HD6432646 Hitachi, HD6432646 Datasheet - Page 779

• Manufacturer Part Number: HD6432646
• Description: (HD64F264x Series) 16-Bit Microcomputer
• Manufacturer: Hitachi

22.7
22.7.1
When the STBY pin is driven low, a transition is made to hardware standby mode from any mode.
In hardware standby mode, all functions enter the reset state and stop operation, resulting in a
significant reduction in power dissipation. As long as the prescribed voltage is supplied, on-chip
RAM data is retained. I/O ports are set to the high-impedance 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 (MD2 to MD0) while the H8S/2646 Series 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 oscillator stabilizes (at least 8 ms—the
oscillation stabilization 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.
Hardware Standby Mode
Hardware Standby Mode
745