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Analog Devices Inc. LTC1285IS8#PBF
- Part No.:
- LTC1285IS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1285IS8#PBF.pdf
- Description:
- IC ADC 12BIT SAR 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:164
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Product details
Overview
LTC1285IS8#PBF from Analog Devices (formerly Linear Technology) is a 12-bit micropower successive approximation ADC with differential analog inputs, single-supply operation (2.7V–6V), 160µA typical supply current at 7.5ksps, auto-shutdown to 1nA, and on-chip sample-and-hold - designed for ultra-low-power sensor digitization in battery-operated systems.
For engineers reviewing the LTC1285IS8#PBF datasheet, LTC1285IS8#PBF pinout, LTC1285IS8#PBF application, or LTC1285IS8#PBF equivalent, this page delivers verified technical context, SO-8 package pin mapping, real-world use-value per application, and two validated alternative parts with precise functional and selection guidance.
Technical Context
The LTC1285IS8#PBF implements a switched-capacitor SAR architecture with integrated sample-and-hold and a 3-wire SPI/Microwire-compatible serial interface. It operates exclusively in unipolar mode with fixed differential input configuration and external reference pin (VREF).
Its shutdown logic is controlled solely by the CS/SHDN pin: low enables conversion and data transfer; high forces full power-down, disabling bias circuitry and placing VREF in high-impedance state - independent of CLK or DOUT activity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit with no missing codes - guarantees monotonicity and full-scale linearity for precision ratiometric measurements. |
| Supply Current | 160µA typ at 7.5ksps; drops to 1nA typ in shutdown - enables multi-year battery life in intermittent-sampling applications. |
| Conversion Time | 100µs (12 clock cycles @ 120kHz) - supports deterministic timing control in real-time embedded firmware. |
| Differential Nonlinearity | ±3/4 LSB max - ensures accurate representation of small signal changes without code ambiguity. |
| Analog Input Range | Differential ±VREF/2 (e.g., ±1.25V with 2.5V reference) - allows direct connection to bridge sensors or instrumentation amplifiers. |
| Reference Input | External VREF pin (Pin 1), 1.5V–VCC+0.05V range - enables flexible scaling and ratiometric operation with external references or supply-derived references. |
| Operating Voltage | 2.7V to 6V single supply - supports direct integration into 3V, 3.3V, or 5V systems without level-shifting. |
Pinout & Package
Package: 8-lead plastic SO (SO-8), 150°C max junction temperature, θJA = 175°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VREF (Pin 1) | Reference voltage input | Defines full-scale span; high-impedance node during shutdown; supports 1.5V–6.05V range for flexible scaling. |
| +IN (Pin 2) | Positive analog input | Differential input terminal; accepts signals up to VCC + 0.05V; used with –IN for common-mode rejection. |
| –IN (Pin 3) | Negative analog input | Differential input terminal; complements +IN; enables true differential measurement relative to VREF/2. |
| GND (Pin 4) | Analog ground reference | Must connect directly to analog ground plane; separates analog return path from digital noise sources. |
| CS/SHDN (Pin 5) | Chip select / shutdown control | Active-low enable; high = full shutdown (1nA); low = active conversion; rail-to-rail switching required for min current. |
| DOUT (Pin 6) | Serial data output | MSB-first 12-bit result; tri-state when CS high; timing-critical for microcontroller sampling (tDO ≤ 1500ns). |
| CLK (Pin 7) | Serial clock input | Synchronizes data transfer; falling edge clocks data out; max 120kHz at 2.7V; frequency scales with VCC. |
| VCC (Pin 8) | Power supply | 2.7V–6V single supply; requires local 10µF tantalum bypass to GND; noise-sensitive - must avoid digital coupling. |
Key Features
| Feature | Design Value |
|---|---|
| Auto shutdown to 1nA | Eliminates need for external power gating; reduces system quiescent current by >5 orders of magnitude between samples. |
| Differential input architecture | Rejects common-mode noise from transducers and long traces; enables direct interface to strain gauges, thermocouples, and current shunts. |
| On-chip sample-and-hold | Removes need for external S/H circuitry; acquires stable input within 1.5 clock cycles - critical for high-Z sensor interfaces. |
| I/O compatibility with SPI/Microwire | 3-wire interface (CS, CLK, DOUT) simplifies MCU integration; no DIN required - reduces GPIO count and PCB routing complexity. |
| Reduced full-scale span support | Operates down to 1.5V full scale (e.g., 366µV LSB with 1.5V reference), enabling high-resolution measurement of low-output sensors. |
Applications
| Pen Screen Digitizing | Battery Monitoring |
|---|---|
Use Scenario: Digitizing analog voltage from resistive touch screen layers under low-duty-cycle polling. IC Role / Device Role / Timing Role: Differential ADC capturing X/Y coordinate voltages with 12-bit resolution and <100µs conversion time. Use Value: 160µA active current and 1nA shutdown extend coin-cell life beyond 5 years in handheld stylus devices. |
Use Scenario: Measuring cell voltage across Li-ion or NiMH battery packs in portable medical devices. IC Role / Device Role / Timing Role: High-impedance ratiometric ADC referenced to internal bandgap or supply rail. Use Value: ±3/4 LSB DNL ensures accurate state-of-charge estimation without calibration drift over temperature. |
| Remote Data Acquisition | Isolated Data Acquisition |
Use Scenario: Sensor node collecting temperature/humidity data via LoRaWAN or NB-IoT with multi-hour sleep intervals. IC Role / Device Role / Timing Role: Micropower ADC triggered by MCU wake-up; converts only during active transmission window. Use Value: Auto-shutdown eliminates software-controlled power sequencing - simplifies firmware and improves reliability. |
Use Scenario: Industrial current/voltage sensing across opto- or capacitive isolation barriers in motor drives. IC Role / Device Role / Timing Role: ADC placed on field-side; serial output clocked across isolator to host controller. Use Value: 3-wire interface minimizes isolated signal lines; low EMI emissions due to 120kHz max clock reduce filter complexity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 12-bit micropower ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADS7822U | 8-pin SO, 12-bit, 200ksps, 1.2mA active current, no auto-shutdown, internal reference only | Higher speed but 7.5× higher active current; unsuitable for sub-µA shutdown requirements | Select only if sampling rate >10ksps is mandatory and battery life is secondary to throughput. |
| MAX11131ASA+ | 8-pin SO, 12-bit, 100ksps, 350µA active, 2µA shutdown, SPI interface, internal reference | Lower shutdown current than ADS7822 but still 2000× higher than LTC1285IS8#PBF; no external VREF pin | Choose when board space is constrained and internal reference suffices, but expect reduced battery runtime vs LTC1285IS8#PBF. |
Compared with ADS7822U and MAX11131ASA+, the LTC1285IS8#PBF uniquely delivers sub-nA shutdown, external reference flexibility, and differential input topology - making it irreplaceable for ultra-low-power, precision ratiometric, or isolated analog front-ends where energy budget is measured in nanoamps.
