SC16IS762 : External Oscillator Selection

[arijeet06]

Hi Team,

We are using SC16IS762 for Dual UART-SPI Interface.
We have requirements of UART Baud rates of 9.6kbps, 38.4kbps, 115.2kbps.

Please let us know if we are good to go with an oscillator part (SG-8018CG 3.0720M-TJHSA0) of 3.072 MHz with +/- 50ppm for our application to support these baud rates.

Also, if you have some better OSC/XTAL parts, please suggest.

[TomasVaverka]

Hi Arijeet,

115.2kbps is not achievable with this crystal oscillator.

Please use a 1.8432MHz oscillator to achieve the 115.2kbps baud rate.

Best regards,

Tomas

[arijeet06]

Hi Thomas,

Thanks for the reply.

Got it. If we are going with 1.8432MHz crystal, Prescaler factor=1 we will have divisor=1 for the desired frequency=115200.

But please clear this doubt; If we are going with 3.072MHz crystal, Prescaler factor=1 we will have divisor=1.6 for the desired frequiency=115200 which is a divisor in the range between 1 and (2^16 - 1). Can,t we proceed with this config.?

Please correct me if I am wrong, also please suggest to us the stability factor, load capacitance for the Oscillator part.

Thanks in advance.

[arijeet06]

Hi NXP Team,

We have selected an XO, Spec:Osc, XO, 18.432MHz, +/- 20ppm, 3.3V, CMOS, 15pF, SMD.
Hope this works for us.

Second: We do have requirements for only UART RX & TX. So, can we use the GPIOs as normal GPIO for toggling purposes? What config. do we need to make it?