MC908JL16CFAE FREESCALE [Freescale Semiconductor, Inc], MC908JL16CFAE Datasheet - Page 67

• Manufacturer Part Number: MC908JL16CFAE
• Description: Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Low Power Modes
5.4.4 XTAL Oscillator Clock (XTALCLK)
XTALCLK is the XTAL oscillator output signal. It runs at the full speed of the crystal (f
) and comes
XCLK
directly from the crystal oscillator circuit.
Figure 5-2
shows only the logical relation of XTALCLK to OSC1
and OSC2 and may not represent the actual circuitry. The duty cycle of XTALCLK is unknown and may
depend on the crystal and other external factors. Also, the frequency and amplitude of XTALCLK can be
unstable at start-up.
5.4.5 RC Oscillator Clock (RCCLK)
RCCLK is the RC oscillator output signal. Its frequency is directly proportional to the time constant of the
external R and C.
Figure 5-3
shows only the logical relation of RCCLK to OSC1 and may not represent
the actual circuitry.
5.4.6 Oscillator Out 2 (2OSCOUT)
2OSCOUT is same as the input clock (XTALCLK or RCCLK). This signal is driven to the SIM module.
5.4.7 Oscillator Out (OSCOUT)
The frequency of this signal is equal to half of the 2OSCOUT, this signal is driven to the SIM for generation
of the bus clocks used by the CPU and other modules on the MCU. OSCOUT will be divided again in the
SIM and results in the internal bus frequency being one fourth of the XTALCLK or RCCLK frequency.
5.4.8 Internal Oscillator Clock (ICLK)
ICLK is the internal oscillator output signal (typically 50-kHz), for the COP module and the SIM. Its
frequency depends on the V
voltage. (See
Chapter 17 Electrical Specifications
for ICLK parameters.)
DD
5.5 Low Power Modes
The WAIT and STOP instructions put the MCU in low-power consumption standby modes.
5.5.1 Wait Mode
The WAIT instruction has no effect on the oscillator logic. OSCOUT, 2OSCOUT, and ICLK continues to
drive to the SIM module.
5.5.2 Stop Mode
The STOP instruction disables the XTALCLK or the RCCLK output, hence, OSCOUT and 2OSCOUT are
disabled.
The STOP instruction also turns off the ICLK input to the COP module if the STOP_ICLKDIS bit is set in
configuration register 2 (CONFIG2). After reset, the STOP_ICLKDIS bit is clear by default and ICLK is
enabled during stop mode.
5.6 Oscillator During Break Mode
The OSCOUT, 2OSCOUT, and ICLK clocks continue to be driven out when the device enters the break
state.
MC68HC908JL16 Data Sheet, Rev. 1.1
Freescale Semiconductor
67