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1 A Low-Dropout Regulator AMS - AMS1117
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Advanced Monolithic Systems AMS1117 - the original three-terminal 1 A low-dropout linear regulator. Fixed 1.5/1.8/2.5/2.85/3.3/5.0 V or adjustable, in SOT-223, TO-252 (DPAK) and 8-lead SOIC.
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README.md+46−46@@ -1,45 +1,45 @@-# AMS1117 — 1 A Low-Dropout Regulator (Advanced Monolithic Systems)+# AMS1117: 1 A Low-Dropout Regulator (Advanced Monolithic Systems) The **original** AMS1117: a three-terminal **1 A low-dropout linear voltage regulator** from Advanced Monolithic Systems, available in fixed 1.5 / 1.8 / 2.5 / 2.85 / 3.3 / 5.0 V versions or as an adjustable regulator set by two resistors around a 1.25 V reference. It operates down to 1 V input-to-output differential (1.3 V max dropout at 0.8 A), is trimmed on-chip to 1.5 %, and includes internal current limiting and thermal shutdown. It is pin-compatible with older three-terminal SCSI regulators, and comes in SOT-223, TO-252 (DPAK) and 8-lead SOIC. -> **This page is the Advanced Monolithic Systems part only.** Everything here comes from the AMS datasheet and applies to AMS-branded silicon. The same part number is second-sourced by UMW with a different voltage lineup, different packages and materially different limits — if your BOM says UMW, use [1 A Low-Dropout Regulator UMW — AMS1117](https://wiki.adom.inc/adom/umw-ams1117) instead.+> **This page is the Advanced Monolithic Systems part only.** Everything here comes from the AMS datasheet and applies to AMS-branded silicon. The same part number is second-sourced by UMW with a different voltage lineup, different packages and materially different limits. If your BOM says UMW, use [1 A Low-Dropout Regulator UMW - AMS1117](https://wiki.adom.inc/adom/umw-ams1117) instead. The interactive **symbol** and **footprint** viewers above are rendered by the wiki from the CAD shipped with this page. Use the toggle at the **bottom-right of the footprint viewer** to switch between **SOT-223**, **TO-252** and **SO-8**. ## Specifications -- **Output current** — 1 A-- **Fixed output voltages** — 1.5 / 1.8 / 2.5 / 2.85 / 3.3 / 5.0 V; also available adjustable-- **Reference voltage** — 1.250 V typ (1.232 – 1.268 V at 25 °C)-- **Dropout voltage** — 1.1 V typ, 1.3 V max at 0.8 A; higher above 0.8 A-- **Input voltage** — 15 V absolute maximum-- **Line regulation** — 0.2 % max (0.015 % typ)-- **Load regulation** — 0.4 % max (0.1 % typ)-- **Current limit** — 900 mA min / 1100 mA typ / 1500 mA max-- **Quiescent current** — 5 mA typ, 11 mA max-- **Minimum load current** — 5 mA typ, 10 mA max (adjustable version)-- **Ripple rejection** — 60 dB min; 75 dB typ adjustable, 72 dB fixed, 68 dB on the 5.0 V version-- **Adjust pin current** — 55 µA typ, 120 µA max-- **Thermal regulation** — 0.008 %/W typ, 0.04 %/W max-- **RMS output noise** — 0.003 % of VOUT (10 Hz – 10 kHz)-- **Long term stability** — 0.3 % typ, 1 % max (1000 h at 125 °C)-- **Protection** — internal current limit and thermal shutdown at 165 °C junction-- **Thermal resistance θJA** — SOT-223 90 °C/W, TO-252 80 °C/W, SO-8 160 °C/W (θJC 15 °C/W max)-- **Operating junction temperature** — −40 to +125 °C; storage −65 to +150 °C-- **Required output capacitor** — 22 µF solid tantalum (part of the loop compensation)+- **Output current**: 1 A+- **Fixed output voltages**: 1.5 / 1.8 / 2.5 / 2.85 / 3.3 / 5.0 V; also available adjustable+- **Reference voltage**: 1.250 V typ (1.232 to 1.268 V at 25 °C)+- **Dropout voltage**: 1.1 V typ, 1.3 V max at 0.8 A; higher above 0.8 A+- **Input voltage**: 15 V absolute maximum+- **Line regulation**: 0.2 % max (0.015 % typ)+- **Load regulation**: 0.4 % max (0.1 % typ)+- **Current limit**: 900 mA min / 1100 mA typ / 1500 mA max+- **Quiescent current**: 5 mA typ, 11 mA max+- **Minimum load current**: 5 mA typ, 10 mA max (adjustable version)+- **Ripple rejection**: 60 dB min; 75 dB typ adjustable, 72 dB fixed, 68 dB on the 5.0 V version+- **Adjust pin current**: 55 µA typ, 120 µA max+- **Thermal regulation**: 0.008 %/W typ, 0.04 %/W max+- **RMS output noise**: 0.003 % of VOUT (10 Hz to 10 kHz)+- **Long term stability**: 0.3 % typ, 1 % max (1000 h at 125 °C)+- **Protection**. Internal current limit and thermal shutdown at 165 °C junction+- **Thermal resistance θJA**: SOT-223 90 °C/W, TO-252 80 °C/W, SO-8 160 °C/W (θJC 15 °C/W max)+- **Operating junction temperature**: −40 to +125 °C; storage −65 to +150 °C+- **Required output capacitor**: 22 µF solid tantalum (part of the loop compensation) ## Pin configuration -On **both SOT-223 and TO-252 the metal tab is VOUT**, internally bonded to pin 2. It is the heat path, so solder it to a copper pour on the output net — never to ground. Both footprints shipped here carry the tab as pad 2.