Availability
LTC1285IS8#PBF is available at Aetrix Electronics and suitable for battery-operated systems, remote data acquisition nodes, and isolated industrial sensors requiring stable component supply with guaranteed long-term availability.
Supply support for LTC1285IS8#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 product support, documentation, and manufacturing continuity for legacy Linear parts including the LTC1285 series.
The LTC1285IS8#PBF belongs to Linear's micropower precision ADC family, engineered specifically for energy-constrained applications demanding high resolution, low noise, and minimal quiescent current without sacrificing accuracy.
FAQ
What is the maximum clock frequency supported by the LTC1285IS8#PBF at 3V supply?
The LTC1285IS8#PBF supports a maximum clock frequency of 120kHz when operating at VCC = 2.7V. At higher supply voltages (e.g., 5V), the maximum clock increases - reaching ~200kHz at 6V - as confirmed in the "Maximum Clock Frequency vs Supply Voltage" plot (TPC21). Exceeding the rated frequency risks incomplete conversions and increased DNL error.
Does the LTC1285IS8#PBF require an external reference, or can it operate with VCC as reference?
The LTC1285IS8#PBF requires an external reference applied to the VREF pin (Pin 1); it does not support internal reference or VCC-as-reference operation. The LTC1288 variant ties VREF to VCC, but the LTC1285IS8#PBF is explicitly designed for external reference flexibility - enabling ratiometric measurements, low-noise references, or reduced-span operation down to 1.5V full scale.
Can the LTC1285IS8#PBF interface directly with an 8051 microcontroller using only three wires?
Yes - the LTC1285IS8#PBF uses a true 3-wire SPI/Microwire interface (CS/SHDN, CLK, DOUT) with no DIN required. Application Note TA01 shows direct connection to an 8051 (e.g., P1.2–P1.4), where CS controls enable, CLK synchronizes, and DOUT streams MSB-first 12-bit data - eliminating level shifters or additional GPIOs.
What is the guaranteed differential nonlinearity (DNL) specification for the LTC1285IS8#PBF?
The LTC1285IS8#PBF guarantees ±3/4 LSB maximum DNL across the full operating temperature range (0°C to 70°C), as stated in the "Converter and Multiplexer Characteristics" table (Page 3). This ensures monotonic behavior and absence of missing codes - critical for closed-loop control and precision measurement applications.
How does the LTC1285IS8#PBF achieve 1nA shutdown current, and what conditions must be met?
The LTC1285IS8#PBF achieves 1nA typical shutdown current when the CS/SHDN pin is driven fully high (to VCC), which gates off all internal bias circuitry and places VREF in high-impedance state. To reach this spec, CS must be rail-to-rail - partial logic levels increase leakage. CLK and DOUT may remain active during shutdown with zero impact on current draw.
LTC1285IS8#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):
- 7.5k
- Number of Inputs:
- 1
- Input Type:
- Differential
- 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 ~ 6V
- Voltage - Supply, Digital:
- 2.7V ~ 6V
- Features:
- -
- Operating Temperature:
- 0°C ~ 70°C
- Supplier Device Package:
- 8-SO
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
LTC1285IS8#PBF FAQ
1.How can I place an order for LTC1285IS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1285IS8#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 LTC1285IS8#PBF reliable?
The price and inventory of LTC1285IS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1285IS8#PBF is usually 5 days.
3.What payment methods are accepted for LTC1285IS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1285IS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1285IS8#PBF?
LTC1285IS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1285IS8#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 LTC1285IS8#PBF?
For technical support, including LTC1285IS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1285IS8#PBF requirements.
6.How does Aetrix verify that LTC1285IS8#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1285IS8#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 LTC1285IS8#PBF meets industry standards.
7.What is the process for return or replacement of LTC1285IS8#PBF?
All LTC1285IS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1285IS8#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 LTC1285IS8#PBF part is unused and in its original packaging.
Return procedure for LTC1285IS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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