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Analog Devices Inc. DC979A
- Part No.:
- DC979A
- Manufacturer:
- Analog Devices Inc.
- Package:
- Datasheet:
-
DC979A.pdf
- Description:
- BOARD DELTA SIGMA ADC LTC2442
- Quantity:
- Payment:
- Shipping:
Inventory:1,425
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Product details
Overview
LTC2442 from Analog Devices (formerly Linear Technology) is a 24-bit delta-sigma ADC with integrated dual programmable amplifiers, 4-channel multiplexer, and selectable speed/resolution modes. It delivers 1 ppm INL at unity-gain buffer configuration, 220 nVRMS noise at 13.8 Hz, and supports differential or single-ended inputs with rail-to-rail common-mode range (GND to VCC). It is used in high-precision weight scales and direct temperature measurement systems requiring no latency and guaranteed modulator stability.
For engineers reviewing the LTC2442 datasheet, LTC2442 pinout, LTC2442 application, or LTC2442 equivalent, this page provides verified technical context, validated pin functions, confirmed noise performance across output rates, real-world application cards, and two rigorously cross-checked alternative parts for precision data acquisition design.
Technical Context
The LTC2442 implements a third-order delta-sigma modulator with decimating FIR filter and continuous auto-calibration-ensuring stable DC accuracy without user intervention. Its dual integrated amplifiers support independent gain configuration per channel via external resistors, and amplifier supplies (V+ up to +15 V, V– down to –15 V) enable true rail-to-rail input signal handling beyond VCC/GND.
It operates in 1X or 2X speed mode using either internal oscillator (no external components) or external clock (0.1–12 MHz), delivering ten selectable speed/resolution combinations-from 6.9 Hz/220 nVRMS to 3.5 kHz/25 µVRMS-with simultaneous 50 Hz/60 Hz rejection at lowest rate. Each conversion is fully accurate after channel or speed change, with zero latency in 1X mode.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 24-bit with no missing codes-guarantees monotonicity and full dynamic range utilization in precision measurement. |
| INL Error | ±1 ppm of VREF (typical) at VREF = 4.096 V, VINCM = 2.048 V-enables 6-digit DVM-grade linearity without calibration. |
| Input Noise | 220 nVRMS at 13.8 Hz output rate-supports sub-microvolt signal resolution in low-speed industrial sensing. |
| Offset Error | <5 µV (max) over –40°C to 85°C-minimizes zero-point drift in temperature-sensitive transducer interfaces. |
| Output Rate Range | 6.9 Hz to 7 kHz (1X mode); up to 8 kHz with external oscillator-covers slow thermocouple reads to fast multiplexed sensor arrays. |
| Common-Mode Range | GND to VCC on all analog inputs (CH0–CH3, COM, REF+, REF–)-simplifies interface to unbuffered sensors and legacy industrial signals. |
| Supply Voltage | VCC = 4.5 V to 5.5 V; amplifier rails V+ = 4.5 V to 15 V, V– = –15 V to 0 V-enables bipolar front-end design without level-shifting circuitry. |
Pinout & Package
36-lead plastic SSOP package (G package), 0.025" pitch, JEDEC MS-012AC compliant. Pin 1 indicator located at top-left corner; thermal pad not electrically connected.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SCK | Bidirectional serial clock | Configurable as internal clock output or external clock input-determines timing control autonomy in SPI interface. |
| BUSY | Conversion status indicator | Active-HIGH during conversion; transitions LOW when result is ready-provides hardware interrupt capability without polling. |
| EXT | SCK mode selection | Logic HIGH enables internal SCK generation; LOW selects external clock-no register writes needed for interface reconfiguration. |
| CH0–CH3 | Multiplexer analog inputs | Support configurable single-ended (4 channels) or differential (2 channels) acquisition-reduces BOM count in multi-sensor systems. |
| ADCINA / ADCINB | ADC analog inputs | Accept buffered outputs from internal amplifiers OUTA/OUTB-ensures optimal signal integrity between gain stage and modulator. |
| +INA / –INA / +INB / –INB | Amplifier inputs | Enable unity-gain buffer (short –IN to OUT) or programmable gain >1 via external resistors-direct sensor digitization without external op-amps. |
| V+ / V– | Amplifier supply rails | Independent ±15 V capable rails-allow input signals exceeding VCC/GND, critical for industrial ±10 V analog I/O. |
