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Analog Devices Inc. LTC1668IG#TRPBF
- Part No.:
- LTC1668IG#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Digital to Analog Converters (DAC)
- Package:
- 28-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1668IG#TRPBF.pdf
- Description:
- IC DAC 16BIT A-OUT 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,346
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Product details
Overview
LTC1668IG#TRPBF from Analog Devices (formerly Linear Technology) is a 16-bit, 50Msps differential current-output DAC implemented in high-performance BiCMOS with laser-trimmed thin-film resistors. It delivers 87dB SFDR at 1MHz fOUT, 5pV·s differential glitch impulse, 20ns settling time, and operates from ±5V supplies with TTL/CMOS-compatible 3.3V/5V digital inputs. It is used in high-fidelity direct digital synthesis and multicarrier base station signal generation.
For engineers reviewing the LTC1668IG#TRPBF datasheet, LTC1668IG#TRPBF pinout, LTC1668IG#TRPBF application, or LTC1668IG#TRPBF equivalent, key selection criteria include guaranteed 16-bit monotonicity, ±1LSB DNL over industrial temperature (–40°C to +85°C), differential output compliance of ±1V, internal 2.5V reference with 25ppm/°C drift, and 28-pin SSOP package compatibility with LTC1666/LTC1667 for design reuse.
Technical Context
The LTC1668IG#TRPBF employs a segmented current-steering architecture: the four MSBs use 15 equal-weight current segments, while the 12 LSBs use binary-weighted current sources combined with a differential resistive attenuator ladder. This structure ensures precise DC linearity and low glitch energy across full-scale transitions.
Its internal 2.5V bandgap reference drives REFOUT (Pin 15) and controls full-scale output current IOUTFS via IREFIN (Pin 16) and external RSET, enabling IOUTFS adjustment from 1mA to 10mA using Equation IOUTFS = 8 × (VREF/RSET). The reference control loop requires 0.1µF compensation on COMP1 (Pin 21) tied to VSS for stability and optimal AC performance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 16-bit - guarantees monotonic operation up to 65,535 codes with ±1LSB DNL |
| Update Rate | 50Msps - supports real-time waveform synthesis up to Nyquist frequency of 25MHz |
| SFDR @ 1MHz | 87dB - enables clean spectral purity in wireless baseband and DDS applications |
| Glitch Impulse | 5pV·s (differential) - minimizes transient-induced spurs during code transitions |
| Settling Time | 20ns to 0.1% FSR - ensures accurate sampling at high clock rates without timing margin loss |
| Supply Voltage | ±4.75V to ±5.25V - compatible with standard dual-rail analog power domains |
| Full-Scale Current | 10mA nominal - sets output voltage swing when loaded with 52.3Ω for 1VP-P differential |
Pinout & Package
The LTC1668IG#TRPBF is housed in a 28-lead plastic SSOP (G package) with 0.635mm lead pitch, rated for –40°C to +85°C operation. Pin functions are validated per Linear Technology's official datasheet revision.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DB0–DB15 | Digital input data bus (LSB to MSB) | 16-bit parallel interface latched on CLK rising edge; accepts 3.3V or 5V CMOS logic |
| CLK | Clock input | Positive-edge-triggered update; minimum pulse width 5ns high / 8ns low |
| IOUT A / IOUT B | Differential current outputs | Complementary outputs delivering full-scale current (10mA) with ±1V compliance range |
| REFOUT / IREFIN | Internal reference output & control input | 2.5V reference (25ppm/°C drift); sets IOUTFS via external RSET (e.g., 2kΩ → 10mA) |
| COMP1 / COMP2 | Reference loop compensation nodes | 0.1µF bypass to VSS required on COMP1 for stability; COMP2 is internal bypass point |
| VDD / VSS | Positive / negative supply rails | ±5V nominal; supports 180mW total power dissipation at 50Msps |
| AGND / DGND / LADCOM | Analog ground / digital ground / ladder common | Separate AGND/DGND reduces digital noise coupling; LADCOM ties to load reference potential |
Key Features
| Feature | Design Value |
|---|---|
| Pin-compatible family | Shares identical 28-pin SSOP footprint and register mapping with LTC1666 (12-bit) and LTC1667 (14-bit) for scalable resolution upgrades |
