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Analog Devices Inc. LTC3873IDDB-5#TRMPBF
- Part No.:
- LTC3873IDDB-5#TRMPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3873IDDB-5#TRMPBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:539
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Product details
Overview
LTC3873IDDB-5#TRMPBF from Analog Devices (formerly Linear Technology) is a constant-frequency current-mode DC/DC controller for boost, flyback, and SEPIC topologies, driving external N-channel MOSFETs in high-input-voltage telecom and automotive power supplies. It delivers ±1.5% output voltage accuracy, 200 kHz fixed switching frequency, 4.1 V VCC undervoltage lockout threshold, and operates across –40°C to +125°C with 300 μA quiescent current.
For engineers reviewing the LTC3873IDDB-5#TRMPBF datasheet, LTC3873IDDB-5#TRMPBF pinout, LTC3873IDDB-5#TRMPBF application, or LTC3873IDDB-5#TRMPBF equivalent, key selection criteria include its No RSENSE current sensing capability, programmable current limit via IPRG pin, internal 3.3 ms soft-start, 9.3 V integrated shunt regulator, and compatibility with high-VDS MOSFETs up to 60 V SW node rating.
Technical Context
The LTC3873IDDB-5#TRMPBF implements peak-current-mode control with built-in slope compensation to prevent subharmonic oscillation at duty cycles above 50%. Its error amplifier drives the ITH pin (0.7–1.9 V range) to set the current comparator threshold, enabling tight line/load transient response.
It supports dual powering schemes: direct low-impedance supply ≤9 V to VCC, or high-input-voltage biasing via external resistor into the 9.3 V shunt regulator. The RUN/SS pin provides shutdown control and external soft-start timing via capacitor, while the IPRG pin selects one of three peak current sense thresholds (95/165/265 mV).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 200 kHz fixed - enables predictable EMI filtering and consistent magnetics design. |
| Output Voltage Accuracy | ±1.5% - ensures stable regulation under varying load, line, and temperature conditions. |
| VCC UVLO Threshold | Rising: 4.1 V - prevents MOSFET gate drive below safe VGS level in logic-level applications. |
| Quiescent Current | 300 μA normal / 50 μA shutdown - minimizes standby power loss in always-on systems. |
| Max Duty Cycle | 78% typical - limits transformer core saturation in flyback and constrains max boost ratio. |
| SW Pin Rating | –0.3 V to 60 V - supports high-output-voltage boost and wide-input flyback designs. |
| Operating Temp Range | –40°C to +125°C - qualified for under-hood automotive and industrial telecom environments. |
Pinout & Package
Package: 8-lead (3 mm × 2 mm) plastic DFN with exposed thermal pad (Pin 9 = GND), 0.75 mm height, θJA = 76°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IPRG (Pin 1) | Current limit select input | Configures peak sense threshold to 95 mV (GND), 165 mV (float), or 265 mV (VIN) - sets overcurrent protection level without external resistor. |
| ITH (Pin 2) | Error amplifier output / compensation node | 0.7–1.9 V range controls current comparator trip point - used for loop compensation and soft-start ramping. |
| VFB (Pin 3) | Feedback input | Monitors resistor-divider output voltage; regulates to 1.2 V reference - enables precise output programming and remote sensing. |
| GND (Pin 4) | Analog and power ground | Common return for feedback, error amp, and internal regulators - must be tied to exposed pad for thermal and noise performance. |
| NGATE (Pin 5) | N-channel MOSFET gate driver output | Drives external high-side switch; swings 0 V to VIN - requires careful layout to minimize shoot-through and ringing. |
| VCC (Pin 6) | Supply input / shunt-regulated bias | Accepts 4.1–9 V directly or >9 V via resistor into 9.3 V internal shunt - eliminates need for external LDO in high-input systems. |
| RUN/SS (Pin 7) | Shutdown and soft-start control | Logic-level enable (0.7 V threshold); open-circuit enables 3.3 ms internal soft-start - prevents inrush current and eases system sequencing. |
| SW (Pin 8) | Switch node / current sense input | Connects to MOSFET drain and inductor; senses voltage drop across RDS(ON) or external resistor - rated to 60 V for robust high-VOUT operation. |
Key Features
| Feature | Design Value |