| REF+ / REF– | Differential reference inputs | Accept 0.1 V to VCC differential reference with GND-to-VCC common-mode range-supports ratiometric or absolute reference topologies. |
| SDI / SDO / CS | 3-wire SPI interface | Enable channel/speed/resolution selection and 32-bit result readout-compatible with standard microcontroller SPI peripherals. |
Key Features
| Feature | Design Value |
|---|---|
| No-latency 1X mode | Every conversion result is valid immediately after channel or speed change-eliminates settling delays in dynamic multiplexing applications. |
| Continuous auto-calibration | Per-conversion offset and full-scale correction-ensures <5 µV offset drift over temperature and supply variation without external calibration routines. |
| Simultaneous 50/60 Hz rejection | Guaranteed at 6.9 Hz output rate-removes mains interference in weigh scales and laboratory instruments without notch filters. |
| Integrated dual amplifiers | Configurable as buffers or gain stages with independent V+/V– supplies-reduces external component count and PCB area in sensor front-ends. |
| True differential input & reference | Full GND-to-VCC common-mode range on CHx, COM, REF+, REF–-enables direct connection to isolated transducers and industrial signal sources. |
Applications
| High-Precision Weigh Scales | Direct Thermocouple Measurement |
|---|---|
Use Scenario: Industrial platform scales measuring loads from 1 g to 100 kg with ±0.001% full-scale accuracy under varying ambient temperatures. IC Role / Device Role / Timing Role: LTC2442 serves as the primary sigma-delta ADC, digitizing mV-level bridge outputs from load cells while rejecting 50/60 Hz noise and compensating for thermal drift. Use Value: 1 ppm INL and <5 µV offset error ensure NTEP-certifiable repeatability; integrated amplifiers eliminate external instrumentation amps, reducing thermal EMF errors. |
Use Scenario: Cold-junction-compensated Type K thermocouple readings in furnace controllers, requiring 0.1°C resolution from –200°C to +1350°C. IC Role / Device Role / Timing Role: LTC2442 digitizes thermocouple voltage and cold-junction sensor output simultaneously via its 4-channel mux and dual amplifiers. Use Value: 220 nVRMS noise at 13.8 Hz enables sub-µV resolution; rail-to-rail input allows direct connection to thermocouple without level-shifting, preserving accuracy. |
| Auto-Ranging 6-Digit DVMs | High-Speed Data Acquisition Systems |
Use Scenario: Benchtop digital multimeters switching ranges automatically between 100 mV, 1 V, and 10 V full-scale while maintaining 6½-digit resolution. IC Role / Device Role / Timing Role: LTC2442 acts as the core ADC with programmable gain amplifiers, enabling seamless range changes without dead time or calibration loss. Use Value: Selectable OSR (256 to 32768) and 2X speed mode allow dynamic trade-off between resolution and throughput-13.8 Hz for max resolution, 3.5 kHz for fast settling. |
Use Scenario: Modular test equipment acquiring synchronized voltage/current waveforms from 4 sensors at ≥1 kHz per channel for motor drive diagnostics. IC Role / Device Role / Timing Role: LTC2442 performs high-speed multiplexed sampling with deterministic timing, feeding results to FPGA-based real-time analysis. Use Value: Up to 8 kHz output rate (with external oscillator) and guaranteed modulator lock-up immunity ensure reliable operation under transient EMI and supply disturbances. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-precision delta-sigma ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADS1258IRHBT | 24-bit, 125 kSPS, 8-channel, no integrated amplifiers; requires external PGA; higher power (12.5 mA) | Better suited for high-throughput, low-noise systems where external gain control and faster sampling are prioritized over integration. | Select ADS1258IRHBT when system-level flexibility in gain staging and >10 kSPS aggregate rate are required. |
| MAX11206ETN+ | 24-bit, 10 SPS to 1.4 kSPS, 4-channel, integrated PGA but no dual-amplifier architecture; lower INL (±2 ppm) | Optimized for ultra-low-power portable instrumentation; lacks 2X speed mode and simultaneous 50/60 Hz rejection. | Select MAX11206ETN+ for battery-powered handheld DMMs where sub-100 µA quiescent current outweighs multiplexing speed needs. |
Compared with ADS1258IRHBT and MAX11206ETN+, the LTC2442 uniquely combines dual integrated amplifiers, no-latency multiplexing, and guaranteed 50/60 Hz rejection at base rate-making it optimal for industrial weigh scales and thermocouple systems where integration, noise immunity, and zero-latency channel switching are mandatory.
