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  "id": "atlas-lesson-voltage-regulator",
  "title": "Voltage regulator module",
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  "description": "Converts a distribution voltage into tightly controlled low-voltage rails for processors and memory.",
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  "revisionDate": "2026-10-07",
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  "topic": "Power delivery",
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      "id": "section-1",
      "title": "Voltage regulator module",
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      "title": "The mechanism",
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      "title": "Inductor volt-seconds set the ideal buck ratio",
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      "title": "Engineering example",
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      "title": "Specifications and interfaces",
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      "title": "Check your understanding",
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      "title": "At an illustrative 1 V, how much current corresponds to a 1,000 W load?",
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      "title": "Continue exploring",
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      "title": "Foundations",
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  "citations": [
    {
      "title": "Explore in Atlas",
      "url": "https://semiaifoundry.com/ai-atlas/#voltage-regulator"
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    {
      "title": "Texas Instruments: multiphase processor core power",
      "url": "https://www.ti.com/product-category/power-management/multiphase.html"
    },
    {
      "title": "Texas Instruments: 48 V to 12 V, 1.1 kW converter reference design",
      "url": "https://www.ti.com/lit/ug/tiduff3/tiduff3.pdf"
    },
    {
      "title": "Texas Instruments: Basic calculation of a buck converter power stage",
      "url": "https://www.ti.com/lit/an/slva477b/slva477b.pdf"
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    },
    {
      "title": "Atlas releases and licensing",
      "url": "https://semiaifoundry.com/ai-atlas/licenses.html"
    },
    {
      "title": "Metal–oxide–semiconductor field-effect transistor",
      "url": "https://semiaifoundry.com/learn/atlas/mosfet/"
    },
    {
      "title": "Insulators and low-k films",
      "url": "https://semiaifoundry.com/learn/atlas/dielectric/"
    },
    {
      "title": "Power supply and power shelf",
      "url": "https://semiaifoundry.com/learn/atlas/power-supply/"
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    {
      "title": "Package substrate",
      "url": "https://semiaifoundry.com/learn/atlas/package-substrate/"
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    {
      "title": "Compute baseboard and tray",
      "url": "https://semiaifoundry.com/learn/atlas/compute-baseboard/"
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    {
      "title": "GPU logic dies",
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  "content": "Power delivery · Atlas v1.3.0\n\n# Voltage regulator module\n\nConverts a distribution voltage into tightly controlled low-voltage rails for processors and memory.\n\n[Explore in Atlas](https://semiaifoundry.com/ai-atlas/#voltage-regulator)Centimeter-scale circuit around the processor; millimeter power components\n\nLearning objectiveEstimate the duty cycle and inductor ripple of an ideal buck converter while keeping the power-stage assumptions explicit.\n\n## The mechanism\n\nA VRM sits electrically between the power distribution system and the chip. Switching stages, inductors, capacitors, and a controller turn an incoming supply into the rail the load needs. Multiple phases share current and can reduce ripple while responding to rapid changes in demand. GPU activity changes quickly as kernels start, synchronize, or wait for data, so stable voltage requires more than matching average power. Phases share the conversion work, while capacitors temporarily support changes in load; the controller must restore the regulated voltage after a disturbance. Use illustrative voltages where product values are not public. A large current is compatible with a modest voltage because power is their product; this explains why short, low-resistance connections matter so much near the silicon.\n\n1.  Switching stages draw energy from the incoming DC distribution rail in controlled intervals.\n2.  Inductors and capacitors smooth the output while multiple phases share the demanded current.\n3.  Feedback adjusts switching as the processor load changes, keeping the supply rail within its required operating limits.