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Analog Devices Inc. LT3479EDE#PBF
- Part No.:
- LT3479EDE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LT3479EDE#PBF.pdf
- Description:
- IC REG BOOST ADJ 3A 14DFN
- Quantity:
- Payment:
- Shipping:
Inventory:309
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Product details
Overview
LT3479EDE#PBF from Analog Devices (formerly Linear Technology) is a current-mode, fixed-frequency step-up DC/DC converter with an integrated 3A, 42V NPN switch. It delivers up to 89% efficiency across 2.5V–24V input and supports programmable switching frequency (200kHz–3.5MHz), soft-start, and inrush current protection. It enables both positive and negative output configurations and is used in high-power LED drivers and distributed power systems.
For engineers reviewing the LT3479EDE#PBF datasheet, LT3479EDE#PBF pinout, LT3479EDE#PBF application, or LT3479EDE#PBF equivalent, key selection criteria include its 3A internal switch rating, 42V switch voltage limit, 1.235V reference accuracy, thermal performance in the 4mm × 3mm DFN package, and dual-polarity feedback architecture enabling ±VOUT designs.
Technical Context
The LT3479EDE#PBF employs fixed-frequency current-mode control with slope compensation, using an external resistor on the RT pin to set oscillator frequency between 200kHz and 3.5MHz. Its error amplifier features fully accessible FBP and FBN inputs, allowing flexible feedback topologies for both positive and negative output voltages.
It integrates inrush current protection via an internal 8.5mΩ sense resistor in series with the inductor, triggering soft-start when inductor current exceeds 5A. The device also includes overcurrent shutdown, thermal shutdown at 125°C junction temperature, and robust input short-circuit/hot-plug resilience.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Rating | 3A continuous, 42V collector-emitter breakdown - supports high-current boost and inverting topologies without external switch. |
| Input Voltage Range | 2.5V to 24V - enables direct operation from single-cell Li-ion (2.8V–4.2V), 5V rails, or industrial 12V/24V supplies. |
| Reference Voltage | 1.235V ±19mV (min/max) - sets output regulation accuracy for precision feedback networks in ±VOUT designs. |
| Switching Frequency | 200kHz to 3.5MHz (RT-programmable) - allows trade-off between EMI, inductor size, and efficiency (e.g., 1MHz typical for compact 5V→12V converters). |
| Soft-Start Control | SS pin accepts external capacitor (e.g., 10nF = ~1.65ms ramp) - limits peak inductor current during startup to prevent overshoot and stress. |
| Thermal Performance | θJA = 43°C/W (DFN package) - requires exposed pad soldered to PCB ground plane for reliable 3A operation at 85°C ambient. |
| Protection Features | Inrush current protection (5A threshold), thermal shutdown (125°C), and input short-circuit resilience - eliminates need for external fault-handling circuitry. |
Pinout & Package
LT3479EDE#PBF is housed in a 14-lead, 4mm × 3mm × 0.75mm plastic DFN package (DE14) with exposed power ground pad (Pin 15) requiring solder connection to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pins 1, 2) | Switch Collector | Connects to inductor and flyback diode; high dv/dt node requiring minimized trace area to reduce EMI. |
| L (Pin 3) | Inductor Connection | Return path for inductor current; ties to VS internally for gate drive supply - must be locally bypassed. |
| VS (Pin 4) | Inductor Supply Rail | Powers internal switch driver; tie to VIN if single supply is used, otherwise decouple separately for noise isolation. |
| VIN (Pin 5) | Control Circuit Supply | Powers bias and logic circuitry; requires local ceramic bypass (≥2.2μF) near pin for stable start-up. |
| RT (Pin 6) | Oscillator Timing Input | Accepts external resistor (1.78kΩ–113kΩ) to set switching frequency; open-circuit disables operation. |
| SHDN (Pin 7) | Enable/Shutdown Control | Active-high logic: >1.5V enables, <0.3V disables; draws ≤60μA when active, <1μA in shutdown. |
| VREF (Pin 8) | Bandgap Reference Output | 1.235V reference source (±19mV); supplies current to feedback divider and may be bypassed with 100pF. |
| FBP (Pin 9) | Error Amp Non-Inverting Input | Used for negative-output configurations - connect to resistive divider tap referenced to –VOUT. |
