How to Choose a Digital Potentiometer's End-to-End Resistance

1. Separate End-to-End and Wiper Resistance

Start with the exact digital-potentiometer family and the resistance requirement supplied by the circuit owner. Identify what resistance the requirement refers to before comparing a catalogue value. A description of a variable resistor can leave the end terminals, wiper and intended use unspecified. Retain the released circuit reference so the component reviewer can follow the actual function being requested.

Analog Devices' AD5160 explanation distinguishes end-to-end resistance, RAB, from the wiper contribution, RW. The rheostat discussion keeps that wiper contribution in the resistance relationship. These are device-specific definitions from the document, not a measured resistance for an offered unit. Keep the manufacturer's terms beside the required quantity instead of treating every resistance description in the inquiry as the same field.

Record separately the selected nominal option and the variable setting required by the application. Ask engineering which connection and setting context its requirement covers. An endpoint code cannot simply replace the resistance definition. If the original request contains only a family name or digital resolution, obtain the missing resistance meaning before asking purchasing to compare candidate ordering options.

2. Distinguish Divider and Rheostat Requirements

Describe the intended use as a divider or rheostat where that distinction is supported by the design. The AD5160 specification table presents those mode contexts separately. Retain the logical terminal roles associated with the customer's requirement, using its approved circuit record. A general product category does not describe which resistance or divider relationship the component reviewer must assess for that application.

Keep A, B and W as logical terminal descriptions when communicating the requirement. Physical terminal assignments need the exact package documentation and a separate verified circuit reference. This guide supplies no pin-number map or connection instruction. Its purpose is to make the required electrical quantity clear before the design owner decides whether an exact candidate provides the needed function.

Where a proposed part changes the documented mode or terminal-use requirement, preserve that difference explicitly. Do not translate the incumbent's requirement into the candidate's description without an engineering decision. A supplier can identify a family and resistance option while the circuit question remains unresolved. Keep that technical status visible so an incomplete comparison is not circulated as a confirmed replacement requirement.

3. Keep Nominal Tolerance Separate from Code

Preserve nominal-resistance tolerance separately from the digitally selected setting. AD5160 Table2 includes nominal resistor tolerance and its stated conditions alongside other mode-specific characteristics. A code describes a setting; it does not erase the manufacturer's nominal-resistance tolerance. Read the relevant field and context for the exact option instead of assuming that resolution defines the actual resistance accuracy in the circuit.

Keep the source of an application value visible. If engineering provides an existing estimate or measurement, retain its method, conditions and covered device or circuit revision. The manufacturer table and that application record answer different questions. Do not fill a missing measured result from the nominal ordering option, or label a proposed setting verified because its digital code can be described.

Use a comparison with separate entries for nominal option, required resistance meaning, mode, setting context and applicable tolerance evidence. This is a suggested record for the reviewer, with unresolved quantities left open. It provides no endpoint arithmetic, programmed-resistance calculation or current recommendation. Engineering determines the further evidence needed before accepting the device for the actual requirement.

4. Match the Complete Resistance Ordering Option

The AD5160 Ordering Guide associates complete model strings with distinct end-to-end resistance options and other ordering fields. Match the exact requested string to that table rather than treating AD5160 alone as the purchase item. Preserve all characters in the proposed code and keep its source reference available. A resistance option and a package description are parts of identity, not the entire circuit decision.

Keep unverified suffix meanings outside the comparison. Retaining an ordering string does not require inventing a carrier interpretation or reconstructing an unreadable code. Ask for the applicable manufacturer record when another ordering attribute matters. Where a proposed option differs from the released resistance requirement, identify the difference and its review status before offers are treated as covering the same component.

For an ICULTRA digital-pot sourcing inquiry, provide the approved full code and permitted circuit-requirement summary, keeping any proposed resistance option separate. Include the mode, wiper question and tolerance context that engineering needs to resolve. Update the confirmed procurement requirement only after its owner accepts a change. This preparation establishes neither current availability nor a measured setting, compatible substitute or accepted circuit performance.

Sources and further reading

• Analog Devices AD5160 datasheet

AD5160 documentation supports the resistance, mode, tolerance and ordering distinctions. The circuit-requirement record is a preparation suggestion; no carrier decoding, resistance calculation, electrical measurement or replacement approval is supplied.