|---|---|
| No RSENSE current sensing | Uses MOSFET RDS(ON) for current detection - eliminates sense resistor losses and board space, improving efficiency and power density. |
| Internal 9.3 V shunt regulator | Enables direct high-voltage biasing (e.g., 36–75 V telecom rails) without external pre-regulator - simplifies supply architecture and reduces BOM count. |
| Programmable current limit | Three thresholds selectable via IPRG pin - allows optimization of overcurrent protection for different MOSFETs and load profiles without redesign. |
| Constant-frequency operation | 200 kHz fixed switching - supports standardized filter design, predictable EMI behavior, and simplified thermal management. |
| Low-temperature-grade packaging | I-grade DFN rated –40°C to +125°C - meets automotive AEC-Q200 stress requirements and industrial extended-temp needs. |
Applications
| Telecom Housekeeping Supply | Automotive Infotainment Rail |
|---|---|
Use Scenario: Generating isolated 10 V/100 mA auxiliary power from 36–75 V telecom battery bus using flyback topology. IC Role / Device Role / Timing Role: Primary-side controller regulating output via optocoupler feedback; provides 200 kHz timing reference and current-mode stability. Use Value: Enables compact, efficient, and reliable housekeeping supply meeting GR-1089 immunity and -40°C cold-crank startup requirements. | Use Scenario: Boosting 9–16 V vehicle battery to stable 12 V for infotainment head unit in start-stop vehicles. IC Role / Device Role / Timing Role: High-efficiency boost controller with No RSENSE sensing and 4.1 V UVLO - ensures operation during cranking dips down to 6 V. Use Value: Delivers regulated 12 V at 2 A with <300 μA quiescent current, supporting ASAM compliance and low-power sleep modes. |
| Industrial PoE Midspan Power | Isolated Negative Buck Converter |
Use Scenario: Generating 12 V/2 A from 36–57 V PoE midspan input using SEPIC topology for isolated data interface modules. IC Role / Device Role / Timing Role: Constant-frequency SEPIC controller with programmable soft-start and current limiting - manages inrush and fault recovery in Ethernet-powered systems. Use Value: Provides robust, standards-compliant power delivery with fast transient response and no external current-sense resistor. | Use Scenario: Converting –10 V to –15 V input to regulated –5 V/3 A output for analog sensor front-ends using negative-buck (inverting) configuration. IC Role / Device Role / Timing Role: Controller repurposed in inverted topology; uses SW pin as current-sense node and NGATE to drive P-channel switch (with level shift). Use Value: Achieves high-efficiency negative rail generation without dedicated inverting IC, reducing component count and cost in bipolar supply designs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost/flyback/SEPIC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3803EDD-5#TRMPBF | Same 200 kHz frequency and DFN package, but lacks No RSENSE; requires external current-sense resistor. | Better suited for designs needing precise current monitoring or where RDS(ON) variation is unacceptable. | Choose when absolute current measurement accuracy outweighs efficiency gains from No RSENSE. |
| LTC3703IGN#TRPBF | Higher 100 V input rating, SSOP-16 package, synchronous rectification support - not pin-compatible. | Targeted at high-voltage industrial converters (>60 V input) requiring synchronous FET control and higher power. | Select for >60 V input systems or where synchronous rectification improves efficiency beyond 10 W. |
Compared with LTC3803EDD-5#TRMPBF and LTC3703IGN#TRPBF, the LTC3873IDDB-5#TRMPBF uniquely combines No RSENSE operation, 60 V SW rating, and I-grade DFN in a single 8-pin solution - offering optimal balance of efficiency, integration, and thermal performance for mid-power telecom and automotive boost/flyback designs.
Availability
LTC3873IDDB-5#TRMPBF is available at Aetrix Electronics and suitable for telecom housekeeping supplies, automotive infotainment rails, and PoE midspan power converters requiring stable component supply, extended temperature operation, and high reliability.
Supply support for LTC3873IDDB-5#TRMPBF 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, manufacturing, and documentation for legacy Linear parts including the LTC3873 series.
