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The Qi2 MPP Ferrite Sheet Guide: What Changed at 360 kHz

Qi2's Magnetic Power Profile is the first mainstream wireless-charging standard with a fixed operating frequency. That single change — 360 kHz, no sweep — reshapes how the magnetic sheet behind your coil should be specified. This guide covers the frequency facts, the material choice, and the drawing details that decide MPP performance.

Qi2 MPP in One Paragraph

The Wireless Power Consortium's Qi2 standard introduced MPP — the Magnetic Power Profile — built around Apple's MagSafe-style magnetic alignment. A ring of alignment magnets snaps TX and RX into position, and power transfers at a fixed 360 kHz instead of the frequency sweep used by older Qi profiles. Fixed frequency means the magnetic sheet behind the coil now works at a single, knowable operating point — which is good news, if your datasheet actually covers it.

Fixed at 360 kHz. MPP operates at 360 kHz. The 127.7 kHz figure you will still see in older articles and some legacy datasheets comes from early MPP drafts and is outdated. When comparing ferrite or nanocrystalline sheets for Qi2, check the μ′/μ″ curves at 360 kHz.

BPP, EPP, MPP: the Frequency Facts

ProfileFrequency behaviorAlignmentTypical powerWhat the sheet sees
Qi BPPVariable, ~110–205 kHzNone (free placement)≤ 5 WWideband, forgiving
Qi EPPVariable, 87–205 kHzOptional (guided)≤ 15 WWideband, FOD-aware
Qi2 MPPFixed 360 kHzMagnetic ring, snap-to-align15 W (Qi2); 25 W class emergingSingle point, tighter magnetic circuit

Why the single frequency matters: in a swept system the sheet had to behave reasonably across a whole band; average performance was enough. At 360 kHz fixed, the sheet's permeability at that one point sets coupling, and its losses at harmonics of that point set heating.

What 360 kHz Changes for the Magnetic Sheet

  • Characterization point. Ask for μ′ and μ″ at 360 kHz, not only at 100 kHz or 127.7 kHz. A sheet with fine 100 kHz numbers can roll off steeply by 360 kHz.
  • Thickness tolerance and flatness. The MPP magnet ring makes the magnetic circuit tighter; gap variation from a warped or out-of-tolerance sheet shows up directly as coupling variation unit-to-unit.
  • DC bias from the alignment magnets. The magnet ring biases the sheet magnetically. Saturation induction Bs becomes a real selection parameter — one reason nanocrystalline (Bs 1.25 T) holds up well in thin MPP stacks.
  • Thermal budget. Misalignment is rarer with magnets, but partial misalignment still happens — and at a fixed frequency, eddy heating in the housing concentrates at predictable spots. Sheet flux confinement is the lever.

Ferrite vs Nanocrystalline for the MPP Receiver

ParameterFerrite sheet (XAK-WPT class)Nanocrystalline (XAK F-N)
μ′ at 100 kHz≈ 100–150 (grade-dependent)≈ 13,000
Bs~0.3–0.5 T class1.25 T
Practical min. thickness~0.3 mm plate0.06 mm
FlexibilityRigid plate (flexible polymer-bonded variants exist)Flexible ribbon, die-cuts to outline
CostLowerHigher
Choose when…Stack has ≥0.3 mm; cost-driven consumer buildStack <0.3 mm; curved housing; thermal margin tight

There is no electrical loser here — both materials couple MPP well. The honest decision path: measure your Z-height budget, then decide. And if ferrite fits and the program is cost-driven, ferrite is the right answer; we supply both so the recommendation stays honest.

The MPP Module Stack, Layer by Layer

A typical MPP receiver from TX-facing side to battery: TX coil face → RX coil (FPC or wire) → magnetic sheet (ferrite or nanocrystalline) → NFC antenna with its own ferrite sheet (offset from the coil axis) → battery / shield. Two rules that first builds usually violate: keep the NFC sheet's field path clear of the charging coil's axis, and never substitute an absorber sheet for the coupling sheet — absorbers eat the 360 kHz field the same way they eat 13.56 MHz.

Your Drawing Checklist for an MPP Sheet

  • Operating point stated explicitly: "characterized at 360 kHz" — not just "for Qi2"
  • Thickness with tolerance (±0.02 mm class for thin sheets) and flatness callout
  • Outline: DXF preferred; keep-out for the magnet ring and screw bosses marked
  • Target inductance or coupling range for the assembled coil+sheet, measured at 360 kHz
  • Adhesive system (PSA / double-sided / bare) and operating temperature range
  • Quantity split: validation samples vs. pilot-run volumes

Frequently Asked Questions

Is Qi2 MPP really fixed at 360 kHz — what about the 127.7 kHz I keep seeing?
Yes — MPP (Magnetic Power Profile) operates at a fixed 360 kHz. The 127.7 kHz figure comes from early MPP drafts and still circulates in older articles and even some datasheets. When you evaluate sheet specs, make sure the permeability data covers 360 kHz; characterization only at 100 kHz or 127.7 kHz tells you less than you need. We characterize XAK-WPT and F-N sheets at 360 kHz on request.
Can I use the same magnetic sheet for Qi BPP and Qi2 MPP designs?
Often yes for TX, with caution — but don't assume it. BPP sweeps across 87–205 kHz while MPP sits at a single 360 kHz point; a sheet whose permeability rolls off steeply between those frequencies behaves differently in the two systems. If one SKU must serve both, tell us — we'll pick a grade whose curve covers both regimes and say so explicitly.
Ferrite or nanocrystalline for a Qi2 MPP receiver?
Both couple well at 360 kHz. Choose ferrite (XAK-WPT class) when you have ≥0.3 mm behind the coil and cost matters; choose nanocrystalline (F-N) when the stack is slimmer than that, the housing curves, or misalignment temperature rise is a problem. The decision is mechanical and thermal, not electrical — see the comparison table above.
How do the MPP alignment magnets change the sheet spec?
The magnet ring sits between coil and sheet in most MPP modules, closer to the coil than in older designs. Two consequences: the sheet sees a stronger DC bias flux (saturation margin matters — that's why Bs is in our comparison table), and flatness/thickness tolerance of the sheet affects coupling consistency because the magnetic circuit is tighter. Specify tolerance and flatness on your drawing.
Do I need a different sheet for the NFC antenna in the same device?
Almost always yes — and it must not be an absorber. The NFC antenna at 13.56 MHz wants its own low-loss ferrite sheet (XAK-NFC), placed behind the antenna and clear of the charging coil's field path. The two sheets do different jobs at different frequencies; stacking them in the wrong order is a classic first-build failure.

Specifying a Qi2 MPP module?

Send the coil outline, your Z-height budget and the target coupling — we respond within 24 hours with a sheet recommendation characterized at 360 kHz and a samples plan. Product pages: wireless-charging ferrite sheets and nanocrystalline sheets.

Request a 360 kHz Sheet Recommendation → info@xakmag.com