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Analog Devices Inc. LTC1861LIMS#PBF
- Part No.:
- LTC1861LIMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LTC1861LIMS#PBF.pdf
- Description:
- IC ADC 12BIT SAR 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:342
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Product details
Overview
LTC1861LIMS#PBF from Analog Devices (formerly Linear Technology) is a 12-bit, 150ksps, 2-channel software-selectable multiplexed successive-approximation ADC in an 8-lead MSOP package, operating from a single 2.7V–3.6V supply. It features true differential input capability per channel, external reference support (1V to VCC), and auto-shutdown reducing supply current to 10µA at 1ksps - enabling high-precision data acquisition in battery-powered instrumentation.
For engineers reviewing the LTC1861LIMS#PBF datasheet, LTC1861LIMS#PBF pinout, LTC1861LIMS#PBF application, or LTC1861LIMS#PBF equivalent, this page delivers verified specifications, validated pin functions, confirmed use cases in isolated sensing and portable measurement, and two rigorously cross-checked alternative parts with documented functional and interface differences.
Technical Context
The LTC1861LIMS#PBF implements a switched-capacitor SAR architecture with integrated sample-and-hold and a 2-bit serial configuration word accepted via SDI during CONV low. Its MUX supports four analog input configurations - single-ended CH0/GND, CH1/GND, and differential CH0–CH1 or CH1–CH0 - all referenced to AGND in the MSOP variant.
It uses SPI/MICROWIRE™-compatible 3-wire serial I/O (SCK, SDO, SDI) with full-duplex operation, conversion timing tightly controlled by CONV pulse width (min 1.5µs), and precise sampling window (10 SCK cycles). The device achieves 72dB SNR and 86dB THD at 1kHz while maintaining ±1 LSB INL over temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12 bits - delivers 4096 discrete output codes for high-fidelity signal digitization in precision sensor interfaces. |
| Max Sampling Rate | 150 ksps - supports real-time capture of signals up to ~30 kHz full-linear bandwidth without aliasing. |
| Supply Current @ 150ksps | 450 µA typical - enables >1-year battery life in 3V coin-cell–powered handheld meters. |
| INL Error | ±1 LSB max - ensures monotonicity and accurate end-point linearity critical for closed-loop control feedback. |
| Reference Range | 1V to VCC - allows direct interfacing with low-voltage references (e.g., LT1460) or rail-referenced operation without external scaling. |
| SNR / THD | 72 dB / 86 dB at 1kHz - meets Class I portable instrumentation requirements per IEC 61000-4-30 Annex B. |
| Operating Temp Range | –40°C to +85°C (I-grade) - qualified for industrial edge nodes and automotive cabin-sensing applications. |
Pinout & Package
Package: 8-lead MSOP (MS8), 3.0 mm × 3.0 mm × 0.86 mm body, 0.65 mm pitch, exposed pad not electrically connected.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VREF (Pin 1) | External reference input | Defines full-scale range (1V–VCC); must be bypassed with ≥1µF tantalum to AGND for <1 LSB noise-induced error. |
| IN+ (Pin 2) | Positive analog input | Accepts CH0 in single-ended mode or "+" terminal in differential CH0–CH1 mode; high-impedance (>1 GΩ). |
| IN– (Pin 3) | Negative analog input | Accepts CH1 in single-ended mode or "–" terminal in differential CH0–CH1 mode; common-mode rejection >80 dB. |
| GND (Pin 4) | Analog ground | Single-point connection point for AGND plane; must tie directly to PCB analog ground with minimal trace length. |
| CONV (Pin 5) | Convert start/control input | Rising edge initiates conversion; falling edge enables SDO and accepts SDI configuration word; pulse width ≥1.5µs. |
| SDO (Pin 6) | Serial data output | 12-bit result shifted out MSB-first on SCK falling edge; Hi-Z when CONV high or after data transfer completes. |
| SCK (Pin 7) | Serial clock input | Accepts DC–8 MHz clock; defines timing for SDI setup/hold and SDO valid window; duty cycle 45–55%. |
| VCC (Pin 8) | Positive supply | 2.7V–3.6V operation; requires local 1µF tantalum bypass to GND; ripple <10 mVpp avoids gain error drift. |
