Structure and method for SDRAM dynamic self refresh entry and exit using JTAG

摘要

JTAG test logic and a memory controller place an SDRAM in a self refresh mode prior to beginning JTAG testing. The memory controller can complete a current memory access and otherwise prepare for the JTAG test. During the JTAG test, self refresh mode operation of the SDRAM retains data without the need for a clock signal or refresh signals which are suspended for the JTAG test. Accordingly, after the JTAG test, circuit operation can continue without reinitializing data in the SDRAM.