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Analog Devices Inc. LTC3873EDDB-5#TRPBF
- Part No.:
- LTC3873EDDB-5#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3873EDDB-5#TRPBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,085
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Product details
Overview
LTC3873EDDB-5#TRPBF from Analog Devices (formerly Linear Technology) is a constant-frequency current-mode DC/DC controller for boost, flyback, and SEPIC topologies, designed to drive external N-channel MOSFETs in high-input-voltage applications. 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 +85°C. It enables high-efficiency telecom and PoE housekeeping supplies with no external current-sense resistor required.
For engineers reviewing the LTC3873EDDB-5#TRPBF datasheet, LTC3873EDDB-5#TRPBF pinout, LTC3873EDDB-5#TRPBF application, or LTC3873EDDB-5#TRPBF equivalent, key selection criteria include its No RSENSE sensing capability, programmable current limit via IPRG pin, internal 3.3 ms soft-start, 300 µA quiescent current, and compatibility with high-VDS MOSFETs in isolated/non-isolated converters.
Technical Context
The LTC3873EDDB-5#TRPBF implements peak-current-mode control with built-in slope compensation and a 200 kHz oscillator. Its error amplifier regulates output voltage by adjusting the ITH pin voltage (0.7–1.9 V range), which sets the current-comparator threshold dynamically during load transients.
It supports dual power schemes: direct low-impedance VCC supply ≤9 V or high-voltage biasing via external resistor into the 9.3 V internal shunt regulator. The RUN/SS pin provides shutdown control and external soft-start timing, while the NGATE driver delivers rail-to-rail swing (0 V to VIN) to drive N-MOSFET gates.
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-regulation in telecom auxiliary rails |
| VCC UVLO Threshold | 4.1 V rising / 2.9 V falling - prevents MOSFET gate underdrive during brownout |
| Quiescent Current | 300 µA normal / 50 µA shutdown - extends battery life in always-on PoE endpoints |
| Max Duty Cycle | 78% typical - limits transformer core saturation in flyback designs and constrains max boost ratio |
| Current Sense Options | IPRG-selectable thresholds (95/165/265 mV) - allows RDS(ON) sensing or discrete resistor trade-offs |
| Package | 8-lead 3 mm × 2 mm DFN with exposed pad - provides 76°C/W θJA for thermally constrained board areas |
Pinout & Package
Package: 8-lead plastic DFN (3 mm × 2 mm), 0.75 mm height, exposed thermal pad (Pin 9) soldered to PCB ground plane per manufacturer layout guidelines.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IPRG (Pin 1) | Current limit select input | Configures peak sense threshold: GND = 95 mV, float = 165 mV, VIN = 265 mV |
| ITH (Pin 2) | Error amplifier output / compensation node | 0.7–1.9 V range sets current comparator trip point; requires external RC network |
| VFB (Pin 3) | Feedback input | Compares divided output voltage to 1.2 V reference; 25 nA input bias minimizes divider loss |
| GND (Pin 4) | Power and signal ground | Reference for all analog circuitry; must be low-impedance connection to exposed pad |
| NGATE (Pin 5) | N-MOSFET gate driver output | Rail-to-rail swing (0 V to VIN); drives gate capacitance up to 3 nF with 40 ns rise/fall times |
| VCC (Pin 6) | Supply input | Accepts 4.1–9 V; internal 9.3 V shunt regulator enables high-voltage biasing via resistor |
| RUN/SS (Pin 7) | Shutdown and soft-start control | Below 0.7 V disables IC; open-circuit enables 3.3 ms internal soft-start; external cap extends ramp |
| SW (Pin 8) | Switch node / internal sense input | Connects to MOSFET drain and inductor; senses VDS for No RSENSE operation; rated to 60 V |
Key Features
| Feature | Design Value |
|---|---|
| No RSENSE current sensing | Eliminates power loss and board space of external sense resistor; uses MOSFET RDS(ON) as current sensor |
| Programmable current limit | Three thresholds selectable via IPRG pin - optimizes overcurrent protection for varying MOSFET RDS(ON) |
| Internal 3.3 ms soft-start | Prevents inrush current and output overshoot; extended via capacitor on RUN/SS pin |
| Low quiescent current | 300 µA operating / 50 µA shutdown - critical for energy-sensitive PoE-powered devices |
| High-voltage VCC biasing | 9.3 V internal shunt regulator allows direct connection to >9 V inputs via series resistor |
Applications
| Telecom Housekeeping Supply | PoE Powered Device (PD) |
|---|---|
Use Scenario: Generating isolated 10 V/100 mA bias rail from 36–75 V telecom input in line cards. IC Role / Device Role / Timing Role: Primary-side flyback controller regulating output via optocoupler feedback; 200 kHz switching enables compact magnetics. Use Value: No RSENSE operation reduces component count and improves efficiency at light loads typical of standby logic rails. | Use Scenario: Providing 12 V/2 A non-isolated boost output from 9–15 V PoE midspan input for Ethernet switches. IC Role / Device Role / Timing Role: Boost controller driving Si4840 N-MOSFET; RUN/SS enables hot-plug sequencing with controlled start-up. Use Value: 4.1 V UVLO ensures reliable startup even with cable voltage drop; 300 µA IQ minimizes idle power draw. |
| Automotive Infotainment Core Rail | Negative Buck Converter |
