SH7046 Datasheet, PDF (545/611 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7046 Series

Section 21 Power-Down Modes
21.3 Operation
21.3.1 Sleep Mode
Transition to Sleep Mode: If SLEEP instruction is executed while the SSBY bit in SBYCR = 0,
the CPU enters sleep mode. In sleep mode, CPU operation stops, however the contents of the
CPU's internal registers are retained. Peripheral functions except the CPU do not stop.
In sleep mode, data should not be accessed by the DTC.
Clearing Sleep Mode: Sleep mode is cleared by the conditions below.
• Clearing by the power-on reset
When the RES pin is driven low, the CPU enters the reset state. When the RES pin is driven
high after the elapse of the specified reset input period, the CPU starts the reset exception
handling.
When an internal power-on reset by the WDT occurs, sleep mode is also cleared.
• Clearing by the manual reset
When the MRES pin is driven low while the RES pin is high, the CPU shifts to the manual
reset state and thus sleep mode is cleared.
When an internal manual reset by the WDT occurs, sleep mode is also cleared.
21.3.2 Software Standby Mode
Transition to Software Standby Mode: A transition is made to software standby mode if the
SLEEP instruction is executed while the SSBY bit in SBYCR is set to 1. In this mode, the CPU,
on-chip peripheral functions, and the oscillator, all stop.
However, the contents of the CPU's internal registers and on-chip RAM data are retained as long
as the specified voltage is supplied. There are two types of on-chip peripheral module registers;
ones which are initialized by software standby mode, and those not initialized by that mode. For
details, refer to appendix A.3, Register States in Each Operating Mode. The port high-impedance
bit (HIZ) in SBYCR sets the state of the I/O port either to "retained" or "high-impedance". For the
state of pins, refer to appendix B, Pin States. In software standby mode, the oscillator stops and
thus power consumption is significantly reduced.
Rev. 4.00 Dec 05, 2005 page 501 of 564
REJ09B0270-0400