+On **both SOT-223 and TO-252 the metal tab is VOUT**, internally bonded to pin 2. It is the heat path, so solder it to a copper pour on the output net: never to ground. Both footprints shipped here carry the tab as pad 2. -### SOT-223 and TO-252 — 3 terminals plus tab+### SOT-223 and TO-252: 3 terminals plus tab | Pin | Name | Function | |---|---|---| | 1 | GND/ADJ | Ground on fixed versions; feedback (adjust) node on the adjustable version |-| 2 | VOUT | Regulated output — also the metal tab |+| 2 | VOUT | Regulated output. Also the metal tab | | 3 | VIN | Unregulated input, 15 V max |-| — | TAB | Thermal pad, bonded to pin 2 (VOUT) |+| n/a | TAB | Thermal pad, bonded to pin 2 (VOUT) | ### 8-lead SOIC @@ -47,7 +47,7 @@ On **both SOT-223 and TO-252 the metal tab is VOUT**, internally bonded to pin 2 |---|---|---| | 1 | GND/ADJ | Ground on fixed versions; adjust node on the adjustable version | | 2 | VOUT | Regulated output |-| 3 | VOUT | Regulated output — tie all VOUT leads together |+| 3 | VOUT | Regulated output. Tie all VOUT leads together | | 4 | VIN | Unregulated input, 15 V max | | 5 | N/C | No internal connection | | 6 | VOUT | Regulated output |@@ -58,29 +58,29 @@ On **both SOT-223 and TO-252 the metal tab is VOUT**, internally bonded to pin 2 All variants are the **same AMS1117 silicon**. The order code carries two independent choices: the **package** (a letter pair after the base part) and the **output voltage** (a suffix). A blank voltage suffix means the **adjustable** version. Every version is available in all three packages. -The order code is `AMS1117` `{CD | CS | blank}` `-{voltage}` — where `CD` = TO-252 (DPAK), `CS` = 8-lead SOIC, blank = SOT-223.+The order code is `AMS1117` `{CD | CS | blank}` `-{voltage}`. Where `CD` = TO-252 (DPAK), `CS` = 8-lead SOIC, blank = SOT-223. | Package | Code | Body | θJA | Max dissipation | Fixed order codes | |---|---|---|---|---|---|-| SOT-223 | *(none)* | 6.30–6.71 × 3.30–3.71 mm, 1.80 mm max | 90 °C/W | 1.2 W | `AMS1117-1.5` … `AMS1117-5.0` |-| TO-252 (DPAK) | `CD` | 6.48–6.73 × 5.97–6.22 mm, 2.21–2.39 mm | 80 °C/W | 2.2 W | `AMS1117CD-1.5` … `AMS1117CD-5.0` |-| 8-lead SOIC | `CS` | 4.80–5.00 × 3.81–3.99 mm, 1.27 mm pitch | 160 °C/W | 780 mW | `AMS1117CS-1.5` … `AMS1117CS-5.0` |+| SOT-223 | *(none)* | 6.30 to 6.71 × 3.30 to 3.71 mm, 1.80 mm max | 90 °C/W | 1.2 W | `AMS1117-1.5` … `AMS1117-5.0` |+| TO-252 (DPAK) | `CD` | 6.48 to 6.73 × 5.97 to 6.22 mm, 2.21 to 2.39 mm | 80 °C/W | 2.2 W | `AMS1117CD-1.5` … `AMS1117CD-5.0` |+| 8-lead SOIC | `CS` | 4.80 to 5.00 × 3.81 to 3.99 mm, 1.27 mm pitch | 160 °C/W | 780 mW | `AMS1117CS-1.5` … `AMS1117CS-5.0` | ### Output voltage versions Limits at TJ = 25 °C. Load regulation is measured at 0 ≤ IOUT ≤ 0.8 A. -| Version | VOUT typ | Min – max | Test VIN | Line reg. typ / max | Load reg. typ / max | Ripple rej. typ |+| Version | VOUT typ | Min to max | Test VIN | Line reg. typ / max | Load reg. typ / max | Ripple rej. typ | |---|---|---|---|---|---|---|-| AMS1117-1.5 | 1.500 V | 1.478 – 1.522 V | 3.0 V | 0.3 / 5 mV | 3 / 10 mV | 72 dB |-| AMS1117-1.8 | 1.800 V | 1.773 – 1.827 V | 3.3 V | 0.3 / 5 mV | 3 / 10 mV | 72 dB |-| AMS1117-2.5 | 2.500 V | 2.463 – 2.537 V | 4.0 V | 0.3 / 6 mV | 3 / 12 mV | 72 dB |-| AMS1117-2.85 | 2.850 V | 2.808 – 2.892 V | 4.35 V | 0.3 / 6 mV | 3 / 12 mV | 72 dB |-| AMS1117-3.3 | 3.300 V | 3.251 – 3.349 V | 4.8 V | 0.5 / 10 mV | 3 / 15 mV | 72 dB |-| AMS1117-5.0 | 5.000 V | 4.925 – 5.075 V | 6.5 V | 0.5 / 10 mV | 5 / 20 mV | 68 dB |-| AMS1117 (ADJ) | 1.250 V ref | 1.232 – 1.268 V | — | 0.015 / 0.2 % | 0.1 / 0.3 % | 75 dB |+| AMS1117-1.5 | 1.500 V | 1.478 to 1.522 V | 3.0 V | 0.3 / 5 mV | 3 / 10 mV | 72 dB |+| AMS1117-1.8 | 1.800 V | 1.773 to 1.827 V | 3.3 V | 0.3 / 5 mV | 3 / 10 mV | 72 dB |+| AMS1117-2.5 | 2.500 V | 2.463 to 2.537 V | 4.0 V | 0.3 / 6 mV | 3 / 12 mV | 72 dB |+| AMS1117-2.85 | 2.850 V | 2.808 to 2.892 V | 4.35 V | 0.3 / 6 mV | 3 / 12 mV | 72 dB |+| AMS1117-3.3 | 3.300 V | 3.251 to 3.349 V | 4.8 V | 0.5 / 10 mV | 3 / 15 mV | 72 dB |+| AMS1117-5.0 | 5.000 V | 4.925 to 5.075 V | 6.5 V | 0.5 / 10 mV | 5 / 20 mV | 68 dB |+| AMS1117 (ADJ) | 1.250 V ref | 1.232 to 1.268 V | n/a | 0.015 / 0.2 % | 0.1 / 0.3 % | 75 dB | -**2.85 V is here for SCSI.