Patent ID: 9142280
Filing Date: 2015-09-22
Classification: G11C

Abstract:
1. An integrated circuit (IC), operable in high and low power modes, connected to an external memory that stores a boot program to be executed by the integrated circuit, the integrated circuit comprising: a processor that generates a memory refresh command when the IC is in the high power mode, generates a memory self-refresh command when the IC transitions from the high power mode to the low power mode, and is powered off when the IC is in the low power mode; a memory controller, connected to the processor, that receives the memory refresh command and generates reset and clock enable signals when the IC is in the high power mode, receives the memory self-refresh command and generates the reset signal when the IC transitions from the high power mode to the low power mode, and is powered off when the IC is in the low power mode; a first input/output (IO) pad, connected between the memory controller and the external memory, that receives and outputs the reset signal when the IC is in the high power mode, and is powered off when the IC is in the low power mode; a second input/output (IO) pad, connected between the memory controller and the external memory, that receives and outputs the clock enable signal when the IC is in the high power mode, and is powered off when the IC is in the low power mode, whereby the external memory receives the reset and the clock enable signals and operates in a refresh mode when the IC is in the high power mode; a pull-up resistor, connected between the first IO pad and a first supply voltage, that pulls up a voltage at an output of the first IO pad to a first supply voltage level when the IC is in the low power mode; and a pull-down resistor, connected between the second IO pad and ground, that pulls down a voltage at an output of the second IO pad to a ground voltage level when the IC is in the low power mode, thereby configuring the external memory in a self-refresh mode when the IC is in the low power mode.