At a glance: resistance range and network configuration, tolerance class, per‑element power, package type, and why verifying the NOMC16031003FT5 matters for system reliability. Point: engineers need these baseline numbers to budget accuracy and thermal headroom. Evidence: the datasheet lists nominal values and ratings. Explanation: this note presents spec breakdown, measured test data, and repeatable verification procedures.
Goal: provide a concise, repeatable validation plan so an engineer can confirm fit‑for‑purpose before PCB sign‑off. Point: the focus is on reproducible measurements and practical pass/fail thresholds. Evidence: common failure modes impact system gain and offset. Explanation: follow the test plans and PCB guidance below to reduce field risk and design iterations.
Point: decode the part code to confirm the correct resistor network variant for the design. Evidence: part codes encode element count, configuration, tolerance and package. Explanation: verify package pitch and pinout against PCB footprint; confirm the network type and tolerance before placing orders to avoid mistaking similar codes from different families.
Simple labeled pinout (text diagram): _________ | 1 . . 8 | | . NOMC | | 8 . . 1 | --------- Key: pins 1–8 correspond to element termini; check datasheet pin map and recommended land pattern.
Point: capture critical specs in a single table for bench planning. Evidence: nominal resistance, tolerance, TCR, power and voltage limits determine measurement methods. Explanation: annotate units (Ω, %, ppm/°C, W, V, °C) and acceptable test tolerances when recording results.
| Spec | Value | Unit / Note |
|---|---|---|
| Resistance per element | 3.01k (example) | Ω — verify against datasheet |
| Network config | 3 resistors, common node | — confirm pinmap |
| Tolerance | ±0.1 | % |
| TCR | ±25 | ppm/°C |
| Power per element | 0.063 | W |
| Max working voltage | 50 | V |
| Operating range | -55 to +125 | °C |
Point: tolerance and TCR set initial and temperature‑dependent error budgets. Evidence: worst‑case tolerance stack = tolerance + (ΔT × TCR/10⁶ × 100%). Explanation: for a ±0.1% part with 25 ppm/°C TCR and a 80°C swing, temperature contribution = 0.20% so total worst‑case = 0.30%; use this in system accuracy budgeting.
Point: element power rating must be derated by board thermal environment. Evidence: package thermal resistance and copper area change allowable dissipation. Explanation: apply derating; if 0.063 W rating at 25°C rises with ambient, reduce continuous power by specified percentage per datasheet guidance and monitor temperature rise in thermal simulations.
| Ambient | Derating factor |
|---|---|
| 25°C | 100% |
| 60°C | 70–80% |
| 85°C | ≤60% |
Point: a repeatable setup reduces measurement variability. Evidence: use four‑wire Kelvin measurement, stable source, and temperature chamber. Explanation: recommended sample N≥30, soak 15 min at temperature, sequence: DC resistance (room), TCR sweep, power soak, isolation test; log CSV fields: ID, temp, measurement, timestamp, operator.
Point: present statistics, not just individual values. Evidence: include mean, σ, min/max and histogram. Explanation: define pass if |measured − nominal| ≤ tolerance and TCR trend within spec; report percentage out of spec and recommended lot rejection criteria (e.g., >2% units out of spec triggers investigation).
Point: follow explicit steps to validate electrical performance. Evidence: DC resistance use 4‑wire, TCR sweep in chamber, power test with controlled current ramp. Explanation: example DC test: 1 mA current source, 4‑wire, 10 readings averaged; TCR: measure at −40/25/85°C and compute ppm/°C; power soak: apply rated power for 1 hour and re‑measure resistance shift threshold ≤0.1%.
Point: accelerated stress tests reveal marginal parts. Evidence: thermal cycle 500 cycles −40/+125°C, HAST with bias for humidity susceptibility, and surge per expected field transients. Explanation: monitor for open circuits, >1% resistance drift, or insulation breakdown; report per unit: pre/post resistance, percent shift, and condition that triggered failure.
Point: PCB layout materially affects derating and accuracy. Evidence: copper pours alter thermal resistance and can double allowed dissipation in some cases. Explanation: checklist: verify footprint pad sizes, add thermal vias under high‑dissipation nets, avoid routing narrow traces under network, and allocate derating margin when multiple elements dissipate simultaneously.
Point: identify quick root causes and remediation. Evidence: common signs—open = infinite resistance, drift = temp/time correlated change, imbalance = mismatch between elements. Explanation: troubleshooting: re‑measure with Kelvin, apply gentle power to observe heating, inspect solder joints, replace suspect units; reject lot if >2% units show drift beyond spec.
Measure DC resistance (4‑wire) at room temp, TCR across defined temperature points, power‑soak resistance shift, and inter‑element insulation/leakage. Capture sample mean, standard deviation and percent out‑of‑spec. Include measurement conditions and fixture details in the CSV for traceability.
Use a temperature chamber with a stable soak (≥15 min) at each setpoint and a four‑wire measurement. Compute ppm/°C from slope between two temperatures: TCR = (ΔR/R)/ΔT × 10⁶. Repeat on multiple samples and report mean and σ to assess lot variation.
Suggest rejecting a lot if >2% of sampled units exceed datasheet tolerance after conditioning, or if mean shift after power‑soak or thermal cycling exceeds the designed system margin. Document failure modes and perform root‑cause before rework or alternate sourcing.