深圳市子锦年科技有限公司

The following is a complete method for selecting surface mount resistors for comprehensive circuit design requirements, structured according to key steps:

1. Selection of core parameters

Resistance and accuracy

Resistance calculation:

Calculate the theoretical resistance value based on circuit functions (voltage division/feedback/filtering, etc.), and prioritize selecting E24 (± 5%) or E96 (± 1%) standard sequence values (such as 1.2k Ω, 4.7k Ω).

Precision matching:

High precision circuit (RC oscillation, ADC reference): Select ± 0.1%~± 1% accuracy;

Universal circuit (decoupling, LED current limiting): ± 5%~± 20% accuracy can be met.

Resistance identification:

Three digit codes (such as' 102 '=1k Ω) are suitable for ± 5% accuracy;

A four digit code (such as' 1002 '=10k Ω) is used for ± 1% accuracy.

Power and packaging

Power calculation: rated power>actual power consumption × 1.5~2 times (formula: P ≥ I ² R or P ≥ U ²/R).

Packaging selection:

Temperature coefficient (TCR)

High/low temperature environment: Choose a low temperature drift resistor (such as ± 25ppm/℃) to avoid resistance drift affecting circuit stability;

Normal environment: ± 100ppm/℃~± 200ppm/℃ can meet the demand.

2、 Environmental adaptability design

3、 Special scenario selection strategy

Automotive Electronics

·Compliant with AEC-Q200 certification, resistant to high temperatures above 125 ℃, and resistant to mechanical vibration.

precision measurement

Accuracy above ± 0.1%, TCR<± 5ppm/℃ (such as Murata film resistors).

power circuit

Power redundancy of more than 2 times, preferably packaged in 1206/2512, with a withstand voltage value greater than 2 times the actual voltage.

domestic substitution

Fenghua High tech (automotive grade) and Thick Sound (high cost-effectiveness for civilian use) cover mainstream specifications.

4、 Summary of Selection Process

A [Clarify circuit requirements] -->B {Key parameters}

B -->B1 (resistance/accuracy)

B -->B2 (power/packaging)

B -->B3 (temperature coefficient)

A -->C {Environmental Factors}

C -->C1 (temperature range)

C -->C2 (corrosion/vibration)

C -->C3 (frequency characteristics)

B&C -->D [Select brand and model]

D -->E [Verify Reliability]

E -->F [Mass Production Plan]

Key points: Consumer electronics prioritize size and cost (0402/0603+thick sound); The automotive/industrial scene focuses on reliability (vehicle certification+sulfur resistance). During actual selection, parameters such as voltage resistance and temperature rise curves in the data manual should be cross checked.

How to choose surface mount resistors based on circuit requirements?

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