** It is the SCSI-2 active-termination voltage — the datasheet lists "Active SCSI Terminators" as an application, and 2.85 V regulators exist almost entirely to hold a SCSI bus at spec through 110 Ω series resistors. It is the one version the UMW second source does not carry.+**2.85 V is here for SCSI.** It is the SCSI-2 active-termination voltage. The datasheet lists "Active SCSI Terminators" as an application, and 2.85 V regulators exist almost entirely to hold a SCSI bus at spec through 110 Ω series resistors. It is the one version the UMW second source does not carry. ## Thermal design @@ -110,23 +110,23 @@ The tab is attached to the top-side copper in every row. The spreading copper do ## Applications -1. [**AMS1117-3.3 Molecule**](https://wiki.adom.inc/adom/ams1117-3v3-molecule) — a 5 V → 3.3 V regulator brick: AMS1117-3.3 in SOT-223 with 10 µF input and 22 µF output decoupling on a machine-pin carrier.-2. [**1 A Low-Dropout Regulator UMW — AMS1117**](https://wiki.adom.inc/adom/umw-ams1117) — the second-source part.+1. [**AMS1117-3.3 Molecule**](https://wiki.adom.inc/adom/ams1117-3v3-molecule). A 5 V → 3.3 V regulator brick: AMS1117-3.3 in SOT-223 with 10 µF input and 22 µF output decoupling on a machine-pin carrier.+2. [**1 A Low-Dropout Regulator UMW - AMS1117**](https://wiki.adom.inc/adom/umw-ams1117). The second-source part. ## Application notes - **The 22 µF output capacitor is compensation, not decoupling.** The AMS1117 loop depends on it; a solid tantalum 22 µF guarantees stability across all operating conditions.-- **No protection diodes needed.** Internal resistors limit the adjust-pin current paths. A diode from output to input is only recommended when COUT is very large (1000–5000 µF) and the input can be shorted.+- **No protection diodes needed.** Internal resistors limit the adjust-pin current paths. A diode from output to input is only recommended when COUT is large (1000 to 5000 µF) and the input can be shorted. - **Kelvin the divider, not the load.** On the adjustable version, connect the top of R1 to the regulator case rather than the load. Fixed versions Kelvin the top of R1 internally.-- **Adjust-pin bypassing.** For proper ripple rejection the adjust-pin capacitor's impedance at the ripple frequency must be below R1 (typically 100–200 Ω): >13 µF at 120 Hz with R1 = 100 Ω, but only 0.16 µF at 10 kHz.+- **Adjust-pin bypassing.** For proper ripple rejection the adjust-pin capacitor's impedance at the ripple frequency must be below R1 (typically 100 to 200 Ω): >13 µF at 120 Hz with R1 = 100 Ω, but only 0.16 µF at 10 kHz. - **Adjustable output:** VOUT = VREF(1 + R2/R1) + IADJ·R2, with VREF = 1.25 V and IADJ ≈ 55 µA. ## Provenance -- **Datasheet:** [Advanced Monolithic Systems AMS1117, *1 A Low Dropout Voltage Regulator*](docs/ams1117-datasheet-ams.pdf) — every electrical number on this page is read from it. Nothing from any second source is mixed in.+- **Datasheet:** [Advanced Monolithic Systems AMS1117, *1 A Low Dropout Voltage Regulator*](docs/ams1117-datasheet-ams.pdf). Every electrical number on this page is read from it. Nothing from any second source is mixed in. - **Symbols:** generated with `adom-symbol` to the datasheet pin connections.-- **Footprints:** KiCad 10 official library land patterns, renamed — `SOT-223-3_TabPin2`, `TO-252-3_TabPin2`, `SOIC-8_3.9x4.9mm_P1.27mm`. The `TabPin2` variants are correct here because the AMS1117 tab is VOUT, which is pin 2.+- **Footprints:** KiCad 10 official library land patterns, renamed: `SOT-223-3_TabPin2`, `TO-252-3_TabPin2`, `SOIC-8_3.9x4.9mm_P1.27mm`. The `TabPin2` variants are correct here because the AMS1117 tab is VOUT, which is pin 2. - **3D models:** the matching KiCad 10 official STEP models, converted to GLB with `step2glb`. - **Canonical JSON:** imported from the KiCad symbol + SOT-223 footprint with `adom-lbr import-kicad`. - **The SCSI note** draws on the datasheet's own applications list plus the SCSI-2 active-termination literature (Linear Technology Design Note 34, which uses an LT1117-2.85 for exactly this).-- **Fusion and Altium libraries are deliberately absent** — they are generated rather than hand-verified, and the generated Altium symbol encoding has produced wrong geometry before.+- **Fusion and Altium libraries are deliberately absent**. They are generated rather than hand-verified, and the generated Altium symbol encoding has produced wrong geometry before.
