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    Diode selection criteria in circuit design


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    Answer

    According to the selection of circuit function: High-frequency detection circuit should select germanium detection diode, which is characterized by high workpiece frequency, small forward voltage drop and small junction capacitance, 2AP11 ~ 17 is used below 40M, 2AP9 ~ 10 is used for 100M Below, 2AP1 ~ 8 are used below 150M, 2AP30 is used below 400M.

    According to the volume of the whole machine, the whole machine is developing in the direction of miniaturization, thinner and lighter, which requires the miniaturization and chip formation of supporting diodes. The glass bulb length of the DO-35 switching diode and band switching diode is 3.8mm, the glass bulb length of the DO-34 switching diode is 2.2mm, and the length of the SOD-23 plastic varactor diode is 4mm.

    Reasonable selection of diodes according to the cost performance of the whole machine: According to the cost performance of the whole machine and the role of supporting diodes in the whole machine, reasonable selection is made.
    The guidelines for the use of diodes in circuit installation
    1. Use below the maximum rating
    2. Derating
    3. It is used below the maximum junction temperature.
    4. Cut, form and install the diode correctly
    5. Precautions for use Due to the miniaturization of the diode.

    Ultra-miniature and chip development, special attention should be paid to the following items during use:
    1. For point-contact type and glass bulb diodes, to prevent falling on hard ground,
    2. For glass bulb diodes, to prevent the electric iron from directly contacting the glass bulb when soldering,
    3. The forward voltage cannot be added to the voltage stabilizing diode .
    Schottky diodes are easily damaged by static electricity, and people and equipment should be grounded.
    4. For chip diodes, pay attention to the expansion coefficient of the diode itself and the printed board.
    5. For diodes with matching requirements, prevent mixing in use. So as not to affect debugging.


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