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Analog Devices Inc. LTC1861LCS8#PBF
- Part No.:
- LTC1861LCS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1861LCS8#PBF.pdf
- Description:
- IC ADC 12BIT SAR 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,723
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Product details
Overview
LTC1861LCS8#PBF from Analog Devices (formerly Linear Technology) is a 12-bit, 150ksps, 2-channel software-selectable multiplexed successive-approximation ADC in an 8-lead SOIC package operating from a single 2.7V–3.6V supply. It features true differential input capability per channel, external reference support (VREF pin), SPI/MICROWIRE-compatible 3-wire serial interface, and auto-shutdown reducing supply current to 10µA at 1ksps. It is used in compact, battery-powered data acquisition systems requiring high sample-rate-to-power efficiency.
For engineers reviewing the LTC1861LCS8#PBF datasheet, LTC1861LCS8#PBF pinout, LTC1861LCS8#PBF application, or LTC1861LCS8#PBF equivalent, key selection criteria include its 2-channel MUX configuration flexibility, SO-8 package compatibility with space-constrained layouts, 12-bit no-missing-codes performance, 72dB SNR at 1kHz, and support for ratiometric or external-reference operation down to 1V full-scale span.
Technical Context
The LTC1861LCS8#PBF implements a switched-capacitor SAR architecture with integrated sample-and-hold. Its 2-bit SDI configuration word selects between four analog input combinations (single-ended CH0/CH1 or differential CH0–CH1/CH1–CH0), enabling flexible signal routing without external multiplexers.
It uses a 3-wire serial interface (CONV, SCK, SDO/SDI) with full-duplex capability on SO-8 and MSOP variants. Conversion timing is deterministic: tCONV = 4.66µs max, with sampling time of 10 SCK cycles, and supports clock frequencies up to 8MHz - enabling precise synchronization in embedded control loops and isolated sensor interfaces.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit with no missing codes - guarantees monotonicity and full code coverage across temperature and supply range. |
| Max Sampling Rate | 150ksps - supports real-time monitoring of signals up to ~30kHz full-linear bandwidth (S/(N+D) ≥ 68dB). |
| Supply Current | 450µA typical at 150ksps; drops to 10µA at 1ksps via auto-shutdown - enables multi-year battery life in portable instrumentation. |
| INL Error | ±1 LSB max - ensures <0.025% end-point linearity error for precision measurement applications. |
| SNR / THD | 72dB SNR and –86dB THD at 1kHz - suitable for medium-fidelity sensor digitization without post-processing correction. |
| Input Voltage Range | Differential input range = 0 to VREF; absolute input = –0.05V to VCC+0.05V - allows direct connection to op-amp outputs or resistive sensors without level-shifting. |
| Reference Support | VREF pin accepts 1V to VCC (3.6V); SO-8 version ties VREF internally to VCC - simplifies design when rail-referenced operation suffices. |
Pinout & Package
Package: 8-lead plastic SOIC (narrow, 0.150-inch width), JEDEC MS-012AC, body size 4.90mm × 3.90mm, lead pitch 1.27mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - CONV | Convert Control Input | Active-high edge-triggered start signal; low state enables SDO output and initiates serial readout after conversion completes. |
| 2 - CH0 | Analog Input Channel 0 (+) | Positive input for CH0 single-ended or differential mode; referenced to AGND/GND; supports ±0.05V to VCC+0.05V common-mode range. |
| 3 - CH1 | Analog Input Channel 1 (+) | Positive input for CH1 single-ended or differential mode; shares same voltage limits and noise rejection as CH0. |
| 4 - GND | Analog Ground | Single ground reference for all analog circuitry; must be tied directly to low-impedance analog plane to minimize noise coupling. |
| 5 - VCC | Positive Supply | 2.7V–3.6V single supply; requires local 1µF tantalum bypass to GND for stable conversion performance. |
| 6 - SCK | Serial Clock Input | Synchronizes full-duplex data transfer; supports up to 8MHz clock rate; timing-critical for setup/hold compliance (30ns min SDI hold/setup). |
| 7 - SDO | Serial Data Output | Tri-state output delivering 12-bit conversion result on falling SCK edge; enters Hi-Z when CONV is high or during shutdown. |
| 8 - VREF | Reference Input | Defines full-scale span (0 to VREF); in SO-8 package, internally connected to VCC - eliminates external reference component if rail-referenced accuracy is acceptable. |
Key Features
| Feature | Design Value |
|---|---|
| Software-Selectable 2-Channel MUX | Configurable via 2-bit SDI word to measure CH0, CH1, CH0–CH1, or CH1–CH0 - replaces discrete analog switches and reduces BOM count. |
