Crystal Oscillator

The following table provides the values of the ATWINC15x0B crystal oscillator parameters.

Table 1. ATWINC15x0B Crystal Oscillator Parameters
Parameter Min. Typ. Max. Unit
Crystal resonant frequency 26 MHz
Crystal equivalent series resistance 50 150
Stability – Initial offset(1) -100 100 ppm
  1. 1. The initial offset must be calibrated to maintain ±25 ppm in all operating conditions. This calibration is performed during final production testing.

The block diagram in the following figure (a) shows how the internal Crystal Oscillator (XO) is connected to the external crystal. The XO has 5 pF internal capacitance on each terminal XO_P and XO_N. To bypass the crystal oscillator with an external reference, an external signal capable of driving 5 pF can be applied to the XO_N terminal as shown the following figure (b).

The XO has 5 pF internal capacitance on each terminal XO_P and XO_N. This internal capacitance must be considered when calculating the external loading capacitance, c_onboard, for the XTAL.

Figure 1. ATWINC15x0B XO Connections

The following table specifies the electrical and performance requirements for the external clock.

Table 2. ATWINC15x0B Bypass Clock Specification
Parameter Min. Typ. Max. Unit Comments
Oscillator frequency 26 MHz Must drive 5 pF load at desired frequency
Voltage swing 0.5 1.2 Vpp Must be AC coupled
Stability – Temperature and aging -25 +25 ppm
Phase noise -130 dBc/Hz At 10 kHz offset
Jitter (RMS) <1 psec Based on integrated phase noise spectrum from 1 kHz to 1 MHz