| Differential current outputs | Enables true differential voltage generation with transformer or op-amp interfaces, canceling common-mode noise and doubling signal power |
| Internal 2.5V reference | Trimmed bandgap reference with 25ppm/°C drift and 6mV/mA load regulation-eliminates need for external precision reference in many systems |
| Low-glitch architecture | 5pV·s differential glitch impulse ensures minimal transient-induced distortion in sensitive RF and instrumentation applications |
| Industrial temperature grade | Specified over –40°C to +85°C with guaranteed 16-bit monotonicity and ±8LSB INL-suitable for base station and test equipment deployment |
Applications
| Cellular Base Stations | Direct Digital Synthesis (DDS) |
|---|---|
Use Scenario: Generating multi-carrier WCDMA/LTE waveforms in remote radio units with stringent ACLR requirements. IC Role / Device Role / Timing Role: High-speed 16-bit current-output DAC converting baseband I/Q samples into analog IF signals for upconversion. Use Value: 87dB SFDR at 1MHz enables >70dB adjacent channel leakage ratio without post-filtering, reducing front-end complexity. | Use Scenario: Producing agile, phase-continuous sine/cosine waveforms for radar and test signal generation. IC Role / Device Role / Timing Role: Precision waveform engine with deterministic 20ns settling and sub-1LSB DNL ensuring spectral purity across frequency sweeps. Use Value: Differential outputs suppress even-order harmonics; 5pV·s glitch impulse prevents spurious tones near carrier. |
| Automated Test Equipment | Instrumentation |
Use Scenario: Stimulus generation in high-speed digital pattern generators requiring <100ps timing jitter and flat amplitude response to 20MHz. IC Role / Device Role / Timing Role: 50Msps DAC driving 50Ω transmission lines via transformer-coupled differential outputs. Use Value: ±1V output compliance and 1.1kΩ output impedance allow direct 50Ω termination without gain error or bandwidth degradation. | Use Scenario: High-resolution arbitrary waveform generation in benchtop oscilloscopes and spectrum analyzers. IC Role / Device Role / Timing Role: Primary analog output stage converting digital sample buffers into calibrated voltage waveforms. Use Value: Internal 2.5V reference with 25ppm/°C drift eliminates external reference calibration, improving long-term measurement repeatability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-speed DAC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD9767ASTZ | 14-bit, 125Msps, current-output DAC with integrated 1.2V reference; no internal 2.5V reference or LADCOM pin | Higher speed but lower resolution; requires external reference buffering and different layout for analog routing | Select when >100Msps update rate is critical and 14-bit resolution suffices |
| MAX5895EGK+ | 16-bit, 500Msps, current-output DAC with on-chip PLL; consumes 1.2W vs. 180mW and requires complex power sequencing | Targeted at microwave backhaul; over-specified for baseband and instrumentation use cases | Select only for E-band transceiver designs where ultra-high speed justifies thermal and layout overhead |
Compared with AD9767ASTZ and MAX5895EGK+, the LTC1668IG#TRPBF offers optimal balance of 16-bit precision, 50Msps throughput, ultra-low power (180mW), and integrated reference-making it ideal for space-constrained, thermally sensitive baseband and test equipment where spectral purity and ease of integration are prioritized over raw speed.
Availability
LTC1668IG#TRPBF is available at Aetrix Electronics and suitable for cellular infrastructure, automated test equipment, direct digital synthesis, and precision instrumentation requiring stable component supply across extended temperature ranges.
Supply support for LTC1668IG#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 acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for all LTC-branded precision analog ICs.
The LTC1668IG#TRPBF belongs to Linear's high-speed DAC product line, engineered specifically for communications infrastructure and test instrumentation demanding exceptional SFDR, low glitch, and seamless integration with FPGA-based digital backends.
FAQ
What is the guaranteed differential nonlinearity (DNL) specification for LTC1668IG#TRPBF over its full operating temperature range?