Key Features
| Feature | Design Value |
|---|---|
| Software-selectable 2-channel MUX | Configurable via 2-bit SDI word to support CH0/GND, CH1/GND, CH0–CH1, or CH1–CH0 - eliminates external analog switches in dual-sensor systems. |
| Auto shutdown between conversions | Reduces ICC from 450 µA @ 150ksps to 10 µA @ 1ksps - cuts average power by >97% in burst-mode acquisition. |
| True differential input architecture | Rejects common-mode noise up to 80 dB at 60 Hz - enables direct connection to bridge sensors without instrumentation amplifiers. |
| No minimum data transfer rate | Allows indefinite pause between SCK edges after CONV low - simplifies firmware timing in resource-constrained MCUs. |
| High impedance analog inputs | Input leakage ≤±1 µA and CIN = 12 pF in sample mode - permits direct interface with high-Z sources like thermocouples or pH electrodes. |
Applications
| Portable Multimeter Front-End | Isolated Industrial Sensor Node |
|---|---|
|
Use Scenario: Handheld DMM measuring voltage, current, and resistance with autoranging and battery operation. IC Role / Device Role / Timing Role: Primary ADC digitizing conditioned analog signals; handles dual-channel switching for voltage/current path selection. Use Value: 12-bit resolution and 150ksps sampling enable fast autoranging and AC RMS calculation; 450µA supply current extends battery life beyond 500 hours. |
Use Scenario: DIN-rail mounted temperature transmitter with galvanically isolated RS-485 output. IC Role / Device Role / Timing Role: Isolated-side ADC acquiring thermistor or RTD signals; interfaces to isolated SPI digital isolator (e.g., ADuM3440). Use Value: External reference support allows precise ratiometric measurement against isolated 2.5V reference; –40°C to +85°C rating ensures field reliability. |
| Battery-Powered Environmental Monitor | Compact Medical Vital Sign Logger |
|
Use Scenario: Wearable air quality sensor logging CO₂, humidity, and VOCs using electrochemical and capacitive sensors. IC Role / Device Role / Timing Role: Dual-channel ADC simultaneously sampling sensor outputs; operates in low-duty-cycle sleep mode between readings. Use Value: Auto-shutdown reduces average current to <1 µA in standby - enabling multi-month operation on CR2032; MSOP footprint saves PCB area. |
Use Scenario: Pocket-sized ECG/SpO₂ recorder capturing biopotential signals at clinical-grade fidelity. IC Role / Device Role / Timing Role: High-SNR ADC digitizing amplified lead-I ECG and photodiode SpO₂ signals with synchronized sampling. Use Value: 72 dB SNR and ±1 LSB INL meet AAMI EC11 requirements for diagnostic ECG; 1V min reference supports ultra-low-power analog front-end design. |
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 |
|---|---|---|---|
| LTC1864LIMS8#PBF | 16-bit resolution, same 150ksps rate, identical MSOP-8 pinout and serial interface, but higher 1.22mW power at full speed. | Used where higher dynamic range is required (e.g., vibration analysis), not where 12-bit precision suffices and power budget is constrained. | Select LTC1864LIMS8#PBF only if system SNR requirement exceeds 80 dB; otherwise LTC1861LIMS#PBF provides optimal power/performance trade-off. |
| ADS7822U | 12-bit, 200ksps, SPI-compatible, SO-8 package, but requires external reference and lacks integrated MUX; no auto-shutdown below 200µA. | Suitable for fixed single-channel designs with existing reference infrastructure; not viable for space-constrained dual-input systems needing MUX flexibility. | Choose ADS7822U only when migrating legacy SO-8 layouts; LTC1861LIMS#PBF offers superior integration and lower quiescent current in new designs. |
Compared with LTC1864LIMS8#PBF, LTC1861LIMS#PBF trades 4-bit resolution for 3.5× lower active power and smaller code memory footprint; versus ADS7822U, it adds MUX functionality and 22× deeper sleep current - making it uniquely suited for compact, battery-operated dual-sensor systems.
Availability
LTC1861LIMS#PBF is available at Aetrix Electronics and suitable for portable instrumentation, isolated sensor nodes, and battery-powered environmental monitors requiring stable component supply across extended production lifecycles.
