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Analog Devices Inc. LT3479EFE#TRPBF
- Part No.:
- LT3479EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3479EFE#TRPBF.pdf
- Description:
- IC REG BOOST ADJ 3A 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,768
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Product details
Overview
LT3479EFE#TRPBF 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 external RT resistor, and enables both positive and negative output configurations. It is used in high-power LED drivers and DSL modems requiring robust inrush protection.
For engineers reviewing the LT3479EFE#TRPBF datasheet, LT3479EFE#TRPBF pinout, LT3479EFE#TRPBF application, or LT3479EFE#TRPBF equivalent, key selection criteria include its 3A internal switch rating, ±1.235V reference accuracy, soft-start programmability, inrush current protection threshold at 5A, and thermal performance in the 16-lead TSSOP package with exposed PGND pad.
Technical Context
The LT3479EFE#TRPBF employs fixed-frequency current-mode control with slope compensation, using an internal 8.5mΩ sense resistor for inductor current monitoring. Its dual feedback amplifier inputs (FBP/FBN) allow flexible configuration for positive or negative outputs, while VC pin enables type-II compensation.
It integrates inrush current protection that triggers a soft-start cycle upon detecting >5A inductor current, independent of PWM comparator action. The 1.235V bandgap reference (±1.5% over temperature) feeds both error amplifier inputs and supports external resistor-divider programming for precise output regulation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 24V - supports wide-range industrial and battery-powered inputs including Li-ion (2.8V–4.2V) and 5V/12V rails. |
| Switch Rating | 3A, 42V NPN - handles peak inductor currents up to 6.5A (guaranteed limit), enabling high-output-power boost designs. |
| Reference Voltage | 1.235V ±1.5% (–40°C to 85°C) - sets output accuracy for both positive and negative configurations via FBP/FBN divider networks. |
| Switching Frequency | 200kHz to 3.5MHz (RT-programmable) - allows trade-off between EMI, component size, and efficiency (e.g., 1MHz typical for 5V→12V). |
| Soft-Start Control | 10μA constant-current source into SS pin - enables controlled ramp of VC voltage to limit startup inductor current and prevent overshoot. |
| Inrush Protection Threshold | 5A inductor current detection - initiates automatic soft-start recovery during shorts or hot-plug transients, protecting bond wires and external components. |
| Quiescent Current | 1μA shutdown current, 5mA operating IQ - ensures low standby power in always-on systems like DSL line cards. |
Pinout & Package
The LT3479EFE#TRPBF is housed in a 16-lead plastic TSSOP (FE package) with thermally enhanced exposed pad (Pin 17 = PGND), measuring 4.4mm × 5.0mm × 1.1mm and rated for θJA = 38°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pins 1, 2) | Switch Collector | Connects to inductor and Schottky diode anode; high dv/dt node requiring minimal trace area and ground-plane shielding. |
| L (Pin 3) | Inductor Connection | Low-impedance path to inductor; ties to internal 8.5mΩ current-sense resistor for inrush protection. |
| VS (Pin 4) | Inductor Supply Rail | Provides power to switch driver; must be locally bypassed; can be tied to VIN if single supply is used. |
| VIN (Pin 5) | Control Circuit Supply | Powers internal bias, oscillator, and logic; requires local 2.2μF ceramic bypass capacitor. |
| RT (Pin 6) | Frequency Set Resistor | Connects to external resistor (e.g., 17.8kΩ for 1MHz); open-circuit disables operation. |
| SHDN (Pin 7) | Enable/Shutdown Input | Active-high logic: ≥1.5V enables, ≤0.3V disables; draws <1μA in shutdown. |
| VREF (Pin 9) | Bandgap Reference Output | 1.235V source (100μA max sink/source); connects to FBP for positive outputs or external divider for negative outputs. |
| FBP (Pin 10) | Error Amp Non-Inverting Input | Used for negative-output feedback; connects to top of resistor divider referenced to –VOUT. |
| FBN (Pin 11) | Error Amp Inverting Input | Used for positive-output feedback; connects to divider tap between R1/R2 on VOUT rail. |
| VC (Pin 12) | Compensation Node | Output of error amplifier; connects to RC network (e.g., 10kΩ + 2.2nF) to GND for loop stability. |
