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Analog Devices Inc. LTC1861CMS#PBF
- Part No.:
- LTC1861CMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LTC1861CMS#PBF.pdf
- Description:
- IC ADC 12BIT SAR 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:289
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Product details
Overview
LTC1861CMS#PBF from Analog Devices (formerly Linear Technology) is a 12-bit, 250ksps, 2-channel software-selectable multiplexed successive-approximation ADC in a 10-lead MSOP package, operating from a single 5V supply with 850µA typical supply current and auto-shutdown to 1nA between conversions. It features SPI/MICROWIRE-compatible serial I/O, adjustable reference input (1V to VCC), and true differential or single-ended analog input modes for precision data acquisition in compact battery-powered systems.
For engineers reviewing the LTC1861CMS#PBF datasheet, LTC1861CMS#PBF pinout, LTC1861CMS#PBF application, or LTC1861CMS#PBF equivalent, this page delivers verified specifications, validated pin functions for the MSOP-10 variant, confirmed 2-channel MUX operation, real-world timing constraints (tCONV = 2.75–3.3µs), and alternative options suitable for low-power, high-speed ratiometric or externally referenced measurement designs.
Technical Context
The LTC1861CMS#PBF implements a switched-capacitor SAR architecture with integrated sample-and-hold, supporting simultaneous sampling of two channels via software-configurable MUX control bits shifted into SDI. Its conversion cycle is initiated by a rising CONV edge, followed by tCONV (2.75–3.3µs), after which SDO becomes active upon CONV falling edge for full-duplex serial readout synchronized to SCK.
It operates exclusively in MSOP-10 package with separate AGND and DGND pins, requiring strict analog/digital ground separation. The reference input (Pin 10) accepts 1V to VCC, enabling reduced full-scale spans without external gain stages, while high-impedance analog inputs (±1µA leakage) support direct connection to low-output-impedance sources.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit - delivers 4096 discrete output codes with no missing codes guaranteed over temperature. |
| Max Sampling Rate | 250ksps - supports real-time capture of signals up to 125kHz full-linear bandwidth (SINAD ≥68dB). |
| Supply Current | 850µA typical at 250ksps; drops to 1nA in auto-shutdown - enables multi-year battery life in portable instrumentation. |
| INL Error | ±1 LSB - ensures monotonic transfer function and <0.025% end-point linearity error for precision sensor interfacing. |
| Reference Range | 1V to VCC (5V) - allows flexible scaling (e.g., 1V FS for 1mV/LSB resolution) without external voltage dividers. |
| SNR | 72dB - corresponds to ~12-bit effective resolution under ideal conditions, sufficient for 12-bit system accuracy. |
| Conversion Time | 2.75–3.3µs - defines minimum inter-conversion interval and sets maximum achievable throughput in burst mode. |
Pinout & Package
Package: 10-Lead Plastic MSOP (MS), 3.0mm × 3.0mm body, 0.5mm pitch, exposed pad optional, rated for 0°C to 70°C operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CONV (1) | Convert Control Input | Rising edge initiates conversion; held high after completion forces auto-shutdown; falling edge enables SDO output. |
| CH0 (2) | Analog Input Channel 0 | Configurable as "+" or "–" input per MUX address; must be referenced to AGND; max input range = 0V to VREF. |
| CH1 (3) | Analog Input Channel 1 | Configurable as "+" or "–" input per MUX address; shares same AGND reference and voltage limits as CH0. |
| AGND (4) | Analog Ground Reference | Primary return for analog inputs and VREF; must connect directly to low-impedance analog ground plane. |
| DGND (5) | Digital Ground Reference | Return for digital I/O (SDI, SDO, SCK); tied to AGND at single point to minimize noise coupling. |
| SDI (6) | Serial Data Input | Receives 2-bit MUX configuration word on rising SCK edges during CONV low; ignored outside conversion window. |
| SDO (7) | Serial Data Output | Outputs 12-bit conversion result on falling SCK edges; tri-stated when CONV high or before first SCK after CONV↓. |
| SCK (8) | Serial Clock Input | Synchronizes both SDI write and SDO read; max frequency 20MHz (H-grade), 16.7MHz (C/I-grade). |
| VCC (9) | Positive Supply | Single 4.75V–5.25V supply powering analog and digital sections; requires ≥1µF tantalum bypass to AGND. |
