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Analog Devices Inc. LTC3873EDDB#TRMPBF
- Part No.:
- LTC3873EDDB#TRMPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3873EDDB#TRMPBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:914
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Product details
Overview
LTC3873EDDB#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, 200kHz fixed switching frequency, 300µA quiescent current, and supports RDS(ON) current sensing up to 60V on the SW node - enabling compact, high-efficiency 36–72V input telecom converters.
For engineers reviewing the LTC3873EDDB#TRMPBF datasheet, LTC3873EDDB#TRMPBF pinout, LTC3873EDDB#TRMPBF application, or LTC3873EDDB#TRMPBF 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#TRMPBF implements current-mode control with built-in slope compensation and a 200kHz oscillator, enabling stable regulation under wide line/load transients. Its error amplifier outputs to the ITH pin (0.7V–1.9V range), directly setting the peak current comparator threshold.
It features dual shutdown mechanisms: VCC undervoltage lockout (8.4V turn-on / 4.0V turn-off) and RUN/SS pin threshold (0.7V falling edge), plus an internal 9.3V shunt regulator allowing direct biasing from high-input rails via resistor feed. The SW pin serves as both switch-node connection and current-sense input for RDS(ON) or discrete resistor sensing.
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% - enables tight regulation without post-conversion trimming in telecom systems. |
| Quiescent Current | 300 µA normal / 55 µA micropower start-up - extends battery life in backup power and portable equipment. |
| SW Node Max Voltage | 60 V - supports RDS(ON) sensing in 48V and 60V bus applications without external sense resistor. |
| VCC Shunt Regulator | 9.3 V - permits direct biasing from 36–72V inputs using a single series resistor, reducing BOM count. |
| Current Sense Threshold | 110–295 mV (selectable via IPRG) - allows optimization of conduction loss vs noise immunity in high-current designs. |
| Max Duty Cycle | 78% typical - constrains transformer turns ratio and prevents core saturation in flyback/SEPIC designs. |
Pinout & Package
The LTC3873EDDB#TRMPBF is housed in an 8-lead, 2mm × 3mm plastic DFN package with exposed thermal pad (Pin 9 = GND), optimized for high-power density and thermal performance (θJA = 76°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IPRG (Pin 1) | Current limit select | Configures peak current threshold to 110 mV (GND), 185 mV (float), or 295 mV (VIN) - sets MOSFET overcurrent protection level. |
| ITH (Pin 2) | Error amplifier output | 0.7–1.9 V range controls PWM duty cycle; used for loop compensation and soft-start ramping. |
| VFB (Pin 3) | Feedback input | Monitors divided output voltage; regulates to 1.2 V reference - enables precise remote sensing of 3.3V, 5V, or 12V rails. |
| GND (Pin 4) | Power and signal ground | Reference for all analog circuitry; must be low-impedance connection to PCB ground plane. |
| NGATE (Pin 5) | N-MOSFET gate driver | Drives external high-side N-channel MOSFET; swings 0 V to VIN - requires robust gate drive path for fast switching. |
| VCC (Pin 6) | Supply input | Accepts 9 V max; internally regulated to 9.3 V - can be fed from input rail via resistor or auxiliary winding. |
| RUN/SS (Pin 7) | Enable & soft-start | 0.7 V shutdown threshold; open-circuit enables 3.3 ms internal soft-start - prevents inrush current during power-up. |
| SW (Pin 8) | Switch node & sense input | Connects to MOSFET drain and provides current sense signal - supports RDS(ON) sensing up to 60 V. |
| Exposed Pad (Pin 9) | Thermal & electrical ground | Mandatory solder connection to PCB ground plane - critical for thermal dissipation and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| No RSENSE™ current sensing | Eliminates external sense resistor by using MOSFET RDS(ON), reducing cost, board area, and conduction losses. |
| Programmable current limit | Three thresholds (110/185/295 mV) via IPRG pin - enables tailored overcurrent protection without redesigning feedback network. |
