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Doing some research about SD card adapters, I found these boards with a chip on them.

enter image description here

They are actually very common. They have a linear voltage regulator because UNO for example use 5V but SD card adapters use 3.3V. The voltage regulator has two capacitors one on the input one on the output. but what is C3? Looks like it is between the output and GND.

The other question is what is the other chip? I guess it turns sd card signals from 3.3 to 5v and viceversa. What is the name of this and what could be this chip model?

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  • It's probably a 74HCT08 or something similar.
    – Majenko
    Jun 24 '21 at 22:12
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    C3 is a capacitor
    – jsotola
    Jun 24 '21 at 22:15
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but what is C3? Looks like it is between the output and GND.

C3 is likely a 10 uF cap for the 3v3 output of the regulator.

schematic
(Source: datasheet for Sunrom SD module (PDF))

The circuit design used in the AMS1117 series requires the use of an output capacitor as part of the device frequency compensation. The addition of 22µF solid tantalum on the output will ensure stability for all operating conditions. When the adjustment terminal is bypassed with a capacitor to improve the ripple rejection, the requirement for an output capacitor increases. The value of 22µF tantalum covers all cases of bypassing the adjustment terminal. Without bypassing the adjustment terminal smaller capacitors can be used with equally good results.

(Source: datasheet for AMS1117 voltage regulator (PDF))


The other question is what is the other chip? I guess it turns sd card signals from 3.3 to 5v and viceversa. What is the name of this and what could be this chip model?

At least some of these modules use the LVC125A quad bus buffer gate.

enter image description here

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  • Thank you, your answer was very complete.
    – Espada86
    Jun 26 '21 at 17:59

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