A low-power processor for portable navigation devices: 456 mW at 400 MHz and 24 mW in software standby mode

摘要

We have developed a processor (SH-MobileR2) optimized for both low power and high performance. SH-MobileR2 includes a 32-bit RISC type SuperH CPU with 720 MIPS performance at 400MHz operating frequency, and a Floating Point unit with 2.8 GFLOPS performance. The CPU also has a 256-KByte secondary unified cache on top of the 64-KByte primary split cache. Compared to the previous SH-MobileR processor, SH-MobileR2 introduces four peripheral modules: a DDR-SDRAM controller, an Interconnect Buffers with 128-Kbyte embedded Media RAM, an improved Video Processing unit (VPU5F), and an enhanced 2-D Graphics accelerator for higher performance in map rendering and graphic applications. Low-power consumption is achieved by optimizing blends of a 90nm CMOS triple Vth cells, and applying four power-down modes. The low-power consumption and the high performance of SH-MobileR2 processor is the most suitable for portable navigation devices.