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Analog Devices Inc. LTC1857IG#PBF
- Part No.:
- LTC1857IG#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 28-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1857IG#PBF.pdf
- Description:
- IC ADC 12BIT SAR 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:495
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Product details
Overview
LTC1857IG#PBF 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 ±1 LSB integral nonlinearity, 40mW typical power dissipation, and operates across –40°C to +85°C for industrial data acquisition systems.
For engineers reviewing the LTC1857IG#PBF datasheet, LTC1857IG#PBF pinout, LTC1857IG#PBF application, or LTC1857IG#PBF equivalent, key selection criteria include its SoftSpan™ programmable input range per channel, ±25V overvoltage tolerance on unused channels, internal 2.5V reference with REFCOMP buffer, 28-pin SSOP package, and guaranteed 100ksps sampling rate with 5µs max conversion time.
Technical Context
The LTC1857IG#PBF implements a successive approximation register (SAR) architecture with an integrated sample-and-hold and factory-trimmed internal reference. Its SoftSpan™ multiplexer uses on-chip resistor networks to scale inputs before routing to ADC+ and ADC–, eliminating multiplexer on-resistance errors and enabling per-channel span selection without external components.
It supports mixed single-ended and differential input configurations across eight channels, with independent channel addressing via 8-bit serial command. Fault protection isolates ±25V transients on unselected channels, preserving conversion integrity on the active channel - critical for multiplexed industrial sensor interfaces where signal sources vary widely in voltage level and grounding.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit - delivers 4096 discrete output codes with natural binary format; sufficient for high-fidelity sensor digitization in PLC I/O modules. |
| Sampling Rate | 100 ksps - guarantees real-time capture of signals up to 50 kHz (Nyquist), suitable for motor current monitoring and vibration analysis. |
| INL Error | ±1 LSB (max, full temp range) - ensures monotonicity and <0.025% full-scale linearity error, enabling accurate calibration without per-channel correction. |
| Input Span Flexibility | Software-selectable 0V–5V / 0V–10V / ±5V / ±10V - eliminates need for external gain/level-shifting circuitry when interfacing diverse sensors (e.g., 4–20 mA loops, thermocouples, strain gauges). |
| Power Dissipation | 40 mW (typ) at 100 ksps - enables dense channel count in space-constrained industrial controllers without forced cooling. |
| Analog Input Protection | ±25V fault tolerance on CH0–CH7 and COM - prevents latch-up or damage during field wiring faults or ESD events in factory-floor environments. |
| Digital Interface | SPI/MICROWIRE-compatible serial I/O with BUSY and RD handshake - simplifies connection to microcontrollers (e.g., ARM Cortex-M4) and avoids parallel bus resource contention. |
Pinout & Package
Package: 28-lead plastic SSOP (G package), 5.6 mm × 10.2 mm body, 0.65 mm lead pitch, RoHS-compliant lead-free finish (Pb-free).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COM (1) | Common reference for single-ended inputs | Must be low-noise analog ground connection; defines zero point for all CH0–CH7 single-ended measurements. |
| CH0–CH7 (2–9) | Analog multiplexer inputs | ±25V tolerant; each configurable as single-ended (vs. COM) or differential pair; software-selected per conversion. |
| MUXOUT+ / MUXOUT– (10–11) | Multiplexer output differential pair | Drives ADC+ and ADC–; internal rescaling applied here - no external scaling needed for selected input span. |
| ADC+ / ADC– (12–13) | Differential analog inputs to SAR core | High-impedance inputs (Hi-Z); accept rescaled signals from MUXOUT; used directly only in direct-input mode (bypassing MUX). |
| AGND1–AGND3 (14,17–18) | Analog ground connections | Separate AGND1 (signal reference), AGND2 (REFCOMP return), AGND3 (substrate tie) minimize ground bounce and reference noise. |
| VREF (15) | 2.5 V internal reference output | Factory-trimmed ±10 ppm/°C; bypass with 1 µF tantalum; can be overdriven by external reference for higher accuracy. |
| REFCOMP (16) | 4.096 V buffered reference output | 1.6384× gain buffer of VREF; drives internal DAC; supports ≤2 mA DC load; bypass with 10 µF + 0.1 µF. |
| AVDD / DVDD / OVDD (19–21) | Analog/digital/output supply rails | AVDD/DVDD = 4.75–5.25 V; OVDD = 3–5 V (3V logic compatible); separate bypassing required per rail to suppress supply coupling. |
| BUSY (22) | Conversion status indicator | Active-low open-drain output; asserts during conversion; used for interrupt-driven or polling-based data ready detection. |