| FBN (Pin 10) | Error Amp Inverting Input | Used for positive-output configurations - connect to resistive divider tap referenced to +VOUT. |
| VC (Pin 11) | Compensation Node | Output of error amplifier; connect series RC (e.g., 10kΩ + 2.2nF) to GND for loop stability. |
| SS (Pin 12) | Soft-Start Ramp Input | Charged by internal 10μA current source; controls VC ramp rate to limit inrush current during start-up. |
| GND (Pins 13, 14) | Analog Ground | Reference for control circuitry; must be tied directly to low-impedance ground plane, separate from power ground where possible. |
| Exposed Pad (Pin 15) | Power Ground (PGND) | Mandatory solder connection to PCB ground plane - critical for thermal dissipation and switch return path integrity. |
Key Features
| Feature | Design Value |
|---|---|
| Programmable Switching Frequency | 200kHz–3.5MHz via single external resistor - enables optimization of size, efficiency, and EMI in space-constrained applications. |
| Dual-Polarity Feedback Architecture | Separate FBP/FBN inputs allow identical IC to generate either positive or negative regulated outputs - reduces BOM count in multi-rail systems. |
| Inrush Current Protection | Internal 8.5mΩ inductor current sense triggers automatic soft-start on >5A transients - protects switch and external components during hot-plug or short-circuit events. |
| Low VCE(SAT) | 200mV typical at 1A - minimizes conduction loss and improves full-load efficiency in high-current boost stages. |
| Thermally Enhanced DFN Package | 4mm × 3mm footprint with exposed PGND pad - achieves 43°C/W θJA, supporting 3A continuous operation without heatsink at 85°C ambient. |
Applications
| High-Power LED Driver | DSL Modem Power Supply |
|---|---|
|
Use Scenario: Driving 12 white LEDs (3.3V each) from a 3.3V–4.2V Li-ion battery in photo-flash or torch mode. IC Role / Device Role / Timing Role: Step-up controller generating constant-current 12V output with adjustable torch/flash modes via external MOSFET control. Use Value: Integrated 3A switch and inrush protection eliminate external switch and fault-handling circuitry, reducing solution size by >30% vs discrete alternatives. |
Use Scenario: Generating isolated ±12V and +5V rails from a 5V input in DSL line card power management. IC Role / Device Role / Timing Role: Primary boost regulator in triple-output configuration (e.g., +8V, +16V, –8V) for TFT-LCD panel bias supplies. Use Value: Dual feedback inputs enable precise tracking of complementary outputs, while 2.5V–24V input range accommodates wide AC/DC adapter tolerances. |
| Distributed Power System | Inverting DC/DC Converter |
|
Use Scenario: Local 12V boost conversion from 5V backplane in industrial I/O modules with strict EMI requirements. IC Role / Device Role / Timing Role: High-efficiency (89%) step-up regulator operating at 1MHz to minimize inductor size and conducted emissions. Use Value: Programmable frequency and low-noise current-mode control meet EN55022 Class B limits without added filtering components. |
Use Scenario: Generating –5V @ 600mA from 5V input for op-amp biasing or RS-232 interface circuits. IC Role / Device Role / Timing Role: Inverting buck-boost controller using FBP/VREF feedback topology to regulate negative output voltage. Use Value: Eliminates need for isolated transformer or charge-pump IC - achieves >85% efficiency at –5V/600mA with standard Schottky diode and 4.7μH inductor. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3436 | 3A switch, 34V max, TSSOP-16 package, higher quiescent current (0.9mA vs 7.5μA in shutdown) | Optimized for 3V–25V input; lacks inrush current protection and dual-polarity feedback capability | Prefer LTC3436 only when higher output voltage (≤34V) is required and negative output generation is unnecessary. |
| LT3466 | Dual-channel, integrated Schottky, 40V max, 2MHz fixed frequency, QFN package | Designed specifically for white LED driving with torch/flash control; no general-purpose FBP/FBN flexibility | Select LT3466 only for dedicated LED applications requiring dual independent channels and integrated diode - not suitable for generic boost or inverting use. |
Compared with LTC3436 and LT3466, the LT3479EDE#PBF uniquely combines 42V switch rating, programmable frequency, inrush protection, and dual-polarity feedback in a thermally efficient DFN package - making it the only option among the three capable of robust ±VOUT generation across 2.5V–24V inputs.
