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Analog Devices Inc. LTC1857CG#TRPBF
- Part No.:
- LTC1857CG#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 28-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1857CG#TRPBF.pdf
- Description:
- IC ADC 12BIT SAR 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,329
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Product details
Overview
LTC1857CG#TRPBF from Analog Devices (formerly Linear Technology) is a 12-bit, 8-channel, 100ksps software-programmable analog-to-digital converter with ±25V fault-protected inputs, single 5V supply operation, and SPI/MICROWIRE-compatible serial interface. It supports unipolar (0V–5V, 0V–10V) and bipolar (±5V, ±10V) input spans, features ±1LSB integral nonlinearity, and targets industrial data acquisition systems requiring channel multiplexing and robust input protection.
For engineers reviewing the LTC1857CG#TRPBF datasheet, LTC1857CG#TRPBF pinout, LTC1857CG#TRPBF application, or LTC1857CG#TRPBF equivalent, key selection criteria include its 12-bit resolution with ±1LSB INL, 100ksps sampling rate across 8 channels, ±25V overvoltage tolerance on all analog inputs, and support for both single-ended and differential configurations via software-selectable SoftSpan™ ranges.
Technical Context
The LTC1857CG#TRPBF implements a successive approximation register (SAR) architecture with an integrated sample-and-hold and factory-trimmed 2.5V bandgap reference. Its programmable resistor-divider network precedes the 8-channel analog multiplexer, eliminating multiplexer on-resistance errors and enabling per-channel span selection without external components.
It delivers DC accuracy of ±1LSB INL and ±1LSB DNL over 0°C to 70°C, supports dual power shutdown modes (Nap: 5.5mA, Sleep: 8µA), and provides synchronized internal clocking with guaranteed 5µs max conversion time. The device interfaces via 3-wire SPI-compatible serial I/O with active-low RD, SCK, SDI, and SDO, plus dedicated CONVST and BUSY signals for microprocessor/DSP timing control.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit - Provides 4096 discrete output codes for precise digitization of analog sensor or process signals. |
| Sampling Rate | 100ksps - Enables real-time capture of signals up to 50kHz (Nyquist-limited), suitable for motor control feedback and vibration monitoring. |
| Integral Nonlinearity | ±1LSB - Ensures monotonicity and high code-to-code accuracy critical for closed-loop control calibration. |
| Analog Input Protection | ±25V on CH0–CH7 and COM - Allows direct connection to industrial field wiring without external clamping, reducing BOM count. |
| Power Dissipation | 40mW typical - Supports thermally constrained embedded designs while maintaining full performance at 100ksps. |
| Digital Interface | SPI/MICROWIRE-compatible - Simplifies integration with ARM Cortex-M, PIC, and DSP platforms using standard peripheral drivers. |
| Reference | Internal 2.5V ±10ppm/°C - Eliminates need for external precision reference in cost-sensitive applications; REFCOMP provides 4.096V buffered output. |
Pinout & Package
Package: 28-pin Plastic SSOP (G package), 0°C to 70°C operating temperature range, lead-free finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COM (1) | Common reference for single-ended inputs | Must be low-noise and tied to analog ground plane; defines zero-reference point for all CH0–CH7 single-ended measurements. |
| CH0–CH7 (2–9) | Analog multiplexer inputs | Each accepts ±25V fault-protected unipolar/bipolar signals; software-configurable per channel for span and mode. |
| MUXOUT+ / MUXOUT– (10–11) | Multiplexer differential output | Drives ADC+ and ADC– internally; accessible for external signal conditioning or diagnostic probing. |
| ADC+ / ADC– (12–13) | Differential analog input to SAR core | Accepts rescaled signal from MUXOUT; high-impedance input (Hi-Z) during hold phase minimizes loading effects. |
| VREF (15) | 2.5V internal reference output | Bypass with 1µF tantalum to AGND1; can be overdriven by external reference for enhanced accuracy. |
| REFCOMP (16) | 4.096V buffered reference output | Drives internal DAC; decouple with 10µF + 0.1µF capacitors; supports ≤2mA DC load only. |
| CONVST (28) | Conversion start trigger | Rising-edge initiated; initiates acquisition after sixth SCK edge in command word, enabling precise timing control. |
| BUSY (22) | Conversion status indicator | Active-low open-drain output; asserts during conversion and releases upon data readiness for synchronous readout. |