The LTC1668IG#TRPBF guarantees ±1LSB DNL over the industrial temperature range (–40°C to +85°C), as confirmed in the Electrical Characteristics table of the official datasheet. This ensures monotonic 16-bit operation across all codes and temperatures without missing codes or step reversals-critical for closed-loop control and precision waveform generation where code-to-code consistency is mandatory. The LTC1668IG#TRPBF achieves this via laser-trimmed thin-film resistors and matched BiCMOS current sources.
Can LTC1668IG#TRPBF operate with an external reference, and how does that affect gain error?
Yes, LTC1668IG#TRPBF supports external reference operation by connecting an external voltage source to IREFIN (Pin 16) while leaving REFOUT (Pin 15) unconnected or buffered. Gain error drops to ±1% FSR (vs. ±2% with internal reference), and gain error drift improves to 30ppm/°C. However, external reference noise directly modulates IOUTFS, so low-noise, high-PSRR references are essential. The LTC1668IG#TRPBF reference input has 20kHz small-signal bandwidth, limiting usable reference slew rate.
What is the maximum recommended clock frequency for reliable operation of LTC1668IG#TRPBF?
The LTC1668IG#TRPBF is fully specified for 50Msps operation, with absolute maximum clock rating of 75Msps. At 50Msps, it maintains guaranteed 87dB SFDR at 1MHz fOUT, 20ns settling, and ±1LSB DNL. Operation above 50Msps degrades AC performance: SFDR falls to 81dB at 5MHz fOUT and 70dB at 20MHz fOUT. The LTC1668IG#TRPBF clock input requires minimum high/low times of 5ns/8ns and exhibits 8ns propagation delay (tPD) from CLK to IOUT transition.
How does the LADCOM pin function in LTC1668IG#TRPBF, and what happens if it is left floating?
LADCOM (Pin 18) is the common node for the internal attenuator ladder and must be connected to the same potential as the IOUT A/IOUT B load return-typically AGND or the center-tap of a transformer. If left floating, the DAC's LSB segment accuracy degrades significantly due to undefined bias conditions, causing increased INL (up to ±12LSB) and elevated glitch energy. The LTC1668IG#TRPBF draws ~0.32×IOUTFS through LADCOM to VSS, so proper grounding ensures stable ladder operation and full 16-bit linearity.
Is LTC1668IG#TRPBF pin-compatible with earlier members of the LTC166x family, and what design changes are needed for migration?
Yes, LTC1668IG#TRPBF is fully pin-compatible with LTC1666IG#TRPBF (12-bit) and LTC1667IG#TRPBF (14-bit) in the same 28-pin SSOP package, sharing identical pinout, power sequencing, and digital interface timing. Migration requires only firmware updates to handle 16-bit data width and verification of analog output filtering-no PCB layout changes. The LTC1668IG#TRPBF retains identical VDD/VSS, AGND/DGND, REFOUT/IREFIN, and COMP1/COMP2 connections, enabling drop-in resolution upgrade in existing designs.
LTC1668IG#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Not Verified
- Number of Bits:
- 16
- Number of D/A Converters:
- 1
- Settling Time:
- 20ns (Typ)
- Output Type:
- Current - Unbuffered
- Differential Output:
- Yes
- Data Interface:
- Parallel
- Reference Type:
- External, Internal
- Voltage - Supply, Analog:
- ±5V
- Voltage - Supply, Digital:
- -
- INL/DNL (LSB):
- ±8 (Max), ±1
- Architecture:
- Current Steering
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 28-SSOP
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
LTC1668IG#TRPBF FAQ
1.How can I place an order for LTC1668IG#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1668IG#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 LTC1668IG#TRPBF reliable?
The price and inventory of LTC1668IG#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1668IG#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1668IG#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1668IG#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1668IG#TRPBF?
LTC1668IG#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1668IG#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 LTC1668IG#TRPBF?
For technical support, including LTC1668IG#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1668IG#TRPBF requirements.
6.How does Aetrix verify that LTC1668IG#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1668IG#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 LTC1668IG#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1668IG#TRPBF?
All LTC1668IG#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1668IG#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 LTC1668IG#TRPBF part is unused and in its original packaging.
Return procedure for LTC1668IG#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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