Components

What is the the IMPD bit for the MAX11200EEE+ / MAX112100EEE+?

On the MAX11200EEE+ and the MAX112100EEE+, bit 3 of the command byte is named IMPD but this bit is never described in detail in the datasheet.

The meaning of this bit is Immediate power-down. When you set it to 1, the IC will switch to power-down mode. This is evidenced by the power-down example in Table 8 in the datasheet.

Posted by Uli Köhler in Components, Electronics

What is the correct SPI mode for MAX11200EEE+ / MAX112100EEE+?

The MAX11200EEE+ and the MAX112100EEE+ operate using SPI Mode 0Therefore, CPHA=0 & CPOL=0.

For more information, see the datasheet.

Posted by Uli Köhler in Components, Electronics

Where to find cheap SMD ferrite beads?

Generally, SMD ferrites of a given size are characterized by:

  • The RF impedance (typically specified @100 MHz)
    • Low impedance (e.g. 100 Ω @ 100 MHz) do not filter EMI that well, but also distort your data signals less. Use them for high speed signals above 1 MHz
    • High impedance ferrites, e.g. 1kΩ @ 100 MHz, filter EMI really well but will distort any high speed signal. Use them for low speed signals below 1 MHz
  • The current rating
    • For data signals, you don’t need any form of high current rating. Generally, I would recommend to require at least 0.1A of current rating to be able to handle soft short circuits
    • For power lines, use whatever power rating is suitable (the specified current + 20% is typically fine)
  • The DC resistance. This mostly only matters for power lines.
    • Keep in mind to keep the ferrite cool by choosing the DC resistance so that the

As with most passive parts, LCSC generally has the lowest pricing if you buy a bunch of parts.

Keep in mind the expensive shipping, but since they are often 50 times cheaper (!) than other distributors, it might be worth it even if just ordering a reel of ferrites.

Signal ferrites

This section contains cheap SMD ferrite beads for < 1A current rating.

Low impedance (<= 500Ω):

High impedance (>= 500Ω):

Power ferrites

This section contains cheap SMD ferrite beads for > 1A current rating.

Low impedance (<= 500Ω):

High impedance (>= 500Ω):

Posted by Uli Köhler in Components, Electronics

Where to find cheap general purpose SMD optocouplers?

I generally use the LTV-356T optocoupler (phototransistor output) for general purpose applications. It has a smaller footprint than most DIP-derived SMD optocouplers and a thinner package. Its pin pitch is 2.54mm whereas the center-distance between the pads is 6.5mm. It it rated

It is available:

Even cheaper?

The LTV-356T has the advantage of being available from different sources in large quantities. However, you can get a pin-compatible variant LTV-356T-C which is only rated for 35V on the output:

Even smaller?

At LCSC, you can also get the half-width OR-3H7B-TP-Gwith a pin pitch of only 1.27mm for 0,0424€/[email protected]

 

Posted by Uli Köhler in Components, Electronics

Where to find cheap general purpose resistors?

Typically, 1% thick film resistors are used as general purpose SMD resistors. Most of these are spec’d with a 100ppm/°C temperature coefficient.

From all the “normal” distributors, in my experience LCSC has by far the cheapest resistors – around 3€ per reel (5000pcs) of 0603 resistors. Note, however, that they charge around 35€ of shipping to Germany. So you have to buy a lot of resistors in order to compensate for the expensive shipping. However, you can also order other components on LCSC (they’re usually quite cheap, especially for passives and other standard components).

0603 resistors

 

Posted by Uli Köhler in Components, Electronics

Where to find cheap X5R/X7R capacitors?

LCSC is typically the cheapest vendor for buying reels. Note, however, that the shipping fee is rather expensive (around 35€ to Germany), so it will only be worth the saving if you order larger quantities of components.

Posted by Uli Köhler in Components, Electronics

Where to find cheap tactile switches / push buttons?

LCSC has a really cheap all-metal push button for only 0.0129€/pc @50pc

HCTL TC-0522C-1.6-160G

Direct datasheet link

It works with the KiCAD 6.0

Button_Switch_SMD:SW_SPST_TL3342

footprint and the KiCAD 6.0

Switch:SW_Push

symbol.

Posted by Uli Köhler in Components, Electronics, KiCAD