Why “Test & Calibration Hooks” Matter
Add power test pads, Kelvin sense hooks, and calibration nodes so PMIC/Power IC boards can achieve safe bring-up, accurate telemetry, and repeatable validation—especially in small-batch engineering builds. Hooks reduce re-spins, protect prototypes from uncontrolled faults, and shorten lab time.
Bring-Up Safety & Efficiency
Controlled isolation jumpers and bypass paths prevent damage during first power-on. Standardized test pads (Vin/Vout, amplifier in/out) give scopes and meters reliable access.
Measurement Consistency
Kelvin sense around the shunt resistor plus pre/post-amp pads minimize lead and contact errors. Calibrate ADC offset/gain/temperature with known references and store the constants.
Repeatable Validation
Define a minimal test matrix (load step amplitude/edge, frequency points, temperature points) tied to fixed hook interfaces. Use a lightweight log template (unit ID, jig ID, FW version, calibration set).
ROI quick rules: Re-spin cost ÷ Hook cost is usually > 20×; saving 2–4 lab hours per iteration across 5 rounds yields > $400–$850; controlled isolation & injection significantly reduce prototype damage risk.
Board-Level Hook Topology
Hooks are mapped along the power path—Vin → protection/switch → regulator (PMIC/LDO/Buck) → load—with four layers: measurement, injection, isolation, and calibration. Place pads near their true nodes and keep return paths short.
Measurement
TP_VIN/TP_VOUT near decoupling; Kelvin pads at shunt ends; amplifier IN/OUT pads; local temp pad for hotspot mapping.
Injection
Electronic/load-step port (optional series 50 Ω), ripple/EMI injection nodes at input/output, fault injection on UVLO/OVP/PG.
Isolation
0Ω/headers/DIP to open/bridge paths; ideal-diode OR / FET bypass switches; temporary measurement bypass path.
Calibration
Reference ports for known V/I; ADC offset/gain/temperature workflow; constants written via I²C/PMBus/NVM with read-back pads.
Hook Types for PMIC / Power IC Boards
Four families of power test & calibration hooks improve bring-up and validation repeatability: measurement, injection, isolation, and calibration. Use clear pad names and keep returns short.
Measurement
- Vin/Vout Test Pads:
TP_VIN,TP_VOUT(place near decoupling; addTP_GND_NEAR). - Kelvin @ Shunt:
TP_ISNS_P/TP_ISNS_Nwith matched, tight routing. - Amp IN/OUT Pads:
TP_AMP_IN,TP_AMP_OUTfor current/DIFF amplifiers. - Hotspot Temp Pad:
TP_TEMP1for thermocouple/NTC placement.
Injection
- Load/Step Port:
INJ_LOAD(optional series 50 Ω protection). - Ripple/Noise Nodes:
INJ_IN(input) /INJ_OUT(output). - Fault Injection:
INJ_UVLO,INJ_OVP,INJ_PG,INJ_FAULT.
Isolation
- 0 Ω / Jumpers / Headers:
JP_ISO1,JP_ISO2for controlled opens/bridges. - FET Bypass / Ideal-Diode OR:
SW_BYPASS,OR_IDEAL. - Measurement Bypass:
BYP_ISNSto bypass measurement path during calibration.
Calibration
- Reference Ports:
CAL_VREF,CAL_IREFfor voltage/current standards. - Zero/Short:
CAL_SHORTfor ADC offset calibration. - Write/Read:
CAL_SDA/CAL_SCL(I²C/PMBus/NVM), plus read-back pad. - Limits/Thresholds:
TRIM_ILIM,TRIM_UVLOor resistor options.
Design Rules — PI/EMI First, Testability Balanced
Layout hooks so they do not degrade power integrity or EMI. Keep Kelvin routes tight, loop areas minimal, ground references unambiguous, and probe returns short.
Kelvin Routing
Kelvin lines carry measurement only—never power. Pair and match lengths; avoid SW nodes. Target differential loop area ≤ 10 mm².
Loop Areas
Minimize input/output power loops and keep them adjacent. For probe loops, recommend TP_GND_NEAR to keep returns co-located.
Ground Reference
Same-side ground for pads/ports; star or single-point joins for analog vs power. Mark the recommended ground explicitly on silk and docs.
Probe Path Impedance
Assume 10× scope probes with bandwidth margin ≥ 10× target frequency. Add series ~50 Ω on injection ports; RC isolate sensitive nodes.
Fixtures & Cables
Separate power and sense harnesses; use short same-side returns; coax/shield for noisy lines (shield grounded at one side).
TP_GND_NEAR.
Validation & Debug — Bring-Up, Load Steps, Logs, Root Cause
Standardize power bring-up and validation on PMIC / Power IC boards using fixed test pads, Kelvin hooks, and calibration nodes. Follow the script, keep a minimal log, and use a structured root-cause tree for deviations.
