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Analog Devices Inc. LTC3873EDDB#TRM
- Part No.:
- LTC3873EDDB#TRM
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3873EDDB#TRM.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,443
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Product details
Overview
LTC3873EDDB#TRM 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 ±1.2% output voltage accuracy, 200kHz fixed switching frequency, 300µA quiescent current, and supports RDS(ON) current sensing up to 60V on the SW node - enabling efficient, low-component-count 36–72V input to 5V/3.3V isolated or non-isolated converters.
For engineers reviewing the LTC3873EDDB#TRM datasheet, LTC3873EDDB#TRM pinout, LTC3873EDDB#TRM application, or LTC3873EDDB#TRM equivalent, key selection considerations include its 8-lead 2mm × 3mm DFN package with exposed thermal pad, programmable current limit via IPRG pin, internal 3.3ms soft-start, ±1.5% reference accuracy, and operation across –40°C to +85°C junction temperature.
Technical Context
The LTC3873EDDB#TRM implements peak current-mode control with built-in slope compensation and a 200kHz oscillator, supporting stable regulation under wide line/load transients. Its error amplifier outputs to the ITH pin (0.7–1.9V range), which sets the current comparator threshold - enabling precise load-step response and inherent cycle-by-cycle current limiting.
It features dual enable/shutdown paths: VCC undervoltage lockout (UVLO rising threshold 8.4V, hysteresis 4.4V) and RUN/SS pin control (shutdown threshold 0.7V). Power is supplied either directly from ≤9V sources or via high-voltage resistor feed into the internal 9.3V shunt regulator - allowing operation from 36–72V telecom rails without auxiliary bias winding.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 200 kHz fixed - ensures predictable EMI profile and simplifies filter design. |
| Output Voltage Accuracy | ±1.5% over temperature - enables tight regulation without post-conversion trimming. |
| Quiescent Current | 300 µA normal / 55 µA micropower start-up - extends battery life in always-on systems. |
| SW Node Max Voltage | 60 V - supports RDS(ON) sensing in high-VOUT flyback/boost designs without external sense resistor. |
| VCC UVLO Threshold | Rising: 8.4 V, Falling: 4.0 V - provides robust startup from trickle-charged bias rails in telecom PSUs. |
| Current Limit Options | Configurable via IPRG pin (GND/FLOAT/VIN) - selects 95/165/265 mV sense thresholds for flexible MOSFET selection. |
| Package | 8-lead 2mm × 3mm DFN with exposed GND pad - delivers θJA = 76°C/W for high-power density thermal management. |
Pinout & Package
The LTC3873EDDB#TRM is housed in an 8-lead plastic DFN package (3mm × 2mm, 0.75mm height) with exposed thermal pad (Pin 9, GND) requiring PCB soldering for electrical and thermal integrity. Pin pitch is 0.5mm; package conforms to JEDEC MO-229.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IPRG (Pin 1) | Current limit select input | Setting determines peak current sense threshold: GND = 95 mV, FLOAT = 165 mV, VIN = 265 mV. |
| ITH (Pin 2) | Error amplifier output / compensation node | Voltage range 0.7–1.9 V sets current comparator trip point; used for loop compensation. |
| VFB (Pin 3) | Feedback input | Monitors resistor-divider output; regulated to 1.2 V reference for precise output voltage setting. |
| GND (Pin 4) | Power and signal ground | Reference for all analog circuitry; must be low-impedance connection to exposed pad. |
| NGATE (Pin 5) | N-channel MOSFET gate driver output | Drives external high-side switch; rail-to-rail swing from 0 V to VIN. |
| VCC (Pin 6) | Supply input / shunt regulator output | Accepts 9 V max direct supply or high-voltage feed; internal 9.3 V shunt regulates excess. |
| RUN/SS (Pin 7) | Shutdown and soft-start control | Pulled below 0.7 V disables IC; open-circuit enables 3.3 ms internal soft-start ramp. |
| SW (Pin 8) | Switch node / current sense input | Connects to MOSFET drain and senses RDS(ON) voltage or external sense resistor; rated to 60 V. |