\n\n## Science and assumptions\n\n### Inductor volt-seconds set the ideal buck ratio\n\n$$\nV_{\\mathrm{out}}\\approx D V_{\\mathrm{in}},\\qquad\\Delta I_L\\approx\\frac{(V_{\\mathrm{in}}-V_{\\mathrm{out}})D}{L f_s}\n$$\n\nIdeal buck output is duty fraction times input voltage. Inductor current ripple is approximately input-minus-output voltage times duty fraction divided by inductance times switching frequency.\n\nSymbols and units\n\nV\\_out\n\nOutput voltage\n\nV\n\nD\n\nSwitch-on duty fraction\n\nfraction\n\nV\\_in\n\nInput voltage\n\nV\n\nΔI\\_L\n\nPeak-to-peak phase-inductor current ripple\n\nA\n\nL\n\nPhase inductance\n\nH\n\nf\\_s\n\nSwitching frequency\n\nHz\n\nD is switch-on fraction of each cycle, L is phase inductance, and fs is switching frequency. A buck converter alternates charging and discharging the inductor; average inductor voltage must be zero in steady operation. The ripple relation shows how inductance and switching frequency affect phase-current variation, which interacts with capacitor choice and transient response.\n\nAssumptions Ideal continuous-conduction buck stage with fixed input/output voltage and negligible switch losses. Multiphase cancellation, nonlinear inductors, dead time, control dynamics, and discontinuous conduction require further analysis; no GPU power-stage values are assumed.\n\n## Engineering example\n\nSynthetic buck stage: 12 V input and 1 V output imply D = 1/12. With L = 1 μH and switching frequency 1 MHz, ΔI ≈ (12 − 1) × (1/12)/(1 μH × 1 MHz) ≈ 0.917 A peak-to-peak. These values describe one hypothetical stage, not a GPU regulator.\n\n## Distinctions and tradeoffs\n\nLow chip voltage does not imply low electrical current. At a fixed power, lower voltage requires more current, making distribution resistance and transients important.\n\nMore phases and larger filters can improve current delivery but occupy board space and add losses or cost. The best operating point balances efficiency, stability, response, and temperature.\n\nEvery arithmetic operation depends on a stable electrical supply. Poor transient response or excessive distribution loss can limit the usable compute power of the accelerator.\n\n## Specifications and interfaces\n\nConversion principle\n\nP = V × I\n\nA 1,000 W load at an illustrative 1 V requires 1,000 A, excluding conversion loss.\n\nReference conversion\n\n48 V → 12 V at 1.1 kW\n\nTI reference design example; not a GB200 power-stage specification.\n\nControl architecture\n\nMultiphase switching regulation\n\nCurrent sharing and transient response are design objectives.\n\n### Interfaces\n\nDistribution supply Input\n\nBoard or intermediate DC voltage\n\nRegulated rails Output\n\nLow-voltage high-current power\n\nFeedback Input\n\nMeasured voltage, current, and temperature\n\n## Check your understanding\n\n### At an illustrative 1 V, how much current corresponds to a 1,000 W load?\n\n1.  1 A.\n2.  1,000 A.\n3.  1,000,000 A.\n\nAnswer and reasoning\n\n1,000 A.\n\nUsing P = V × I gives I = 1,000 W / 1 V = 1,000 A. This is an illustration, not an asserted GPU rail specification.\n\n## Evidence and scope\n\nThe relation is the lesson’s ideal continuous-conduction model. Switch losses, control dynamics, phase cancellation, saturation and discontinuous conduction are excluded; the cited power-conversion sources supply the physical context.\n\nUse the manufacturing investigation to trace compatible inputs, assembly and operating constraints; no current standalone calculator models this lesson’s full mechanism.\n\n## Sources\n\n-   [Texas Instruments: multiphase processor core power](https://www.ti.com/product-category/power-management/multiphase.html)\n-   [Texas Instruments: 48 V to 12 V, 1.1 kW converter reference design](https://www.ti.com/lit/ug/tiduff3/tiduff3.pdf)\n-   [Texas Instruments: Basic calculation of a buck converter power stage](https://www.ti.com/lit/an/slva477b/slva477b.pdf)\n\n[Published lesson data](https://semiaifoundry.com/ai-atlas/lesson-data/voltage-regulator-ea1e1068153c6264.json) · [Atlas releases and licensing](https://semiaifoundry.com/ai-atlas/licenses.html)\n\n## Continue exploring\n\n### Foundations\n\n-   [Metal–oxide–semiconductor field-effect transistor](https://semiaifoundry.com/learn/atlas/mosfet/)\n-   [Insulators and low-k films](https://semiaifoundry.com/learn/atlas/dielectric/)\n\n### Related lessons\n\n-   [Power supply and power shelf](https://semiaifoundry.com/learn/atlas/power-supply/)\n-   [Package substrate](https://semiaifoundry.com/learn/atlas/package-substrate/)\n-   [Compute baseboard and tray](https://semiaifoundry.com/learn/atlas/compute-baseboard/)\n-   [GPU logic dies](https://semiaifoundry.com/learn/atlas/gpu-die/)"
}