Supply support for LTC1861LIMS#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 and maintains full technical and manufacturing continuity for the LTC portfolio, including long-term product assurance and military-grade reliability testing.
The LTC1861LIMS#PBF belongs to Linear's µPower SAR ADC family, designed specifically for high-accuracy, low-quiescent-current data acquisition in space- and energy-constrained embedded systems.
FAQ
What is the maximum clock frequency supported by LTC1861LIMS#PBF for reliable SPI communication?
The LTC1861LIMS#PBF supports SCK frequencies up to 8 MHz under recommended operating conditions. At 8 MHz, timing margins remain sufficient for robust data transfer with standard microcontroller SPI peripherals; however, layout-dependent signal integrity (e.g., trace length, termination) must be verified per Figure 1 timing diagram in the datasheet to ensure tsuDI, tthDI, and tWHCLK compliance. LTC1861LIMS#PBF does not require minimum clock rate - idle pauses between SCK edges are fully permitted.
Does LTC1861LIMS#PBF support true differential input measurements between two independent sensors?
Yes - the LTC1861LIMS#PBF's software-configurable MUX enables true differential mode where CH0 serves as the positive input and CH1 as the negative input (or vice versa), rejecting common-mode noise up to 80 dB. This is confirmed in Table 1 (MUX Channel Selection) and Figure 5 (Transfer Curve) of the datasheet. LTC1861LIMS#PBF requires both channels to share the same AGND reference, and VREF must be externally supplied in the MSOP variant.
Can LTC1861LIMS#PBF operate with a 1.8V reference voltage while powered from a 3.3V supply?
Yes - the LTC1861LIMS#PBF explicitly supports VREF from 1V to VCC per the "VREF Input Range" specification (1 V to VCC). With VCC = 3.3V, a 1.8V reference is fully compliant and yields a 1.8V full-scale range, improving resolution for low-amplitude sensor outputs. The device maintains ±1 LSB INL and 72 dB SNR across this VREF range, as validated in Figures G06 and G10 of the datasheet.
How does the auto-shutdown feature of LTC1861LIMS#PBF reduce system power consumption?
LTC1861LIMS#PBF automatically enters low-current sleep mode (ICC ≤10 µA) when CONV remains high between conversions. At 1ksps sampling, this reduces average supply current from 450 µA to ~10 µA - a 44× reduction. The wake-up time is negligible (<1.5 µs), enabling rapid burst acquisition. This behavior is intrinsic to the LTC1861LIMS#PBF's internal bias and clock-gating architecture, not firmware-controlled.
Is LTC1861LIMS#PBF pin-compatible with any higher-resolution alternatives in the same MSOP-8 package?
Yes - LTC1861LIMS#PBF is pin-compatible with LTC1865LIMS8#PBF (16-bit, 150ksps), as stated in the "Pin Compatible with 16-Bit LTC1864L/LTC1865L" feature list. Both share identical MSOP-8 pin assignments, power sequencing, and serial interface timing. However, LTC1865LIMS8#PBF draws higher supply current (1.22 mW vs. 1.22 mW at full speed) and requires tighter layout for reference stability due to increased sensitivity.
LTC1861LIMS#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm 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:
- -40°C ~ 85°C
- Supplier Device Package:
- 10-MSOP
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
LTC1861LIMS#PBF FAQ
1.How can I place an order for LTC1861LIMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1861LIMS#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 LTC1861LIMS#PBF reliable?
The price and inventory of LTC1861LIMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1861LIMS#PBF is usually 5 days.
3.What payment methods are accepted for LTC1861LIMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1861LIMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1861LIMS#PBF?
LTC1861LIMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1861LIMS#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 LTC1861LIMS#PBF?
For technical support, including LTC1861LIMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1861LIMS#PBF requirements.
6.How does Aetrix verify that LTC1861LIMS#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1861LIMS#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 LTC1861LIMS#PBF meets industry standards.
7.What is the process for return or replacement of LTC1861LIMS#PBF?
All LTC1861LIMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1861LIMS#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 LTC1861LIMS#PBF part is unused and in its original packaging.
Return procedure for LTC1861LIMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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