3 . The set-feature command  705  is followed by the desired feature  710 . An op-code  707  corresponding to the set-feature command  705  and a feature code  712  corresponding to the desired feature  710  are provided on a data bus DQ, which may correspond to data bus  210  in  FIG. 2  in some embodiments. The set-feature command  705  may indicate to the memory group, for example memory group  340  or  345  in  FIG. 3 , that the following feature  710  is to be applied to the entire memory group, not an individual LUN. The set-feature command  705  and feature  710  are then followed by one or more sub-feature parameters  715 . Codes  717  corresponding to the sub-feature parameters  715  are provided on the data bus DQ. These sub-feature parameters  715  may define the desired configuration of the LUNs in the memory group, such as LUN 0 _ 0 -N  340  in  FIG. 3  Configurations may include power modes, but other features may also be defined by the sub-feature parameters  715 . A ready/busy (R/B#) signal is provided by the memory device to indicate that the memory device is busy while the features are being set. The R/B# signal returns to a logic level high upon completion of being set. In some embodiments, the R/B# signal may be provided by control logic, for example, control logic  220  in  FIG. 2 . Other command-address protocols may be used in other embodiments. 
         [0031]    Those of ordinary skill would further appreciate that the various illustrative logical blocks, configurations, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software executed by a processor, or combinations of both. Various illustrative components, blocks, configurations, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or processor executable instructions depends on the particular application and design constraints is on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure. 
         [0032]    The previous description of the disclosed embodiments is provided to enable a person skilled in the art to make or use the disclosed embodiments. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the principles defined herein may be applied to other embodiments without departing from the scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope possible consistent with the principles and novel features as defined by the following claims.