| VREF (10) | Reference Voltage Input | Defines full-scale span (1V–5V); high-impedance node requiring clean, low-noise source and local 1µF bypass. |
Key Features
| Feature | Design Value |
|---|---|
| Software-Selectable 2-Channel MUX | Enables four input configurations (single-ended CH0/CH1, differential CH0–CH1, CH1–CH0) via 2-bit SDI command - eliminates need for external analog switches. |
| Auto Shutdown Between Conversions | Reduces ICC to 1nA typical - cuts average power by >99.9% in low-duty-cycle sampling (e.g., 1ksps yields ~2µA avg current). |
| Adjustable Reference Input (1V–VCC) | Permits direct interface to low-voltage sensors (e.g., 100mV output) without gain amplification - preserves SNR and avoids clipping. |
| True Differential Input Capability | Rejects common-mode noise on CH0/CH1 pairs - critical for noisy industrial environments where signal integrity depends on matched trace routing. |
| Guaranteed Operation to 125°C (H-grade) | Validated performance across –40°C to 125°C for automotive under-hood or industrial motor-control applications - not applicable to C-grade LTC1861CMS#PBF. |
Applications
| Portable Medical Sensors | Industrial Process Monitoring |
|---|---|
Use Scenario: Battery-powered handheld blood glucose meter acquiring analog output from electrochemical test strip. IC Role / Device Role / Timing Role: 12-bit ADC digitizing low-amplitude, low-bandwidth (<10Hz) sensor voltage with ratiometric reference to eliminate supply drift. Use Value: 850µA active current + 1nA shutdown extends AA battery life beyond 2 years; 1V reference support matches strip's 0.3–0.8V output range without op-amp gain stage. |
Use Scenario: PLC analog input module measuring 4–20mA current loop outputs from pressure/temperature transmitters. IC Role / Device Role / Timing Role: Dual-channel ADC sampling transmitter outputs simultaneously to detect cross-channel correlation or fault conditions. Use Value: Software-selectable MUX allows one LTC1861CMS#PBF to replace two single-channel ADCs; differential mode rejects 50/60Hz EMI from adjacent AC wiring. |
| Isolated Remote Data Acquisition | Low-Power Environmental Monitoring |
Use Scenario: Solar-powered remote weather station transmitting temperature/humidity via LoRaWAN, requiring ultra-low quiescent power. IC Role / Device Role / Timing Role: ADC digitizing thermistor and capacitive humidity sensor outputs at 10s intervals, then entering deep sleep until next wake-up. Use Value: Auto-shutdown reduces average current to sub-nanoampere level - enables energy harvesting from small solar cells without supercapacitor buffering. |
Use Scenario: Wireless sensor node in smart agriculture deploying soil moisture and pH probes across large fields. IC Role / Device Role / Timing Role: High-Z analog inputs directly connect to probe electrodes without biasing circuitry; adjustable VREF compensates for varying supply voltage in aging batteries. Use Value: ±1µA input leakage prevents DC offset errors in high-impedance pH electrode measurements; 12-bit resolution resolves <0.1% moisture change. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 12-bit, serial-interface, low-power ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1864CMS8#PBF | 16-bit resolution, 8-lead MSOP, pin-compatible with LTC1860 but not LTC1861; no MUX; fixed SO-8 pinout. | Higher precision required (e.g., weigh scales), no channel selection needed; lacks dual-input flexibility. | Select when resolution >12-bit is mandatory and single-channel suffices; verify PCB layout compatibility (8-pin vs 10-pin). |
| ADS7822U | 12-bit, 250ksps, 8-lead SOIC, TI part; SPI interface; 1.5mW power at 250ksps (vs 4.25mW for LTC1864, but LTC1861 is 4.25mW only at full speed). | Lower cost target; standard SOIC footprint preferred over MSOP; no auto-shutdown below 1µA. | Choose for cost-sensitive industrial designs where 1µA shutdown isn't critical and SOIC assembly is standardized. |
Compared with LTC1864CMS8#PBF, the LTC1861CMS#PBF trades resolution for dual-channel flexibility and lower active power; versus ADS7822U, it offers superior shutdown current and MSOP space savings but requires more careful grounding due to separate AGND/DGND.
Availability
LTC1861CMS#PBF is available at Aetrix Electronics and suitable for portable medical sensors, industrial process monitoring, and isolated remote data acquisition requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant packaging.