Key Features
| Feature | Design Value |
|---|---|
| SoftSpan™ software-programmable input ranges | Per-channel selection of 0V–5V, 0V–10V, ±5V, or ±10V eliminates external gain/attenuation circuitry and enables mixed-signal acquisition in one system. |
| ±25V fault protection on all analog inputs | Prevents damage and data corruption during transient overvoltage events common in industrial PLC and motor drive environments. |
| On-chip 2.5V reference with 4.096V buffered output | Reduces component count and layout complexity; REFCOMP's 1.6384× gain matches 12-bit full-scale requirements (2.5V × 1.6384 = 4.096V). |
| Dual shutdown modes (Nap/Sleep) | Nap mode draws 5.5mA for rapid wake-up; Sleep mode draws only 8µA for battery-backed monitoring applications. |
| Single 5V supply operation | Eliminates need for dual ±5V or ±15V rails, simplifying power design and improving compatibility with modern 5V logic families. |
| Channel-to-channel isolation >120dB | Ensures accurate crosstalk-free measurement when acquiring signals from multiple sensors sharing a common ADC. |
Applications
| Industrial Process Monitoring | Programmable Logic Controller (PLC) I/O Module |
|---|---|
|
Use Scenario: Continuous acquisition of temperature, pressure, and flow sensor outputs across eight field points in a chemical plant control loop. IC Role / Device Role / Timing Role: 8-channel multiplexed ADC with per-channel SoftSpan™ configuration handles mixed 4–20mA, 0–10V, and ±10V sensor outputs without external signal conditioning. Use Value: ±25V input protection prevents field-wiring transients from disrupting control integrity; ±1LSB INL ensures calibrated accuracy for regulatory compliance reporting. |
Use Scenario: Modular analog input card in a DIN-rail mounted PLC, supporting hot-swappable configuration of voltage/current input types per channel. IC Role / Device Role / Timing Role: Central 12-bit sampling engine with SPI interface synchronizes to PLC backplane clock and reports BUSY status for deterministic scan-cycle timing. Use Value: Software-selectable ranges eliminate hardware jumpers or DIP switches, enabling firmware-defined I/O flexibility and reducing inventory SKUs. |
| Motor Drive Current Sensing | Test & Measurement Data Logger |
|
Use Scenario: Simultaneous sampling of three-phase motor currents and DC bus voltage in an industrial inverter, with overcurrent detection capability. IC Role / Device Role / Timing Role: High-speed 100ksps acquisition captures current ripple and commutation events; differential mode rejects common-mode noise from PWM switching. Use Value: 40mW power dissipation allows dense packaging near heat-generating IGBTs; ±1LSB DNL preserves torque control linearity under dynamic load conditions. |
Use Scenario: Portable battery-powered logger capturing environmental sensor data (thermocouples, strain gauges, humidity) over extended periods. IC Role / Device Role / Timing Role: Low-power ADC with Sleep mode (8µA) extends battery life; internal reference removes need for external voltage reference IC. Use Value: Single 5V supply simplifies power architecture; REFCOMP's 4.096V output directly supports 12-bit full-scale resolution without scaling resistors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multichannel, software-programmable ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7928BRUZ | 8-channel, 12-bit, 1MSPS SAR ADC; no built-in ±25V fault protection; requires external reference and level-shifting for ±10V inputs. | Higher speed but lacks integrated overvoltage protection and software-programmable spans; suited for clean lab environments, not harsh industrial fields. | Select AD7928BRUZ only if 1MSPS throughput is required and external protection/conditioning is acceptable. |
| LTC1859CG#TRPBF | 16-bit resolution, ±3LSB INL, same pinout and SoftSpan™ architecture; higher SNR (87dB vs 74dB) and improved DNL. | Delivers higher precision for metrology-grade applications; shares identical footprint and software interface, enabling drop-in upgrade path. | Choose LTC1859CG#TRPBF when 16-bit resolution and <100ppm full-scale accuracy are mandatory for calibration-critical systems. |
Compared with AD7928BRUZ, LTC1857CG#TRPBF offers integrated fault protection and span flexibility at lower speed, while LTC1859CG#TRPBF provides a seamless 16-bit upgrade within the same family-enabling scalable design reuse without PCB revision.
