K20P144M120SF3_1210 Datasheet, PDF (33/86 Pages) Freescale Semiconductor, Inc – K20 Sub-Family

Peripheral operating requirements and behaviors
Table 17. Oscillator frequency specifications (continued)
Symbol
t_cst
Description
Crystal startup time — 32 kHz low-frequency,
low-power mode (HGO=0)
Crystal startup time — 32 kHz low-frequency,
high-gain mode (HGO=1)
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)
Min.
—
—
—
—
Typ.
1000
500
0.6
1
Max.
—
—
—
—
Unit
Notes
ms
4, 5
ms
ms
ms
1. Frequencies less than 8 MHz are not in the PLL range.
2. Other frequency limits may apply when external clock is being used as a reference for the FLL or PLL.
3. 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.
4. Proper PC board layout procedures must be followed to achieve specifications.
5. Crystal startup time is defined as the time between the oscillator being enabled and the OSCINIT bit in the MCG_S register
being set.
NOTE
The 32 kHz oscillator works in low power mode bu default and
cannot be moved into high power/gain mode.
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 18. 32kHz oscillator DC electrical specifications
Symbol
V_BAT
R_F
C_para
V_pp1
Description
Min.
Typ.
Max.
Unit
Supply voltage
1.71
—
3.6
V
Internal feedback resistor
—
100
—
MΩ
Parasitical capacitance of EXTAL32 and XTAL32
—
5
7
pF
Peak-to-peak amplitude of oscillation
—
0.6
—
V
1. When a crystal is being used with the 32 kHz oscillator, the EXTAL32 and XTAL32 pins should only be connected to
required oscillator components and must not be connected to any other devices.
K20 Sub-Family Data Sheet, Rev. 4, 10/2012.
Freescale Semiconductor, Inc.
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