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20

Simple answer is you don't split planes unless you know what you are doing and why you are doing it. Separate the ground planes and route signals over the the gap in a split ground planes at your own peril. The lowest inductance path for return currents is on the ground plane directly under the signal trace. This forms the smallest possible 3D loop. But the ...


6

Following up on the excellent answer of DKNguyen, you can best localize the Ground currents of that 1.8volt super-delicate sensor ---- by using a LOCAL BATTERY. A local battery is a resistor PLUS large capacitor, acting as a LOW PASS FILTER for trash from the outside, and providing almost all surge currents needed by your sensor from that LARGE CAPACITOR. ...


4

I agree - Don't cut planes What I'd do is connect the 1.8 regulator ground to your IC pin 12 with a nice fat trace. Then connect pin 4 and pin 12 to the ground plane with vias right at the pins. So the two grounds meet at only one place (pin 12's via). The idea is prevent currents from either voltage domain from mixing with the other. If you have only 1 ...


4

Actually reading that datasheet seems to indicate that you are overestimating the sensitivity of the MAX30102 to noise by a lot. There are Arduino compatible eval boards plugged into breadboards that work fine; it's actually remarkably insensitive to noise. LED currents max out at 200mA and flow between pins 10 and 4--a standard 1.0oz plane won't even ...


3

My colleague told me that there will be potential difference between PGND in bottom layer and AGND of analog section and it is not good for the design but my understanding is that if I have intact ground plane then it will not be any potential difference. There will be a potential difference, if the ground plane was made from a superconductor, then there ...


2

Yes, that's correct. But keep in mind that at this frequency, any conductor of nonzero dimension is far from a "direct short". In this case, it is partly the current flowing through the left-hand terminal that couples energy to the rest of the antenna chip. And because of the length and resulting impedance of that upper copper stub, there is also a ...


1

According to the datasheet the PCF8523 has integrated oscillator load capacitors, so all you need to do is add the crystal close to the OSC pins and select the capacitance you need (7 pF or 12.5 pF). It is defined by the 4th bit of the CONTROL_1 register (00h). Datasheet Edit: In general your crystal layout looks fine. The main thing to keep in mind is that ...


1

You will generally be using around 50 Ω tracks on the board. It will be difficult to have enough metal around a castellated edge connection to get the impedance down to that, so the connection will look a bit inductive. It will be very short however, so it will be easy to tune up with a sniff of capacitance on either side, to make a low pass filter. This ...


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