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Analog Devices Inc. LTC1278-4ISW#PBF
- Part No.:
- LTC1278-4ISW#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
LTC1278-4ISW#PBF.pdf
- Description:
- IC ADC 12BIT SAR 24SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,229
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Product details
Overview
LTC1278-4ISW#PBF from Analog Devices (formerly Linear Technology) is a 12-bit, 400ksps successive-approximation ADC with internal 2.42V reference, 200ns sample-and-hold, and power-down mode. It operates from single 5V or ±5V supplies, delivers ±1LSB INL/DNL, 70dB S/(N+D) at 100kHz, and supports unipolar (0V–5V) and bipolar (±2.5V) input ranges. Used in high-speed data acquisition systems requiring low-power, precision sampling.
For engineers reviewing the LTC1278-4ISW#PBF datasheet, LTC1278-4ISW#PBF pinout, LTC1278-4ISW#PBF application, or LTC1278-4ISW#PBF equivalent, key selection criteria include guaranteed no missing codes over temperature, internal synchronized clock eliminating external timing constraints, 8.5mW shutdown power, and SW package compatibility with industrial-grade operation (–40°C to +85°C).
Technical Context
The LTC1278-4ISW#PBF implements a 12-bit capacitive DAC-based successive approximation register (SAR) architecture with integrated sample-and-hold and factory-trimmed internal clock. Its control logic accepts asynchronous CONVST (active-low conversion start) and RD/CS for parallel microprocessor interface, with BUSY indicating conversion status.
It features separate analog (AGND) and digital (DGND) ground pins, high-impedance analog input (±1µA leakage), and internal reference output capable of sourcing up to 1mA. The device guarantees monotonicity and no missing codes across its full industrial temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit with guaranteed no missing codes - ensures monotonic transfer function for precision measurement. |
| Max Sampling Rate | 400ksps - defines maximum throughput for time-critical acquisition without pipeline latency. |
| INL / DNL | ±1LSB - enables accurate DC measurement and linearity-critical applications like sensor conditioning. |
| S/(N + D) | 70dB at 100kHz - supports >11.3 ENOB for medium-bandwidth signal analysis (e.g., audio, telecom). |
| Power Dissipation | 75mW typical at 400ksps - allows thermal management in dense PCB layouts without forced cooling. |
| Shutdown Power | 8.5mW - reduces system idle power by >90%, enabling duty-cycled operation in battery-sensitive designs. |
| Analog Input Range | 0V to 5V (unipolar) or ±2.5V (bipolar) - matches standard sensor outputs and op-amp rails without external scaling. |
| Reference Output | 2.42V ±10ppm/°C - provides stable, trimmed reference for self-contained operation or external span adjustment. |
Pinout & Package
Package: 24-lead plastic SO wide (SW), RoHS-compliant, industrial temperature grade (–40°C to +85°C).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| AIN (Pin 1) | Analog Input | High-impedance node accepting 0V–5V or ±2.5V signals; requires <200ns settling after sample hold recharge. |
| VREF (Pin 2) | Reference Output | 2.42V bandgap reference output; decoupling (10µF + 0.1µF) required for low-noise operation. |
| AGND (Pin 3) | Analog Ground | Dedicated analog return path; must be star-connected separately from DGND to minimize noise coupling. |
| D11–D4 (Pins 4–11) | Data Outputs (MSB) | Three-state parallel bus outputs; active when CS and RD are low - interfaces directly to 12-bit microprocessor data buses. |
| DGND (Pin 12) | Digital Ground | Isolated digital return; connects to system logic ground but kept physically separate from AGND plane. |
| D3–D0 (Pins 13–16) | Data Outputs (LSB) | Completes 12-bit parallel word; same timing and drive strength as D11–D4. |
| DVDD (Pin 17) | Digital Supply | +5V supply for digital core; tied directly to AVDD to avoid supply rail mismatch and timing skew. |
| SHDN (Pin 18) | Shutdown Control | Active-low input; pulls current consumption to 8.5mW within 350ns wake-up delay upon deassertion. |
| CONVST (Pin 19) | Conversion Start | Falling-edge triggered; initiates SAR cycle only when CS is low - enables precise timing control in burst-mode systems. |
| RD (Pin 20) | Read Strobe | Enables output drivers during CS low; controls data valid window timing relative to BUSY assertion. |
