Reconcile one selected LED series-resistor candidate against entered supply, forward-voltage, resistance-tolerance, current-ceiling and derated-power records.
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A quick decision brief for this specific tool
Inputs that matter
One de-identified completed engineering-reviewed, manufacturer-application or controlled-characterization record; responsible record/revision/date/reviewer; exact supply/source/connection and accepted steady-state minimum/maximum basis; exact LED product/order code/lot, forward-voltage envelope source and current/temperature/duty applicability; one dedicated-resistor/one-series-string topology; an already selected exact resistor product, nominal resistance, tolerance source and allowable derated power record; driver/source capability, environment/duty, protection/safety and retention records; whole series LED count; entered supply and per-LED Vf extrema; externally controlled current ceiling; completed same-basis maximum-current and worst-case-power report; user-owned current/power agreement tolerances; and an optional same-basis independent source plus both values
Output to expect
Entered total LED-Vf and resistor-headroom intervals, candidate minimum/maximum resistance, reproduced low/high current interval, high-case resistor power, current and power margins against entered external limits, a minimum nominal-resistance arithmetic lower bound accounting for tolerance, completed-report differences and optional independent same-basis differences
How it works
Validate every provenance field, ordered numeric interval, whole series count and optional triple; freeze one steady-DC source, exact LED product/accepted Vf envelope, one dedicated series string and one already selected resistor product; apply resistance tolerance; use maximum source minus minimum total Vf over minimum resistance for reproduced maximum current and power; clamp only the nonpositive low-headroom current case to zero; compare entered current and derated-power limits descriptively; reconcile completed and optional independent values inside user-owned tolerances; normalize only mathematical zero
Confirm exact part/order codes, lot when material, source/load/connection, Vf source and operating-envelope applicability, topology, resistor tolerance and allowable-power derating all match. Another source interval, component, lot, string count, temperature, mounting, airflow, duty, transient or protection state needs another responsible review.
Use the result only for bounded steady-DC arithmetic reconciliation. It does not model LED I–V or temperature behavior, startup, PWM, pulse, reverse, fault, shared-parallel or regulator behavior; choose an E-series value or product; prove availability, brightness, lifetime, thermal rise, reliability, source/driver capability, wiring, protection, compliance or safety; diagnose failure; or authorize purchase, assembly, energizing, probing, installation, production or use.
Choose your path
Built around the job you need to finish
Reconcile one already selected resistor candidate for one documented steady-DC LED series string against accepted source, forward-voltage, resistance-tolerance, current-ceiling and derated-power records without choosing an E-series value or approving a circuit.
Electronics engineer checking a selected indicator-string candidate
Expose high-supply, low-forward-voltage and minimum-resistance current and power instead of relying on nominal values.
Freeze the exact source, LED, dedicated series topology and resistor-product records; enter accepted extrema, tolerance and derated power; reconcile the completed calculation.
Gets reproducible worst-case arithmetic and signed current/power margins while product selection, I–V behavior, thermal design and approval stay with the responsible record.
Repair technician reconciling a controlled service calculation
Compare an existing same-basis report without accepting a colour hint, nearest E24 value or generic wattage as component evidence.
Retain part/order codes, source and measurement basis, operating envelope, protection and de-energized-work record; reproduce and deliberately save only the reviewed result.
Can identify a calculation mismatch or exact-basis agreement without energizing, probing, selecting a replacement or declaring the repair safe.
Demonstrate resistance tolerance and supply/Vf extrema without turning a simplified model into a universal design recipe.
Use the reviewed example, inspect current and power equations, trigger ordered-bound, whole-count, report and optional-independent errors, then review the Decision Boundary.
Learners reproduce the arithmetic and can explain why I–V curves, temperature, PWM, parallel sharing, driver limits, thermal rise and construction need separate evidence.
Authoritative checks for this tool
Outputs and checklists are planning aids. Review the linked current authorities and the records, terms, instructions, and requirements that apply to your exact situation before a consequential decision.
Use one source interval, one exact LED product and accepted forward-voltage envelope, one dedicated series string and one already selected resistor product. Colour or nominal supply labels are not substitutes for these records.
Apply candidate resistance tolerance
The reproduced maximum current uses the entered minimum resistance, maximum source voltage and minimum accepted total LED forward voltage.
The high-headroom, minimum-resistance case supplies the arithmetic worst case for this limited steady-DC model. The entered allowable power must already reflect the exact product's ambient, mounting and duty derating.
P_max = (V_s,max − N × V_f,min)² / R_min
Reconcile without selecting a component
Compare a completed same-basis report and optional independent calculation. IEC preferred values do not prove availability, ratings, thermal suitability or circuit approval, so this Tool never chooses an E-series value or recommends a product.
Updated: August 2026
Example Scenarios
Retain exact source, LED, resistor, tolerance, ambient and driver records; reproduce current and power before the responsible design review.
Compare a controlled calculation report with the same supply extrema, LED envelope, topology and candidate-product basis without energizing or probing the circuit.
Show how resistor tolerance changes reproduced current and power while keeping I–V curves, thermal behavior, parallel sharing and component approval explicit.
Common Mistakes to Avoid
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Treating a typical forward voltage as a guaranteed minimum
✓
Retain an accepted low/high envelope from the exact product data or characterization and record its current and temperature applicability.
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Using nominal resistance in the maximum-current case
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Apply the entered tolerance and use the candidate's minimum resistance for the reproduced high-current and high-power case.
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Calling a preferred number a selected product
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Verify exact resistance, tolerance, package, voltage, power, thermal, pulse, lifecycle and availability records outside the Tool.
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Treating arithmetic margins as an approval
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Keep source capability, LED behavior, current sharing, transients, thermal rise, protection, construction, compliance and responsible authorization separate.
FAQ
No. Enter a current ceiling already controlled by the exact LED, source, driver, temperature, duty and responsible design record. An absolute maximum is not automatically a normal operating target.
Not as device evidence. Forward voltage depends on the exact product and operating conditions. Retain part-specific datasheet curves, characterized bounds and their applicability.
The high-supply, low-forward-voltage case increases resistor headroom and reproduced current; the low-supply, high-forward-voltage case may not establish conduction. Both bounds must come from the responsible record.
No. The bounded arithmetic does not validate the LED I–V curve, brightness, lifetime, driver capability, wiring, polarity, protection, thermal rise, transients, compliance or construction.
Not necessarily. Use the exact manufacturer's derating information for the actual ambient, mounting, airflow, enclosure and duty, plus the responsible thermal review.
IEC 60063 defines preferred-number series, not stock, product ratings or suitability. Enter an already selected exact resistor candidate and keep procurement and approval in the controlled design process.
About LED Resistor Check
Check one already selected resistor candidate on one documented steady-DC LED series string. Retain exact component and operating records, reproduce bounded current and power, and keep product selection and circuit approval outside the arithmetic.
