Patent ID: 8724415

Claim:
A storage device comprising: N storage units U i arranged in stages, where N≧2 and i is an index from 1 to N that designates the stages of the respective storage units; and a control unit configured to output a refresh command, wherein each of the storage units U i includes: a temperature sensor adapted to detect a temperature condition and to generate own-temperature-information T 0 i , a temperature information selection section configured to output outputted-temperature-information T 1 i , a refresh command reception section configured to receive the refresh command, and a trigger issuance frequency setting section configured to generate a refresh trigger in response to the reception of the refresh command, where the refresh trigger causes a memory array to perform a refresh and a frequency F i of the refresh trigger is based on: the refresh command, the outputted-temperature-information T 1 N of the storage unit U N at the final stage, and the own temperature information T 0 i , wherein the respective temperature information selection sections of the storage units U i≠1 that are in a stage after the first stage are each configured to: receive outputted-temperature-information T 1 i−1 from a previous stage storage unit U i−1 , and select either the outputted-temperature-information T 1 i−1 from the previous stage storage unit U i−1 or the own-temperature-information T 0 i of the storage unit U i to be outputted as the outputted-temperature-information T 1 i of the storage unit U i and wherein the control unit is configured to set a transmission frequency at which the refresh command is output according to the outputted-temperature-information T 1 N of the storage unit U N at the final stage.