On-die termination control
A memory control component outputs a memory write command to a memory IC and also outputs write data to be received via data inputs of the memory IC. Prior to reception of the write data within the memory IC, the memory control component asserts a termination control signal that causes the memory IC to apply to the data inputs a first on-die termination impedance during reception of the write data followed by a second on-die termination impedance after the write data has been received. The memory control component deasserts the termination control signal to cause the memory IC to apply no termination impedance to the data inputs.
1. A method of controlling an integrated-circuit memory device (“memory IC”), the method comprising:
outputting a memory write command to the memory IC;
outputting write data to be received via data inputs of the memory IC;
prior to reception of the write data within the memory IC, asserting a termination control signal that causes the memory IC to apply to the data inputs a first on-die termination impedance during reception of the write data followed by a second on-die termination impedance after the write data has been received; and
deasserting the termination control signal to cause the memory IC to apply no termination impedance to the data inputs.
2. The method of claim 1 wherein asserting the termination control signal that causes the memory IC to apply to the data inputs the first on-die termination impedance during reception of the write data followed by the second on-die termination impedance after the write data has been received comprises asserting the termination control signal to cause the memory IC to apply the second on-die termination impedance to the data inputs concurrently with execution of a precharge operation within the memory IC.
3. The method of claim 1 further comprising programming first and second termination values within one or more registers of the memory IC, the first termination value specifying a resistance value of the first on-die termination impedance and the second termination value specifying a resistance value of the second on-die termination impedance.
4. The method of claim 1 wherein outputting the memory write command comprises outputting the memory write command prior to outputting the write data.
5. The method of claim 1 further comprising asserting a chip-select signal to enable the memory IC to receive and respond to the memory write command.
6. The method of claim 1 wherein asserting the termination control signal to cause the memory IC to apply to the data inputs the first on-die termination impedance during reception of the write data followed by the second on-die termination impedance after the write data has been received comprises asserting the termination control signal to cause the memory IC to couple a respective first plurality of termination load elements to each of the data inputs during reception of the write data and to couple a respective second plurality of termination load elements to each of the data inputs after the write data has been received.
7. The method of claim 6 wherein each respective first plurality of termination load elements comprises at least one termination load element not included in any second plurality of termination load elements.
8. The method of claim 6 wherein the first and second pluralities of termination load elements constitute respective subsets of pull-up elements and pull-down elements within an output driver circuit of the memory IC.
9. The method of claim 1 wherein the memory IC comprises a memory array, and wherein outputting the write data comprises outputting the write data to the memory IC for storage within the memory array.
10. The method of claim 1 wherein the data inputs of the memory IC serve also as data outputs, the method further comprising outputting a read command to the memory IC to cause the memory IC to transmit read data via the data outputs and wherein deasserting the termination control signal to cause the memory IC to apply no termination impedance to the data inputs comprises deasserting the termination control signal to cause the memory IC to apply no termination impedance to the data inputs while transmitting the read data via the data outputs.
11. A memory controller component for controlling an integrated-circuit memory device (“memory IC”), the memory controller component comprising:
a first signaling interface to output a memory write command to the memory IC;
a second signaling interface to output write data to be received via data inputs of the memory IC; and
a termination control output to:
assert a termination control signal prior to reception of the write data within the memory IC to cause the memory IC to apply to the data inputs a first on-die termination impedance during reception of the write data followed by a second on-die termination impedance after the write data has been received; and
deassert the termination control signal to cause the memory IC to apply no termination impedance to the data inputs.
12. The memory controller component of claim 11 wherein the termination control output asserts the termination control signal to cause the memory IC to apply the second on-die termination impedance to the data inputs concurrently with execution of a precharge operation within the memory IC.
13. The memory controller component of claim 11 wherein the first signaling interface outputs the memory write command before the second signaling interface outputs the write data.
14. The memory controller component of claim 11 wherein the first signaling interface is further to output one or more register programming commands that cause the memory IC to store first and second termination values within one or more registers of the memory IC, the first termination value specifying a resistance value of the first on-die termination impedance and the second termination value specifying a resistance value of the second on-die termination impedance.
15. The memory controller component of claim 11 further comprising a chip-select output to assert a chip-select signal that enables the memory IC to receive and respond to the memory write command.
16. The memory controller component of claim 11 wherein the termination control output asserts the termination control signal to cause the memory IC to couple a respective first plurality of termination load elements to each of the data inputs to effect the first termination on-die impedance and to couple a respective second plurality of termination load elements to each of the data inputs to effect the second on-die termination impedance.
17. The memory controller component of claim 15 wherein each respective first plurality of termination load elements comprises at least one termination load element not included in any second plurality of termination load elements.
18. A method of controlling an integrated-circuit memory device (“memory IC”), the method comprising:
outputting to the memory IC information that specifies storage, in registers of the memory IC, of first and second values that indicate respective first and second on-die termination impedances;
asserting a termination control signal at a termination control input of the memory IC;
outputting write data to be received via data inputs of the memory IC during a write-data reception interval; and
outputting a write command to the memory IC prior to the write-data reception interval to cause the memory IC to (i) transition to a first internal state that spans the write-data reception interval and then to a second internal state, (ii) receive the write data while in the first internal state and (iii) respond to assertion of the termination control signal by applying either the first or the second on-die termination impedance depending on the internal state including applying the first on-die termination impedance to each of the data inputs while in the first internal state and applying the second on-die termination impedance to each of the data inputs while in the second state.
19. The method of claim 18 further comprising deasserting the termination control signal to cause the memory IC to apply no termination impedance to the data inputs.
20. The method of claim 17 wherein the data inputs of the memory IC serve also as data outputs, the method further comprising outputting a read command to the memory IC to cause the memory IC to transition to a third internal state during which the memory IC transmits read data via the data outputs and applies neither of the first and second on-die termination impedances to the data outputs.