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Analog Devices Inc. LTC3873IDDB-5#TRPBF
- Part No.:
- LTC3873IDDB-5#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3873IDDB-5#TRPBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,710
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Product details
Overview
LTC3873IDDB-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, 200kHz fixed switching frequency, 4.1V VCC undervoltage lockout threshold, and operates across –40°C to +125°C with 300μA quiescent current. It enables telecom power supplies requiring stable 12V outputs from 36–75V inputs.
For engineers reviewing the LTC3873IDDB-5#TRPBF datasheet, LTC3873IDDB-5#TRPBF pinout, LTC3873IDDB-5#TRPBF application, or LTC3873IDDB-5#TRPBF equivalent, key selection criteria include its No RSENSE current sensing capability, internal 9.3V shunt regulator for high-VIN biasing, programmable current limit via IPRG pin, 8-lead DFN (3mm × 2mm) package with exposed thermal pad, and compatibility with isolated housekeeping converters.
Technical Context
The LTC3873IDDB-5#TRPBF implements current-mode control with internal slope compensation and a 200kHz oscillator, supporting duty cycles up to 84%. Its error amplifier regulates feedback voltage (VFB) against a 1.2V reference, modulating ITH voltage to set peak current thresholds dynamically during load transients.
It features dual shutdown mechanisms: VCC UVLO (4.1V turn-on / 2.9V turn-off) and RUN/SS pin threshold (0.7V nominal), enabling precise start-up sequencing and micropower operation at 50μA. The SW pin serves as both switch-node connection and internal current-sense input when using RDS(ON) sensing, with maximum sense voltage configurable via IPRG pin (GND/float/VIN).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 200kHz fixed - ensures predictable EMI profile and simplifies filter design for telecom and PoE applications. |
| Output Voltage Accuracy | ±1.5% - guarantees tight regulation over temperature and line/load variations without trimming. |
| VCC UVLO Threshold | 4.1V rising / 2.9V falling - prevents MOSFET gate drive below safe VGS, ensuring reliable startup in automotive and industrial supplies. |
| Quiescent Current | 300μA normal / 50μA shutdown - minimizes standby loss in always-on telecom systems. |
| Current Sense Options | No RSENSE (MOSFET RDS(ON)) or external resistor - eliminates sense resistor losses and PCB area in efficiency-critical designs. |
| Package | 8-lead DFN (3mm × 2mm, 0.75mm height) with exposed GND pad - provides low thermal resistance (θJA = 76°C/W) for high-power density layouts. |
| Operating Temperature | –40°C to +125°C - qualified for under-hood automotive and industrial environments without derating. |
Pinout & Package
Package: 8-lead plastic DFN (3mm × 2mm), 0.75mm nominal height, exposed thermal pad (Pin 9) soldered to PCB for electrical and thermal performance. Pin 1 identified by marking bar.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IPRG (Pin 1) | Current limit select | Configures peak sense threshold: 95mV (GND), 165mV (float), or 265mV (VIN) - enables optimization for MOSFET RDS(ON) or discrete sense resistors. |
| ITH (Pin 2) | Error amplifier output / compensation node | 0.7–1.9V range sets current comparator threshold - used for loop compensation and soft-start ramp control. |
| VFB (Pin 3) | Feedback input | Monitors divided output voltage against 1.2V reference - determines regulation point; input current ≤50nA minimizes divider error. |
| GND (Pin 4) | Power and signal ground | Common return for all internal circuits and exposed pad - must be low-impedance connection for stability and thermal performance. |
| NGATE (Pin 5) | N-channel MOSFET gate driver | Drives external high-side switch with rail-to-rail swing (0V to VIN) - supports fast switching with 40ns rise/fall times into 3000pF. |
| VCC (Pin 6) | Supply input with 9.3V shunt regulator | Accepts 4.1–9V directly or higher VIN via series resistor - internal shunt sinks up to 25mA, enabling wide-input biasing without external LDO. |