Use Scenario: Generating stable 5 V core supply from 9–16 V automotive battery in head unit mainboard. IC Role / Device Role / Timing Role: SEPIC controller supporting wide input range and maintaining regulation during cold-crank (6 V). Use Value: Adjustable current limit protects against short-circuit faults in noisy automotive environments. | Use Scenario: Converting –10 V to –15 V input to regulated –5 V/3 A output for analog sensor interfaces. IC Role / Device Role / Timing Role: Negative-to-negative buck controller using inverted topology; SW pin referenced to negative input rail. Use Value: Use Value: Internal slope compensation stabilizes control loop despite variable duty cycle in negative-buck configuration. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar current-mode boost/flyback/SEPIC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3803EDD-5#TRPBF | 200 kHz fixed frequency, same package, but lacks IPRG-selectable current limit and No RSENSE capability | Requires external current-sense resistor; lower integration for cost-sensitive flyback-only designs | Choose when RSENSE-based sensing is preferred or IPRG flexibility is unnecessary |
| LTC3872EDDB-5#TRPBF | Same No RSENSE architecture and pinout, but adds synchronous rectifier drive and 5 V LDO for gate bias | Enables higher efficiency in medium-power boost/flyback by replacing output diode with MOSFET | Choose when synchronous rectification is needed to reduce conduction loss at >1 A loads |
Compared with LTC3873EDDB-5#TRPBF, LTC3803EDD-5#TRPBF offers lower BOM cost but sacrifices No RSENSE efficiency and current-limit flexibility, while LTC3872EDDB-5#TRPBF adds synchronous drive capability at the expense of slightly higher complexity and cost-making it optimal for efficiency-critical, higher-current applications.
Availability
LTC3873EDDB-5#TRPBF is available at Aetrix Electronics and suitable for telecom power supplies, PoE-powered devices, and automotive infotainment systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LTC3873EDDB-5#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 legacy Linear parts including the LTC3873 family.
The LTC3873 product line targets high-efficiency, high-voltage DC/DC conversion in space-constrained applications where No RSENSE operation, low quiescent current, and robust thermal performance are essential.
FAQ
What is the maximum input voltage the LTC3873EDDB-5#TRPBF can handle?
The LTC3873EDDB-5#TRPBF itself has an absolute maximum SW pin rating of 60 V, and VCC is internally clamped to 9.3 V via shunt regulator. However, the controller's input voltage limit is determined by external components - notably the breakdown voltage of the driven N-MOSFET and the transformer or inductor ratings. In practice, designs using LTC3873EDDB-5#TRPBF have successfully operated with 75 V input in telecom flyback applications.
Does the LTC3873EDDB-5#TRPBF require an external current-sense resistor?
No - the LTC3873EDDB-5#TRPBF implements No RSENSE current sensing by monitoring the voltage drop across the external N-MOSFET's RDS(ON). This eliminates the power loss and board area associated with a discrete sense resistor. An external resistor may still be used if higher accuracy or temperature stability is required, but it is optional.
How does the IPRG pin affect current limiting on the LTC3873EDDB-5#TRPBF?
The IPRG pin on the LTC3873EDDB-5#TRPBF selects one of three peak current sense thresholds: 95 mV (IPRG = GND), 165 mV (IPRG = floating), or 265 mV (IPRG = VIN). This allows designers to match the current limit to the chosen MOSFET's RDS(ON) value and desired fault-current margin without changing external components.
Can the LTC3873EDDB-5#TRPBF be used in flyback configurations with optocoupler feedback?
Yes - the LTC3873EDDB-5#TRPBF is explicitly validated for flyback operation with optocoupler-based secondary-side regulation. Its VFB pin accepts feedback from a standard resistive divider or optocoupler-connected TL431, and its current-mode architecture provides excellent transient response and loop stability in isolated topologies.
What is the purpose of the exposed pad on the LTC3873EDDB-5#TRPBF DFN package?
The exposed pad (Pin 9) on the LTC3873EDDB-5#TRPBF DFN package is electrically and thermally connected to GND. It must be soldered to a PCB copper pour to achieve the specified 76°C/W θJA thermal resistance and ensure reliable operation under continuous load. Leaving it unconnected degrades thermal performance and risks junction overheating.
LTC3873EDDB-5#TRPBF 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 ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-DFN (3x2)
LTC3873EDDB-5#TRPBF FAQ
1.How can I place an order for LTC3873EDDB-5#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3873EDDB-5#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 LTC3873EDDB-5#TRPBF reliable?
The price and inventory of LTC3873EDDB-5#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3873EDDB-5#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3873EDDB-5#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3873EDDB-5#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3873EDDB-5#TRPBF?
LTC3873EDDB-5#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3873EDDB-5#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 LTC3873EDDB-5#TRPBF?
For technical support, including LTC3873EDDB-5#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3873EDDB-5#TRPBF requirements.
6.How does Aetrix verify that LTC3873EDDB-5#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3873EDDB-5#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 LTC3873EDDB-5#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3873EDDB-5#TRPBF?
All LTC3873EDDB-5#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3873EDDB-5#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 LTC3873EDDB-5#TRPBF part is unused and in its original packaging.
Return procedure for LTC3873EDDB-5#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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