readme.html+36−36@@ -1,6 +1,6 @@ <!doctype html><html lang=en><head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"> <style>-/* Adom theme system — studio-dark token base (adom/adom-theme-system) */+/* Adom theme system: studio-dark token base (adom/adom-theme-system) */ :root{ --bg:#0d1117;--surface:#161b22;--elevated:#1c2128;--overlay:#21262d;--border:#30363d; --text:#e6edf3;--text-body:#c9d1d9;--text-2:#8b949e;--text-3:#484f58;@@ -83,7 +83,7 @@ code{background:rgba(139,148,158,.16);padding:1px 6px;border-radius:5px;font-siz <div class=ident><h1>AMS1117</h1><span class=mfr>Advanced Monolithic Systems</span><span class=badge>1 A LDO · AMS</span></div> <p class=oneline>The <b>original</b> AMS1117: a three-terminal <b>1 A low-dropout linear voltage regulator</b> from Advanced Monolithic Systems, in fixed 1.5 / 1.8 / 2.5 / 2.85 / 3.3 / 5.0 V versions or an adjustable version set by two resistors around a 1.25 V reference. Operates down to <b>1 V input-to-output differential</b> (1.3 V max dropout at 0.8 A), trimmed on-chip to 1.5 %, with internal current limit and thermal shutdown. Pin-compatible with older three-terminal SCSI regulators. Offered in SOT-223, TO-252 (DPAK) and 8-lead SOIC.</p>-<div class=sib><b>This page is the Advanced Monolithic Systems part only.</b> Everything below comes from the AMS datasheet and applies to AMS-branded silicon. The same part number is second-sourced by UMW with a <b>different voltage lineup, different packages and materially different limits</b> — if your BOM says UMW, use <a href="https://wiki.adom.inc/adom/umw-ams1117">1 A Low-Dropout Regulator UMW — AMS1117</a> instead.</div>+<div class=sib><b>This page is the Advanced Monolithic Systems part only.</b> Everything below comes from the AMS datasheet and applies to AMS-branded silicon. The same part number is second-sourced by UMW with a <b>different voltage lineup, different packages and materially different limits</b>. If your BOM says UMW, use <a href="https://wiki.adom.inc/adom/umw-ams1117">1 A Low-Dropout Regulator UMW - AMS1117</a> instead.</div> <div class=metarow> <span class=m>Output <b>1 A</b></span><span class=m>Dropout <b>1.3 V max</b></span><span class=m>V<sub>IN</sub> <b>15 V max</b></span> <span class=m>Versions <b>6 fixed + ADJ</b></span><span class=m>Packages <b>SOT-223 · TO-252 · SO-8</b></span><span class=m>Pins <b>3 (8 on SO-8)</b></span>@@ -102,9 +102,9 @@ code{background:rgba(139,148,158,.16);padding:1px 6px;border-radius:5px;font-siz <h2>Specifications</h2> <div> <div class=spec><span class=lbl>Output current</span><span>1 A</span></div>-<div class=spec><span class=lbl>Fixed output voltages</span><span>1.5 / 1.8 / 2.5 / 2.85 / 3.3 / 5.0 V — also available adjustable</span></div>-<div class=spec><span class=lbl>Reference voltage</span><span>1.250 V typ (1.232 – 1.268 V at 25 °C, I<sub>OUT</sub> = 10 mA)</span></div>-<div class=spec><span class=lbl>Dropout voltage</span><span>1.1 V typ, 1.3 V max at I<sub>OUT</sub> = 0.8 A — higher above 0.8 A</span></div>+<div class=spec><span class=lbl>Fixed output voltages</span><span>1.5 / 1.8 / 2.5 / 2.85 / 3.3 / 5.0 V. Also available adjustable</span></div>+<div class=spec><span class=lbl>Reference voltage</span><span>1.250 V typ (1.232 to 1.268 V at 25 °C, I<sub>OUT</sub> = 10 mA)</span></div>+<div class=spec><span class=lbl>Dropout voltage</span><span>1.1 V typ, 1.3 V max at I<sub>OUT</sub> = 0.8 A. Higher above 0.8 A</span></div> <div class=spec><span class=lbl>Input voltage</span><span>15 V absolute maximum</span></div> <div class=spec><span class=lbl>Line regulation</span><span>0.2 % max (0.015 % typ)</span></div> <div class=spec><span class=lbl>Load regulation</span><span>0.4 % max (0.1 % typ), 10 mA ≤ I<sub>OUT</sub> ≤ 0.8 A</span></div>@@ -114,7 +114,7 @@ code{background:rgba(139,148,158,.16);padding:1px 6px;border-radius:5px;font-siz <div class=spec><span class=lbl>Ripple rejection</span><span>60 dB min; 75 dB typ adjustable, 72 dB fixed, 68 dB on the 5.0 V version (120 Hz, C<sub>OUT</sub> = 22 µF)</span></div> <div class=spec><span class=lbl>Adjust pin current</span><span>55 µA typ, 120 µA max · change 0.2 µA typ, 5 µA max</span></div> <div class=spec><span class=lbl>Thermal regulation</span><span>0.008 %/W typ, 0.04 %/W max (30 ms