Z80185 Datasheet, PDF (35/95 Pages) Zilog, Inc. – SMART PERIPHERAL CONTROLLERS

Zilog
PRELIMINARY
Z80185/Z80195
SMART PERIPHERAL CONTROLLES
IDLE Mode
IDLE mode is another power-down mode offered by the
Z8S180. To enter IDLE mode:
1. Set D6 and D3 to 0 and 1, respectively.
2. Set the I/O STOP bit (D5 of ICR,
I/O Address = 3FH) to 1.
Standby-Quick Recovery Mode
STANDBY-QUICK RECOVERY mode is an option offered
in STANDBY mode to reduce the clock recovery time in
STANDBY mode from 2¹⁷ clock cycles (6.5 ms at 20 MHz)
to 2⁶ clock cycles (3.2 µs at 20 MHz). This feature can only
be used when providing an oscillator as clock source.
To enter STANDBY-QUICK RECOVERY mode:
3. Execute the SLEEP instruction.
1. Set D6 and D3 to 1 and 1, respectively.
When the part is in IDLE mode, the clock oscillator is kept
oscillating, but the clock to the rest of the internal circuit,
including the CLKOUT, is stopped completely. IDLE mode
is exited in a similar way as STANDBY mode, in other
words, RESET, BUS REQUEST or EXTERNAL INTER-
RUPTS, except that the 2¹⁷ bit wake-up timer is bypassed;
all control signals are asserted eight clock cycles after the
exit conditions are gathered.
2. Set the I/O STOP bit (D5 of ICR,
I/O Address = 3FH) to 1.
3. Execute the SLEEP instruction.
When the part is in STANDBY-QUICK RECOVERY mode,
the operation is identical to STANDBY mode except when
exit conditions are gathered, in other words, RESET, BUS
REQUEST or EXTERNAL INTERRUPTS. The clock and
other control signals are recovered sooner than the
STANDBY mode.
Note: If STANDBY-QUICK RECOVERY is enabled, the
user must make sure stable oscillation is obtained within
64 clock cycles.
DS971850301
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