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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > DC DC Switching Controllers

Analog Devices Inc. LTC3873EDDB-5#TRMPBF

Name: LTC3873EDDB-5#TRMPBF
Brand: Analog Devices Inc.
SKU: LTC3873EDDB-5#TRMPBF
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LTC3873EDDB-5#TRMPBF

Manufacturer:: Analog Devices Inc.

Category:: DC DC Switching Controllers

Package:: 8-WFDFN Exposed Pad

Datasheet:: LTC3873EDDB-5#TRMPBF.pdf

Description:: IC REG CTRLR MULT TOPOLOGY 8DFN

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Product details

Overview

LTC3873EDDB-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 applications. It delivers ±1.5% output voltage accuracy, 200kHz fixed switching frequency, 4.1V VCC undervoltage lockout threshold, 300μA quiescent current, and operates across –40°C to +85°C.

For engineers reviewing the LTC3873EDDB-5#TRMPBF datasheet, LTC3873EDDB-5#TRMPBF pinout, LTC3873EDDB-5#TRMPBF application, or LTC3873EDDB-5#TRMPBF equivalent, key selection criteria include its No RSENSE current sensing capability, internal 9.3V shunt regulator for high-VIN biasing, programmable soft-start, adjustable current limit via IPRG pin, and compatibility with telecom, PoE, and automotive power supplies requiring stable, low-quiescent-current control.

Technical Context

The LTC3873EDDB-5#TRMPBF implements current-mode control with built-in slope compensation to prevent subharmonic oscillation at duty cycles above 50%. Its error amplifier outputs a voltage at the ITH pin that sets the peak current comparator threshold, enabling fast line and load transient response.

It supports dual current-sense methods: MOSFET R_DS(ON) sensing (via SW pin) for zero-resistor efficiency gains, or external sense resistor placement with optional external slope compensation. The RUN/SS pin provides shutdown control and soft-start timing via external capacitor or logic-level input.

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 and PoE systems.
VCC UVLO Threshold	Rising: 4.1 V - prevents MOSFET gate drive below safe V_GS turn-on in 5V–12V logic-level applications.
Quiescent Current	300 μA normal / 50 μA shutdown - extends battery life in always-on housekeeping rails.
Max Duty Cycle	78% typical - constrains transformer core saturation in flyback and limits max boost ratio (e.g., 5V→12V).
Current Sense Options	No RSENSE (MOSFET R_DS(ON)) or external resistor - eliminates sense resistor losses and BOM cost.
Package	8-lead 3mm × 2mm DFN (DDB) - 0.75mm height enables ultra-thin power modules and dense PCB layouts.

Pinout & Package

Package: 8-lead plastic DFN (3mm × 2mm), exposed pad (Pin 9) tied to GND for thermal and electrical integrity. Pin pitch: 0.5 mm. Max height: 0.75 mm.

Pin/Terminal	Circuit Role	Design Meaning
IPRG (Pin 1)	Current limit select input	Configures peak current threshold: 95 mV (GND), 185 mV (float), or 295 mV (VIN) - enables wide-range overcurrent protection tuning.
ITH (Pin 2)	Error amplifier output / compensation node	Carries loop compensation signal; nominal 0.7–1.9 V range - direct interface to Type II/III compensation networks.
VFB (Pin 3)	Feedback input	Monitors divided output voltage against 1.2 V reference - sets regulated output via external resistor divider (e.g., 12V = 1.2V × (R1/R2 + 1)).
GND (Pin 4)	Power and signal ground	Common return for VCC bypass, feedback, and gate drive - 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 (0 V to V_IN) - supports logic-level MOSFETs up to 60 V drain voltage.
VCC (Pin 6)	Supply input with internal 9.3 V shunt regulator	Accepts 4.1–9 V directly or >9 V via series resistor - enables high-input-voltage biasing without external LDO.
RUN/SS (Pin 7)	Shutdown and soft-start control	Pulled high (>0.7 V) to enable; open for 3.3 ms internal soft-start; capacitor to GND extends ramp - prevents inrush and controls startup sequencing.
SW (Pin 8)	Switch node / current sense input	Connects to MOSFET drain and inductor; senses voltage drop across R_DS(ON) or external R_SENSE - integrates slope compensation ramp for stability.

Key Features

Feature	Design Value
No RSENSE current sensing	Eliminates sense resistor power loss and board space; leverages MOSFET R_DS(ON) for full-efficiency current limiting in boost/flyback.
Internal 9.3 V shunt regulator	Allows direct biasing from high-VIN sources (e.g., 36–75 V telecom) using only a series resistor - avoids external regulators.
Programmable current limit	Three thresholds (95/185/295 mV) selected by IPRG pin state - adapts protection level to MOSFET R_DS(ON) or sense resistor value.
Constant 200 kHz frequency	Enables consistent EMI filtering, predictable inductor sizing, and simplified compliance testing across input/output conditions.
Low-profile DFN package	3 mm × 2 mm footprint with 0.75 mm max height - supports compact, thermally efficient designs in space-constrained telecom and industrial modules.