pulse)</span></div>-<div class=spec><span class=lbl>RMS output noise</span><span>0.003 % of V<sub>OUT</sub> (10 Hz – 10 kHz)</span></div>+<div class=spec><span class=lbl>RMS output noise</span><span>0.003 % of V<sub>OUT</sub> (10 Hz to 10 kHz)</span></div> <div class=spec><span class=lbl>Temperature stability</span><span>0.5 % typ</span></div> <div class=spec><span class=lbl>Long term stability</span><span>0.3 % typ, 1 % max (1000 h at 125 °C)</span></div> <div class=spec><span class=lbl>Protection</span><span>Internal current limit + thermal shutdown at 165 °C junction</span></div>@@ -122,30 +122,30 @@ code{background:rgba(139,148,158,.16);padding:1px 6px;border-radius:5px;font-siz <div class=spec><span class=lbl>Thermal resistance θ<sub>JC</sub></span><span>15 °C/W max, all packages</span></div> <div class=spec><span class=lbl>Operating junction temp</span><span>−40 to +125 °C · storage −65 to +150 °C</span></div> <div class=spec><span class=lbl>Soldering</span><span>Lead temperature 265 °C, 25 s</span></div>-<div class=spec><span class=lbl>Required output cap</span><span>22 µF solid tantalum — part of the loop compensation, not optional</span></div>+<div class=spec><span class=lbl>Required output cap</span><span>22 µF solid tantalum. Part of the loop compensation, not optional</span></div> </div> <h2>Symbol & footprint</h2> <div class=viewers2>-<div><div class=vh>Schematic symbol — hover a pin for its function</div>+<div><div class=vh>Schematic symbol: hover a pin for its function</div> <iframe class=vframe height=520 loading=lazy title="AMS1117 schematic symbol" src="https://wiki.adom.inc/api/v1/pages/adom/ams-ams1117/files/viewer-symbol.html"></iframe></div>-<div><div class=vh>PCB footprint — switch package bottom-right (SOT-223 / TO-252 / SO-8)</div>+<div><div class=vh>PCB footprint: switch package bottom-right (SOT-223 / TO-252 / SO-8)</div> <iframe class=vframe height=520 loading=lazy title="AMS1117 footprint (SOT-223 / TO-252 / SO-8)" src="https://wiki.adom.inc/api/v1/pages/adom/ams-ams1117/files/viewer-footprints.html"></iframe></div> </div> -<h2>Pin map <span style="color:var(--text-2);font-weight:400;font-size:14px">— 3 terminals on SOT-223 / TO-252, 8 leads on SOIC</span></h2>+<h2>Pin map <span style="color:var(--text-2);font-weight:400;font-size:14px">3 terminals on SOT-223 / TO-252, 8 leads on SOIC</span></h2> <div class=callout>On <b>both SOT-223 and TO-252 the metal tab is V<sub>OUT</sub></b>, internally bonded to pin 2. It is the heat path, so it must be soldered to a copper pour on the output net, never to ground. Both footprints shipped here carry the tab as pad 2.</div> <div class=pinwrap> <div class=pg><div class=pgh style="border-color:#00b8b1"><span class=dot style="background:#00b8b1"></span>SOT-223 & TO-252<span class=ct>3 + tab</span></div><table class=pt><tbody> <tr><td class=pn>1</td><td class=nm>GND/ADJ</td><td class=fx>Ground on fixed versions; feedback (adjust) node on the adjustable version</td></tr>-<tr><td class=pn>2</td><td class=nm>VOUT</td><td class=fx>Regulated output — also the metal tab</td></tr>+<tr><td class=pn>2</td><td class=nm>VOUT</td><td class=fx>Regulated output. Also the metal tab</td></tr> <tr><td class=pn>3</td><td class=nm>VIN</td><td class=fx>Unregulated input, 15 V max</td></tr>-<tr><td class=pn>—</td><td class=nm>TAB</td><td class=fx>Thermal pad, bonded to pin 2 (V<sub>OUT</sub>)</td></tr>+<tr><td class=pn>n/a</td><td class=nm>TAB</td><td class=fx>Thermal pad, bonded to pin 2 (V<sub>OUT</sub>)</td></tr> </tbody></table></div> <div class=pg><div class=pgh style="border-color:#8c6bf7"><span class=dot style="background:#8c6bf7"></span>8-lead SOIC<span class=ct>8</span></div><table class=pt><tbody> <tr><td class=pn>1</td><td class=nm>GND/ADJ</td><td class=fx>Ground on fixed versions; adjust node on the adjustable version</td></tr> <tr><td class=pn>2</td><td class=nm>VOUT</td><td class=fx>Regulated output</td></tr>-<tr><td class=pn>3</td><td class=nm>VOUT</td><td class=fx>Regulated output — tie all V<sub>OUT</sub> leads together</td></tr>+<tr><td class=pn>3</td><td class=nm>VOUT</td><td class=fx>Regulated output. Tie all V<sub>OUT</sub> leads together</td></tr> <tr><td class=pn>4</td><td class=nm>VIN</td><td class=fx>Unregulated input, 15 V max</td></tr> <tr><td class=pn>5</td><td class=nm>N/C</td><td class=fx>No internal connection</td></tr> <tr><td class=pn>6</td><td class=nm>VOUT</td><td class=fx>Regulated output</td></tr>@@ -159,47 +159,47 @@ code{background:rgba(139,148,158,.16);padding:1px 6px;border-radius:5px;font-siz <div class=occode> <div class=ocbig><span style="color:#e6edf3">AMS1117</span><span style="color:#8c6bf7">CD</span><span style="color:#00e6dc">-3.3</span></div> <div class=oclegend>-<div class=ocitem><div class=octop><span class=sw style="background:#8b949e"></span><b style="color:#e6edf3">AMS1117</b></div><div class=ocdesc>base part — 1 A LDO</div></div>+<div class=ocitem><div class=octop><span class=sw style="background:#8b949e"></span><b style="color:#e6edf3">AMS1117</b></div><div class=ocdesc>base part: 1 A LDO</div></div> <div class=ocitem><div class=octop><span class=sw style="background:#8c6bf7"></span><b style="color:#a98bf9">CD / CS / blank</b></div><div class=ocdesc><code>CD</code> = TO-252 (DPAK) · <code>CS</code> = 8-lead SOIC · blank = SOT-223</div></div>-<div class=ocitem><div class=octop><span class=sw style="background:#00e6dc"></span><b style="color:#00e6dc">-3.3</b></div><div class=ocdesc>fixed output voltage — blank means the adjustable version</div></div>+<div class=ocitem><div class=octop><span class=sw style="background:#00e6dc"></span><b style="color:#00e6dc">-3.3</b></div><div class=ocdesc>fixed output voltage. Blank means the adjustable version</div></div> </div> </div> <div class=vgrid> <div class=vcard> <h3>SOT-223<span class=chip style="background:rgba(139,148,158,.18);color:#8b949e">no letter</span></h3>-<div class=sub>6.30–6.71 × 3.30–3.71 mm, 1.80 mm max height · 2.30 mm lead pitch · tab = V<sub>OUT</sub></div>+<div class=sub>6.30 to 6.71 × 3.30 to 3.71 mm, 1.80 mm max height · 2.30 mm lead pitch · tab = V<sub>OUT</sub></div> <div class=oc><b>Fixed:</b> <code>AMS1117-1.5</code> <code>-1.8</code> <code>-2.5</code> <code>-2.85</code> <code>-3.3</code> <code>-5.0</code></div> <div class=oc><b>Adjustable:</b> <code>AMS1117</code></div> <div class=oc>θ<sub>JA</sub> <b>90 °C/W</b> · 1.2 W max dissipation</div> </div> <div class=vcard> <h3>TO-252 (DPAK) <code style="font-size:13px">CD</code></h3>-<div class=sub>6.48–6.73 × 5.97–6.22 mm body, 2.21–2.39 mm height · tab = V<sub>OUT</sub></div>+<div class=sub>6.48 to 6.73 × 5.97 to 6.22 mm body, 2.21 to 2.39 mm height · tab = V<sub>OUT</sub></div> <div class=oc><b>Fixed:</b> <code>AMS1117CD-1.5</code> <code>-1.8</code> <code>-2.5</code> <code>-2.85</code> <code>-3.3</code> <code>-5.0</code></div> <div class=oc><b>Adjustable:</b> <code>AMS1117CD</code></div>-<div class=oc>θ<sub>JA</sub> <b>80 °C/W</b> · 2.2 W max dissipation — the best thermal option</div>+<div class=oc>θ<sub>JA</sub> <b>80 °C/W</b> · 2.2 W max dissipation. The best thermal option</div> </div> <div class=vcard> <h3>8-lead SOIC <code style="font-size:13px">CS</code></h3>-<div class=sub>4.80–5.00 × 3.81–3.99 mm body, 1.27 mm pitch · V<sub>OUT</sub> on four leads</div>+<div class=sub>4.80 to 5.00 × 3.81 to 3.99 mm body, 1.27 mm pitch · V<sub>OUT</sub> on four leads</div> <div class=oc><b>Fixed:</b> <code>AMS1117CS-1.5</code> <code>-1.8</code> <code>-2.5</code> <code>-2.85</code> <code>-3.3</code> <code>-5.0</code></div> <div class=oc><b>Adjustable:</b> <code>AMS1117CS</code></div>-<div class=oc>θ<sub>JA</sub> <b>160 °C/W</b> · 780 mW max dissipation — lowest power</div>+<div class=oc>θ<sub>JA</sub> <b>160 °C/W</b> · 780 mW max dissipation: lowest power</div> </div> </div> <h2>Output voltage versions</h2> <p style="color:var(--text-2);font-size:14px;margin:0 0 10px">Limits at T<sub>J</sub> = 25 °C. The test V<sub>IN</sub> is the datasheet condition for each part; load regulation is measured at 0 ≤ I<sub>OUT</sub> ≤ 0.8 A.</p>-<table class=vt><thead><tr><th>Version</th><th>V<sub>OUT</sub> typ</th><th>Min – max</th><th>Test V<sub>IN</sub></th><th>Line reg. typ / max</th><th>Load reg. typ / max</th><th>Ripple rej. typ</th></tr></thead><tbody>-<tr><td>AMS1117-1.5</td><td>1.500 V</td><td>1.478 – 1.522 V</td><td>3.0 V</td><td>0.3 / 5 mV</td><td>3 / 10 mV</td><td>72 dB</td></tr>-<tr><td>AMS1117-1.8</td><td>1.800 V</td><td>1.773 – 1.827 V</td><td>3.3 V</td><td>0.3 / 5 mV</td><td>3 / 10 mV</td><td>72 dB</td></tr>-<tr><td>AMS1117-2.5</td><td>2.500 V</td><td>2.463 – 2.537 V</td><td>4.0 V</td><td>0.3 / 6 mV</td><td>3 / 12 mV</td><td>72 dB</td></tr>-<tr><td>AMS1117-2.85</td><td>2.850 V</td><td>2.808 – 2.892 V</td><td>4.35 V</td><td>0.3 / 6 mV</td><td>3 / 12 mV</td><td>72 dB</td></tr>-<tr><td>AMS1117-3.3</td><td>3.300 V</td><td>3.251 – 3.349 V</td><td>4.8 