h8s-2138 Renesas Electronics Corporation., h8s-2138 Datasheet - Page 752

• Manufacturer Part Number: h8s-2138
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

Section 24 Power-Down State
In order to retain on-chip RAM data, the RAME bit in SYSCR should be cleared to 0 before
driving the STBY pin low.
Do not change the state of the mode pins (MD1 and MD0) while the chip is in hardware standby
mode.
Hardware standby mode is cleared by means of the STBY pin and the RES pin. When the STBY
pin is driven high while the RES pin is low, the reset state is set and clock oscillation is started.
Ensure that the RES pin is held low until the clock oscillation settles (at least 8 ms—the oscillation
settling time—when using a crystal oscillator). When the RES pin is subsequently driven high, a
transition is made to the program execution state via the reset exception handling state.
24.7.2
Figure 24.4 shows an example of hardware standby mode timing.
When the STBY pin is driven low after the RES pin has been driven low, a transition is made to
hardware standby mode. Hardware standby mode is cleared by driving the STBY pin high, waiting
for the oscillation settling time, then changing the RES pin from low to high.
Rev. 4.00 Jun 06, 2006 page 698 of 1004
REJ09B0301-0400
Oscillator
RES
STBY
Hardware Standby Mode Timing
Figure 24.4 Hardware Standby Mode Timing
Oscillation
settling time
Reset exception
handling