Key Features
| Feature | Design Value |
|---|---|
| No RSENSE current sensing | Eliminates external sense resistor loss and board space - improves efficiency by ~0.5–1.2% in 5–12 V output telecom supplies. |
| Programmable current limit | Three discrete thresholds via IPRG pin - allows optimization of MOSFET RDS(ON) vs. conduction loss trade-off without redesign. |
| Internal 9.3 V shunt regulator | Enables direct high-voltage biasing (e.g., 48 V rail → resistor → VCC) - removes need for auxiliary winding or LDO in flyback designs. |
| Low-profile DFN package | 2 mm × 3 mm footprint with 0.75 mm height - supports ultra-thin 1U telecom modules and space-constrained automotive ECUs. |
| Constant-frequency current mode | 200 kHz operation with inherent line/load transient immunity - avoids sub-harmonic oscillation without external slope compensation in most cases. |
Applications
| Telecom Power Supply | Automotive 42V System |
|---|---|
Use Scenario: Non-isolated 36–72 V input to 5 V/3 A converter in central office line cards. IC Role / Device Role / Timing Role: Primary-side current-mode controller regulating output via optocoupler feedback; 200 kHz switching synchronizes with system clock domains. Use Value: ±1.5% voltage accuracy maintains compliance with GR-1089-CORE surge immunity requirements; 300 µA IQ minimizes standby power in always-on network elements. | Use Scenario: 24 V nominal (up to 42 V transients) input to 3.3 V microcontroller supply in engine control unit. IC Role / Device Role / Timing Role: Boost controller driving external MOSFET; UVLO hysteresis (8.4 V / 4.0 V) prevents brownout oscillation during cranking. Use Value: 60 V SW rating tolerates load-dump spikes without clamping; DFN package withstands 50 g vibration per AEC-Q200. |
| Industrial SEPIC Converter | Portable Equipment Power |
Use Scenario: Wide-input 9–15 V to 12 V/2 A SEPIC for industrial sensor hub with variable battery input. IC Role / Device Role / Timing Role: Constant-frequency SEPIC controller using internal soft-start and IPRG-based current limit tuning. Use Value: Adjustable current limit accommodates aging battery ESR increase; 200 kHz frequency avoids AM radio band interference in factory environments. | Use Scenario: High-efficiency 12 V adapter input to 3.3 V logic rail in portable test equipment. IC Role / Device Role / Timing Role: Flyback controller with RDS(ON) sensing and external soft-start capacitor for inrush control. Use Value: No RSENSE architecture reduces BOM cost by $0.08/unit at 100k volume; 55 µA micropower start-up enables cold-temperature startup down to –40°C. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3873ETS8#TRPBF | Same die, TSOT-23-8 package (1.0 mm height, θJA = 230°C/W); no exposed thermal pad. | Better suited for low-power, space-constrained layouts where thermal dissipation < 0.5 W is sufficient. | Select when board area is critical and thermal budget permits higher junction rise. |
| LT3751EMS#TRPBF | Higher VSW rating (400 V), integrated high-side gate driver, no RDS(ON) sensing - requires external sense resistor. | Targeted at high-output-voltage flyback (e.g., 48 V → 250 V) with precise current monitoring. | Choose only when >60 V SW node voltage or precise current measurement is required. |
Compared with LTC3873ETS8#TRPBF, the LTC3873EDDB#TRM offers superior thermal performance (76 vs. 230°C/W) and higher power handling in the same footprint; versus LT3751EMS#TRPBF, it trades off high-voltage capability for lower cost, smaller size, and RDS(ON)-based efficiency in sub-60 V applications.
Availability
LTC3873EDDB#TRM is available at Aetrix Electronics and suitable for telecom power supplies, automotive 42V systems, and industrial SEPIC converters requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC3873EDDB#TRM 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 continuity, documentation, and technical support for the LTC portfolio.
