A TLVR uses coupled windings and an auxiliary loop to coordinate phase response. Select its magnetic components as part of the complete regulator: an ordinary single-winding Buck inductor with the same nominal inductance is not a drop-in substitute.
1. Start with the regulator requirements
Record input and output voltage, phase count, switching frequency, allowed ripple, load-step amplitude and slew rate, output capacitance and the voltage tolerance at the load. Obtain the controller vendor’s supported TLVR circuit before choosing parts. These requirements define what the magnetic circuit must do; a large current number in a catalogue does not establish compliance.
2. Distinguish the windings and the loop
The main winding carries the phase current. Coupled secondary windings form an auxiliary path with a compensation inductor in conventional TLVR implementations. Keep winding polarity and pin assignments explicit in the schematic and layout. Check the controller reference design for the intended topology; do not turn an auxiliary winding rating into a main-winding current rating. [1]
3. Compare under the same test conditions
Request inductance versus bias and temperature, saturation criteria, thermal test conditions, DCR per winding and leakage measurements. Record whether a winding was open or shorted during an inductance measurement. The source distinguishes nominal inductance, full-load inductance, Irms, Isat and leakage; each describes a different operating constraint. [1]
4. Validate the assembly
Review the compensation inductance together with interconnect parasitics and the manufacturer model. Simulate the supported circuit, then measure start-up, steady load, load release and load application at hot and cold limits. Measure phase-current balance, winding temperature and output excursions. Keep the test fixture, firmware/controller settings and airflow with the results so an alternate can be evaluated against the same baseline.
5. Build an evidence-based shortlist
Use the original TLVR application note below to identify supported magnetic families. Ask the supplier for an exact orderable suffix, winding diagram, model revision and qualified land pattern. Magdir’s ordinary inductor pages and comparison tools help organize parameters, but their presence in the catalogue does not qualify a part for TLVR service. Vishay’s IHTL overview lists IHTL3825JE and IHTL4020LZ among its TLVR families; these are research entry points, not a claim that Magdir stocks them or that either fits a particular board. [2]
Parameter review table
| Parameter | Evidence to request | Selection consequence |
|---|---|---|
| Main/secondary inductance | Winding, frequency, bias and temperature | Do not compare open-circuit and short-circuit values as identical |
| Leakage and loop inductance | Measurement method and PCB contribution | Evaluate the complete transient path |
| Isat / Irms | Inductance drop / temperature rise and test setup | Check peak and RMS conditions independently |
| DCR per winding | Maximum or typical value and reference temperature | Estimate each winding loss separately |
| Terminals and polarity | Drawing, pin numbering and land pattern | Validate routing and assembly before substitution |
Put the review into practice
Review worksheet: put the reference part and candidate in two columns. A blank leakage measurement or missing winding polarity is an unresolved item, even if both list the same inductance. Request that evidence before a prototype substitution; do not convert “unknown” into a pass.
Frequently asked questions
Can a standard Buck inductor replace a TLVR part?
Not by matching inductance alone. The coupled windings, polarity, auxiliary loop and controller requirements must be satisfied.
Is Isat the allowable continuous current?
No. Isat describes an inductance-drop criterion. Continuous operation also depends on RMS loss, temperature rise, PCB and cooling.
Which winding does a current rating apply to?
Use the winding and thermal conditions stated by the manufacturer. If the data sheet does not identify them, request clarification.
Original technical references
This is an engineering selection guide, not a manufacturer specification. Use current exact-part documentation and application measurements for procurement and substitution.