| Auto Power-Down Between Conversions | Reduces ICC from 450µA @ 150ksps to 10µA @ 1ksps - extends battery runtime without firmware intervention. |
| True Differential Input Architecture | Rejects common-mode noise on paired inputs - improves immunity in noisy industrial or motor-drive environments. |
| No Minimum Data Transfer Rate | Allows indefinite idle periods between conversions - simplifies integration with low-speed microcontrollers lacking continuous clock generation. |
| High Impedance Analog Inputs | Input leakage ≤ ±1µA and CIN = 12pF in sample mode - permits direct connection to high-output-impedance sources (e.g., thermistors, RTDs) with minimal loading error. |
Applications
| Portable Sensor Node | Industrial Process Monitor |
|---|---|
Use Scenario: Battery-powered wireless node measuring temperature and pressure from two remote sensors using a single ADC. IC Role / Device Role / Timing Role: Dual-channel SAR ADC performing synchronized or alternating sampling; CONV and SCK coordinate timing with MCU's low-power sleep/wake cycle. Use Value: 450µA active current and auto-shutdown enable >2-year coin-cell operation; SO-8 footprint fits compact PCBs; 12-bit resolution meets Class A sensor accuracy requirements. | Use Scenario: DIN-rail mounted PLC module acquiring analog signals from 4–20mA transmitters and thermocouples in factory automation. IC Role / Device Role / Timing Role: Precision front-end ADC interfacing with isolation amplifiers; VREF pin accepts stable 2.5V reference for ratiometric rejection of supply drift. Use Value: ±1 LSB INL and 72dB SNR ensure <0.025% measurement uncertainty; differential input rejects 50/60Hz EMI from adjacent AC wiring. |
| Isolated Data Logger | Medical Vital Sign Monitor |
Use Scenario: Galvanically isolated data logger capturing vibration and current waveforms from rotating machinery via optocoupled or digital isolators. IC Role / Device Role / Timing Role: Isolated-side ADC feeding serial data across barrier; SDO Hi-Z behavior during CONV high prevents backfeed into isolator. Use Value: Tri-state SDO and no-minimum-clock requirement simplify isolated interface design; 150ksps supports 20kHz waveform capture for bearing fault analysis. | Use Scenario: Portable ECG or pulse oximeter digitizing low-amplitude bio-signals amplified by instrumentation amplifiers. IC Role / Device Role / Timing Role: Low-noise, low-power ADC sampling conditioned analog front-end; operates from 3V coin cell or USB power. Use Value: 12pF input capacitance and high-Z inputs prevent settling errors from fast op-amps (e.g., LT1807); 72dB SNR preserves diagnostic fidelity in sub-µV signal ranges. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 12-bit, low-power, serial ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1861LIMS8#PBF | Same functionality and pinout, but rated for –40°C to +85°C industrial temperature range vs. 0°C to +70°C for LTC1861LCS8#PBF. | Required for outdoor or under-hood automotive/industrial deployments where extended thermal stability is mandatory. | Select LTC1861LIMS8#PBF when ambient operating temperature exceeds 70°C or requires guaranteed performance over full industrial range. |
| LTC1864LCS8#PBF | 16-bit resolution, same 150ksps rate and SO-8 package, but higher 1.22mW power dissipation and ±2 LSB INL vs. ±1 LSB for LTC1861LCS8#PBF. | Used where higher resolution outweighs SNR trade-off (e.g., precision weight scales, calibration equipment). | Choose LTC1864LCS8#PBF only when 16-bit quantization is essential and system can accommodate higher noise floor and cost premium. |
Compared with LTC1861LIMS8#PBF, the LTC1861LCS8#PBF offers lower cost and sufficient accuracy for commercial-grade instrumentation, while LTC1864LCS8#PBF trades resolution for increased dynamic range at higher power and reduced linearity - making the LTC1861LCS8#PBF optimal for cost-sensitive, battery-operated 12-bit applications demanding proven thermal margin and low standby current.
Availability
LTC1861LCS8#PBF is available at Aetrix Electronics and suitable for portable instrumentation, industrial process monitors, and isolated data loggers requiring stable component supply, long-lifecycle availability, and RoHS-compliant packaging.
Supply support for LTC1861LCS8#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 semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC1861LCS8#PBF belongs to ADI's legacy Linear Technology precision data acquisition product line, designed specifically for ultra-low-power, high-speed, space-constrained measurement systems operating from single 3V supplies.