Applications

Telecom Housekeeping Supply	PoE Powered Device (PD) Bias Rail
Use Scenario: Generating isolated 10 V @ 100 mA from 36–75 V telecom input for microcontroller, PHY, and monitoring circuitry. IC Role / Device Role / Timing Role: Primary-side flyback controller regulating output via optocoupler feedback; 200 kHz switching enables small transformer and low EMI. Use Value: No RSENSE operation reduces component count and improves efficiency >88% at light loads; 4.1 V UVLO ensures reliable start-up across wide input range.	Use Scenario: Providing 12 V @ 2 A auxiliary rail in IEEE 802.3af/at PD equipment powered from PoE midspan or endspan. IC Role / Device Role / Timing Role: SEPIC controller handling input transients and maintaining regulation during PoE classification and power negotiation phases. Use Value: Internal soft-start prevents inrush into capacitive PD loads; 300 μA quiescent current minimizes standby loss during detection mode.
Automotive LED Driver Support Rail	Industrial Isolated Auxiliary Supply
Use Scenario: Generating 5 V @ 2 A from 9–16 V automotive battery for LED driver ICs and CAN transceivers in headlight modules. IC Role / Device Role / Timing Role: Boost controller with wide input range and robust UVLO hysteresis (4.1 V rise / 2.9 V fall) tolerating cold-crank dips. Use Value: 78% max duty cycle prevents instability under low-VIN conditions; DFN package withstands automotive thermal cycling (–40°C to +85°C).	Use Scenario: Delivering isolated –5 V @ 3 A from –10 to –15 V input in industrial negative-buck configurations for op-amp biasing and sensor interfaces. IC Role / Device Role / Timing Role: Negative-output buck controller using inverted topology; RUN/SS pin enables synchronized power-up with main system controller. Use Value: Adjustable current limit protects against short-circuit faults on sensitive analog rails; ±1.5% V_OUT accuracy ensures precision sensor excitation.

Telecom Housekeeping Supply

PoE Powered Device (PD) Bias Rail

Use Scenario: Generating isolated 10 V @ 100 mA from 36–75 V telecom input for microcontroller, PHY, and monitoring circuitry.

IC Role / Device Role / Timing Role: Primary-side flyback controller regulating output via optocoupler feedback; 200 kHz switching enables small transformer and low EMI.

Use Value: No RSENSE operation reduces component count and improves efficiency >88% at light loads; 4.1 V UVLO ensures reliable start-up across wide input range.

Use Scenario: Providing 12 V @ 2 A auxiliary rail in IEEE 802.3af/at PD equipment powered from PoE midspan or endspan.

IC Role / Device Role / Timing Role: SEPIC controller handling input transients and maintaining regulation during PoE classification and power negotiation phases.

Use Value: Internal soft-start prevents inrush into capacitive PD loads; 300 μA quiescent current minimizes standby loss during detection mode.

Automotive LED Driver Support Rail

Industrial Isolated Auxiliary Supply

Use Scenario: Generating 5 V @ 2 A from 9–16 V automotive battery for LED driver ICs and CAN transceivers in headlight modules.

IC Role / Device Role / Timing Role: Boost controller with wide input range and robust UVLO hysteresis (4.1 V rise / 2.9 V fall) tolerating cold-crank dips.

Use Value: 78% max duty cycle prevents instability under low-VIN conditions; DFN package withstands automotive thermal cycling (–40°C to +85°C).

Use Scenario: Delivering isolated –5 V @ 3 A from –10 to –15 V input in industrial negative-buck configurations for op-amp biasing and sensor interfaces.

IC Role / Device Role / Timing Role: Negative-output buck controller using inverted topology; RUN/SS pin enables synchronized power-up with main system controller.

Use Value: Adjustable current limit protects against short-circuit faults on sensitive analog rails; ±1.5% V_OUT accuracy ensures precision sensor excitation.

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#TRMPBF	200 kHz fixed frequency, same DFN package, but optimized for flyback-only; lacks IPRG pin and No RSENSE capability.	Suitable for cost-sensitive flyback designs where MOSFET R_DS(ON) sensing is unnecessary and external sense resistor is acceptable.	Select LTC3803EDD-5#TRMPBF when topology is strictly flyback and lower BOM count is prioritized over No RSENSE flexibility.
LTC3703IGN#TRPBF	100 V input rating, SSOP-16 package, 600 kHz frequency; supports synchronous rectification and higher power levels.	Targeted at high-voltage industrial or server PSUs requiring >60 V input and >10 A output; not pin-compatible or drop-in.	Choose LTC3703IGN#TRPBF for >60 V input applications needing higher integration and synchronous drive, accepting larger footprint and layout redesign.

