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MAX31855 Thermocouple Converter
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Cold-junction compensated thermocouple-to-digital converter with 14-bit SPI output.
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README.md+61−2@@ -1,5 +1,64 @@ # MAX31855 -Thermocouple-to-digital converter, SPI, SOIC-8+**Analog Devices** · Thermocouple Interface · SOIC-8 -The MAX31855 is a cold-junction compensated thermocouple-to-digital converter from Maxim. Reads K, J, N, S, T, E, or R type thermocouples via SPI. 14-bit resolution covering -200C to +1800C.+The MAX31855 is a thermocouple-to-digital converter that digitizes a thermocouple with cold-junction compensation and a 14-bit, 0.25 C resolution result over a read-only SPI interface. It detects open, short-to-GND, and short-to-VCC faults. This page shows the K-type (MAX31855K); the family also covers J, N, T, S, R, and E types.++## Pinout++| Pin | Name | Type | Function |+|---|---|---|---|+| 1 | GND | power_in | Ground reference. Connect to system ground; a large ground plane improves temperature-measurement accuracy. |+| 2 | T- | input | Negative thermocouple input (see Table 1 for wire type per part suffix). Do NOT connect to GND. Recommend a 10nF differential capacitor across T+/T- for noise filtering. |+| 3 | T+ | input | Positive thermocouple input (see Table 1 for wire type per part suffix). Bias current -100nA to +100nA at 100mV across inputs. |+| 4 | VCC | power_in | Power-supply voltage input, 3.0V to 3.6V (3.3V typical). Bypass to GND with a 0.1µF ceramic capacitor placed close to the pin. ICC ≈ 900µA typical, 1500µA max. |+| 5 | SCK | input | SPI serial-clock input, up to 5MHz. Minimum high/low pulse width 100ns; rise/fall ≤ 200ns. |+| 6 | CS | input | Active-low chip-select input. Drive CS low to enable the serial interface and clock out 32 bits of thermocouple + reference-junction data on SO. |+| 7 | SO | output | SPI serial-data output (MISO). Read-only 32-bit frame containing 14-bit thermocouple temperature, fault bit, 12-bit internal cold-junction temperature, and SCV/SCG/OC fault bits. VOH ≥ VCC-0.4V at IOUT=-1.6mA; VOL ≤ 0.4V at IOUT=1.6mA. |+| 8 | DNC | unconnected | Do Not Connect. Leave floating. |++## Key specifications++| Parameter | Value |+|---|---|+| Type | Thermocouple-to-digital converter |+| Thermocouple (this variant) | K-type (family: J/N/T/S/R/E/K) |+| Resolution | 14-bit, 0.25 C |+| Temperature range | -270 C to +1800 C (type dependent) |+| Cold-junction compensation | Internal |+| Interface | SPI (read-only) |+| Fault detection | Open, short-to-GND, short-to-VCC |+| Supply voltage | 3.0 V to 3.6 V |++## Ordering variants++- `MAX31855KASA+`+- `MAX31855KASA+T`+- `MAX31855JASA+`+- `MAX31855JASA+T`+- `MAX31855NASA+`+- `MAX31855NASA+T`+- `MAX31855SASA+`+- `MAX31855SASA+T`+- `MAX31855TASA+`+- `MAX31855TASA+T`+- `MAX31855EASA+`+- `MAX31855EASA+T`+- `MAX31855RASA+`+- `MAX31855RASA+T`++## CAD (KiCad official)++- Symbol: `max31855.kicad_sym`+- Footprint: `max31855.kicad_mod`+- 3D model: SOIC-8 body from KiCad `Package_SO/SOIC-8_3.9x4.9mm_P1.27mm`.++## Provenance++Data extracted from the manufacturer datasheet, not a distributor listing:++- **Datasheet:** [Analog Devices datasheet](https://www.analog.com/media/en/technical-documentation/data-sheets/MAX31855.pdf) (13 pp, sha256 `0da8c21e66d26950`, retrieved 2026-08-17, tier: manufacturer)+- **Extractor:** `ds2sf` (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.+- **CAD:** KiCad official libraries (CC-BY-SA 4.0).++[Datasheet PDF](docs/max31855-datasheet.pdf)
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package.jsonadded+30@@ -0,0 +1,30 @@+{+ "slug": "max31855",+ "version": "0.1.0",+ "type": "component",+ "description": "Cold-junction compensated thermocouple-to-digital converter with 14-bit SPI output.",+ "tags": [+ "thermocouple",+ "temperature",+ "spi",+ "cold-junction",+ "adi",+ "soic-8"+ ],+ "dependencies": {},+ "hero": {+ "type": "image",+ "path": "docs/hero.png"+ },+ "files": [+ "page.json",+ "README.md",+ "max31855.kicad_sym",+ "max31855.kicad_mod",+ "max31855.glb",+ "docs/hero.png",+ "docs/max31855-datasheet.pdf",+ "viewers/symbol.html",+ "viewers/footprint.html"+ ]+}
page.json+27−7@@ -4,8 +4,15 @@ "slug": "max31855", "title": "MAX31855", "brief": "Thermocouple-to-digital converter, SPI, SOIC-8",- "version": "1.0.0",- "tags": [],+ "version": "0.1.0",+ "tags": [+ "thermocouple",+ "temperature",+ "spi",+ "cold-junction",+ "adi",+ "soic-8"+ ], "license": "MIT", "component": { "mpn": "MAX31855",@@ -20,18 +27,31 @@ }, "readme": "# MAX31855\n\nThermocouple-to-digital converter, SPI, SOIC-8\n\nThe MAX31855 is a cold-junction compensated thermocouple-to-digital converter from Maxim. Reads K, J, N, S, T, E, or R type thermocouples via SPI. 14-bit resolution covering -200C to +1800C.", "author": {- "id": "695820315b5f1e4db2fcf602", "name": "Kyle Bergstedt", "email": "[email protected]" },- "visibility": {- "public": true+ "visibility": "public",+ "hero": {+ "type": "image",+ "path": "docs/hero.png" },- "hero": null, "sample_prompts": [], "discovery_triggers": [], "discovery_pitch": null, "metadata": {}, "created_at": "2026-05-28T05:33:46.807Z",- "updated_at": "2026-05-28T05:33:46.807Z"+ "updated_at": "2026-05-28T05:33:46.807Z",+ "description": "Cold-junction compensated thermocouple-to-digital converter with 14-bit SPI output.",+ "dependencies": {},+ "files": [+ "page.json",+ "README.md",+ "max31855.kicad_sym",+ "max31855.kicad_mod",+ "max31855.glb",+ "docs/hero.png",+ "docs/max31855-datasheet.pdf",+ "viewers/symbol.html",+ "viewers/footprint.html"+ ] }