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Analog Devices Inc. LTC1861IS8#PBF
- Part No.:
- LTC1861IS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1861IS8#PBF.pdf
- Description:
- IC ADC 12BIT SAR 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:250
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Product details
Overview
LTC1861IS8#PBF from Analog Devices (formerly Linear Technology) is a 12-bit, 250ksps, 2-channel serial ADC in SO-8 package operating on single 5V supply. It features software-selectable MUX, adjustable reference input, SPI/MICROWIRE-compatible 3-wire interface, and auto-shutdown reducing supply current to 1nA between conversions. It is used in low-power portable instrumentation requiring precise dual-sensor digitization with minimal board space.
For engineers reviewing the LTC1861IS8#PBF datasheet, LTC1861IS8#PBF pinout, LTC1861IS8#PBF application, or LTC1861IS8#PBF equivalent, key selection criteria include its −40°C to +85°C industrial temperature grade, SO-8 pin compatibility with legacy LTC1298/LTC1864 designs, differential/single-ended channel switching via SDI, and guaranteed 250ksps sampling at full 12-bit resolution without missing codes.
Technical Context
The LTC1861IS8#PBF implements a switched-capacitor successive approximation architecture with integrated sample-and-hold. Its 2-channel multiplexer is configured via a 2-bit word clocked into SDI before conversion, supporting four modes: single-ended CH0/GND, CH1/GND, or differential CH0–CH1/CH1–CH0.
Reference voltage is internally tied to VCC in the SO-8 variant, fixing full-scale span to VCC (4.75V–5.25V); analog inputs accept 0V to VCC range with high-impedance inputs enabling direct sensor connection. Conversion timing is deterministic: tCONV = 3.3µs max, with SDO data valid 30ns after SCK↓.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit with no missing codes - ensures monotonic transfer function for precision control loops. |
| Sampling Rate | 250ksps maximum - supports real-time acquisition of signals up to 125kHz full linear bandwidth. |
| Supply Current | 850µA typical at 250ksps; drops to 1nA in auto-shutdown - enables battery operation for >1 year in duty-cycled systems. |
| INL Error | ±1 LSB max - guarantees absolute accuracy within ±0.024% of full scale for calibration-critical applications. |
| SNR | 72dB typical - delivers 11.9 effective bits for clean signal capture in noisy industrial environments. |
| Operating Temp | −40°C to +85°C - qualified for industrial embedded systems without derating. |
| Interface | SPI/MICROWIRE 3-wire serial - compatible with standard MCU GPIO or dedicated SPI peripherals without level shifters. |
Pinout & Package
Package: 8-lead plastic SO (narrow, 0.150-inch width), RoHS-compliant, lead-free finish (PBF), JEDEC MS-012AC compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CONV | Convert Control Input | Active-high start trigger; falling edge enables SDO output and initiates serial readout. |
| CH0 | Analog Input Channel 0 | Positive input for CH0–GND or CH0–CH1 differential mode; accepts 0V to VCC range. |
| CH1 | Analog Input Channel 1 | Positive input for CH1–GND or CH1–CH0 differential mode; shares same voltage range as CH0. |
| GND | Analog Ground Reference | Single ground plane tie point for analog section; must be low-impedance and star-connected. |
| SDI | Serial Data Input | Receives 2-bit MUX configuration word on rising SCK edges prior to conversion. |
| SDO | Serial Data Output | Outputs 12-bit result MSB-first on falling SCK edges; tri-stated when CONV is high. |
| SCK | Serial Clock Input | Synchronizes both SDI write and SDO read; supports up to 20MHz (H-grade) clock rate. |
| VCC | Positive Supply | Single 4.75V–5.25V supply; requires ≥1µF tantalum bypass to GND adjacent to pin. |
Key Features
| Feature | Design Value |
|---|---|
| Software-Selectable 2-Channel MUX | Configurable via SDI to support single-ended or differential acquisition across two sensors without external switches. |
| Auto Shutdown Between Conversions | Reduces ICC to 1nA typical - eliminates need for external power gating in ultra-low-duty-cycle monitoring. |
| Internal VREF = VCC | Removes external reference component and layout complexity while maintaining ratiometric accuracy vs. supply. |
| Guaranteed Operation to 85°C | Validated performance across full industrial temperature range - no design margin loss in hot enclosures. |
| High Input Impedance & Low Leakage | ±1µA max analog input leakage - allows direct connection to high-Z sources like thermocouples or pH electrodes. |
Applications
| Portable Battery-Powered Data Logger | Industrial Sensor Signal Conditioning |
|---|---|
Use Scenario: Compact handheld device acquiring temperature and pressure readings from two isolated RTD bridges using a single ADC channel per sensor. IC Role / Device Role / Timing Role: Dual-channel ADC performs time-multiplexed sampling with <3.3µs conversion latency and automatic power-down between reads. Use Value: Eliminates need for two separate ADCs or external analog MUX, reducing BOM cost and PCB area by 35% while maintaining 12-bit fidelity. | Use Scenario: DIN-rail mounted PLC module digitizing 4–20mA current loop outputs from two field transmitters. IC Role / Device Role / Timing Role: Configured in single-ended mode (CH0/GND, CH1/GND) with internal VREF = VCC to provide ratiometric immunity to supply drift. Use Value: Achieves ±0.024% absolute accuracy without trimming, meeting IEC 61000-4-5 surge immunity requirements for industrial analog inputs. |
| Isolated Remote Monitoring Node | Low-Power Environmental Sensor Hub |
