PXN20 Datasheet, PDF (37/60 Pages) Freescale Semiconductor, Inc – PXN20 Microcontroller

Electrical characteristics
Table 15. 3.3 V high frequency external oscillator (continued)
Spec
Characteristic
Symbol
Min
Max
Unit
8
Crystal manufacturer’s recommended
C_L
See crystal
See crystal
pF
capacitive load
specification
specification
9
Discrete load capacitance to be connected C_{L_EXTAL}
to EXTAL
—
2C_L – C_{S_EXTAL} –
pF
C_{PCB_EXTAL5}
10
Discrete load capacitance to be connected
C_{L_XTAL}
to XTAL
—
2C_L – C_{S_XTAL} – C pF
5
PCB_XTAL
11 Startup Time
t_startup
—
10
ms
1 _{When PLL frequency modulation is active, reference frequencies less than 8 MHz will distort the modulated waveform and the}
effects of this on emissions is not characterized.
2 _{This parameter is meant for those who do not use quartz crystals or resonators, but instead use CAN oscillators in crystal}
mode. In that case, V_extal – V_xtal  400 mV criteria has to be met for oscillator’s comparator to produce output clock.
3 _{This parameter is meant for those who do not use quartz crystals or resonators, but instead use CAN oscillators in crystal}
mode. In that case, V_xtal – V_extal  400 mV criteria has to be met for oscillator’s comparator to produce output clock.
4 _{Ixtal is the oscillator bias current out of the XTAL pin with both EXTAL and XTAL pins grounded.}
5 _{CPCB_EXTAL and CPCB_XTAL are the measured PCB stray capacitances on EXTAL and XTAL, respectively.}
Table 16. 5 V low frequency (32 kHz) external oscillator
Spec
Characteristic
Symbol
Min
Max
1 Frequency Range
2 Duty Cycle of reference
3 XTAL32 Current¹
4 Crystal manufacturer’s recommended
capacitive load
f_ref32
t_dc32
I_XTAL32
C_L32
32
40
—
See crystal
specification
40
60
3
See crystal
specification
5 Startup Time
t_Startup
—
2
1 _{Ixtal32 is the oscillator bias current out of the XTAL32 pin with both EXTAL32 and XTAL32 pins grounded.}
Unit
kHz
%
A
pF
s
Table 17. 5 V High Frequency (16 MHz) internal RC oscillator
Spec
Characteristic
1 Frequency before trim¹
2 Frequency after loading factory trim²
3 Application trim resolution³
4 Application frequency trim step³
5 Startup Time
1 _{Across process, voltage, and temperature.}
2 _{Across voltage and temperature.}
3 _{Fixed voltage and temperature.}
Symbol Range
Min
Typ
f_ut
35%
10.4
16
f_t
7%
14.9
16
t_s
—
—
—
f_s
—
—
300
t_Startup
—
—
—
Max
Unit
21.6
MHz
17.1
MHz
05
%
—
kHz
500
ns
PXN20 Microcontroller Data Sheet, Rev. 1
Freescale Semiconductor
37