MEC1404 Datasheet, PDF (72/572 Pages) Microchip Technology – Keyboard and Embedded Controller Products for Notebook PC

MEC140X/1X
TABLE 3-6: DERIVED CLOCK DEFINITIONS (CONTINUED)
Clock Name
1.8432MHz_Clk
1MHz_Clk
100kHz_Clk
32KHz_Clk
5Hz_Clk
Frequency
1.843 MHz
1 MHz
100 kHz
32.768 kHz
Description
Derived clock for UART
Derived clock for 8042 Emulated
Keyboard Controller
Derived clock for PWM and TACH
blocks
Internal 32kHz clock domain
5 Hz
Derived clock for Breathing LED
block
Source
48 MHz Ring Oscillator
48 MHz Ring Oscillator
48 MHz Ring Oscillator
Pin Interface or 48 MHz Ring Oscil-
lator:
Pins:
XTAL2: 32 kHz Crystal input/ single-
ended clock source input pin.
XTAL1: 32 kHz Crystal output
The XOSEL bit configures the
source of this clock domain as either
a single-ended 32.768 kHz clock
input (SUSCLK) or the 32.768 kHz
Crystal Oscillator. If neither of these
is available, this clock domain is
derived from the 32kHz_INT_OSC
or the 48 MHz Ring Oscillator, as
configured by bits in the Clock
Enable Register.
(See Note 3-8)
48 MHz Ring Oscillator
Note 3-8 Bits[4:0] of the Clock Enable Register on page 444 determine the source of the 32KHz_Clk.
3.5.3 GENERATED CLOCK OUTPUTS
This section describes clocks generated by the MEC140x/1x that may be used by the external system.
TABLE 3-7: GENERATED CLOCK DEFINITIONS
Clock Name
32KHZ_OUT
Frequency
32.768 kHz
Description
32.768 kHz output.
Configured 32kHz clock source
routed to pin interface.
Source
Derived 32KHz_Clk
3.5.4 32 KHZ CLOCK SWITCHING
The 32kHz clock switching logic switches the clock source of the 32kHz clock domain to be either the single-ended
32.768 kHz clock input (SUSCLK), the 32.768 kHz Crystal Oscillator, the 32kHz_INT_OSC or 48 MHz Ring Oscillator.
Following a VBAT_POR, the XOSEL, 32KHz Clock Switcher Control, INT_32K_OSC_EN and EXT_32K_OSC_EN bits
in the Clock Enable Register are programmed to configure the source of this clock domain. See Table 35-3, “32kHz
Clock Control,” on page 445.
Note 1: Switching delay when configuring the 32k Hz clock source will be on the order of 100 us or three 32k Hz
clocks.
DS00001956D-page 72
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