Use Scenario: Wireless node powered by energy harvesting (solar + supercap) measuring soil moisture and ambient humidity via resistive and capacitive sensors. IC Role / Device Role / Timing Role: ADC operates in burst mode: wakes on timer interrupt, samples both channels, transmits data, then returns to 1nA sleep. Use Value: Enables >5-year battery life with coin-cell supply due to sub-nA quiescent current and deterministic 3.3µs conversion window. | Use Scenario: Smart agriculture gateway collecting data from distributed NPK (nitrogen/phosphorus/potassium) chemical sensors deployed across 1km². IC Role / Device Role / Timing Role: Acts as front-end digitizer for two chem-resistive sensors, rejecting common-mode noise via simultaneous sampling. Use Value: Delivers 72dB SNR and ±1 LSB INL to resolve <0.1% nutrient concentration changes despite EMI from nearby motor drives. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 12-bit, 2-channel, serial ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1298CS8#PBF | 12-bit, 2-channel, 11.1ksps max; no auto-shutdown; VREF externally supplied; SO-8 pinout identical. | Lower speed and higher 1.7mW power dissipation limit use to non-real-time monitoring only. | Select when cost sensitivity outweighs speed/power needs and external reference is already present. |
| LTC1864CS8#PBF | 16-bit, 1-channel, 250ksps; pin-compatible SO-8; same VCC/VREF architecture but no MUX. | Higher resolution but lacks dual-input capability - requires external MUX or two devices for two sensors. | Select when absolute precision >12-bit is required and channel count can be managed externally. |
Compared with LTC1298CS8#PBF, LTC1861IS8#PBF offers 22× faster sampling and 99.9% lower idle current; versus LTC1864CS8#PBF, it trades 4-bit resolution for integrated dual-channel flexibility and identical footprint-enabling drop-in upgrade where 12-bit suffices.
Availability
LTC1861IS8#PBF is available at Aetrix Electronics and suitable for portable instrumentation, industrial sensor interfaces, and isolated remote monitoring requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC1861IS8#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 acquired Linear Technology in 2017; Linear pioneered high-performance analog ICs including precision ADCs, references, and power management solutions.
The LTC1861 belongs to Linear's µPower Serial ADC family, designed specifically for space-constrained, battery-operated, and industrial systems demanding high-speed 12-bit digitization with minimal quiescent power.
FAQ
What is the maximum sampling rate of the LTC1861IS8#PBF while maintaining full 12-bit resolution?
The LTC1861IS8#PBF achieves 250ksps maximum sampling rate with guaranteed no missing codes and ±1 LSB INL across its full operating temperature range. This rate is supported at VCC = 4.75V to 5.25V and requires SCK ≤ 20MHz. At this rate, conversion time is 3.3µs max, and the device draws 850µA typical supply current.
Does the LTC1861IS8#PBF require an external reference voltage?
No. The LTC1861IS8#PBF uses an internal connection that ties VREF to VCC in the SO-8 package, establishing a fixed full-scale range equal to the supply voltage (4.75V–5.25V). This eliminates external reference components and simplifies layout while preserving ratiometric accuracy for current-loop or bridge-sensor interfaces.
How is channel selection implemented on the LTC1861IS8#PBF?
Channel selection on the LTC1861IS8#PBF is performed via a 2-bit configuration word shifted into the SDI pin during the CONV low period, prior to conversion initiation. The word defines single-ended (CH0/GND or CH1/GND) or differential (CH0–CH1 or CH1–CH0) acquisition mode. This occurs synchronously with SCK rising edges and does not require additional control lines.
What is the shutdown current of the LTC1861IS8#PBF and how is it activated?
The LTC1861IS8#PBF automatically enters shutdown mode drawing just 1nA typical supply current when CONV remains high after conversion completion. No software command or external signal is needed - the feature is hardware-managed. This enables ultra-low-power operation in wake-on-event architectures without firmware overhead.
Is the LTC1861IS8#PBF pin-compatible with other members of the LTC1860/LTC1861 family?
Yes - the LTC1861IS8#PBF shares identical SO-8 pinout with LTC1860IS8#PBF (1-channel) and LTC1298CS8#PBF (legacy 2-channel), enabling direct PCB replacement in existing designs. However, functional differences exist: LTC1860 lacks MUX/SDI, and LTC1298 lacks auto-shutdown and has lower speed.
LTC1861IS8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Number of Bits:
- 12
- Sampling Rate (Per Second):
- 250k
- Number of Inputs:
- 2
- Input Type:
- Differential, Single Ended
- Data Interface:
- SPI
- Configuration:
- S/H-ADC
- Ratio - S/H:ADC:
- 1:1
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- External
- Voltage - Supply, Analog:
- 5V
- Voltage - Supply, Digital:
- 5V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 8-SO
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
LTC1861IS8#PBF FAQ
1.How can I place an order for LTC1861IS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1861IS8#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 LTC1861IS8#PBF reliable?
The price and inventory of LTC1861IS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1861IS8#PBF is usually 5 days.
3.What payment methods are accepted for LTC1861IS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1861IS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1861IS8#PBF?
LTC1861IS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1861IS8#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 LTC1861IS8#PBF?
For technical support, including LTC1861IS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1861IS8#PBF requirements.
6.How does Aetrix verify that LTC1861IS8#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1861IS8#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 LTC1861IS8#PBF meets industry standards.
7.What is the process for return or replacement of LTC1861IS8#PBF?
All LTC1861IS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1861IS8#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 LTC1861IS8#PBF part is unused and in its original packaging.
Return procedure for LTC1861IS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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