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Analog Devices Inc. LTM2985CY#PBF
- Part No.:
- LTM2985CY#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Sensor, Transducer Amplifiers
- Package:
- Datasheet:
-
LTM2985CY#PBF.pdf
- Description:
- ISOLATED HI ACCURACY DIGITAL TEM
- Quantity:
- Payment:
- Shipping:
Inventory:1,128
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Product details
Overview
LTM2985CY#PBF from Analog Devices is an isolated 10-channel high-accuracy digital temperature measurement system with integrated 5kV isolation barrier, SPI interface, and user-programmable EEPROM. It directly digitizes thermocouples (Types B, E, J, K, N, S, R, T), 2-/3-/4-wire RTDs, thermistors, and diodes with 0.1°C accuracy, 24-bit resolution, and simultaneous 50Hz/60Hz rejection - deployed in industrial process control, power plant monitoring, and high-reliability test equipment.
For engineers reviewing the LTM2985CY#PBF datasheet, LTM2985CY#PBF pinout, LTM2985CY#PBF application, or LTM2985CY#PBF equivalent, key selection criteria include its galvanic isolation rating (5000VRMS), cold junction compensation architecture, ratiometric excitation current matching for RTD/thermistor measurements, and compatibility with LTC2986-1 software ecosystem.
Technical Context
The LTM2985CY#PBF integrates a precision 24-bit sigma-delta ADC, on-chip 2.5V reference (15ppm/°C max), isolated DC/DC converter (VCC2 = 4.75–5.25V), and fault-detection circuitry for open/short conditions across all 10 analog inputs. Its dual-domain architecture separates logic-side SPI (VL = 1.62–5.5V) from isolated analog domain (VCC2/GND2), enabling safe measurement of sensors referenced to noisy or floating grounds.
It implements automatic sensor-type detection per channel, supports 2- and 3-cycle conversion modes (164ms / 246ms typical), and embeds NIST-traceable polynomial coefficients for thermocouple linearization up to 14th order. The device performs real-time cold junction compensation using any supported sensor type connected to CH1–CH10, with no external components required for standard configurations.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Accuracy | ±0.1°C over full range - enables Class A RTD or Type K thermocouple compliance without system-level calibration. |
| Resolution | 24 bits with no missing codes - delivers 0.001°C effective resolution for fine-grained thermal trending. |
| Isolation Rating | 5000VRMS (1 min) - meets IEC 61010-1 reinforced insulation requirements for CAT II 1000V environments. |
| Input Channels | 10 flexible analog inputs (CH1–CH10) + COM - supports mixed-sensor deployments (e.g., 4x RTD + 3x thermocouple + 2x thermistor + 1x diode) on single board. |
| Reference Stability | 15ppm/°C max (C-grade) - ensures measurement integrity across 0°C to 70°C operating range without external reference. |
| Conversion Time | 164ms (2-cycle) / 246ms (3-cycle) - balances speed vs. 50/60Hz noise rejection for factory-floor EMI resilience. |
| EEPROM Endurance | 10,000 write cycles with 10-year data retention - stores custom coefficients, channel configurations, and calibration offsets persistently. |
Pinout & Package
Package: 66-ball BGA (22mm × 15mm × 3.66mm), RoHS-compliant SAC305 finish, MSL Level 4, 0°C to 70°C ambient operating range.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CH1–CH10 | Analog input channels | Configurable per-channel for thermocouple, RTD, thermistor, or diode sensing; support single-ended, differential, or ratiometric modes. |
| COM | Common reference node | Negative input for all single-ended measurements; tied to GND2 but not electrically identical to it due to isolation barrier. |
| VCC / VCC2 | Primary & isolated supply rails | VCC powers logic side (4.5–5.5V); VCC2 is internally generated 5V rail (±250mV) for analog domain - eliminates need for external isolated DC/DC. |
| SCK / SDI / SDO / CS / SDOE | SPI interface signals | Logic-side SPI bus (VL-referenced); SDOE enables tri-state control for multi-device buses; all meet 1.5MHz timing specs with 350ns min pulse width. |
| ON | System enable control | Active-high enable: asserts power-up sequence and isolation barrier handshake; low state places logic outputs in Hi-Z and disables VCC2 generation. |
| INT | Conversion completion interrupt | Open-drain output referenced to GND2; transitions HIGH after conversion completes - used for deterministic polling or IRQ-driven firmware. |
