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Analog Devices Inc. LTC1855CG#PBF
- Part No.:
- LTC1855CG#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 28-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1855CG#PBF.pdf
- Description:
- IC ADC 14BIT SAR 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,062
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Product details
Overview
LTC1855CG#PBF from Analog Devices (formerly Linear Technology) is a 14-bit, 8-channel, 100ksps analog-to-digital converter with ±10V bipolar input range, ±30V fault-protected multiplexer, and SPI/MICROWIRE-compatible serial interface. It operates from a single 5V supply, features internal 2.5V reference and synchronized clock, and delivers ±1.5LSB integral nonlinearity for precision industrial data acquisition.
For engineers reviewing the LTC1855CG#PBF datasheet, LTC1855CG#PBF pinout, LTC1855CG#PBF application, or LTC1855CG#PBF equivalent, key selection considerations include its 14-bit resolution with guaranteed no missing codes, ±10V input range supporting single-ended or differential configurations, 87dB SINAD at 1kHz, and dual power shutdown modes (27.5mW Nap, 40µW Sleep).
Technical Context
The LTC1855CG#PBF employs a successive approximation register (SAR) architecture with integrated sample-and-hold, internal 2.5V bandgap reference trimmed to ±10ppm/°C, and factory-calibrated resistor network for accurate ±10V input scaling. Its 8-channel analog multiplexer precedes the ADC core, eliminating channel-to-channel gain error from switch resistance.
Conversion is initiated by CONVST rising edge, with BUSY signaling active conversion; serial data is read via SDO using SPI timing (up to 20MHz SCK), supporting both RD-controlled and RD-permanent-low interface modes. All digital inputs accept 3V/5V logic, while OVDD independently sets SDO/BUSY output swing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 14-bit - guarantees monotonic transfer function and no missing codes across full temperature range. |
| Sampling Rate | 100ksps - maximum sustained throughput with guaranteed 4–5µs conversion time and 1µs acquisition time through MUX inputs. |
| INL | ±1.5LSB - ensures high DC accuracy for calibration-critical applications like sensor signal conditioning. |
| SINAD | 83dB at 1kHz - enables >13.5 effective number of bits (ENOB) for medium-bandwidth signal capture. |
| Input Range | ±10V bipolar - supports direct connection to industrial transducers without external level-shifting amplifiers. |
| Overvoltage Protection | ±30V on all MUX inputs - prevents damage or latch-up during field wiring faults or transient surges. |
| Power Dissipation | 40mW at 100ksps; 27.5mW in Nap mode; 40µW in Sleep mode - enables low-power portable or battery-backed DAQ systems. |
Pinout & Package
Package: 28-pin plastic SSOP (G package), exposed pad soldered to PCB ground for thermal and noise performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COM (1) | Common reference for single-ended inputs | Low-noise analog ground reference point; must be isolated from digital return paths. |
| CH0–CH7 (2–9) | Analog multiplexer inputs | ±30V fault-protected channels accepting ±10V signals; impedance 31kΩ requires low-Z drive. |
| MUXOUT+ / MUXOUT– (10–11) | Differential MUX output | Drives ADC+ and ADC– directly; decoupling not required as internal path. |
| ADC+ / ADC– (12–13) | Differential ADC input | Accepts rescaled ±10V signal from MUXOUT; 12pF sample-mode capacitance affects anti-aliasing design. |
| VREF (15) | 2.5V internal reference output | Bypass with 1µF tantalum to AGND1; usable as external reference source if overdriven. |
| REFCOMP (16) | 4.096V buffered reference output | Drives internal DAC; supports ≤2mA DC load; bypass with 10µF + 0.1µF for stability. |
| CONVST (28) | Conversion start trigger | Rising-edge sensitive; minimum 40ns pulse width; initiates acquisition and conversion sequence. |
| BUSY (22) | Conversion status indicator | Active-low open-drain output; asserts low for entire 4–5µs conversion period. |
| SDO / SDI / SCK / RD (23,25,26,27) | SPI/MICROWIRE serial interface | 3V/5V logic compatible; OVDD (Pin 21) sets SDO/BUSY output voltage level independently. |
Key Features
| Feature | Design Value |
|---|---|
| Software-programmable input configuration | Per-channel selection of single-ended or differential mode via 8-bit configuration word, enabling mixed-signal acquisition without hardware rework. |
| Channel fault isolation | ±30V protection on unselected channels prevents cross-talk or corruption of active channel conversion results. |
| Internal synchronized clock | Factory-trimmed for ≤5µs max conversion time-no external crystal or oscillator required for 100ksps operation. |
| Three-state serial output control | RD pin enables/disables SDO driver, allowing direct connection to shared microprocessor data buses without external buffers. |
| Multi-ground architecture | Dedicated AGND1/AGND2/AGND3 and DGND pins minimize digital switching noise coupling into analog signal path. |
Applications
| Industrial Process Monitoring | Multiplexed Sensor Data Acquisition |
|---|---|
Use Scenario: Continuous monitoring of 8 pressure, temperature, and flow sensors in PLC-based control cabinets with ±10V industrial outputs. IC Role / Device Role / Timing Role: 14-bit SAR ADC with integrated MUX and ±30V fault tolerance acts as central digitizer, sampling each channel at 12.5ksps in round-robin mode. Use Value: Eliminates need for external protection diodes and op-amp level shifters, reducing BOM count and board area by 30% versus discrete solutions. | Use Scenario: High-density data logger capturing vibration, strain, and acceleration from 8 piezoelectric and bridge sensors in test benches. IC Role / Device Role / Timing Role: Precision ADC with ±1.5LSB INL and 83dB SINAD serves as front-end digitizer, synchronized to external trigger for burst-mode acquisition. Use Value: Internal 2.5V reference and matched gain/offset tracking across channels enable <1 LSB inter-channel mismatch without per-channel calibration. |
| PC-Based High-Speed DAQ | DSP-Controlled Motor Drive Feedback |
