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438 SA-1110 Developer’s Manual
32.768–KHz Oscillator Specifications
While the 32.768-kHz oscillator will start with parasitic capacitances which are approximately
twice the values given; the startup time in this situation will be about double the specified startup
time and the current consumption will increase. Capacitances larger than twice the specified values
may prevent the oscillator from starting.
C.1.1.4. Frequency Shift Due to Temperature Effect on the Circuit
The frequency shift due to temperature effect on the circuit is the influence of the oscillator circuit
on the frequency of oscillation due to temperature effect. The appropriate temperature range is the
junction temperature on the SA-1110, not the ambient temperature. Note that this specification
does not include either the temperature effects on the quartz or the aging of the crystal. It includes
the temperature effect of the circuit only. The frequency shift of the crystal itself due to temperature
may be significantly larger than that of the oscillator circuit. However, for a long-term stability
calculation, it may be appropriate to consider the average temperature of the crystal rather than the
extreme values of temperature.
C.1.1.5. Parasitic Capacitance Off-chip Between TXTAL and TEXTAL
The parasitic capacitance off-chip between TXTAL and TEXTAL is the board capacitance between
the TXTAL and TEXTAL pins.
C.1.1.6. Parasitic Capacitance Off-chip Between TXTAL or TEXTAL and VSS
The parasitic capacitance off-chip between TXTAL or TEXTAL and VSS is the parasitic board
capacitance between the TXTAL or TEXTAL pins and the VSS wire surrounding the crystal
connections.
C.1.1.7. Parasitic Resistance Between TXTAL and TEXTAL
The parasitic resistance between TXTAL and TEXTAL is the parasitic resistance between the
TXTAL and TEXTAL pins due to moisture and other effects.
C.1.1.8. Parasitic Resistance Between TXTAL or TEXTAL and VSS
The parasitic resistance between TXTAL or TEXTAL and VSS is the parasitic resistance between
the TXTAL or TEXTAL pins to VSS due to moisture and other effects.
The following table describes the specifications of the oscillator circuit.
Specification Minimum Typical Maximum Unit
Temperature range 0 100
o
C
Supply voltage 3 3.3 3.6 V
Ripple voltage on the supply ——0.3 V
Current consumption — 12µA
Startup time ——2s
Frequency shift due to temperature effect on the circuit ——+/-3 ppm
Parasitic capacitance off-chip
between TXTAL and TEXTAL
——1pF