| SS (Pin 13) | Soft-Start Capacitor | 10μA current charges external capacitor (e.g., 10nF = 1.65ms ramp); floating disables soft-start. |
| GND (Pins 8, 14, 15, 16) | Analog/Digital Ground | Must tie directly to low-impedance PCB ground plane; separate from power ground except at PGND pad. |
| Exposed Pad (Pin 17) | Power Ground (PGND) | Mandatory solder connection to PCB ground plane for thermal dissipation and low-noise return path. |
Key Features
| Feature | Design Value |
|---|---|
| Programmable Switching Frequency | 200kHz–3.5MHz via single RT resistor - enables optimization of inductor size, EMI filtering, and efficiency without changing IC. |
| Dual Feedback Inputs (FBP/FBN) | Supports both positive and negative output topologies from same IC - eliminates need for separate inverting regulators in multi-rail supplies. |
| Inrush Current Protection | Automatic soft-start re-initiation at >5A inductor current - prevents damage during output shorts or hot-plug events without external circuitry. |
| Low VCE(SAT) | 200mV at 1A (typical) - reduces conduction loss and improves efficiency in high-current boost stages. |
| Thermally Enhanced TSSOP | θJA = 38°C/W with exposed PGND pad - sustains full 3A load in industrial ambient without forced air or heatsink. |
Applications
| High-Power LED Driver | DSL Modem Power Supply |
|---|---|
|
Use Scenario: Driving 12 white LEDs (3.3V each) from 3.3V–4.2V Li-ion battery in photo-flash or backlight applications. IC Role / Device Role / Timing Role: Step-up regulator with adjustable current limit and torch/flash mode sequencing via ON pin control. Use Value: Delivers stable 500mA LED current at >85% efficiency; soft-start prevents flash capacitor inrush; inrush protection avoids fault lockup during rapid mode transitions. |
Use Scenario: Generating +12V and –12V rails from 5V input in ADSL line interface cards with strict EMI and thermal constraints. IC Role / Device Role / Timing Role: Dual-output DC/DC controller supporting positive and negative outputs with shared switching frequency and synchronized soft-start. Use Value: Eliminates need for two discrete regulators; 1.235V reference accuracy ensures tight output regulation across temperature; exposed PGND pad maintains junction temp <105°C at full load. |
| Distributed Power System | TFT-LCD Triple-Output Supply |
|
Use Scenario: Local 5V-to-12V boost conversion at point-of-load in industrial PLC backplanes with 24V nominal input. IC Role / Device Role / Timing Role: High-efficiency, wide-input DC/DC converter with programmable frequency to avoid noise coupling into analog sensor circuits. Use Value: 89% peak efficiency reduces heat generation in confined enclosures; 200kHz–3.5MHz range allows EMI tuning to avoid critical bands (e.g., 2.4GHz ISM). |
Use Scenario: Generating +8V, +16V, and –8V rails for TFT-LCD panel bias from single 2.8V–4.2V battery source in portable displays. IC Role / Device Role / Timing Role: Triple-output inverting/boost regulator with shared oscillator and coordinated soft-start for rail sequencing. Use Value: Single-chip solution replaces three discrete converters; FBP/FBN flexibility enables all three outputs; RT pin allows unified frequency setting for coherent ripple cancellation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3436EFE#TRPBF | 3A, 34V synchronous boost; higher integration (integrated MOSFETs), lower IQ (0.9mA), no inrush protection circuitry. | Requires external Schottky diode replacement; lacks dedicated inductor current sensing for fault recovery. | Choose LTC3436EFE#TRPBF when higher efficiency at light loads and synchronous rectification are prioritized over fault resilience. |
| LT3466EUD#TRPBF | Dual-channel, 2MHz, 40V boost with integrated Schottky diodes; 2A per channel; no negative-output capability. | Fixed dual-output architecture; optimized for white LED strings rather than general-purpose rails. | Choose LT3466EUD#TRPBF only for dual-LED-driver applications where channel independence and integrated diodes justify reduced flexibility. |
Compared with LT3479EFE#TRPBF, LTC3436EFE#TRPBF offers better light-load efficiency but forfeits inrush protection and negative-output support, while LT3466EUD#TRPBF provides dual-channel LED drive with integrated diodes but lacks programmable frequency and rail-flexible feedback architecture.