Use Scenario: USB-connected DAQ module interfacing with host PC for real-time oscilloscope and spectrum analysis up to 50kHz bandwidth. IC Role / Device Role / Timing Role: 100ksps ADC with SPI interface feeds data directly to FPGA or microcontroller; BUSY signal enables precise DMA timing alignment. Use Value: 20MHz SCK support and 3V/5V I/O compatibility allow seamless integration with modern ARM Cortex-M or Xilinx Zynq SoC platforms. | Use Scenario: Closed-loop servo controller measuring phase currents and rotor position in 3-phase BLDC drives with fast current loop requirements. IC Role / Device Role / Timing Role: ADC provides simultaneous sampling of three shunt voltages and encoder signals; Nap mode reduces idle power during PWM dead time. Use Value: 40µW Sleep mode and 27.5mW Nap mode cut system standby power by >95% versus continuous-conversion alternatives. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 14-bit multichannel ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADS8684IPWR | 16-bit resolution, 500ksps, internal 4.096V reference, SPI interface, same 28-pin TSSOP package | Higher speed and resolution but lacks ±30V fault protection and software-configurable MUX topology | Select when higher ENOB and throughput are critical and external overvoltage protection is acceptable |
| MAX11620ATI+ | 14-bit, 250ksps, ±10.24V input range, internal reference, SPI interface, 24-pin TQFN package | Fewer channels (4 vs 8), no fault protection, smaller footprint, lower power (18mW at 100ksps) | Select for space-constrained designs requiring half the channel count and minimal quiescent power |
Compared with ADS8684IPWR and MAX11620ATI+, the LTC1855CG#PBF uniquely combines 8-channel ±30V fault tolerance, software-selectable input topology, and guaranteed ±1.5LSB INL in a single 28-pin SSOP-making it optimal for ruggedized industrial multiplexed DAQ where channel integrity under fault conditions is non-negotiable.
Availability
LTC1855CG#PBF is available at Aetrix Electronics and suitable for industrial process control, multiplexed data acquisition systems, and high-speed data acquisition for PCs requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC1855CG#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 LTC1855CG#PBF belongs to ADI's legacy Linear Technology precision data acquisition product line, engineered specifically for high-accuracy, multichannel industrial sensing and control applications demanding robust fault tolerance and low-power operation.
FAQ
What is the guaranteed integral nonlinearity (INL) specification for the LTC1855CG#PBF across its operating temperature range?
The LTC1855CG#PBF guarantees ±1.5LSB integral nonlinearity over its full operating temperature range of 0°C to 70°C. This specification is tested and ensured for all production units, enabling high-precision DC measurements without per-unit calibration in industrial environments where ambient temperature varies.
Can the LTC1855CG#PBF operate with an external reference, and how does that affect its full-scale range?
Yes, the LTC1855CG#PBF supports external reference operation via the VREF pin. When an external reference replaces the internal 2.5V source, the full-scale range becomes ±(1.6384 × VREF) - so a 2.5V external reference maintains the standard ±10V range, while a 2.048V reference yields ±3.35V. The internal reference remains available at REFCOMP (4.096V) regardless of external reference use.
How does the LTC1855CG#PBF handle overvoltage events on unselected analog input channels?
The LTC1855CG#PBF provides ±30V overvoltage protection on all CH0–CH7 and COM pins. During an overvoltage event on any unselected channel, internal clamping circuitry limits current and isolates the fault path, ensuring no degradation or corruption of the conversion result on the currently selected channel - a critical feature for reliability in noisy industrial wiring environments.
What are the power consumption values for the LTC1855CG#PBF in Nap and Sleep modes, and how are they activated?
The LTC1855CG#PBF consumes 27.5mW in Nap mode and 40µW in Sleep mode. These states are entered by writing specific bit patterns ('10' for Nap, '11' for Sleep) into bits [1:0] of the 8-bit configuration word shifted into SDI during setup. Both modes retain register contents and reference bias; only the ADC core and clock are gated, enabling sub-millisecond wake-up to full operation.
Is the LTC1855CG#PBF pin-compatible with other members of the LTC1854/LTC1855/LTC1856 family, and what are the implications for PCB design?
Yes, the LTC1855CG#PBF shares identical 28-pin SSOP pinout and footprint with LTC1854CG#PBF and LTC1856CG#PBF. This allows a single PCB layout to support 12-, 14-, or 16-bit variants via firmware and BOM change only - simplifying design reuse, inventory management, and performance tiering without layout revision or requalification.
LTC1855CG#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Number of Bits:
- 14
- 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:
- -
LTC1855CG#PBF FAQ
1.How can I place an order for LTC1855CG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1855CG#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 LTC1855CG#PBF reliable?
The price and inventory of LTC1855CG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1855CG#PBF is usually 5 days.
3.What payment methods are accepted for LTC1855CG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1855CG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1855CG#PBF?
LTC1855CG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1855CG#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 LTC1855CG#PBF?
For technical support, including LTC1855CG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1855CG#PBF requirements.
6.How does Aetrix verify that LTC1855CG#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1855CG#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 LTC1855CG#PBF meets industry standards.
7.What is the process for return or replacement of LTC1855CG#PBF?
All LTC1855CG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1855CG#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 LTC1855CG#PBF part is unused and in its original packaging.
Return procedure for LTC1855CG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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