| VREF | Internal reference output | 2.5V ±10mV precision reference (15ppm/°C max); must be bypassed with 10µF to GND2 - not loadable beyond 100µA. |
Key Features
| Feature | Design Value |
|---|---|
| 5kV galvanic isolation barrier | Enables direct connection to high-voltage assets (e.g., motor windings, transformer bushings) without external isolators or level shifters. |
| Automatic cold junction compensation | Eliminates need for discrete cold-junction sensor and associated signal conditioning - uses any channel's RTD/thermistor/diode reading as CJC source. |
| Ratiometric excitation current sources | RTD/thermistor accuracy immune to current-source drift; matching error within ADC noise floor ensures <±0.01% gain error contribution. |
| Simultaneous 50Hz/60Hz rejection | Hardware-based filtering achieves >75dB normal-mode rejection at line frequencies - critical for AC-powered industrial enclosures. |
| On-chip EEPROM storage | Persists channel-specific sensor types, custom polynomials, linearization coefficients, and fault thresholds - enables field-reconfigurable sensor networks. |
Applications
| Industrial Process Control | Power Generation Monitoring |
|---|---|
|
Use Scenario: Real-time temperature profiling of boiler tubes, steam headers, and turbine casings in fossil-fuel and nuclear plants. IC Role / Device Role / Timing Role: Isolated front-end ADC converting Type K/N thermocouple outputs into calibrated °C values for PLC SCADA ingestion via SPI. Use Value: 5000VRMS isolation prevents ground-loop damage during maintenance hot-swaps; 0.1°C accuracy meets ASME PTC 19.3TW thermowell calibration requirements. |
Use Scenario: Distributed temperature sensing across generator stator windings, transformer oil sumps, and switchgear busbars. IC Role / Device Role / Timing Role: Multi-sensor hub digitizing PT-100 RTDs and 3904 diodes with automatic burnout detection and fault flagging. Use Value: 10-channel flexibility reduces board count vs. discrete solutions; built-in 50/60Hz rejection suppresses EMI from nearby VFDs and rectifiers. |
| Test & Measurement Equipment | High-Reliability Data Acquisition |
|
Use Scenario: Modular DAQ modules for semiconductor thermal validation chambers requiring traceable, NIST-compatible readings. IC Role / Device Role / Timing Role: Precision temperature engine performing cold-junction-compensated thermocouple linearization using embedded 14th-order polynomials. Use Value: On-chip EEPROM stores custom coefficients for non-standard thermocouples; 24-bit resolution enables sub-millidegree delta-T tracking over 1000+ hour soak tests. |
Use Scenario: Redundant sensor nodes in aerospace ground-support systems where single-point failure must be avoided. IC Role / Device Role / Timing Role: Fault-tolerant temperature monitor with automatic open/short detection, buffered inputs for external TVS protection, and INT-driven alerting. Use Value: Buffered inputs tolerate ±15mA transient currents; simultaneous channel scanning ensures no thermal event escapes detection between conversions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated temperature measurement applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC2986-1 | No integrated isolation barrier; requires external isolated power and signal isolators; same software stack and sensor math engine. | Better suited for space-constrained designs where isolation can be implemented at system level (e.g., using ADuM series isolators). | Select LTC2986-1 when board layout allows separation of isolation components and higher design flexibility is needed. |
| AD7415ARMZ | Non-isolated, single-channel, 10-bit I²C local temperature sensor; no thermocouple/RTD support; ±2°C accuracy. | Limited to PCB-local die temperature monitoring; cannot interface with industrial sensors or withstand ground potential differences. | Choose AD7415ARMZ only for cost-sensitive, non-isolated board-temperature supervision - not a functional substitute. |
Compared with LTC2986-1, the LTM2985CY#PBF trades software compatibility for integrated isolation and reduced BOM count; versus AD7415ARMZ, it delivers 14× higher resolution, 20× better accuracy, and full sensor-type versatility - making it the sole option for certified isolated multi-sensor systems.
