MEC1404 Datasheet, PDF (73/572 Pages) Microchip Technology – Keyboard and Embedded Controller Products for Notebook PC

MEC140X/1X
2: The 48 MHz Ring Oscillator will reach frequency lock if either the external 32kHz clock source or the 32 kHz
Internal Oscillator is used, as selected via the 48MHz Oscillator Reference Select bit in the Clock Enable
Register on page 444. The 48 MHz Ring Oscillator will remain locked when the external 32kHz clock source
is removed.
3.5.5 CLOCK DOMAINS VS. ACPI POWER STATES
Table 3-8, "Typical MEC140X/1X Clocks vs. ACPI Power States" shows the relationship between ACPI power states
and MEC140X/1X clock domains:
TABLE 3-8: TYPICAL MEC140X/1X CLOCKS VS. ACPI POWER STATES
Clock
Name
SUSCLK
32.768 kHz Crystal
Oscillator
32KHz_Clk
48 MHz Ring Oscil-
lator
32kHz_INT_OSC
S0
(FULL
ON)
ON
ON
ON
ON
ON
ACPI Power State
S1
(POS)
ON
S3
(STR)
ON
S4
(STD)
ON
S5
(Soft
Off)
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
ON
G3
(MECH
Off)
Description
OFF
ON
ON/
OFF
OFF
OFF
This clock is the system
suspend clock source.
(Note 3-5).
This clock is generated
from a 32.768 kHz par-
allel resonant crystal
connected between the
XTAL1 and XTAL2 pins.
This clock domain is
generated from the 32
kHz clock input (SUS-
CLK) when available or
the crystal oscillator
pins. Otherwise it is
generated internally
from the
32kHz_INT_OSC or the
48 MHz Ring Oscillator.
This clock is powered
by the MEC140X/1X
suspend supply (VTR)
but may start and stop
as described in Section
3.7, "Chip Power Man-
agement Features," on
page 76 (see also
Note 3-3).
This clock is powered
by the MEC140X/1X
VBAT power supply.
This clock may be used
when 48 MHz Ring
Oscillator is not avail-
able.
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DS00001956D-page 73