FAQ
What is the maximum sampling frequency supported by the LTC1861LCS8#PBF?
The LTC1861LCS8#PBF supports a maximum sampling frequency of 150ksps, with guaranteed performance across its specified operating temperature range (0°C to +70°C) and supply voltage (2.7V to 3.6V). This rate corresponds to a minimum conversion time of 3.7µs and enables accurate digitization of signals with up to ~30kHz full-linear bandwidth. The LTC1861LCS8#PBF maintains 72dB SNR and ±1 LSB INL at this rate, making it suitable for medium-bandwidth sensor applications without oversampling.
Does the LTC1861LCS8#PBF require an external reference voltage?
The LTC1861LCS8#PBF does not require an external reference voltage - its SO-8 package internally connects the VREF pin to VCC, enabling rail-referenced operation. However, an external reference (1V to VCC) may be applied to VREF for improved accuracy, ratiometric rejection, or reduced sensitivity to supply ripple. When using external VREF, ensure low-noise layout and 1µF bypassing to GND, as reference noise directly modulates conversion gain error. The LTC1861LCS8#PBF's reference current is only 0.01–0.1mA, minimizing burden on reference sources.
How does the 2-channel multiplexer in the LTC1861LCS8#PBF operate?
The LTC1861LCS8#PBF uses a 2-bit configuration word shifted into SDI during the CONV low period to select among four input modes: single-ended CH0, single-ended CH1, differential CH0–CH1, or differential CH1–CH0. This occurs before each conversion and allows dynamic reconfiguration without hardware changes. The MUX is implemented within the SAR capacitor array, preserving 12-bit linearity and ±1 LSB INL across all modes. Unlike external MUX solutions, this integrated approach avoids added offset, crosstalk, and settling delays - critical for time-aligned dual-channel measurements in the LTC1861LCS8#PBF.
What is the purpose of the CONV pin on the LTC1861LCS8#PBF?
The CONV pin on the LTC1861LCS8#PBF serves three critical functions: (1) rising edge initiates conversion, (2) high state after completion triggers auto-shutdown (reducing ICC to 10µA), and (3) falling edge enables SDO output for serial readout. Its timing is tightly specified: tCONV ≤ 4.66µs, and SDO becomes valid 45–60ns after SCK falling edge. This dual-role control eliminates need for separate CS/EN lines, simplifying interface to resource-constrained MCUs. In the LTC1861LCS8#PBF, CONV also gates SDI sampling - ensuring configuration word is latched only once per conversion cycle.
Can the LTC1861LCS8#PBF interface directly with a microcontroller GPIO without level-shifting?
Yes, the LTC1861LCS8#PBF is fully compatible with 3V microcontrollers: VIH = 1.9V min and VIL = 0.45V max at VCC = 2.7V, ensuring robust logic-level recognition. Its SDO output drives VOH ≥ 2.3V and VOL ≤ 0.3V under 400µA load, meeting standard 3V CMOS thresholds. Input leakage is ±2.5µA, and output drive strength (±6.5mA) supports direct connection to most MCU SPI peripherals without buffers. No level-shifting is needed when both LTC1861LCS8#PBF and MCU share the same 3V supply and ground - a key enabler for minimalist, low-cost embedded designs.
LTC1861LCS8#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):
- 150k
- 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:
- 2.7V ~ 3.6V
- Voltage - Supply, Digital:
- 2.7V ~ 3.6V
- Features:
- -
- Operating Temperature:
- 0°C ~ 70°C
- Supplier Device Package:
- 8-SO
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
LTC1861LCS8#PBF FAQ
1.How can I place an order for LTC1861LCS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1861LCS8#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 LTC1861LCS8#PBF reliable?
The price and inventory of LTC1861LCS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1861LCS8#PBF is usually 5 days.
3.What payment methods are accepted for LTC1861LCS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1861LCS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1861LCS8#PBF?
LTC1861LCS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1861LCS8#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 LTC1861LCS8#PBF?
For technical support, including LTC1861LCS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1861LCS8#PBF requirements.
6.How does Aetrix verify that LTC1861LCS8#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1861LCS8#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 LTC1861LCS8#PBF meets industry standards.
7.What is the process for return or replacement of LTC1861LCS8#PBF?
All LTC1861LCS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1861LCS8#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 LTC1861LCS8#PBF part is unused and in its original packaging.
Return procedure for LTC1861LCS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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