The LTC3873 family was designed specifically for high-efficiency, high-input-voltage DC/DC conversion in telecom, automotive, and industrial applications - emphasizing No RSENSE sensing, wide input range, and robust thermal packaging.
FAQ
What is the function of the IPRG pin on the LTC3873IDDB-5#TRMPBF?
The IPRG pin on the LTC3873IDDB-5#TRMPBF selects the peak current sense threshold: 95 mV when tied to GND, 165 mV when left floating, or 265 mV when connected to VIN. This allows flexible overcurrent protection tuning without external components. The LTC3873IDDB-5#TRMPBF uses this setting to adjust the current comparator trip point during each switching cycle, ensuring accurate foldback under fault conditions.
Does the LTC3873IDDB-5#TRMPBF support external soft-start, and how is it implemented?
Yes, the LTC3873IDDB-5#TRMPBF supports external soft-start via a capacitor from RUN/SS to GND. A 3 μA internal current charges the capacitor, delaying the rise of the RUN/SS voltage and thus controlling the ITH ramp rate. The LTC3873IDDB-5#TRMPBF achieves longer soft-start times than the default 3.3 ms internal ramp - critical for managing inrush current in high-capacitance output stages.
Can the LTC3873IDDB-5#TRMPBF be powered directly from a 48 V input rail?
Yes, the LTC3873IDDB-5#TRMPBF can be powered from a 48 V input rail using a series resistor into the VCC pin, leveraging its internal 9.3 V shunt regulator to clamp voltage and sink up to 25 mA. This eliminates external regulators. The LTC3873IDDB-5#TRMPBF datasheet confirms this biasing method is validated for telecom applications with 36–75 V inputs.
What is the maximum allowable duty cycle for the LTC3873IDDB-5#TRMPBF, and why is it limited?
The LTC3873IDDB-5#TRMPBF has a maximum duty cycle of 78% typical, enforced by internal circuitry to prevent subharmonic oscillation and ensure stable current-mode control. This limit also protects flyback transformers from core saturation and constrains boost converter output voltage ratios. The LTC3873IDDB-5#TRMPBF's internal slope compensation and latch timing define this boundary, not external components.
How does the LTC3873IDDB-5#TRMPBF achieve No RSENSE current sensing?
The LTC3873IDDB-5#TRMPBF achieves No RSENSE current sensing by measuring the voltage drop across the external N-channel MOSFET's RDS(ON) during switch conduction, using the SW pin as the sense node. It compensates for temperature drift and gate-drive dynamics internally. The LTC3873IDDB-5#TRMPBF avoids external resistors entirely - reducing losses, cost, and PCB area while maintaining ±1.5% output regulation accuracy.
LTC3873IDDB-5#TRMPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Boost, Flyback, SEPIC
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 4.1V ~ 60V
- Frequency - Switching:
- -
- Duty Cycle (Max):
- 78%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-DFN (3x2)
LTC3873IDDB-5#TRMPBF FAQ
1.How can I place an order for LTC3873IDDB-5#TRMPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3873IDDB-5#TRMPBF 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 LTC3873IDDB-5#TRMPBF reliable?
The price and inventory of LTC3873IDDB-5#TRMPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3873IDDB-5#TRMPBF is usually 5 days.
3.What payment methods are accepted for LTC3873IDDB-5#TRMPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3873IDDB-5#TRMPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3873IDDB-5#TRMPBF?
LTC3873IDDB-5#TRMPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3873IDDB-5#TRMPBF 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 LTC3873IDDB-5#TRMPBF?
For technical support, including LTC3873IDDB-5#TRMPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3873IDDB-5#TRMPBF requirements.
6.How does Aetrix verify that LTC3873IDDB-5#TRMPBF is sourced from the original manufacturer or authorized distributors?
All LTC3873IDDB-5#TRMPBF 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 LTC3873IDDB-5#TRMPBF meets industry standards.
7.What is the process for return or replacement of LTC3873IDDB-5#TRMPBF?
All LTC3873IDDB-5#TRMPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3873IDDB-5#TRMPBF, 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 LTC3873IDDB-5#TRMPBF part is unused and in its original packaging.
Return procedure for LTC3873IDDB-5#TRMPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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