| RUN/SS (Pin 7) | Shutdown and soft-start control | 0.7V threshold enables/disables operation; open-circuit gives 3.3ms internal soft-start - external capacitor extends ramp for inrush limiting. |
| 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 60V max. |
Key Features
| Feature | Design Value |
|---|---|
| No RSENSE current sensing | Eliminates sense resistor losses and board space by using MOSFET RDS(ON) - improves efficiency in high-current boost converters. |
| Internal 9.3V shunt regulator | Allows direct biasing from high-VIN sources (e.g., 36–75V telecom rails) using only a series resistor - avoids external regulators and reduces BOM count. |
| Programmable current limit | Three thresholds (95/165/265mV) selected via IPRG pin - matches diverse MOSFET RDS(ON) values or sense resistors without component changes. |
| 200kHz constant-frequency operation | Enables consistent EMI filtering and predictable transient response - avoids sub-harmonic oscillation via built-in slope compensation. |
| –40°C to +125°C operation | Qualified for extended temperature range - supports automotive engine control units and industrial power modules without thermal derating. |
Applications
| Telecom Housekeeping Supply | Automotive Infotainment Power |
|---|---|
Use Scenario: Generating isolated 10V/100mA auxiliary power from 36–75V telecom battery bus for control logic and interface ICs. IC Role / Device Role / Timing Role: Primary-side flyback controller regulating output via optocoupler feedback, driving external MOSFET and transformer. Use Value: No RSENSE sensing and 200kHz operation reduce component count and EMI filtering requirements while maintaining ±1.5% regulation across input range. | Use Scenario: Non-isolated 12V boost converter powering infotainment head unit from 9–16V automotive battery with cold-crank support down to 6V. IC Role / Device Role / Timing Role: Constant-frequency current-mode boost controller with internal soft-start and UVLO, managing MOSFET gate drive and current limiting. Use Value: 4.1V VCC UVLO ensures reliable startup during cranking; 300μA quiescent current minimizes battery drain in parked state. |
| PoE Powered Device (PD) Auxiliary Rail | Industrial Sensor Node SEPIC Supply |
Use Scenario: Deriving 5V/2A auxiliary supply from IEEE 802.3af/at PoE input (37–57V) for Ethernet PHY and microcontroller in networked devices. IC Role / Device Role / Timing Role: SEPIC controller implementing non-inverting topology to handle input voltage overlapping output, with current-mode loop stability. Use Value: VIN and VOUT limited only by external components - enables single design to cover multiple PoE classes without topology change. | Use Scenario: Providing regulated 3.3V for low-power sensor nodes from variable 5–12V industrial bus with brownout resilience. IC Role / Device Role / Timing Role: SEPIC DC/DC controller supporting wide input range and seamless transition between buck and boost behavior. Use Value: Adjustable current limit and ±1.5% accuracy ensure stable operation during transient load steps common in wireless sensor wake-up cycles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3803EDD-5#TRPBF | 200kHz flyback-only controller; no boost/SEPIC support; lower IQ (100μA); same DFN package. | Restricted to flyback topology; lacks IPRG pin and No RSENSE capability for MOSFET sensing. | Select when topology is fixed to flyback and ultra-low quiescent current is prioritized over versatility. |
| LTC3703IGN#TRPBF | 100V synchronous step-up/step-down controller; 600kHz; SSOP-16; supports synchronous rectification. | Higher voltage rating and synchronous capability enable higher efficiency at >1A loads but requires more complex layout and external MOSFET drivers. | Choose for high-efficiency, high-current (>2A) applications where 100V input tolerance and synchronous rectification justify added complexity. |
Compared with LTC3803EDD-5#TRPBF and LTC3703IGN#TRPBF, the LTC3873IDDB-5#TRPBF uniquely balances multi-topology flexibility (boost/flyback/SEPIC), No RSENSE efficiency, and compact DFN packaging - making it optimal for space-constrained, wide-input telecom and industrial auxiliary supplies where design reuse across topologies is valuable.
