Method and circuit for adjusting a self-refresh rate to maintain dynamic data at low supply voltages
AssigneeMicron Technology, Inc.
InventorLeel S. Janzen
Life of this patent
Estimating the term…
Abstract
A method and circuit for refreshing dynamic data stored in an integrated circuit are disclosed. The integrated circuit receives a supply voltage and operates in a self-refresh mode of operation to refresh the dynamic data at a refresh time that defines how often the dynamic data is refreshed during the self-refresh mode. The method includes monitoring a magnitude of the supply voltage and adjusting the refresh time as a function of the monitored magnitude of the supply voltage. The integrated circuit may be any type of integrated circuit that stores dynamic data, such as a memory device like a dynamic random access memory, DDR DRAM, SLDRAM, or RDRAM, or other type of integrated circuit such as a microprocessor.
Claims14
A method of refreshing dynamic data stored in an integrated circuit, the integrated circuit being adapted to receive a supply voltage and being adapted to operate in a self-refresh mode of operation to refresh the dynamic data at a refresh time that defines how often the dynamic data is refreshed during the self-refresh mode, the method comprising:
- monitoring a magnitude of the supply voltage;
- and
- adjusting the refresh time as a function of the monitored magnitude of the supply voltage, wherein adjusting the refresh time as a function of the monitored magnitude of the supply voltage comprises,
- decreasing the refresh time as the magnitude of the supply voltage decreases to refresh the dynamic data more frequently, wherein decreasing the refresh time as the magnitude of the supply voltage decreases comprises linearly increasing a frequency of a self-refresh clock signal, the self-refresh clock signal defining the refresh time.
The method of claim 6 wherein decreasing the refresh time as a function decreases in the supply voltage once the detected supply voltage is less than or equal to the minimum supply voltage comprises generating a bias voltage from the supply voltage, the bias voltage having a value that is inversely related to the refresh time, and increasing the bias voltage as a function of decreases in the supply voltage once the detected supply voltage is less than or equal to the minimum supply voltage.
A method of refreshing dynamic data stored in an integrated circuit, the integrated circuit being adapted to receive a supply voltage and being adapted to operate in a self-refresh mode of operation to refresh the dynamic data at a refresh time that defines how often the dynamic data is refreshed during the self-refresh mode, the method comprising monitoring a magnitude of the supply voltage and adjusting the refresh time as a function of the monitored magnitude of the supply voltage, wherein monitoring the magnitude of the supply voltage comprises detecting whether the supply voltage is less than or equal to a minimum supply voltage, and adjusting the refresh time as a function of the monitored magnitude of the supply voltage comprises generating a refresh time adjustment command that determines a value of the refresh time, the value being a function of the detected supply voltage, and setting the refresh time to the determined value.
A method of refreshing dynamic data stored in an integrated circuit, the integrated circuit being adapted to receive a supply voltage and including a refresh oscillator that generates a refresh clock signal having a frequency that is a function of a bias voltage, the bias voltage being derived from the supply voltage and the integrated circuit being adapted to operate in a self-refresh mode of operation to refresh the dynamic data at a refresh rate that is a function of the frequency of the refresh clock signal, the method comprising monitoring the magnitude of the supply voltage and controlling the bias voltage as a function of the magnitude of the monitored supply voltage.
Dependencies are inferred from the claim text.