V</td><td>0.5 / 10 mV</td><td>3 / 15 mV</td><td>72 dB</td></tr>-<tr><td>AMS1117-5.0</td><td>5.000 V</td><td>4.925 – 5.075 V</td><td>6.5 V</td><td>0.5 / 10 mV</td><td>5 / 20 mV</td><td>68 dB</td></tr>-<tr><td>AMS1117 (ADJ)</td><td>1.250 V ref</td><td>1.232 – 1.268 V</td><td>—</td><td>0.015 / 0.2 %</td><td>0.1 / 0.3 %</td><td>75 dB</td></tr>+<table class=vt><thead><tr><th>Version</th><th>V<sub>OUT</sub> typ</th><th>Min to max</th><th>Test V<sub>IN</sub></th><th>Line reg. typ / max</th><th>Load reg. typ / max</th><th>Ripple rej. typ</th></tr></thead><tbody>+<tr><td>AMS1117-1.5</td><td>1.500 V</td><td>1.478 to 1.522 V</td><td>3.0 V</td><td>0.3 / 5 mV</td><td>3 / 10 mV</td><td>72 dB</td></tr>+<tr><td>AMS1117-1.8</td><td>1.800 V</td><td>1.773 to 1.827 V</td><td>3.3 V</td><td>0.3 / 5 mV</td><td>3 / 10 mV</td><td>72 dB</td></tr>+<tr><td>AMS1117-2.5</td><td>2.500 V</td><td>2.463 to 2.537 V</td><td>4.0 V</td><td>0.3 / 6 mV</td><td>3 / 12 mV</td><td>72 dB</td></tr>+<tr><td>AMS1117-2.85</td><td>2.850 V</td><td>2.808 to 2.892 V</td><td>4.35 V</td><td>0.3 / 6 mV</td><td>3 / 12 mV</td><td>72 dB</td></tr>+<tr><td>AMS1117-3.3</td><td>3.300 V</td><td>3.251 to 3.349 V</td><td>4.8 V</td><td>0.5 / 10 mV</td><td>3 / 15 mV</td><td>72 dB</td></tr>+<tr><td>AMS1117-5.0</td><td>5.000 V</td><td>4.925 to 5.075 V</td><td>6.5 V</td><td>0.5 / 10 mV</td><td>5 / 20 mV</td><td>68 dB</td></tr>+<tr><td>AMS1117 (ADJ)</td><td>1.250 V ref</td><td>1.232 to 1.268 V</td><td>n/a</td><td>0.015 / 0.2 %</td><td>0.1 / 0.3 %</td><td>75 dB</td></tr> </tbody></table>-<p style="color:var(--text-3);font-size:13px;margin:10px 0 0"><b>2.85 V is here for SCSI.</b> It is the SCSI-2 active-termination voltage — the datasheet lists "Active SCSI Terminators" as an application, and 2.85 V regulators exist almost entirely to hold a SCSI bus at spec through 110 Ω series resistors. It is the one version the UMW second source does not carry.</p>+<p style="color:var(--text-3);font-size:13px;margin:10px 0 0"><b>2.85 V is here for SCSI.</b> It is the SCSI-2 active-termination voltage. The datasheet lists "Active SCSI Terminators" as an application, and 2.85 V regulators exist almost entirely to hold a SCSI bus at spec through 110 Ω series resistors. It is the one version the UMW second source does not carry.</p> <h2>Thermal design</h2> <p style="color:var(--text-2);font-size:14px;margin:0 0 10px">P<sub>D</sub> = (V<sub>IN</sub> − V<sub>OUT</sub>) × I<sub>OUT</sub>, and T<sub>J</sub> = T<sub>A(max)</sub> + P<sub>D</sub>θ<sub>JA</sub> must stay under 125 °C. The datasheet's measured SOT-223 θ<sub>JA</sub> against copper area, on 1/16" FR-4 with 1 oz foil:</p>@@ -211,7 +211,7 @@ code{background:rgba(139,148,158,.16);padding:1px 6px;border-radius:5px;font-siz <tr><td>1000 mm²</td><td>1000 mm²</td><td>1000 mm²</td><td>60 °C/W</td></tr> <tr><td>1000 mm²</td><td>0</td><td>1000 mm²</td><td>65 °C/W</td></tr> </tbody></table>-<p style="color:var(--text-3);font-size:13px;margin:10px 0 0">The tab is attached to the top-side copper in every row. Note the spreading copper does <b>not</b> have to be electrically connected to the tab to be effective — a plane on the opposite side of the board works.</p>+<p style="color:var(--text-3);font-size:13px;margin:10px 0 0">The tab is attached to the top-side copper in every row. Note the spreading copper does <b>not</b> have to be electrically connected to the tab to be effective. A plane on the opposite side of the board works.</p> <h2>Assets</h2> <p style="color:var(--text-2);font-size:14px;margin:0 0 10px">KiCad symbol, all three footprints and matching 3D models, plus the canonical <b>adom-lbr JSON</b> the rest is generated from.</p>@@ -226,16 +226,16 @@ code{background:rgba(139,148,158,.16);padding:1px 6px;border-radius:5px;font-siz <h2>Implementation</h2> <ul class=ul>-<li><a href="https://wiki.adom.inc/adom/ams1117-3v3-molecule"><b>AMS1117-3.3 Molecule</b></a> — a 5 V → 3.3 V regulator brick: AMS1117-3.3 in SOT-223 with 10 µF input and 22 µF output decoupling on a machine-pin carrier.</li>-<li><a href="https://wiki.adom.inc/adom/umw-ams1117"><b>1 A Low-Dropout Regulator UMW — AMS1117</b></a> — the second-source part. Different voltage lineup, different third package, different limits.</li>+<li><a href="https://wiki.adom.inc/adom/ams1117-3v3-molecule"><b>AMS1117-3.3 Molecule</b></a>. A 5 V → 3.3 V regulator brick: AMS1117-3.3 in SOT-223 with 10 µF input and 22 µF output decoupling on a machine-pin carrier.