Availability
LT3479EFE#TRPBF is available at Aetrix Electronics and suitable for high-power LED drivers, DSL modem power supplies, and distributed industrial power systems requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant packaging.
Supply support for LT3479EFE#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 with rigorous qualification and long-term product support.
The LT3479EFE#TRPBF belongs to Linear's high-voltage, high-current boost converter family designed for demanding applications including telecom power, LED lighting, and multi-rail embedded systems where reliability under transient stress is critical.
FAQ
What is the maximum output voltage achievable with the LT3479EFE#TRPBF?
The LT3479EFE#TRPBF supports output voltages up to 40V in practical designs, constrained by the 42V absolute maximum switch voltage rating and external component selection (e.g., diode reverse voltage, capacitor voltage rating). Typical applications target 12V or –12V outputs, but configurations up to ±36V are feasible with appropriate layout and component derating. The LT3479EFE#TRPBF does not impose internal output voltage limits beyond its switch rating.
Can the LT3479EFE#TRPBF generate negative output voltages, and how is feedback configured?
Yes, the LT3479EFE#TRPBF supports negative outputs using its dual feedback inputs: FBP serves as the non-inverting input, connected to the top of a resistor divider referenced to –VOUT, while FBN remains grounded. The VREF pin (1.235V) connects to the divider midpoint. This configuration enables stable regulation of inverted rails such as –5V or –12V without external op-amps. The LT3479EFE#TRPBF datasheet Figure 3 details the exact resistor calculation.
How does the inrush current protection function in the LT3479EFE#TRPBF?
The LT3479EFE#TRPBF monitors inductor current via an internal 8.5mΩ series resistor. When sensed current exceeds 5A, it forces a new soft-start cycle-regardless of normal PWM operation-by resetting the soft-start capacitor voltage. This recovers gracefully after fault clearance, preventing latch-up or switch overstress. Unlike simple current limiting, this feature actively manages startup behavior during shorts. The LT3479EFE#TRPBF implements this entirely internally with no external components required.
What is the recommended minimum output capacitance for stable operation of the LT3479EFE#TRPBF?
The LT3479EFE#TRPBF requires a minimum 4.7μF low-ESR ceramic output capacitor (X5R or X7R dielectric) for most high-current applications (≥500mA). For lower output currents (<100mA), 1μF–2.2μF may suffice. Ceramic capacitors are mandatory to maintain loop stability and minimize ripple; tantalum or electrolytic types are not recommended due to ESR and aging effects. The LT3479EFE#TRPBF evaluation board uses 10μF as standard for 12V/800mA operation.
Is the LT3479EFE#TRPBF pin-compatible with other packages in the LT3479 family?
No, the LT3479EFE#TRPBF (16-pin TSSOP) is not pin-compatible with the LT3479EDE#TRPBF (14-pin DFN). Pin counts, layouts, and terminal assignments differ significantly-e.g., GND is on Pins 8/14/15/16 in the TSSOP versus Pins 13/14 in the DFN, and the exposed pad is Pin 17 (TSSOP) versus Pin 15 (DFN). Board redesign is required when substituting between packages. The LT3479EFE#TRPBF shares functional equivalence but not mechanical compatibility with other LT3479 variants.
LT3479EFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LT3479EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3479EFE#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 LT3479EFE#TRPBF reliable?
The price and inventory of LT3479EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3479EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3479EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3479EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3479EFE#TRPBF?
LT3479EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3479EFE#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 LT3479EFE#TRPBF?
For technical support, including LT3479EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3479EFE#TRPBF requirements.
6.How does Aetrix verify that LT3479EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3479EFE#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 LT3479EFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3479EFE#TRPBF?
All LT3479EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3479EFE#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 LT3479EFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3479EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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