PXA250 INTEL [Intel Corporation], PXA250 Datasheet - Page 33

• Manufacturer Part Number: PXA250
• Description: Intel-R PXA250 and PXA210 Applications Processors
• Manufacturer: INTEL [Intel Corporation]

4.5
4.5.1
Datasheet
Table 11. 32.768 kHz Oscillator Specifications
Oscillator Electrical Specifications
The applications processor contains two oscillators: a 32.768 kHz oscillator and a 3.6864 MHz
oscillator. Each is for a specific crystal. When choosing a crystal, match the crystal parameters as
closely as possible.
32.768 kHz Oscillator Specifications
The 32.768 kHz Oscillator is connected between the TXTAL (amplifier input) and TEXTAL
(amplified output). The 32.768 kHz specifications are shown in Table 11, “32.768 kHz Oscillator
Specifications”.
To drive the 32.768 kHz crystal pins from an external source:
Crystal Specifications - Typical is FOX NC38
Amplifier Specifications
Board Specifications
•
•
COP_XT
Symbol
CIN_XT
RP_XT
CP_XT
IIN_XT
VIH_X
tS_XT
VIL_X
Drive the TEXTAL pin with a digital signal that has a low level near 0 volts and a high level
near VCC. Do not exceed VCC or go below VSS by more than 100 mV. The minimum slew
rate is 1 volt per 1 µs. The maximum current sourced by the external clock source when the
clock is at its maximum positive voltage should be approximately 1 mA.
Float the TXTAL pin or drive it complementary to the TEXTAL pin, with the same voltage
level, slew rate, and input current restrictions.
CMT
RMT
COT
LMT
FXT
CLT
Electrical, Mechanical, and Thermal Specification — PXA250 and PXA210
Crystal Frequency, TXTAL/TEXTAL
Motional Inductance, TXTAL/TEXTAL
Motional Capacitance, TXTAL/TEXTAL
Motional Resistance, TXTAL/TEXTAL
Shunt Capacitance TXTAL to TEXTAL
Load Capacitance TXTAL/TEXTAL
Input High Voltage, TXTAL
Input Low Voltage, TXTAL
Input Leakage, TXTAL
Input Capacitance, TXTAL/TEXTAL
Stabilization Time
Parasitic Resistance, TXTAL/TEXTAL to
any node
Parasitic Capacitance, TXTAL/TEXTAL,
total
Parasitic Shunt Capacitance, TXTAL to
TEXTAL
Description
0.8*VCC
VSS
Min
20
6
2
6827.81
Typical
32.768
3.455
12.5
1.6
16
18
-
0.2*VCC
VCC
Max
0.4
35
25
10
1
5
Units
kHz
M
k
pF
pF
pF
pF
pF
H
fF
V
V
s
A
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