Availability
LTC1857CG#TRPBF is available at Aetrix Electronics and suitable for industrial process control, programmable logic controller (PLC) I/O modules, and motor drive current sensing requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LTC1857CG#TRPBF 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 semiconductors for precision instrumentation, industrial automation, and communications infrastructure.
The LTC1857CG#TRPBF belongs to Linear's SoftSpan™ ADC product line, designed specifically for industrial data acquisition systems needing flexible input configuration, robust field survivability, and minimal external component count in space-constrained modules.
FAQ
What is the maximum sampling rate supported by the LTC1857CG#TRPBF?
The LTC1857CG#TRPBF guarantees a maximum sampling rate of 100ksps across all eight input channels. This is achieved with a typical conversion time of 4µs and maximum acquisition time of 4µs, ensuring deterministic throughput for real-time control loops. The device also supports up to 166kHz sampling when using only the dedicated ADC+ and ADC– pins, bypassing the multiplexer.
Does the LTC1857CG#TRPBF require an external reference voltage?
No, the LTC1857CG#TRPBF includes a factory-trimmed 2.5V internal bandgap reference with ±10ppm/°C temperature coefficient, and a buffered 4.096V output (REFCOMP) for driving the internal DAC. However, VREF can be overdriven with an external precision reference if higher absolute accuracy is required for calibration-critical applications.
How does the SoftSpan™ feature work on the LTC1857CG#TRPBF?
The SoftSpan™ feature on the LTC1857CG#TRPBF uses on-chip resistor dividers and switches to provide software-selectable input ranges per channel: 0V–5V, 0V–10V, ±5V, or ±10V. An 8-bit command word sent via SPI configures both the channel address and span simultaneously, enabling mixed-range acquisition without external gain stages or hardware reconfiguration.
What is the purpose of the REFCOMP pin on the LTC1857CG#TRPBF?
The REFCOMP pin on the LTC1857CG#TRPBF provides a buffered 4.096V output derived from the internal 2.5V reference (2.5V × 1.6384 = 4.096V), optimized for the 12-bit full-scale range. It drives the internal DAC and may supply ≤2mA DC load; AC loading is not recommended as it degrades ADC performance. Decoupling with 10µF + 0.1µF capacitors is mandatory.
Can the LTC1857CG#TRPBF operate with a 3V digital interface?
Yes, the LTC1857CG#TRPBF supports 3V-compatible digital I/O: OVDD can be supplied from 3V to 5V independently of AVDD/DVDD (5V), allowing direct interfacing with 3V microcontrollers or FPGAs. Digital input thresholds (VIH = 2.4V min, VIL = 0.8V max) and output drive levels are fully compatible with 3V logic families when OVDD = 3V.
LTC1857CG#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- SoftSpan™
- Package/Case:
- 28-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Number of Bits:
- 12
- Sampling Rate (Per Second):
- 100k
- Number of Inputs:
- 8
- Input Type:
- Differential, Single Ended
- Data Interface:
- SPI
- Configuration:
- MUX-S/H-ADC
- Ratio - S/H:ADC:
- 1:1
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- External, Internal
- Voltage - Supply, Analog:
- 5V
- Voltage - Supply, Digital:
- 5V
- Features:
- -
- Operating Temperature:
- 0°C ~ 70°C
- Supplier Device Package:
- 28-SSOP
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
LTC1857CG#TRPBF FAQ
1.How can I place an order for LTC1857CG#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1857CG#TRPBF 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 LTC1857CG#TRPBF reliable?
The price and inventory of LTC1857CG#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1857CG#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1857CG#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1857CG#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1857CG#TRPBF?
LTC1857CG#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1857CG#TRPBF 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 LTC1857CG#TRPBF?
For technical support, including LTC1857CG#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1857CG#TRPBF requirements.
6.How does Aetrix verify that LTC1857CG#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1857CG#TRPBF 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 LTC1857CG#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1857CG#TRPBF?
All LTC1857CG#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1857CG#TRPBF, 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 LTC1857CG#TRPBF part is unused and in its original packaging.
Return procedure for LTC1857CG#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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