Lucent Technologies MN10285K User Manual

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The MN102H75K/85K provides two ways to reduce power consumption, con-

trolling CPU operating and standby modes to cut overall consumption and 
shutting down unused functions by stopping the system clock supplied to them.

The MN102H75K/85K has two CPU operating modes, NORMAL and SLOW, 
and two CPU standby modes, HALT and STOP. Effective use of these modes can 

significantly reduce power consumption. Figure 3-1 shows the CPU states in the 
different modes.

You cannot enter STOP mode 

from NORMAL mode.

The CPU mode control register (CPUM) controls transitions between NORMAL 
and SLOW modes and from NORMAL and SLOW modes to the standby modes. 

A normal reset or an interrupt wakes the MCU from a standby mode.

Note that you cannot invoke the STOP mode from NORMAL mode. You can 
only enter STOP from the SLOW mode.

NORMAL Mode

Clock to CPU: 24 MHz
System clock: 12 MHz
CPU and PLL on

SLOW Mode

Clock to CPU: 4 MHz
System clock: 2 MHz
CPU on, PLL on

Program
(Write to CPUM register)

Program

(Write to CPUM register)

STOP Mode

Clock to CPU: off
System clock: off
CPU and PLL off

HALT Mode

Clock to CPU: 4 MHz
System clock: 2 MHz
CPU and PLL off

Program
(Write to CPUM
register)

Interrupt

Program
(Write to CPUM
register)

Interrupt

Program
(Write to CPUM
register)

Interrupt

Clock to CPU: 24 MHz
System clock: 12 MHz
CPU stopped, PLL on

Program

(Write to CPUM register)

IDLE State

Clock to CPU: 24 MHz
System clock: 12 MHz
CPU and PLL on