| CS (Pin 21) | Chip Select | Active-low enable for all control inputs; prevents spurious conversions during bus contention. |
| BUSY (Pin 22) | Conversion Status | Open-drain output low during conversion; used for handshaking with FIFOs, DSPs, or interrupt-driven firmware. |
| VSS (Pin 23) | Negative Supply | –5V for bipolar operation; bypassed to AGND with 0.1µF ceramic - critical for THD performance. |
| AVDD (Pin 24) | Analog Supply | +5V analog supply; bypassed with 10µF tantalum + 0.1µF ceramic - ensures stable reference and DAC operation. |
Key Features
| Feature | Design Value |
|---|---|
| Internal synchronized clock | Factory-trimmed 1.6µs conversion time eliminates need for external clock synchronization and reduces layout sensitivity to clock feedthrough. |
| Flexible unipolar/bipolar input modes | Single device supports both 0V–5V sensor outputs and ±2.5V differential signals without external level-shifting circuitry. |
| Instant wake-up from shutdown | 350ns recovery time enables power gating between individual samples in low-duty-cycle applications. |
| Internally trimmed precision reference | 2.42V ±10ppm/°C output removes need for external reference IC, reducing BOM count and board area. |
| High-impedance analog input | ±1µA max leakage and 45pF input capacitance allow direct connection to high-Z sources (e.g., piezoelectric sensors, thermocouples). |
| Parallel interface with BUSY handshake | Dedicated BUSY signal simplifies timing-critical interfacing to FIFOs and DSPs without requiring tight setup/hold margins. |
Applications
| High-Speed Data Acquisition | Digital Signal Processing |
|---|---|
Use Scenario: Simultaneous sampling of multiple transducer channels in automated test equipment (ATE) with real-time waveform capture. IC Role / Device Role / Timing Role: Primary sampling front-end ADC providing 12-bit resolution at 400ksps with deterministic BUSY-driven readout timing. Use Value: Guaranteed no missing codes and ±1LSB linearity ensure accurate representation of fast-rising edge events without code ambiguity. |
Use Scenario: Digitizing baseband I/Q signals in software-defined radio (SDR) receivers prior to FPGA-based FFT processing. IC Role / Device Role / Timing Role: High-fidelity analog-to-digital conversion stage feeding parallel data bus to FPGA or DSP memory-mapped interface. Use Value: 70dB S/(N+D) at 100kHz and 350kHz full linear bandwidth preserve signal integrity for spectral analysis up to Nyquist frequency. |
| Multiplexed Sensor Systems | Audio and Telecom Processing |
Use Scenario: Multi-channel environmental monitoring (temperature, pressure, humidity) using analog multiplexer and shared ADC resource. IC Role / Device Role / Timing Role: Centralized sampling engine with low 200ns acquisition time enabling rapid channel switching and minimal dead time. Use Value: Internal 2.42V reference and unipolar/bipolar flexibility eliminate per-channel calibration and external reference components. |
Use Scenario: Voice-band codec interface in VoIP gateways requiring low-distortion digitization of analog telephone lines. IC Role / Device Role / Timing Role: Precision ADC stage converting conditioned analog voice signals into 12-bit parallel words for DSP algorithm execution. Use Value: –78dB THD at 100kHz and 74dB THD at Nyquist meet ITU-T G.711 linearity requirements for telephony-grade audio fidelity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 12-bit SAR ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADS7822U | 2.7V–5.25V single-supply only; no internal reference; 200ksps max; SPI interface. | Requires external reference and level-shifting for ±5V systems; suited for low-voltage portable designs. | Select when system uses 3.3V logic and SPI bus is preferred over parallel interface. |
| MAX11200EEE+ | 24-bit delta-sigma architecture; 1ksps typ; internal oscillator; 2.5V reference; SPI interface. | Optimized for high-resolution DC measurements, not high-speed AC; incompatible timing and interface. | Select only for ultra-high-precision, low-bandwidth applications where speed is secondary to ENOB. |
Compared with ADS7822U and MAX11200EEE+, the LTC1278-4ISW#PBF uniquely combines parallel bus interface, internal reference, bipolar/unipolar flexibility, and 400ksps throughput in a single SOIC-24 package - making it optimal for industrial data loggers and real-time control systems needing deterministic timing and minimal external components.