</li>+<li><a href="https://wiki.adom.inc/adom/umw-ams1117"><b>1 A Low-Dropout Regulator UMW - AMS1117</b></a>. The second-source part. Different voltage lineup, different third package, different limits.</li> </ul> <h2>Application notes</h2> <ul class=ul> <li><b>The 22 µF output capacitor is compensation, not decoupling.</b> The AMS1117 loop depends on it; a solid tantalum 22 µF guarantees stability across all operating conditions. Bypassing the adjust pin improves ripple rejection but raises the output-capacitor requirement.</li>-<li><b>No protection diodes needed.</b> Internal resistors limit the adjust-pin current paths, so no diode from ADJ to output or input is required. A diode from output to input is only recommended when C<sub>OUT</sub> is very large (1000–5000 µF) and the input can be shorted; the internal diode already handles 50–100 A microsecond surges.</li>+<li><b>No protection diodes needed.</b> Internal resistors limit the adjust-pin current paths, so no diode from ADJ to output or input is required. A diode from output to input is only recommended when C<sub>OUT</sub> is large (1000 to 5000 µF) and the input can be shorted; the internal diode already handles 50 to 100 A microsecond surges.</li> <li><b>Kelvin the divider, not the load.</b> On the adjustable version, connect the top of R1 to the regulator case rather than the load, so parasitic line resistance is not multiplied by (R2+R1)/R1. Fixed versions Kelvin the top of R1 internally, so the ground pin can do negative-side sensing.</li>-<li><b>Adjust-pin bypassing.</b> For proper ripple rejection the adjust-pin capacitor's impedance at the ripple frequency must be below R1 (typically 100–200 Ω). With R1 = 100 Ω that is >13 µF at 120 Hz, but only 0.16 µF at 10 kHz.</li>+<li><b>Adjust-pin bypassing.</b> For proper ripple rejection the adjust-pin capacitor's impedance at the ripple frequency must be below R1 (typically 100 to 200 Ω). With R1 = 100 Ω that is >13 µF at 120 Hz, but only 0.16 µF at 10 kHz.</li> <li><b>Adjustable output:</b> V<sub>OUT</sub> = V<sub>REF</sub>(1 + R2/R1) + I<sub>ADJ</sub>R2, with V<sub>REF</sub> = 1.25 V and I<sub>ADJ</sub> ≈ 55 µA. The I<sub>ADJ</sub> term is small and constant and can usually be ignored.</li> </ul> @@ -245,9 +245,9 @@ code{background:rgba(139,148,158,.16);padding:1px 6px;border-radius:5px;font-siz <h2>Provenance</h2> <ul class=ul>-<li><b>Every electrical number on this page</b> is read from the Advanced Monolithic Systems datasheet embedded above — features and ordering from page 1, limits from the Electrical Characteristics tables on pages 2–3, application and thermal guidance from pages 4–5, package dimensions from pages 7–8. Nothing from any second source is mixed in.</li>+<li><b>Every electrical number on this page</b> is read from the Advanced Monolithic Systems datasheet embedded above. Features and ordering from page 1, limits from the Electrical Characteristics tables on pages 2 to 3, application and thermal guidance from pages 4 to 5, package dimensions from pages 7 to 8. Nothing from any second source is mixed in.</li> <li><b>Symbols:</b> generated with <code>adom-symbol</code> to the datasheet pin connections (3-pin fixed/adjustable version, and the 8-lead SOIC pinout).</li>-<li><b>Footprints:</b> the KiCad 10 official library land patterns, renamed — <code>SOT-223-3_TabPin2</code>, <code>TO-252-3_TabPin2</code> and <code>SOIC-8_3.9x4.9mm_P1.27mm</code>. The <code>TabPin2</code> variants are the correct choice here because the AMS1117 tab is V<sub>OUT</sub>, which is pin 2.</li>+<li><b>Footprints:</b> the KiCad 10 official library land patterns, renamed: <code>SOT-223-3_TabPin2</code>, <code>TO-252-3_TabPin2</code> and <code>SOIC-8_3.9x4.9mm_P1.27mm</code>. The <code>TabPin2</code> variants are the correct choice here because the AMS1117 tab is V<sub>OUT</sub>, which is pin 2.</li> <li><b>3D models:</b> the matching KiCad 10 official STEP models (<code>SOT-223.step</code>, <code>TO-252-3_TabPin2.step</code>, <code>SOIC-8_3.9x4.9mm_P1.27mm.step</code>), converted to GLB with <code>step2glb</code>.</li> <li><b>Canonical JSON:</b> <code>ams1117.adom-lbr.json</code>, imported from the KiCad symbol + SOT-223 footprint with <code>adom-lbr import-kicad</code>.</li> <li><b>The SCSI note</b> draws on the datasheet's own applications list plus the SCSI-2 active-termination literature (Linear Technology Design Note 34, which uses an LT1117-2.85 for exactly this).</li>