YAGEO RC0402FR-0784K5L 84.5 kΩ Resistor: Specifications, Derating, and Replacement Selection

RC0402FR-0784K5L is an 84.5 kΩ thick-film chip resistor in YAGEO’s RC_L general-purpose series. It uses the 0402 imperial (1005 metric) package and has a ±1% resistance tolerance. Although it is a small and common resistor, a valid design check requires more than resistance and package size: power, working voltage, temperature derating, TCR, mechanical dimensions, and replacement criteria all matter.

1. Core Specifications

2. Decoding the Part Number

The complete ordering code is shown in the source as RC | 0402 | F | R | – | 07 | 84K5 | L. The fields identify the RC_L general-purpose thick-film series, 0402 package, ±1% tolerance, paper-tape reel format, 7-inch standard-power configuration, 84.5 kΩ resistance, and YAGEO’s default suffix. The full code should be preserved in BOMs, purchase orders, and controlled inventory records.

3. What Does ±1% Mean for an 84.5 kΩ Resistor?

An initial tolerance of ±1% gives a resistance range of 83.655 kΩ to 85.345 kΩ. This range describes initial resistance only and does not include later changes caused by temperature, electrical loading, or aging.

4. Power and Voltage Must Be Checked Together

The resistor is rated for 62.5 mW up to an ambient temperature of 70°C. Above 70°C, the permitted power decreases according to the linear derating relationship given in the source and reaches zero at 155°C.

Linear power-derating expression from 70°C to 155°C

The usable voltage is the lower of the voltage implied by the power rating and the specified maximum working voltage.

Allowed-voltage selection rule

For 84.5 kΩ at 0.0625 W, the power-derived voltage is about 72.7 V. However, the specified maximum working voltage is 50 V, so the design limit remains 50 V.

Power-derived voltage is approximately 72.7 V

The lower limit is 50 V

At 50 V across 84.5 kΩ, nominal dissipation is about 29.6 mW, which is below the 62.5 mW rating at temperatures up to 70°C. At higher ambient temperature, the derated power limit must still be checked.

Nominal power dissipation at 50 V is about 29.6 mW

The source also lists a 100 V short-time overload test rating. This value belongs to a specified test condition and must not be interpreted as a permitted continuous operating voltage.

5. Construction and Dimensions

The part uses a thick-film resistive element on a ceramic substrate with a protective overcoat and solderable terminal electrodes. Its main body dimensions are 1.00 ± 0.05 mm × 0.50 ± 0.05 mm × 0.35 ± 0.05 mm. The source notes that component-body dimensions are not the same as PCB land-pattern dimensions.

RC0402 construction and key mechanical dimensions

Circuit symbol and representative 3D model

6. Typical Uses and Design Checks

· Voltage dividers: include tolerance, temperature drift, and loading from the next stage in the error budget.

· Pull-up and pull-down networks: 84.5 kΩ is relatively weak, so leakage current and signal rise time should be checked.

· Bias networks: verify device leakage and temperature-dependent behavior.

· Feedback networks: consider resistor-ratio accuracy and loading.

· Signal conditioning and RC networks: check noise and the input impedance of the connected circuit.

· Low-current limiting: verify normal, startup, fault, and pulse conditions.

Dissipation can be calculated with P = I²R or P = V²/R. The source also cautions that a short pulse can exceed the resistor’s capability even when average power is low, so transient stress must be evaluated separately.

7. Packaging and Identification

The R-07 configuration uses paper tape on a 7-inch reel. The source lists 10,000 pieces as the standard reel quantity for RC0402. There is no resistance marking on the 0402 body, so exact identification depends on the reel label, purchasing records, and controlled inventory. Resistance measurement can verify the approximate value but cannot confirm manufacturer, power rating, TCR, or compliance status.

8. Replacement Comparison

According to the supplied comparison, the Vishay part is the closest documented mechanical and electrical match, the Panasonic part offers a higher power rating, and the Bourns part has a slightly lower nominal height. None should be treated as an automatic drop-in replacement. Before substitution, compare the PCB land pattern, derating curve, overload and pulse capability, soldering conditions, and qualification requirements.

Conclusion

RC0402FR-0784K5L is straightforward only at first glance. A complete design check must combine resistance, tolerance, TCR, power, working voltage, and temperature. The 84.5 kΩ value, ±1% tolerance, and 0402 package are only the starting point; at elevated temperature, higher voltage, or during alternate-source qualification, derating and voltage limits often become the decisive constraints.