1) Pre-Power
- Polarity/short check; verify
JP_ISOdefault population andTP_VIN/TP_VOUTcontinuity. - Bypass sensitive paths if needed (
SW_BYPASS); record baseline refs &TP_TEMP.
2) Soft-Power
- Current-limited ramp; monitor
UVLO/PG/FAULT; logV_IN,I_IN, bias currents. - Freeze state on anomaly (leave jumpers as-is), photograph & note.
3) Nominal-Power
- Close jumpers gradually; record each rail voltage/ripple & temperature rise.
- Check I²C/PMBus read-back; verify register bits.
4) Stress-Power
- Low/high line, cold/hot, load steps; capture
V_droop,t_settle, ringing. - Record ILIM/UVLO thresholds and compensation settings.
INJ_LOAD (series ≈ 50 Ω, same-side return via TP_GND_NEAR). Measure V_droop and t_settle(±x%) under low/high line.Ripple/Noise Injection: use
INJ_IN / INJ_OUT; sweep critical bands; compare AC/DC coupling and bandwidth-limited captures.
Minimal Validation Log — Fields
- Header: project/board, unit ID, jig ID, FW version, date/time, operator
- Environment: VIN, temperature, equipment models (PSU/load/scope)
- Hooks: pad IDs (
TP_VOUT,TP_ISNS_P/N), ports (INJ_LOAD,INJ_IN), ground ref - Set: ΔI, tr/tf, frequency, sample rate/bandwidth limit
- Result: V_droop, t_settle, peak/RMS, ringing?, photo IDs
- Notes: jumper states, anomalies, next actions
Applications — Hook Placement & Key Tests
Examples show how to place hooks and validate PMIC / Power IC rails in three scenarios: audio bias/codec, camera/display, and automotive domain power-up.
Audio PMIC — Codec & Mic Bias
- Hooks:
TP_VMIC,TP_VDD_CODEC,TP_BIAS_OUT,TP_TEMP_CODEC;INJ_OUTsmall ripple;JP_ISO_BIAS;CAL_VREF. - Tests: noise floor & THD, pop/click on power-up/down, bias drift vs temp.
- Criteria: V_droop < x mV, t_settle < y ms, no audible artifacts.
Camera/Display PMIC — Multi-Rail
- Hooks:
TP_AVDD,TP_DVDD,TP_IO,TP_BL_DIM,TP_TEMP_PMIC;INJ_IN,INJ_OUT;JP_ISO_SEQ;TRIM_UVLO,CAL_VREF. - Tests: PG chain & timing, backlight slew/flicker, rail interaction during simultaneous steps.
- Criteria: timing within tolerance (±Δt), droop/settle within spec, no visible flicker/banding.
Automotive Domain — Cold-Crank & Brownout
- Hooks:
TP_BAT,TP_VPRE,TP_VAUX,TP_TEMP_HOT;INJ_UVLO,INJ_LOAD,INJ_IN;OR_IDEAL/SW_BYPASS;TRIM_ILIM,TRIM_UVLO,CAL_IREF. - Tests: cold-crank profile, brownout & recovery, PG/FAULT diagnostics, thermal stability of thresholds.
- Criteria: controlled fail-safe, critical rails maintained, diagnostics match events.
IC Selection — Choose PMICs & Companions with Built-In Hook Readiness
Prioritize hook-ready PMIC / Power IC and companion devices offering telemetry registers, adjustable ILIM/UVLO, calibration writable to NVM, and evaluation boards with standard test pads. This accelerates bring-up and ensures repeatable validation on small-batch builds.
PMIC Capabilities
- Telemetry: readable
V/I/T,PG/FAULT, I²C/PMBus registers. - Thresholds: adjustable
ILIM,UVLO, soft-start/slew control. - Calibration: writable offset/gain/temp constants, NVM/OTP or power-on script.
- Protection: OVP/OCP/OTP, reverse blocking / ideal-diode path options.
- Packages: DFN/QFN/BGA with Kelvin-friendly pins and short routes.
Companion & Ecosystem
- Current-sense amplifiers: high-side/DIFF, GBW & CMRR matched to
Rsense. - Monitors/meters: ADC, temperature, alarm thresholds; scriptable I²C.
- Path controllers: eFuse / load switch / ideal-diode with
PG/FAULT. - Tools: PMBus/I²C bridges, CSV export, sample scripts for calibration.
Evaluation Board & Layout Readiness
- Standard hooks:
TP_*,INJ_*,JP_ISO,CAL_*pads present. - Injection ports: load-step and ripple nodes with same-side returns.
- Docs: bring-up notes, example register files, GUI snapshots.
- DFM/DFT: clear population options, BOM alternatives, test-pad silks.
Still unsure which PMIC or companion IC fits your test hooks and calibration flow? Submit your BOM for a 48h cross-brand recommendation.