Availability
LT3479EDE#PBF is available at Aetrix Electronics and suitable for high-power LED drivers, DSL modem power supplies, and distributed power systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LT3479EDE#PBF 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 ICs for power management, signal conditioning, and precision regulation.
The LT3479EDE#PBF belongs to Linear's high-current DC/DC converter product line, designed for applications demanding robust overcurrent protection, wide input range, and flexible output polarity - especially in space-constrained industrial and telecom power systems.
FAQ
What is the maximum output voltage achievable with the LT3479EDE#PBF?
The LT3479EDE#PBF does not impose a hard limit on output voltage - it is constrained by external component ratings and layout. Its 42V internal switch rating means the SW pin can safely swing up to 42V relative to GND. Therefore, with appropriate inductor, diode, and output capacitor voltage ratings, the LT3479EDE#PBF can generate outputs up to ~40V in boost mode or –40V in inverting mode, provided the total voltage stress on SW remains within 42V.
Can the LT3479EDE#PBF generate negative output voltages?
Yes, the LT3479EDE#PBF explicitly supports negative output generation using its dual-input error amplifier. Connect VREF to FBP and configure a resistive divider from –VOUT to GND, feeding the divider tap to FBN. This topology leverages the internal 1.235V reference to regulate the magnitude of the negative output. Application Note 3479 TA06 demonstrates a verified 5V-to–5V/600mA inverting converter using the LT3479EDE#PBF.
What is the purpose of the VS pin on the LT3479EDE#PBF, and how should it be connected?
The VS pin on the LT3479EDE#PBF supplies power to the internal NPN switch driver and is tied internally to the L pin. It must be locally bypassed with a ceramic capacitor (typically 1μF) close to the pin. If only one input supply is available, VS may be tied directly to VIN. However, separating VS from VIN (e.g., with dedicated LC filtering) improves noise immunity and prevents switching noise from coupling into the control circuitry powered by VIN.
How does the inrush current protection function in the LT3479EDE#PBF?
The LT3479EDE#PBF implements inrush current protection using an internal 8.5mΩ resistor in series with the L pin. When inductor current exceeds 5A, the protection comparator triggers a new soft-start cycle - resetting the SS capacitor discharge and limiting peak switch current until the fault clears. This occurs independently of normal current limiting (which trips at ~3A) and protects against hot-plug transients and output shorts without requiring external circuitry.
Is the LT3479EDE#PBF pin-compatible with the TSSOP version LT3479EFE#PBF?
No, the LT3479EDE#PBF (14-pin DFN) and LT3479EFE#PBF (16-pin TSSOP) are not pin-compatible. They share identical electrical functionality and parameter specifications but differ in pin count, pin assignment, and package dimensions. The DFN version consolidates two GND pins and omits two unused pins present in the TSSOP variant. PCB layout and footprint must be redesigned when switching between these packages.
LT3479EDE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 14-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up
- Output Configuration:
- Positive or Negative
- Topology:
- Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.3V
- Voltage - Input (Max):
- 24V
- Voltage - Output (Min/Fixed):
- 1.235V
- Voltage - Output (Max):
- 42V (Switch)
- Current - Output:
- 3A (Switch)
- Frequency - Switching:
- 200kHz ~ 3.5MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-DFN (4x3)
LT3479EDE#PBF FAQ
1.How can I place an order for LT3479EDE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3479EDE#PBF 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 LT3479EDE#PBF reliable?
The price and inventory of LT3479EDE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3479EDE#PBF is usually 5 days.
3.What payment methods are accepted for LT3479EDE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3479EDE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3479EDE#PBF?
LT3479EDE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3479EDE#PBF 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 LT3479EDE#PBF?
For technical support, including LT3479EDE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3479EDE#PBF requirements.
6.How does Aetrix verify that LT3479EDE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3479EDE#PBF 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 LT3479EDE#PBF meets industry standards.
7.What is the process for return or replacement of LT3479EDE#PBF?
All LT3479EDE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3479EDE#PBF, 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 LT3479EDE#PBF part is unused and in its original packaging.
Return procedure for LT3479EDE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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