Creating a robust design with replacement parts in mind.
Before we discuss how to select alternative components, I would like to point out that designing your product with alternative components/jellybean components in mind is always easier than trying to find a replacement after the product has been designed.
The term jellybean part is used for low cost and readily available components. These primarily include:
- Voltage Regulators,
- Logic ICs,
- Transistors,
- Amplifiers.
Often times they can be recognized by a shared product number scheme. In other cases manufacturers use different naming schemes but the pinouts still match.
Ask yourself during the component selection which key parameters are needed for your design and try to find components that are readily available and share a common footprint.
It is recommended to sign up for product change notifications (PCN), so you’ll know when a component becomes unavailable or if parameters are changed.
When your design requires a component which is only available from one source, it is highly recommended to contact the supplier to reserve stock for your production run. With us you can also purchase the components in advance or have them sent directly to us for assembly in case you secured them beforehand. If you want to purchase and store components for your project, please contact our project managers for inquiry.
Finding replacements for unavailable components.
The first step is to determine if your component is available from other sources, for this, you can check other distributors. Websites like octopart or findchips make this easy.
It is important to point out that components should be purchased exclusively from trusted sources! You can find a list of our preferred distributors here.
If you are unable to find stock at other distributors, check the manufacturer’s website, sometimes the MPN (Manufacturer Product Number) gets changed if a revision is issued or the component is EOL (End Of ´Life).
They may recommend an updated device with improved performance and pricing.
If no useful information can be found on the manufacturers’ website, we can try to find a similar component from another manufacturer.
There are two approaches to this:
- Using the Component Series number
- Using the Key Component Parameters.
Let’s start with the approach of using an equivalent component using the component series number. A part number is often comprised of a manufacturer prefix, series number and information about certain characteristics and package as postfix. Many manufacturers use the same series number as their competitors for compatible parts. If we strip our specific part number from the manufacturer prefix and the postfix, we get the series number, we can use it to search for equivalent parts from other manufacturers.
If this method yields no results, we have to search for a replacement component using a parametric search. Select only the key parameters needed for your application, don’t be too specific, otherwise the search may not give back any results.
Key parameters applying to all components are the footprint, pinout, operating voltage/current, and operating temperature. These must always match with the original part. The more specific parameters depend on your component:
| Component Type | Key Parameters | |||
|---|---|---|---|---|
| Linear Voltage Regulator | Output Voltage, Overcurrent Limit, Quiescent Current, | |||
| MOSFETs | Gate to Source Voltage, On Resistance, Gate Threshold Voltage, Gate Capacitance | |||
| Electrolytic Capacitor | Capacitance, Lifetime at rated Temperature, ESR, Leakage Current | |||
| MLCC Capacitor | Capacitance, DC Bias, Lifetime at rated Temperature, ESR, ESL, DC Bias | |||
| Diode | Forward Voltage, Reverse Voltage | |||
| Schottky Diode | Forward Voltage, Reverse Voltage, Reverse Leakage Current | |||
| LEDs | Forward Voltage, Reverse Voltage, Colour, Brightness | |||
| Inductors | Inductance, Saturation Current, DC Resistance, Temperature Increase |
After a component has been selected through the parametric search, study the datasheet in detail and check if the pinout matches with your original part.