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Understanding PCF8523 Breakout Board Schematic
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Understanding PCF8523 Breakout Board Schematic

by jake11212 on Fri Jun 18, 2021 10:51 am

Hello, I'm trying to add the PCF8523 RTC to a custom PCB. I found the breakout board schematic (attached) and wanted to make sure I was understanding properly before I added it to the PCB. I understand the layout for the part labeled PCF8523, but I wasn't sure how the outputs were set up. The top section labeled JP2 has the output pins, but how are they connected to the PCF8523? For example, can I directly add a line branching from PCF8523 line 5 to create the same output as line 3 in the JP2 section? And just repeat this for the other lines? I just wasn't sure since there aren't clear connections between the two parts.

Also the section that just connects GND to VCC through a 10uF C2 capacitor, does this just mean to connect VCC to ground through a C2 capacitor somewhere in the circuit? I assume this is to stabilize the voltage signal, but wasn't sure where I would implement it.

Thanks!
Attachments
pcf8523 schematic.JPG
pcf8523 schematic.JPG (38.93 KiB) Viewed 1105 times

jake11212
 
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Re: Understanding PCF8523 Breakout Board Schematic

by sj_remington on Fri Jun 18, 2021 9:52 pm

The labels on the "wires" imply connections. So on JP2, the pin 3 wire is labeled SDA, indicating that it is connected to the PCF8523 pin 5 wire, also labeled SDA.

connect VCC to ground through a C2 capacitor
Yes. The cap should be reasonably close to the chip.

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Re: Understanding PCF8523 Breakout Board Schematic

by sj_remington on Fri Jun 18, 2021 11:00 pm

Note: C2, R3 and C1 are actually a circuit design unit, a low pass filter that performs a function called "power supply decoupling", dramatically reducing power supply noise to the chip.

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Please be positive and constructive with your questions and comments.