FAQs — Power Test & Calibration Hooks
Concise, action-oriented answers for PMIC / Power IC bring-up, validation, and calibration. Each entry links to the relevant section for deeper guidance.
What’s the real benefit of Kelvin sense over ordinary test pads on Rsense?
Kelvin pads route tiny measurement currents separately from high current paths, avoiding copper drop and solder joint resistance. Keep paired, equal-length traces and avoid SW nodes to minimize differential loop area (target ≤ 10 mm²). Accuracy improves for ADC gain/offset fitting and thermal drift checks. See Design Rules.
Scope shows different V/I than telemetry registers. How do I triage first?
Follow a fixed order: Rsense value and TCR → amplifier CM/DM range and GBW → ADC reference and S/H timing → firmware scaling and filtering. Use CAL_SHORT for zero, CAL_VREF/IREF for gain, then log raw codes. Compare with a “golden board.” See Validation & Debug.
How should I set ΔI and edge rates for load-step testing on PMIC rails?
Choose ΔI to represent worst-case transients, then use fast tr/tf to excite loop dynamics. Inject at INJ_LOAD with ≈50 Ω series protection and same-side ground. Measure droop, overshoot, and t_settle(±x%). Capture bandwidth-limited and full-band views to avoid misinterpreting ringing. See Validation & Debug.
Where should ripple/noise injection ports be placed, and why same-side returns?
Place INJ_IN near input decoupling and INJ_OUT near the load return. Same-side returns minimize loop area and stray inductance, improving repeatability and EMI behavior. Label polarity and protect with series resistance to prevent overdrive. See Hook Types and Design Rules.
Do 0 Ω links or jumper headers hurt EMI? How to mitigate?
Uncontrolled loops can radiate if jumpers span noisy regions. Place jumpers where loop current is low, keep leads short, and show default population on silk. For sensitive nodes, consider RC isolation or a shielded path. Verify with a repeatable step/ripple setup. See Design Rules.
Where do I store ADC calibration constants—registers or NVM/OTP?
Use registers for quick lab iterations; commit to NVM/OTP once gain/offset/temperature terms stabilize. Ensure read-back verification and versioned logs. For small-batch runs, power-on scripts can load constants without flashing each board. See Hook Types and IC Selection.
Can PG/FAULT lines be used for fault-injection during bring-up?
Yes, with limits. Provide labeled injection pads, series resistance, and ESD protection. Define safe voltage levels and durations to avoid latch-ups. Log jumper states and recover paths to ensure reproducibility across boards. See Hook Types and Validation & Debug.
How do I verify an audio PMIC has no pops/clicks during power sequencing?
Use small-amplitude ripple at INJ_OUT and fast, controlled load steps to check bias rails. Monitor droop and recovery while listening or logging audio output. Validate codec enable sequencing against PG timing. Repeat at cold/room/hot. See Applications.
What’s the best way to validate multi-rail timing for camera/display PMICs?
Segment bring-up using JP_ISO on sequence branches. Probe AVDD/DVDD/IO and backlight dim pins. Verify PG chain timing and look for flicker during simultaneous load steps. Sweep input ripple to reveal coupling paths. See Applications.
How can I reproduce automotive cold-crank and brownout behavior safely?
Use INJ_UVLO with predefined voltage profiles and series limits. Log PG/FAULT transitions and confirm rail hold-up. Validate thresholds over temperature and ensure ideal-diode/bypass paths behave predictably. Keep returns short and shield high-current leads. See Applications and Validation.
How do I create a repeatable minimal validation log for small-batch builds?
Standardize headers (unit/jig/FW/date), environment (VIN/temp/equipment), hook IDs (TP/INJ/JP/CAL), test set (ΔI, tr/tf, bandwidth), and results (droop, t_settle, photos). Include jumper states and next actions. Store versions under revision control. See Validation & Debug.
Which PMIC features matter most for “hook-ready” selection?
Prioritize readable telemetry (V/I/T/FAULT), adjustable ILIM/UVLO/soft-start, writable calibration constants with NVM/OTP, and evaluation boards exposing standard test pads and injection ports. Clear bring-up notes and scripts reduce lab hours dramatically. See IC Selection.
How do I log and compensate temperature-induced measurement drift?
Place TP_TEMP near hotspots, record ambient and local temperatures, and capture raw ADC codes at two points for fitting. Write temperature terms alongside gain/offset and verify read-back. Re-test after thermal soak. See Hook Types and Validation.
How do I maintain replaceability when swapping PMICs in small batches?
Map external resistor networks for ILIM/UVLO, preserve pin-accessible test pads, and maintain hook naming (TP_*, INJ_*, JP_ISO, CAL_*). Keep scripts portable across PMBus/I²C variants and note differences in telemetry scaling. See IC Selection.
Resources & CTA
Still unsure which power test hooks fit your PMIC board? Submit your BOM for a 48h cross-brand recommendation.
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