| SDO / SDI / SCK / RD (23–27) | SPI serial interface signals | SDO: tri-state output; SDI: command input (ignored when RD high); SCK: up to 20 MHz; RD: active-low read enable. |
| CONVST (28) | Conversion start trigger | Rising-edge sensitive; initiates acquisition and conversion sequence; minimum 40 ns pulse width required. |
Key Features
| Feature | Design Value |
|---|---|
| Per-channel software-programmable input span | Enables mixed-sensor systems (e.g., 0–5 V pressure transducer + ±10 V accelerometer) on one IC without external gain switches or op-amps. |
| ±25V fault protection on all analog inputs | Prevents system downtime due to field wiring errors or surge events - no external TVS diodes or clamping circuits required. |
| Internal 2.5V reference + 4.096V REFCOMP buffer | Eliminates need for external precision references; REFCOMP provides stable, low-noise DAC reference with minimal layout sensitivity. |
| Nap and Sleep shutdown modes | Reduces current to 8 mA (Nap) or 5.5 µA (Sleep), extending battery life in portable test equipment or remote sensor nodes. |
| Single 5V supply operation | Simplifies power design in industrial controllers; eliminates dual-rail supplies while supporting both unipolar and bipolar input ranges. |
Applications
| Industrial Process Monitoring | Programmable Logic Controller (PLC) I/O Module |
|---|---|
Use Scenario: Continuous digitization of temperature, pressure, flow, and valve position signals from factory floor sensors with varying output ranges (4–20 mA, 0–10 V, ±5 V). IC Role / Device Role / Timing Role: 8-channel ADC front-end with per-channel SoftSpan™ configuration; handles multiplexed scanning at 100 ksps with automatic range adaptation per sensor type. Use Value: Reduces BOM count by eliminating external level shifters and gain amplifiers; ±25V fault tolerance prevents field-induced failures during maintenance or miswiring. |
Use Scenario: Modular analog input card accepting mixed sensor types across 8 isolated channels, requiring high noise immunity and long-term calibration stability. IC Role / Device Role / Timing Role: Primary A/D conversion engine with internal reference and SPI interface; synchronized to backplane clock for deterministic scan timing in cyclic I/O execution. Use Value: ±1 LSB INL ensures <0.025% absolute accuracy after factory calibration; AGND separation minimizes crosstalk between high-speed digital and precision analog sections. |
| Motor Drive Current Sensing | Portable Data Acquisition System |
Use Scenario: Simultaneous sampling of phase currents and DC bus voltage in servo drives, where current shunts produce ±100 mV signals and bus voltage reaches ±500 V (isolated). IC Role / Device Role / Timing Role: High-speed, fault-tolerant ADC capturing current/voltage waveforms at 100 ksps; uses differential inputs for shunt measurement and bipolar mode for offset-referenced bus sensing. Use Value: 5 µs max conversion time enables precise current vector sampling within PWM cycles; ±25V tolerance protects against isolation barrier failure transients. |
Use Scenario: Battery-powered handheld tester acquiring vibration, acoustic, or environmental data from multiple sensors in field service applications. IC Role / Device Role / Timing Role: Low-power ADC subsystem with Nap/Sleep modes; SPI interface connects to ultra-low-power MCU; internal reference reduces external component count. Use Value: 40 mW typical power enables >8 hours runtime on 2000 mAh Li-ion; 28-pin SSOP footprint allows compact PCB layout without sacrificing channel density. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multichannel, programmable-range ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7606BSTZ | 16-bit, 8-channel, ±10V fixed range, parallel + SPI interface, 200 ksps, requires external reference and ±15V analog supply. | Better resolution but less flexible input scaling; suited for lab-grade instrumentation where fixed ±10V range suffices. | Select AD7606BSTZ when absolute 16-bit precision and higher throughput outweigh need for per-channel range programming and single-supply simplicity. |
| ADS8688IPWR | 16-bit, 8-channel, software-programmable 0–5V/0–10V/±5V/±10V, 1 MSPS, internal reference, 3.3V supply, smaller 32-pin TQFP package. | Higher speed and lower voltage operation, but rated only for –40°C to +125°C industrial grade (not extended temp); lacks ±25V fault protection. | Select ADS8688IPWR for high-speed embedded control where 1 MSPS sampling is critical and field overvoltage risk is mitigated externally. |
Compared with AD7606BSTZ and ADS8688IPWR, the LTC1857IG#PBF uniquely balances 12-bit precision, per-channel SoftSpan™ flexibility, ±25V ruggedness, and single 5V supply - making it optimal for cost-sensitive, field-deployed industrial I/O where adaptability and fault resilience are prioritized over maximum resolution or speed.