Availability
LTC1278-4ISW#PBF is available at Aetrix Electronics and suitable for high-speed data acquisition, digital signal processing, and multiplexed sensor systems requiring stable component supply and long-term industrial-grade availability.
Supply support for LTC1278-4ISW#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. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets.
The LTC1278-4ISW#PBF belongs to ADI's legacy Linear Technology precision data converter family, designed specifically for industrial and instrumentation applications demanding guaranteed linearity, low power, and robust operation across extended temperature ranges.
FAQ
What is the maximum sampling rate supported by the LTC1278-4ISW#PBF?
The LTC1278-4ISW#PBF is rated for a maximum sampling rate of 400ksps, corresponding to a minimum throughput time of 2.5µs (acquisition plus conversion). This is distinct from the faster LTC1278-5 variant (500ksps); the "-4" suffix explicitly denotes the 400ksps speed grade. Operation beyond this rate risks missing codes or degraded AC performance.
Does the LTC1278-4ISW#PBF require an external clock source?
No, the LTC1278-4ISW#PBF does not require an external clock. It integrates a factory-trimmed internal clock that automatically synchronizes to each CONVST command, delivering a typical conversion time of 2.0–2.3µs. This eliminates clock routing complexity and asynchronous noise issues common in externally clocked ADCs.
Can the LTC1278-4ISW#PBF operate with only a single +5V supply?
Yes, the LTC1278-4ISW#PBF supports unipolar operation from a single +5V supply (AVDD = DVDD = 5V, VSS = AGND), accepting 0V to 5V analog inputs. For bipolar (±2.5V) operation, a dual ±5V supply is required (AVDD = +5V, VSS = –5V), with proper bypassing on both rails to maintain THD and S/(N+D) performance.
What is the purpose of the SHDN pin on the LTC1278-4ISW#PBF?
The SHDN (Pin 18) is an active-low shutdown control that reduces total power dissipation from 75mW to 8.5mW. When asserted low, it disables the internal reference, sample-and-hold, and comparator - halting conversions even if CONVST is toggled. Wake-up occurs within 350ns of SHDN deassertion, enabling rapid duty-cycled operation.
How is the reference voltage used in the LTC1278-4ISW#PBF configured for bipolar operation?
In bipolar mode, the LTC1278-4ISW#PBF uses its internal 2.42V reference to set a ±2.5V input range. The VREF pin can be overdriven externally (≥2.45V) to adjust full-scale span - for example, applying 2.5V yields ±2.58V range. Driving VREF above 4.8V is prohibited to avoid exceeding supply rails and causing code loss at full scale.
LTC1278-4ISW#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Number of Bits:
- 12
- Sampling Rate (Per Second):
- 400k
- Number of Inputs:
- 1
- Input Type:
- Single Ended
- Data Interface:
- Parallel
- Configuration:
- S/H-ADC
- Ratio - S/H:ADC:
- 1:1
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- External, Internal
- Voltage - Supply, Analog:
- 5V, -2.45V ~ 5.25
- Voltage - Supply, Digital:
- 5V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 24-SOIC
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
LTC1278-4ISW#PBF FAQ
1.How can I place an order for LTC1278-4ISW#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1278-4ISW#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 LTC1278-4ISW#PBF reliable?
The price and inventory of LTC1278-4ISW#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1278-4ISW#PBF is usually 5 days.
3.What payment methods are accepted for LTC1278-4ISW#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1278-4ISW#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1278-4ISW#PBF?
LTC1278-4ISW#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1278-4ISW#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 LTC1278-4ISW#PBF?
For technical support, including LTC1278-4ISW#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1278-4ISW#PBF requirements.
6.How does Aetrix verify that LTC1278-4ISW#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1278-4ISW#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 LTC1278-4ISW#PBF meets industry standards.
7.What is the process for return or replacement of LTC1278-4ISW#PBF?
All LTC1278-4ISW#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1278-4ISW#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 LTC1278-4ISW#PBF part is unused and in its original packaging.
Return procedure for LTC1278-4ISW#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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