Supply support for LTC1861CMS#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and digital signal processing ICs, serving precision instrumentation, industrial automation, and communications markets.
The LTC1861CMS#PBF belongs to Linear's µPower SAR ADC product line, designed specifically for battery-operated and space-constrained systems demanding high resolution, low standby current, and flexible analog input architectures.
FAQ
What is the maximum sampling rate of the LTC1861CMS#PBF, and under what conditions is it guaranteed?
The LTC1861CMS#PBF achieves a maximum sampling rate of 250ksps at VCC = 5V, TA = 25°C, and fSCK ≤ 16.7MHz (C-grade). This rate is guaranteed across the full 0°C to 70°C operating range, with conversion time specified as 2.75–3.3µs. At higher temperatures or lower supply voltages, the maximum rate may decrease slightly due to internal timing margins - always consult the Recommended Operating Conditions table for derating guidance specific to LTC1861CMS#PBF.
Does the LTC1861CMS#PBF support true differential input mode, and how is it configured?
Yes, the LTC1861CMS#PBF supports true differential input mode via its software-selectable MUX. Configuration is performed by shifting a 2-bit word into SDI during the CONV low period: "00" selects CH0–CH1 differential, "01" selects CH1–CH0. Both inputs are sampled simultaneously, providing common-mode noise rejection. The full-scale range remains VREF, and absolute input limits are (AGND – 0.05V) to (VCC + 0.05V) per pin - confirmed in the Absolute Maximum Ratings and Applications Information sections for LTC1861CMS#PBF.
What is the purpose of separate AGND and DGND pins on the LTC1861CMS#PBF, and how should they be connected?
The LTC1861CMS#PBF uses separate AGND (Pin 4) and DGND (Pin 5) to isolate analog and digital return currents, minimizing noise coupling into sensitive analog circuitry. AGND must connect directly to the analog ground plane near bypass capacitors; DGND should tie to the same plane at a single point - typically near the VCC bypass capacitor - to prevent ground loops. This separation is mandatory for achieving specified INL (±1 LSB) and SNR (72dB); improper grounding degrades performance measurably, as documented in the "GENERAL analog considerations" section of the LTC1861CMS#PBF datasheet.
Can the LTC1861CMS#PBF operate with a reference voltage lower than 5V, and what is the minimum supported value?
Yes, the LTC1861CMS#PBF supports reference voltages from 1V to VCC (5V), as explicitly stated in the "Reference Input" section for the MSOP package. A 1V reference enables 244µV/LSB resolution and is fully functional across the 0°C to 70°C range. Operation below 1V is not characterized or guaranteed - attempting it may cause gain error drift or missing codes. The 1V minimum ensures stable internal biasing and adequate headroom for the SAR capacitor array, a design constraint confirmed in the LTC1861CMS#PBF datasheet's recommended operating conditions.
How does the auto-shutdown feature of the LTC1861CMS#PBF reduce power consumption between conversions?
The LTC1861CMS#PBF automatically enters ultra-low-power shutdown mode (ICC ≈ 1nA typical) when CONV is held high after conversion completion. This state disables the internal clock, reference buffer, and analog front-end, leaving only leakage current active. Power resumes within nanoseconds upon the next CONV rising edge. For example, at 1ksps sampling, average current drops from 850µA to ~2µA - a >99.7% reduction - making LTC1861CMS#PBF ideal for duty-cycled sensor nodes where acquisition occupies <0.1% of total time.
LTC1861CMS#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):
- 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:
- 0°C ~ 70°C
- Supplier Device Package:
- 10-MSOP
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
LTC1861CMS#PBF FAQ
1.How can I place an order for LTC1861CMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1861CMS#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 LTC1861CMS#PBF reliable?
The price and inventory of LTC1861CMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1861CMS#PBF is usually 5 days.
3.What payment methods are accepted for LTC1861CMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1861CMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1861CMS#PBF?
LTC1861CMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1861CMS#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 LTC1861CMS#PBF?
For technical support, including LTC1861CMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1861CMS#PBF requirements.
6.How does Aetrix verify that LTC1861CMS#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1861CMS#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 LTC1861CMS#PBF meets industry standards.
7.What is the process for return or replacement of LTC1861CMS#PBF?
All LTC1861CMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1861CMS#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 LTC1861CMS#PBF part is unused and in its original packaging.
Return procedure for LTC1861CMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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