Availability
LTM2985CY#PBF is available at Aetrix Electronics and suitable for industrial process control, power generation monitoring, and high-reliability test equipment requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant sourcing.
Supply support for LTM2985CY#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTM2985CY#PBF belongs to Analog Devices' isolated precision measurement product line, designed specifically for high-accuracy, safety-certified temperature acquisition in electrically hostile environments where ground separation and noise immunity are mandatory.
FAQ
What is the operating temperature range for the LTM2985CY#PBF?
The LTM2985CY#PBF is specified for 0°C to 70°C ambient operation (C-grade). This range covers most industrial control cabinets and laboratory instrumentation environments. Junction temperature must not exceed 105°C, and thermal design should account for θJA = 31.7°C/W on the demo board layout. Derating is required above 70°C ambient unless heatsinking or airflow is added.
Does the LTM2985CY#PBF require external components for basic thermocouple operation?
No - the LTM2985CY#PBF integrates all necessary circuitry for thermocouple measurement, including cold junction compensation, linearization polynomials, excitation sources, and fault detection. Only decoupling capacitors (2.2µF on VCC/VL, 10µF on VREF) and optional input protection (TVS, RC filters) are needed. No external op-amps, references, or isolators are required for standard Type K/J/E operation.
How does the LTM2985CY#PBF handle RTD excitation current matching?
The LTM2985CY#PBF provides matched ratiometric excitation currents for RTD measurements, with matching error within the ADC's noise floor - eliminating gain error contribution from current-source variation. This ensures absolute accuracy depends only on the RTD's tolerance and lead-wire resistance, not on excitation current stability, simplifying system calibration.
Can the LTM2985CY#PBF measure negative voltages relative to GND2?
Yes - the LTM2985CY#PBF supports analog input voltages from (GND2 – 0.05V) to (VCC2 – 0.3V), enabling direct measurement of thermocouple outputs that swing negative during cold-junction compensation or low-temperature operation. This eliminates the need for level-shifting circuitry when measuring Type T or Type E thermocouples below 0°C.
What EEPROM capabilities does the LTM2985CY#PBF provide for field configuration?
The LTM2985CY#PBF includes 10,000-cycle, 10-year-retention EEPROM storing channel-specific sensor types, custom thermocouple/RTD/thermistor coefficients, fault thresholds, and calibration offsets. Configuration persists through power cycles and enables reprogramming in-system via SPI - critical for deploying identical hardware across diverse sensor fleets.
LTM2985CY#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Packaging:
- Tray
- Product Status:
- Active
- Amplifier Type:
- General Purpose
- Voltage - Supply:
- 4.5V ~ 5.5V
- Output Type:
- SPI
- Current - Supply:
- 80 mA
- Operating Temperature:
- 0°C ~ 70°C
- Mounting Type:
- Surface Mount
LTM2985CY#PBF FAQ
1.How can I place an order for LTM2985CY#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTM2985CY#PBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LTM2985CY#PBF reliable?
The price and inventory of LTM2985CY#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTM2985CY#PBF is usually 5 days.
3.What payment methods are accepted for LTM2985CY#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTM2985CY#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTM2985CY#PBF?
LTM2985CY#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTM2985CY#PBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LTM2985CY#PBF?
For technical support, including LTM2985CY#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTM2985CY#PBF requirements.
6.How does Aetrix verify that LTM2985CY#PBF is sourced from the original manufacturer or authorized distributors?
All LTM2985CY#PBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LTM2985CY#PBF meets industry standards.
7.What is the process for return or replacement of LTM2985CY#PBF?
All LTM2985CY#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTM2985CY#PBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LTM2985CY#PBF part is unused and in its original packaging.
Return procedure for LTM2985CY#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LTM2985CY#PBF Tags
-
SEN-13879
SparkFun Electronics
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GA-311
Panasonic Industrial Automation Sales
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E32-T11N 2M
Omron Automation and Safety
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FX-501P
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FX-501
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E3X-HD44
Omron Automation and Safety
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E3X-HD41 2M
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FX-502
Panasonic Industrial Automation Sales
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ASTC0000
Red Lion Controls
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E3X-HD11 2M
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E3NX-MA11
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