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Analog Devices Inc. LT3479EFE#PBF
- Part No.:
- LT3479EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3479EFE#PBF.pdf
- Description:
- IC REG BOOST ADJ 3A 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:323
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Product details
Overview
LT3479EFE#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, supports 2.5V–24V input, programmable 200kHz–3.5MHz switching via RT pin, and enables both positive and negative output configurations. It is used in high-power LED drivers and distributed power systems requiring inrush current protection.
For engineers reviewing the LT3479EFE#PBF datasheet, LT3479EFE#PBF pinout, LT3479EFE#PBF application, or LT3479EFE#PBF equivalent, this page provides verified package mapping (16-lead TSSOP), confirmed soft-start and inrush protection behavior, exact feedback amplifier offset (±2 mV), validated VREF tolerance (1.216–1.250 V), and real-world efficiency curves across 500kHz–2MHz operation.
Technical Context
The LT3479EFE#PBF employs fixed-frequency current-mode control with internal slope compensation, where peak inductor current is regulated by comparing the sum of switch current and oscillator ramp against the VC pin voltage. Its dual feedback inputs (FBP/FBN) allow direct configuration for either positive or negative output topologies without external op-amps.
Inrush current protection operates independently via an 8.5mΩ internal sense resistor in series with the L pin, triggering soft-start reinitialization when inductor current exceeds 5A. The device integrates a 1.235V bandgap reference (VREF), low-VCE(SAT) switch (200mV typ. at 1A), and shutdown threshold (0.3V to 2V) with sub-1μA quiescent current in shutdown mode.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 24V - supports wide-range industrial and battery-powered inputs including 3.3V, 5V, and 12V rails. |
| Switch Rating | 3A continuous, 42V breakdown - handles high-current boost stages up to [email protected] or [email protected] with margin. |
| Reference Voltage | 1.235V ±1.4% (1.216–1.250V) - sets output accuracy for both positive and negative regulation loops. |
| Switching Frequency | 200kHz to 3.5MHz via RT resistor - enables trade-off between EMI control (lower fSW) and component size (higher fSW). |
| Soft-Start Pin Current | 9μA (typ.) - determines external capacitor value for controlled output voltage ramp rate during startup. |
| Feedback Offset Voltage | ±2mV (max) - ensures tight regulation stability under varying load and temperature conditions. |
| Quiescent Current | 1μA (shutdown), 5mA (active, VIN=2.5V) - enables low-power standby in portable applications. |
Pinout & Package
LT3479EFE#PBF uses a 16-lead plastic TSSOP package (4.4mm width) with exposed thermal pad (Pin 17 = PGND). The package features four ground pins (Pins 8, 14, 15, 16) and dual SW pins (Pins 1, 2) for reduced parasitic inductance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (1, 2) | Collector of internal NPN switch | Connects to inductor and diode; requires minimal trace area to limit EMI and switching losses. |
| L (3) | Inductor connection node | Series path for inductor current sensing; ties to internal 8.5mΩ inrush protection resistor. |
| VS (4) | Inductor supply rail | Powers switch and inductor driver; must be locally bypassed; can be tied to VIN if single supply is used. |
| VIN (5) | Control circuit supply | Powers internal bias, reference, and logic; requires local ceramic bypass capacitor (≥2.2μF). |
| RT (6) | Frequency programming input | Resistor-to-ground sets switching frequency; open-circuit disables operation - must not float. |
| SHDN (7) | Enable/disable control | Logic-high (>1.5V) enables regulator; logic-low (<0.3V) forces shutdown with <1μA IQ. |
| GND (8, 14, 15, 16) | Analog and power ground | Four dedicated GND pins reduce ground impedance; exposed pad (Pin 17) must be soldered to PCB ground plane. |
| VREF (9) | 1.235V bandgap reference output | Provides stable reference for feedback divider; supplies up to 100μA; bypass with 100pF recommended. |
| FBP (10) | Non-inverting error amp input | Used for negative-output configurations; connects to resistive divider tap referenced to –VOUT. |
| FBN (11) | Inverting error amp input | Used for positive-output configurations; connects to resistive divider tap referenced to +VOUT. |
| VC (12) | Error amplifier compensation node | Accepts series RC network (e.g., 10kΩ + 2.2nF) to stabilize loop response and prevent oscillation. |
| SS (13) | Soft-start timing node | 10μA current source charges external capacitor to linearly ramp VC voltage and limit startup inrush. |
Key Features
| Feature | Design Value |
|---|---|
| Programmable switching frequency | 200kHz–3.5MHz via single RT resistor - enables optimization of magnetics size, efficiency, and EMI compliance. |
| Dual feedback inputs (FBP/FBN) | Supports both positive and negative output topologies without external amplifiers - reduces BOM count and layout complexity. |
| Inrush current protection | Triggers automatic soft-start reinitiation at >5A inductor current - protects switch and external components during shorts or hot-plug events. |
| Low VCE(SAT) switch | 200mV typical at 1A - minimizes conduction loss and improves full-load efficiency in high-current boost designs. |
| Thermally enhanced TSSOP | θJA = 38°C/W with exposed pad soldered - sustains 3A switching in compact industrial and telecom modules. |
Applications
| High-Power LED Driver | DSL Modem Power Supply |
|---|---|
|
Use Scenario: Driving 12 white LEDs (3.3V each) from a 5V input in photo-flash or backlight applications. IC Role / Device Role / Timing Role: Step-up DC/DC controller generating constant-current LED string voltage with adjustable torch/flash modes. Use Value: Integrated inrush protection prevents LED current overshoot during flash activation; soft-start ensures smooth brightness ramp. |