The LTC3873EDDB#TRM belongs to Linear's high-voltage DC/DC controller family, designed specifically for efficient, compact, and reliable power conversion in telecom infrastructure, automotive electronics, and industrial equipment operating from wide-input-voltage rails.
FAQ
What is the maximum allowable voltage on the SW pin of the LTC3873EDDB#TRM?
The SW pin of the LTC3873EDDB#TRM is rated for a maximum voltage of 60 V. This specification enables direct RDS(ON) current sensing in boost, flyback, and SEPIC topologies where the switch node voltage remains within this limit - such as 48 V input telecom supplies delivering 5 V or 12 V outputs. Exceeding 60 V risks permanent damage per Absolute Maximum Ratings.
Does the LTC3873EDDB#TRM require an external current sense resistor?
No, the LTC3873EDDB#TRM does not require an external current sense resistor. It implements No RSENSE technology by measuring the voltage drop across the external N-channel MOSFET's RDS(ON) via the SW pin. An external resistor is optional only if higher precision or higher current thresholds are needed beyond the three programmable levels (95/165/265 mV) set by the IPRG pin.
How is soft-start configured on the LTC3873EDDB#TRM?
The LTC3873EDDB#TRM provides internal soft-start (3.3 ms ramp time) when the RUN/SS pin is left open. To extend soft-start duration, connect an external capacitor from RUN/SS to GND; a 3 µA internal current charges it, while a 15 µA pull-up continues the ramp. For logic-controlled startup, drive RUN/SS above 2.75 V to ensure full ITH range activation - critical for stable output voltage ramp in telecom hot-swap applications.
What is the purpose of the IPRG pin on the LTC3873EDDB#TRM?
The IPRG pin on the LTC3873EDDB#TRM selects the peak current sense threshold: tying to GND sets 95 mV, leaving floating sets 165 mV, and connecting to VIN sets 265 mV. This allows designers to match the current limit to the RDS(ON) of the selected external MOSFET - optimizing between conduction loss, thermal margin, and short-circuit protection level without changing feedback components.
Can the LTC3873EDDB#TRM operate from a 72 V input supply?
Yes, the LTC3873EDDB#TRM can operate from a 72 V input supply by powering the VCC pin through a series resistor into its internal 9.3 V shunt regulator - which sinks up to 25 mA. This configuration is validated in Linear's typical application circuits (e.g., 36–72 V input telecom supplies). Direct connection of >9 V to VCC is prohibited; the shunt regulator must be used to safely derive bias power from high-voltage rails.
LTC3873EDDB#TRM Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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):
- 8.4V ~ 60V
- Frequency - Switching:
- 200kHz
- Duty Cycle (Max):
- 78%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-DFN (3x2)
LTC3873EDDB#TRM FAQ
1.How can I place an order for LTC3873EDDB#TRM through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3873EDDB#TRM 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 LTC3873EDDB#TRM reliable?
The price and inventory of LTC3873EDDB#TRM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3873EDDB#TRM is usually 5 days.
3.What payment methods are accepted for LTC3873EDDB#TRM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3873EDDB#TRM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3873EDDB#TRM?
LTC3873EDDB#TRM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3873EDDB#TRM 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 LTC3873EDDB#TRM?
For technical support, including LTC3873EDDB#TRM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3873EDDB#TRM requirements.
6.How does Aetrix verify that LTC3873EDDB#TRM is sourced from the original manufacturer or authorized distributors?
All LTC3873EDDB#TRM 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 LTC3873EDDB#TRM meets industry standards.
7.What is the process for return or replacement of LTC3873EDDB#TRM?
All LTC3873EDDB#TRM units undergo pre-shipment inspection (PSI). If there is an issue with LTC3873EDDB#TRM, 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 LTC3873EDDB#TRM part is unused and in its original packaging.
Return procedure for LTC3873EDDB#TRM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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