Availability
LTC3873IDDB-5#TRPBF is available at Aetrix Electronics and suitable for telecom power supplies, automotive infotainment systems, and PoE-powered device auxiliary rails requiring stable component supply across extended temperature ranges.
Supply support for LTC3873IDDB-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 its precision analog and power management portfolio. Linear pioneered high-performance DC/DC controllers with innovations like No RSENSE sensing and integrated shunt regulators.
The LTC3873 family was designed for high-efficiency, wide-input-voltage DC/DC conversion in space- and thermally constrained applications - specifically targeting telecom, industrial, and automotive auxiliary power where reliability across temperature and input variation is critical.
FAQ
What is the maximum input voltage supported by the LTC3873IDDB-5#TRPBF?
The LTC3873IDDB-5#TRPBF itself has an absolute maximum VCC rating of 9V, but its internal 9.3V shunt regulator allows biasing from higher input voltages (e.g., 36–75V telecom rails) using a series resistor. External component ratings - particularly the MOSFET's VDSS and transformer insulation - determine the practical VIN limit, not the controller IC.
Does the LTC3873IDDB-5#TRPBF require an external current sense resistor?
No, the LTC3873IDDB-5#TRPBF supports No RSENSE operation by sensing voltage across the external N-channel MOSFET's RDS(ON) via the SW pin. An external resistor is optional and used only when higher accuracy or isolation is needed - the IPRG pin selects the appropriate sense threshold for either method.
How does the RUN/SS pin function on the LTC3873IDDB-5#TRPBF?
The RUN/SS pin on the LTC3873IDDB-5#TRPBF serves dual functions: applying <0.7V forces shutdown (50μA IQ), while >0.7V enables operation. Leaving it open provides 3.3ms internal soft-start; adding an external capacitor to GND extends the ramp time linearly (3μA charge current), controlling inrush current during startup.
What package type and thermal characteristics does the LTC3873IDDB-5#TRPBF use?
The LTC3873IDDB-5#TRPBF uses an 8-lead DFN package (3mm × 2mm, 0.75mm height) with an exposed GND pad (Pin 9). Its thermal resistance is θJA = 76°C/W when properly soldered to a 1-in² copper area - significantly lower than the TSOT-23 variant (θJA = 230°C/W), enabling higher power density in compact layouts.
Can the LTC3873IDDB-5#TRPBF be used in SEPIC topology applications?
Yes, the LTC3873IDDB-5#TRPBF explicitly supports SEPIC topology per its datasheet, alongside boost and flyback. Its current-mode architecture, adjustable current limit, and wide VIN/VOUT capability (limited only by external components) make it suitable for non-inverting converters where input voltage may fall below or rise above output voltage - such as industrial sensor nodes with variable bus supplies.
LTC3873IDDB-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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-DFN (3x2)
LTC3873IDDB-5#TRPBF FAQ
1.How can I place an order for LTC3873IDDB-5#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3873IDDB-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 LTC3873IDDB-5#TRPBF reliable?
The price and inventory of LTC3873IDDB-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 LTC3873IDDB-5#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3873IDDB-5#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3873IDDB-5#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3873IDDB-5#TRPBF?
LTC3873IDDB-5#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3873IDDB-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 LTC3873IDDB-5#TRPBF?
For technical support, including LTC3873IDDB-5#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3873IDDB-5#TRPBF requirements.
6.How does Aetrix verify that LTC3873IDDB-5#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3873IDDB-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 LTC3873IDDB-5#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3873IDDB-5#TRPBF?
All LTC3873IDDB-5#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3873IDDB-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 LTC3873IDDB-5#TRPBF part is unused and in its original packaging.
Return procedure for LTC3873IDDB-5#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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