Compared with LTC3803EDD-5#TRMPBF and LTC3703IGN#TRPBF, the LTC3873EDDB-5#TRMPBF uniquely combines No RSENSE operation, 3mm × 2mm DFN packaging, and triple-topology support - making it optimal for space-constrained, efficiency-critical telecom and PoE auxiliary supplies where input voltage stays below 60 V.

Availability

LTC3873EDDB-5#TRMPBF is available at Aetrix Electronics and suitable for telecom power supplies, PoE-powered devices, and automotive LED driver support rails requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for LTC3873EDDB-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 its high-performance analog and power management portfolio. Linear pioneered precision DC/DC controllers with innovations like No RSENSE sensing and integrated shunt regulators.

The LTC3873 product line was designed specifically for high-efficiency, low-component-count boost/flyback/SEPIC converters in telecom, industrial, and automotive applications where input voltage exceeds standard IC supply limits.

FAQ

What is the maximum input voltage the LTC3873EDDB-5#TRMPBF can handle?

The LTC3873EDDB-5#TRMPBF itself has an absolute maximum VCC rating of 9 V, but its internal 9.3 V shunt regulator allows biasing from higher input voltages (e.g., 36–75 V) using a series resistor. The SW pin supports up to 60 V, enabling use with external MOSFETs rated for high input/output voltages. Actual system VIN is limited only by external components.

Does the LTC3873EDDB-5#TRMPBF require an external current sense resistor?

No - the LTC3873EDDB-5#TRMPBF features No RSENSE operation, allowing current sensing via the R_DS(ON) of the external N-channel MOSFET. An external sense resistor is optional and used only when R_DS(ON) sensing is impractical. The IPRG pin selects the appropriate current threshold for either method.

How is soft-start configured on the LTC3873EDDB-5#TRMPBF?

The LTC3873EDDB-5#TRMPBF offers internal 3.3 ms soft-start when the RUN/SS pin is left open. To extend soft-start time, connect an external capacitor from RUN/SS to GND; a 3 μA internal current charges it, and a 15 μA pull-up continues the ramp. For logic-controlled start-up, drive RUN/SS above 2.75 V.

What is the purpose of the IPRG pin on the LTC3873EDDB-5#TRMPBF?

The IPRG pin on the LTC3873EDDB-5#TRMPBF selects the peak current limit threshold: 95 mV (IPRG = GND), 185 mV (IPRG = float), or 295 mV (IPRG = VIN). This allows precise adaptation of overcurrent protection to the chosen MOSFET's R_DS(ON) or external sense resistor value without changing component values.

Can the LTC3873EDDB-5#TRMPBF be used in flyback topology with primary-side regulation?

Yes - the LTC3873EDDB-5#TRMPBF supports flyback topology and can be used with primary-side regulation by sensing reflected output voltage across an auxiliary winding. Its 200 kHz fixed frequency, current-mode control, and built-in slope compensation ensure stable operation without optocoupler feedback in cost-sensitive designs.

LTC3873EDDB-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 ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-DFN (3x2)

LTC3873EDDB-5#TRMPBF FAQ

1.How can I place an order for LTC3873EDDB-5#TRMPBF through Aetrix?

Please submit a Request for Quotation (RFQ) for LTC3873EDDB-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 LTC3873EDDB-5#TRMPBF reliable?

The price and inventory of LTC3873EDDB-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 LTC3873EDDB-5#TRMPBF is usually 5 days.

3.What payment methods are accepted for LTC3873EDDB-5#TRMPBF?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3873EDDB-5#TRMPBF transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LTC3873EDDB-5#TRMPBF?

LTC3873EDDB-5#TRMPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LTC3873EDDB-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 LTC3873EDDB-5#TRMPBF?

For technical support, including LTC3873EDDB-5#TRMPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3873EDDB-5#TRMPBF requirements.

6.How does Aetrix verify that LTC3873EDDB-5#TRMPBF is sourced from the original manufacturer or authorized distributors?

All LTC3873EDDB-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 LTC3873EDDB-5#TRMPBF meets industry standards.

7.What is the process for return or replacement of LTC3873EDDB-5#TRMPBF?

All LTC3873EDDB-5#TRMPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3873EDDB-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 LTC3873EDDB-5#TRMPBF part is unused and in its original packaging.

Return procedure for LTC3873EDDB-5#TRMPBF:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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