| Internal 9.3 V shunt regulator | Allows direct biasing from 36–72 V telecom inputs using only one resistor - removes need for auxiliary LDO or transformer winding. |
| 200 kHz constant-frequency operation | Enables consistent EMI filtering and predictable transient response - avoids sub-harmonic instability via built-in slope compensation. |
| Low-profile DFN package (0.75 mm height) | Supports ultra-thin power modules in space-constrained telecom and industrial equipment - thermal pad improves power handling. |
Applications
| Telecom Power Supply | Automotive 42V System |
|---|---|
|
Use Scenario: Non-isolated 5V/2A DC/DC converter powered from 36–72V telecom rectified bus. IC Role / Device Role / Timing Role: Primary controller managing boost topology, current-mode regulation, and MOSFET gate drive timing. Use Value: Achieves >85% efficiency at full load with no external current sense resistor, reducing component count and thermal stress. |
Use Scenario: 12V output supply for engine control units in 42V automotive architecture. IC Role / Device Role / Timing Role: Flyback controller regulating isolated output while tolerating wide input transients (up to 60V load dump). Use Value: UVLO hysteresis (8.4V/4.0V) and 60V SW rating ensure reliable startup and operation during cold-crank and load-dump events. |
| Portable Test Equipment | Industrial IoT Gateway |
|
Use Scenario: Battery-backed 3.3V/3A SEPIC converter for handheld analyzers operating from 9–15V Li-ion packs. IC Role / Device Role / Timing Role: Dual-mode controller supporting both step-up and step-down behavior within single topology. Use Value: Internal soft-start and 55µA micropower shutdown extend runtime in standby mode without external sequencing ICs. |
Use Scenario: Isolated 3.3V/3A power supply for RS-485/LoRaWAN gateway with reinforced insulation requirements. IC Role / Device Role / Timing Role: Primary-side controller in opto-coupled flyback design, coordinating feedback via LT4430 opto-driver. Use Value: Programmable IPRG threshold and ±1.5% reference accuracy maintain tight output tolerance despite wide ambient temperature swings (–40°C to +85°C). |
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 |
|---|---|---|---|
| LTC3873ETS8#TRPBF | Same die, TSOT-23-8 package (1.1mm height, θJA = 230°C/W) - smaller footprint but higher thermal resistance. | Better suited for low-power, space-constrained PCBs where thermal mass is limited; not recommended for >1.5A continuous output. | Select when board area is critical and power dissipation remains below 0.4W; verify thermal relief via copper pour under TSOT-23. |
| LT3751EFE#TRPBF | Higher VSW rating (400V), integrated high-side gate driver, no RDS(ON) sensing - requires external sense resistor and supports flyback only. | Targeted at high-voltage flyback (e.g., PoE, AC/DC adapters); lacks SEPIC/boost flexibility and No RSENSE capability. | Choose only for >100V input applications requiring primary-side sensing; not drop-in compatible due to different pinout and feature set. |
Compared with LTC3873ETS8#TRPBF and LT3751EFE#TRPBF, the LTC3873EDDB#TRMPBF offers superior thermal performance in high-current telecom designs, retains full topology flexibility (boost/flyback/SEPIC), and uniquely enables RDS(ON) sensing - making it optimal for cost-sensitive, medium-power isolated and non-isolated converters.
Availability
LTC3873EDDB#TRMPBF is available at Aetrix Electronics and suitable for telecom power supplies, 42V automotive systems, and portable electronic equipment requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LTC3873EDDB#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 its legacy of high-performance analog and power management ICs, with focus on precision, reliability, and ruggedness for demanding industrial and communications applications.
The LTC3873EDDB#TRMPBF belongs to Linear's No RSENSE™ controller family, designed specifically for high-efficiency, low-component-count DC/DC conversion in telecom infrastructure, automotive electronics, and portable instrumentation.
FAQ
What is the maximum input voltage the LTC3873EDDB#TRMPBF can handle in a boost configuration?
