Electronics > Repair

Identifying the value / type of a diode

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aroby:
How can I go about identifying the value of the diode with the CA marking in this photo? There are 4 of them on the board, testing with a meter shows 0.14v across 3 of them and the 4th has failed.  They are tiny - I think an 0802 size. 

Their use is in the circuit with the 1362 LED driver.  I'm not sure if this is a zener or a Schottky diode, the datasheet for the 1362 makes no mention of it, it just shows it on the circuit diagram!

Kim Christensen:
The symbol on the datasheet diagram is for a Schottky diode. Maybe it's a PMEG6010CEH or similar.

From page 20 of the datasheet:

--- Quote ---Diode Selection
For maximum efficiency and performance, the rectifier (D1) should be a fast low capacitance Schottky diode* with low reverse leakage at the
maximum operating voltage and temperature.
They also provide better efficiency than silicon diodes, due to a combination of lower forward voltage and reduced recovery time.
It is important to select parts with a peak current rating above the peak coil current and a continuous current rating higher than the maximum
output load current. It is very important to consider the reverse leakage of the diode when operating above +85°C. Excess leakage will increase
the power dissipation in the device and if close to the load may create a thermal runaway condition.
The higher forward voltage and overshoot due to reverse recovery time in silicon diodes will increase the peak voltage on the LX output. If a
silicon diode is used, care should be taken to ensure that the total voltage appearing on the LX pin including supply ripple, does not exceed the
specified maximum value.
*A suitable Schottky diode would be PDS3100.
--- End quote ---

fzabkar:
From the same page in the datasheet ...


--- Quote ---*A suitable Schottky diode would be PDS3100.
--- End quote ---

https://www.diodes.com/assets/Datasheets/ds30487.pdf

aroby:
Thanks all, I completely missed the paragraph in the datasheet!  The suggested diode isn't the one (wrong form factor), but I did find a candidate - Nexperia PMEG2020EJ - that seems to have suitable parameters, is available in the SOD323F form factor and has the CA marking.  Hopefully this gets me back in action!

Thanks again.

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