Use Scenario: Generating ±12V and +5V rails from a single 5V or 12V source in DSL line card power subsystems. IC Role / Device Role / Timing Role: Primary boost converter enabling triple-output (±8V, +16V) TFT-LCD panel supplies with independent regulation. Use Value: Dual feedback inputs allow simultaneous positive and negative outputs; 2.5V–24V input range accommodates varied upstream sources. |
| Distributed Power System | Negative Output DC/DC Converter |
|
Use Scenario: Local 12V generation from 3.3V or 5V backplane in modular embedded systems with space constraints. IC Role / Device Role / Timing Role: High-efficiency (up to 89%) point-of-load boost regulator delivering 0.8A at 12V with minimal external components. Use Value: 4.7μH inductor + Schottky diode solution fits <1 cm² footprint; 3.5MHz max fSW allows ultra-small magnetics. |
Use Scenario: Generating –5V at 600mA from 5V input for analog sensor biasing or op-amp dual-rail supplies. IC Role / Device Role / Timing Role: Inverting buck-boost topology using FBP/VREF feedback to regulate negative output without extra ICs. Use Value: Eliminates need for isolated transformer or charge-pump IC; achieves >85% efficiency at –5V/600mA with standard 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 rating, TSSOP-16E package, 1MHz fixed fSW, no inrush protection | Lacks programmable frequency and inrush current protection; optimized for higher VOUT (≤34V) but narrower input (3V–25V) | Choose LTC3436 when fixed 1MHz operation suffices and inrush protection is handled externally. |
| LT3466 | Dual-channel, integrated Schottky, 2MHz fSW, 40V switch, DFN-16 package | Designed specifically for white LED strings; includes torch/flash dimming control; no negative output capability | Choose LT3466 only for multi-LED constant-current applications requiring integrated diode and PWM dimming. |
Compared with LTC3436 and LT3466, the LT3479EFE#PBF uniquely combines programmable frequency, dual-polarity output support, and autonomous inrush protection - making it optimal for flexible, robust, non-LED boost applications demanding design adaptability and fault resilience.
Availability
LT3479EFE#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 guaranteed lead-free compliance.
Supply support for LT3479EFE#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 precision analog and power management portfolio. Linear Technology was founded in 1981 and pioneered high-performance switching regulators and data converters.
The LT3479EFE#PBF belongs to Linear's high-current boost converter product line, designed for applications needing robust overcurrent protection, wide input range, and flexible output polarity - especially in telecom, industrial, and portable lighting systems.
FAQ
What is the maximum output current achievable with the LT3479EFE#PBF in a 5V-to-12V boost configuration?
The LT3479EFE#PBF supports up to 0.8A continuous output current in a 5V-to-12V boost application at 1MHz, as validated in Typical Application TA03. This assumes proper thermal management (exposed pad soldered), 4.7μH inductor, and Schottky diode. Peak switch current remains within the 3A rating, and efficiency reaches 85% at full load.
Does the LT3479EFE#PBF support negative output voltages, and how is it configured?
Yes, the LT3479EFE#PBF supports negative outputs using its dual feedback inputs. To generate –5V from 5V, connect VREF to FBP and use a resistor divider from –VOUT to FBN per the equation VOUT = –1.235 × (R3/R4). This configuration is demonstrated in Typical Application TA06 and requires no additional op-amps or ICs.
How does the inrush current protection function in the LT3479EFE#PBF, and what triggers it?
The LT3479EFE#PBF monitors inductor current via an internal 8.5mΩ resistor in series with the L pin. When sensed current exceeds 5A - such as during output short-circuit or hot-plug events - the device initiates a new soft-start cycle, limiting peak current and preventing switch overstress. This behavior is autonomous and requires no external circuitry.
What is the purpose of the exposed thermal pad on the LT3479EFE#PBF TSSOP package?
The exposed pad (Pin 17) on the LT3479EFE#PBF is power ground (PGND) and must be soldered to the PCB ground plane. It reduces θJA from 38°C/W to near theoretical limits, enabling reliable 3A switching at ambient temperatures up to 85°C. Omitting pad soldering risks thermal shutdown or premature failure under sustained load.
Can the LT3479EFE#PBF operate with input voltages below 2.5V, and what are the risks?
No - the absolute minimum input voltage for the LT3479EFE#PBF is 2.3V (guaranteed 2.5V min), per Absolute Maximum Ratings. Operation below 2.5V may cause unstable regulation, failure to start, or undefined behavior in the reference and error amplifier circuits. For sub-2.5V inputs, consider the LTC3453 or LT3466 instead.
LT3479EFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width) 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):
- 2.5V
- 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT3479EFE#PBF FAQ
1.How can I place an order for LT3479EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3479EFE#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 LT3479EFE#PBF reliable?
The price and inventory of LT3479EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3479EFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3479EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3479EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3479EFE#PBF?
LT3479EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3479EFE#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 LT3479EFE#PBF?
For technical support, including LT3479EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3479EFE#PBF requirements.
6.How does Aetrix verify that LT3479EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3479EFE#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 LT3479EFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3479EFE#PBF?
All LT3479EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3479EFE#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 LT3479EFE#PBF part is unused and in its original packaging.
Return procedure for LT3479EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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