Peripheral operating requirements and behaviors
5. The EXTAL and XTAL pins should only be connected to required oscillator components and must not be connected to any
other devices.
6.3.2.2 Oscillator frequency specifications
Table 15. Oscillator frequency specifications
Symbol Description
Min.
Typ.
Max.
Unit
Notes
fosc_lo
Oscillator crystal or resonator frequency — low
32
—
40
kHz
frequency mode (MCG_C2[RANGE]=00)
fosc_hi_1
Oscillator crystal or resonator frequency — high
frequency mode (low range)
(MCG_C2[RANGE]=01)
3
8
—
—
8
MHz
MHz
fosc_hi_2
Oscillator crystal or resonator frequency — high
frequency mode (high range)
32
(MCG_C2[RANGE]=1x)
fec_extal
tdc_extal
tcst
Input clock frequency (external clock mode)
Input clock duty cycle (external clock mode)
—
40
—
—
50
50
60
—
MHz
%
1, 2
3, 4
Crystal startup time — 32 kHz low-frequency,
low-power mode (HGO=0)
750
ms
Crystal startup time — 32 kHz low-frequency,
high-gain mode (HGO=1)
—
—
250
0.6
—
—
ms
ms
Crystal startup time — 8 MHz high-frequency
(MCG_C2[RANGE]=01), low-power mode
(HGO=0)
Crystal startup time — 8 MHz high-frequency
(MCG_C2[RANGE]=01), high-gain mode
(HGO=1)
—
1
—
ms
1. Other frequency limits may apply when external clock is being used as a reference for the FLL or PLL.
2. When transitioning from FBE to FEI mode, restrict the frequency of the input clock so that, when it is divided by FRDIV, it
remains within the limits of the DCO input clock frequency.
3. Proper PC board layout procedures must be followed to achieve specifications.
4. Crystal startup time is defined as the time between the oscillator being enabled and the OSCINIT bit in the MCG_S register
being set.
6.3.3 32 kHz Oscillator Electrical Characteristics
This section describes the module electrical characteristics.
6.3.3.1 32 kHz oscillator DC electrical specifications
Table 16. 32kHz oscillator DC electrical specifications
Symbol
Description
Min.
Typ.
Max.
Unit
VBAT
Supply voltage
1.71
—
3.6
V
RF
Internal feedback resistor
—
100
—
MΩ
Table continues on the next page...
K20 Sub-Family Data Sheet, Rev. 4 5/2012.
Freescale Semiconductor, Inc.
29
FREESCALE [ Freescale ]