The LTC3873EDDB#TRMPBF itself does not impose a maximum input voltage limit - instead, the practical limit is determined by the external MOSFET's VDS rating and the 60V absolute maximum rating on the SW pin. In RDS(ON) sensing mode, the SW pin voltage equals VIN during MOSFET off-time; thus, VIN must remain ≤60V. For higher inputs, use a discrete sense resistor and ensure MOSFET VDS exceeds required margin. The LTC3873EDDB#TRMPBF has been validated in 36–72V telecom applications using external sensing.
Does the LTC3873EDDB#TRMPBF support SEPIC topology, and what design considerations apply?
Yes, the LTC3873EDDB#TRMPBF explicitly supports SEPIC topology per its datasheet and typical applications (e.g., Figure TA05). Key considerations include configuring the transformer or coupled inductor with appropriate coupling coefficient, ensuring the IPRG pin is set for desired current limit, and verifying that the maximum duty cycle (78%) accommodates the required voltage conversion ratio. The LTC3873EDDB#TRMPBF's current-mode control and slope compensation ensure stability across the full operating range in SEPIC mode.
How is soft-start implemented on the LTC3873EDDB#TRMPBF, and can it be adjusted?
The LTC3873EDDB#TRMPBF provides internal 3.3ms soft-start when the RUN/SS pin is left open; during this time, a 3µA current ramps the RUN/SS voltage, limiting ITH to prevent output overshoot. Soft-start duration can be extended by adding an external capacitor from RUN/SS to GND - capacitance value scales linearly with time (e.g., 100nF ≈ 33ms). The LTC3873EDDB#TRMPBF does not support shortened soft-start; minimum is the internal 3.3ms ramp.
What is the purpose of the IPRG pin on the LTC3873EDDB#TRMPBF, and how does it affect current limiting?
The IPRG pin on the LTC3873EDDB#TRMPBF selects the peak current sense threshold: 110mV (IPRG = GND), 185mV (IPRG = float), or 295mV (IPRG = VIN). This directly sets the overcurrent trip point for the external MOSFET, allowing designers to match the current limit to the MOSFET's RDS(ON) and thermal capability. The LTC3873EDDB#TRMPBF uses this threshold in conjunction with the sensed voltage on the SW pin to terminate each switching cycle - critical for reliable short-circuit protection.
Can the LTC3873EDDB#TRMPBF operate without an external current sense resistor?
Yes - the LTC3873EDDB#TRMPBF features No RSENSE™ technology, enabling current sensing via the MOSFET's RDS(ON). The SW pin monitors the voltage drop across the MOSFET's channel during on-time, eliminating the need for a discrete sense resistor. This reduces power loss, board area, and cost. The LTC3873EDDB#TRMPBF supports this mode up to 60V SW node voltage and is validated in multiple reference designs using RDS(ON) sensing exclusively.
LTC3873EDDB#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):
- 8.4V ~ 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 ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-DFN (3x2)
LTC3873EDDB#TRMPBF FAQ
1.How can I place an order for LTC3873EDDB#TRMPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3873EDDB#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 LTC3873EDDB#TRMPBF reliable?
The price and inventory of LTC3873EDDB#TRMPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3873EDDB#TRMPBF is usually 5 days.
3.What payment methods are accepted for LTC3873EDDB#TRMPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3873EDDB#TRMPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3873EDDB#TRMPBF?
LTC3873EDDB#TRMPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3873EDDB#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 LTC3873EDDB#TRMPBF?
For technical support, including LTC3873EDDB#TRMPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3873EDDB#TRMPBF requirements.
6.How does Aetrix verify that LTC3873EDDB#TRMPBF is sourced from the original manufacturer or authorized distributors?
All LTC3873EDDB#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 LTC3873EDDB#TRMPBF meets industry standards.
7.What is the process for return or replacement of LTC3873EDDB#TRMPBF?
All LTC3873EDDB#TRMPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3873EDDB#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 LTC3873EDDB#TRMPBF part is unused and in its original packaging.
Return procedure for LTC3873EDDB#TRMPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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