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	Ω
Stability – Initial offset⁽¹⁾	-100	—	100	ppm

Note:

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