Power management in semiconductor memory system
A method for operating a memory module device. The method can include transferring a chip select, command, and address information from a host memory controller. The host memory controller can be coupled to a memory interface device, which can be coupled to a memory module. The memory module can comprise a plurality of memory devices. The chip select, command and address information can be received at the memory interface using a command-and-address-latency (CAL) mode. Control logic can be used to initiate a power state transition from a first power state to a second power state of an input termination circuit in the memory interface device.
1. A method for operating a memory module device, the method comprising:
transferring a chip select, command, and address information from a host memory controller, the host memory controller being coupled to a memory interface device, the memory interface device being coupled to a memory module, the memory module comprising a plurality of memory devices;
receiving the chip select, command, and address information at the memory interface device using a command-and-address-latency (CAL) mode;
using a control logic to initiate a power state transition from a first power state to a second power state of an input termination circuit in the memory interface device.
2. The method of claim 1 wherein the memory interface device is a registering clock driver or a memory buffer.
3. The method of claim 1 wherein each of the plurality of memory devices is a DDR4 SDRAM device or a memory device that includes a CAL mode that follows the definition of CAL mode as specified in JESD79-4.
4. The method of claim 1 wherein the host computer is provided on a separate module; and wherein the transferring is provided through a memory module interface such as the JEDEC standard DDR3 memory module interface or the DDR4 module interface.
5. The method of claim 1 wherein the CAL mode is the command-and-address (CAL) mode as defined in JEDEC DDR4 SDRAM component specification, JESD79-4.
6. The method of claim 1 wherein the control logic comprises a state machine that is operationally coupled to the input receiver for the chip-select signal and a set of control word registers, wherein, depending on the state of the chip-select signal and the setting in the control word registers, the state machine moves the command and address input receivers from a first power state to a second power state; and
wherein the first power state the input termination circuit are set to a first termination value, and in the second power state the input termination circuit is set to a second termination value.
7. The method of claim 1 wherein the input termination circuit comprises a set of resistive elements arranged in parallel, wherein the number of parallel resistive elements connected in the input termination circuit determines the termination value provided by the input termination circuit.
8. A method for operating a memory module device, the method comprising:
receiving a chip select signal at a memory interface device;
receiving an address signal at the memory interface device;
receiving a command signal at the memory interface device;
receiving a parity signal at the memory interface device;
transferring the chip select signal having a first latency from the memory interface device to a rank of DRAM devices;
transferring the address signal and the command signal having a second latency from the memory interface device to the rank of DRAM devices;
transferring the parity signal having a third latency from the memory interface device to the rank of DRAM devices; and
causing each of the DRAM devices to initiate a power state transition from a first power state to a second power state.
9. The method of claim 8 wherein the causing is initiated by receiving the chip select signal at the rank of DRAM devices, the power state transition occurring at each of the input receiver devices associated with each of the DRAM devices.
10. The method of claim 8 wherein the rank of DRAM devices is a plurality of ranks on a DIMM module.
11. The method of claim 8 wherein the first latency is provided by the parameter t PDM , the pin-to-pin propagation delay time of a memory interface device such as the DDR4 registering clock driver.
12. The method of claim 8 wherein the second latency is provided by t CAL , the frequency-dependent command-and-address-latency value as defined by JESD79-4, the DDR4 SDRAM component specification.
13. The method of claim 8 wherein the third latency is provided by t CAL −1.
14. The method of claim 8 further comprising initiating a no-operation (NOP) command when an input address parity error has been detected.
15. A memory module device comprising: an interface device configured for receiving a chip select, command, and address information from a host memory controller, the host memory controller being coupled to the memory interface device, the memory interface device being coupled to a memory module, the memory module comprising a plurality of memory devices, and configured for receiving the chip select, command, and address information at the memory interface device using a command-and-address-latency (CAL) mode; and a control logic to initiate a power state transition from a first power state to a second power state of an input termination circuit in the memory interface device.