Finding a matching part to X1 footprint

RE: Finding a matching part to X1 footprint

Simonr — Wed, 17 Apr 2019 06:10:10 GMT

Yes, the application should work. There is also an internal RC oscillator at 32.768 kHz which you can use. Regarding current consumption, there is a significant difference between a HF and LF clock, but not that much between the internal RC clock and the optional 32.768 kHz crystal. However the external 32.768 kHz is more accurate than the internal one. The product specification of the nRF52832 should have more details on the clock sources.

Best regards,

Simon

RE: Finding a matching part to X1 footprint

sivi — Tue, 16 Apr 2019 13:28:06 GMT

So for testing can I just jump the pads of the 32.768 kHz and it will theoretically still work? How significant is the power saving when using the 32.768 kHz crystal?

RE: Finding a matching part to X1 footprint

Simonr — Tue, 16 Apr 2019 13:14:26 GMT

From the BT832 data sheet: "The following is a block diagram of BT832. Antenna circuit and main clock are integrated."

Yes, the 32MHz clock is integrated in the BT832 module.

Best regards,

Simon

RE: Finding a matching part to X1 footprint

sivi — Tue, 16 Apr 2019 11:31:31 GMT

Do you know/ Can you please check if the Fanstel's BT832 SoC already has a 32 MHz crystal integrated into it? I don't find they refer to it in the specs more than in a drawing. Need to verify that my circuit has the required crystal

Cheers

RE: Finding a matching part to X1 footprint

Simonr — Tue, 16 Apr 2019 07:36:18 GMT

Yes, you're wrong. The 32MHz crystal is required, and the 32.768kHz is optional. Please refer to our reference design schematics for confirmation, which can be downloaded here.

Best regards,

Simon

RE: Finding a matching part to X1 footprint

sivi — Mon, 15 Apr 2019 14:34:59 GMT

I think the 32 MHz is optional and the 32.768 kHz is imperative am I wrong?

RE: Finding a matching part to X1 footprint

Simonr — Mon, 15 Apr 2019 12:53:21 GMT

Due to the Easter holiday you will have to expect a delay in replies, sorry for the inconvenience!

It seems you are mixing up the crystals here. BT-XTAL 2016 is a 32MHz external crystal with 4 pads which is required in our designs. The 32.7680KA-AC is an external optional 32.768 kHz crystal, with only 2 pads. The BT-XTAL 2016 has 4 pads, where two of them should be connected to ground, which is why it only appears as having 2 pads in our schematics.

Best regards and happy Easter,

Simon