A BOM calls for a capacitor that is unavailable. A supplier offers another component with the same capacitance. Is that enough to approve a replacement? No. Capacitance is only one part of the specification.
Start With the Complete Approved Part Number
Use the approved manufacturer ordering code as the purchasing reference. List proposed alternatives separately. Do not replace the original BOM description with a generic value such as “10 µF capacitor.”
Ask Engineering Which Characteristics Matter
Checks can include dielectric type, rated voltage, tolerance, package dimensions, temperature behaviour and application-specific impedance requirements. The circuit determines the relevant checks. Analog Devices’ guidance for LDO applications discusses capacitance behaviour and ESR considerations. Review those requirements against the actual regulator and design.
Nominal Capacitance Is Not the Whole Operating Condition
A catalog value does not describe every behaviour under operating voltage and temperature. Ask engineering to compare the proposed component’s manufacturer data with circuit requirements. Procurement should collect information rather than assume a higher voltage rating or matching package guarantees suitability.
Record the Approval
Keep the original and proposed ordering codes, relevant datasheets and engineering decision together. Once approved, ensure the quotation and purchase order identify the accepted component precisely. Avoid descriptions so broad that another substitution could occur later.
A clear substitution process helps buyers find supply options while keeping technical decisions with the team responsible for the design. Include the original ordering code, quantity and approved alternatives with your enquiry.
Source: Analog Devices AN-1099: https://www.analog.com/media/en/technical-documentation/application-notes/AN-1099.pdf
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