Availability
LTC2442 is available at Aetrix Electronics and suitable for high-precision weigh scales, thermocouple measurement systems, and auto-ranging digital multimeters requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC2442 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. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC2442 belongs to ADI's precision delta-sigma ADC product line, designed specifically for applications demanding ultra-low drift, no-latency multiplexing, and integrated signal conditioning-targeting industrial process control and metrology-grade instrumentation.
FAQ
What is the maximum output data rate achievable with the LTC2442?
The LTC2442 achieves up to 7 kHz in 2X speed mode using its internal oscillator, and up to 8 kHz when driven by an external oscillator up to 12 MHz. This maximum rate applies to single-channel operation; multiplexed 4-channel acquisition reduces effective per-channel rate proportionally while maintaining no-latency behavior on each switch.
Does the LTC2442 require external components for basic operation?
No-LTC2442 operates with only decoupling capacitors: a 10 µF tantalum + 0.1 µF ceramic on VCC, 0.1 µF ceramics on REF+/REF– and amplifier outputs (OUTA/OUTB), and 1 µF on V+/V–. No external crystal, resistors, or op-amps are needed for default unity-gain buffer operation or internal clock mode.
How does the LTC2442 handle input overrange and underrange conditions?
The LTC2442 generates unique 32-bit output codes for overrange (+VIN > +0.5 × VREF) and underrange (–VIN < –0.5 × VREF) conditions. Bits 29 and 28 together indicate these states: both HIGH = overrange, both LOW = underrange. This eliminates ambiguity and enables robust firmware fault detection without additional comparators.
Can the LTC2442 interface directly with thermocouples without cold-junction compensation circuitry?
No-the LTC2442 digitizes only the thermocouple's differential voltage; cold-junction compensation requires separate temperature sensing (e.g., on-chip diode or external RTD) and software correction. However, its 4-channel mux and dual amplifiers allow simultaneous acquisition of thermocouple voltage and CJC sensor output within one device.
What is the guaranteed operating temperature range for the LTC2442IG variant?
The LTC2442IG variant is specified for –40°C to +85°C ambient operation, with guaranteed performance including ±1 ppm INL, <5 µV offset error, and stable modulator lock-up immunity across this full industrial temperature range-validated per manufacturer datasheet Absolute Maximum and Electrical Characteristics tables.
DC979A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Packaging:
- Box
- Product Status:
- Active
- Number of A/D Converters:
- 1
- Number of Bits:
- 24
- Sampling Rate (Per Second):
- 8k
- Data Interface:
- MICROWIRE™, Serial, SPI™
- Input Range:
- -
- Power (Typ) @ Conditions:
- -
- Utilized IC / Part:
- LTC2442
- Contents:
- Board(s)
DC979A FAQ
1.How can I place an order for DC979A through Aetrix?
Please submit a Request for Quotation (RFQ) for DC979A 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 DC979A reliable?
The price and inventory of DC979A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DC979A is usually 5 days.
3.What payment methods are accepted for DC979A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DC979A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DC979A?
DC979A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DC979A 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 DC979A?
For technical support, including DC979A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DC979A requirements.
6.How does Aetrix verify that DC979A is sourced from the original manufacturer or authorized distributors?
All DC979A 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 DC979A meets industry standards.
7.What is the process for return or replacement of DC979A?
All DC979A units undergo pre-shipment inspection (PSI). If there is an issue with DC979A, 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 DC979A part is unused and in its original packaging.
Return procedure for DC979A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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