Availability
LTC1857IG#PBF is available at Aetrix Electronics and suitable for industrial process control, programmable logic controller (PLC) I/O modules, and motor drive current sensing applications requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC1857IG#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, serving industrial, automotive, communications, and healthcare markets.
The LTC1857IG#PBF belongs to ADI's legacy Linear Technology precision data acquisition product line, designed specifically for rugged, software-configurable industrial sensor interfacing - emphasizing fault tolerance, wide input range adaptability, and simplified system-level integration.
FAQ
What is the operating temperature range of the LTC1857IG#PBF?
The LTC1857IG#PBF is specified for operation from –40°C to +85°C, denoted by the "I" grade suffix. This extended industrial temperature range ensures reliable performance in harsh environments such as factory automation cabinets, outdoor control enclosures, and motor drive housings where ambient temperatures fluctuate significantly.
Does the LTC1857IG#PBF require an external reference voltage?
No, the LTC1857IG#PBF includes a factory-trimmed 2.5 V internal bandgap reference (VREF) and a buffered 4.096 V output (REFCOMP) for the internal DAC. An external reference may be applied to VREF only if higher initial accuracy or lower drift is required - the internal reference supports full functionality out-of-the-box.
How does the SoftSpan™ feature work on the LTC1857IG#PBF?
SoftSpan™ enables per-channel software programming of input ranges (0V–5V, 0V–10V, ±5V, ±10V) using on-chip resistor dividers and switches that scale signals before the multiplexer output. The 8-bit serial command sent via SDI configures both channel selection and span simultaneously - eliminating external gain stages and allowing dynamic reconfiguration during runtime.
Can the LTC1857IG#PBF interface directly with a 3.3V microcontroller?
Yes - the LTC1857IG#PBF supports 3V-compatible digital I/O via the OVDD pin (3V–5V), which powers the output buffers. When OVDD = 3.3V, SDO, BUSY, and other outputs meet 3.3V logic thresholds, while AVDD/DVDD remain at 5V to maintain analog performance and internal reference stability.
What is the purpose of the three AGND pins (AGND1, AGND2, AGND3) on the LTC1857IG#PBF?
AGND1 serves as the primary analog ground reference for the input MUX and ADC core; AGND2 returns the REFCOMP buffer; AGND3 ties to the substrate. Separating these grounds minimizes noise coupling between reference circuitry, signal path, and silicon substrate - critical for achieving ±1 LSB INL and clean FFT performance in noisy industrial settings.
LTC1857IG#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- SoftSpan™
- Package/Case:
- 28-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tube
- 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:
- -40°C ~ 85°C
- Supplier Device Package:
- 28-SSOP
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
LTC1857IG#PBF FAQ
1.How can I place an order for LTC1857IG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1857IG#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 LTC1857IG#PBF reliable?
The price and inventory of LTC1857IG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1857IG#PBF is usually 5 days.
3.What payment methods are accepted for LTC1857IG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1857IG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1857IG#PBF?
LTC1857IG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1857IG#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 LTC1857IG#PBF?
For technical support, including LTC1857IG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1857IG#PBF requirements.
6.How does Aetrix verify that LTC1857IG#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1857IG#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 LTC1857IG#PBF meets industry standards.
7.What is the process for return or replacement of LTC1857IG#PBF?
All LTC1857IG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1857IG#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 LTC1857IG#PBF part is unused and in its original packaging.
Return procedure for LTC1857IG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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