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Analog Devices Inc. LT3579EUFD#PBF
- Part No.:
- LT3579EUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LT3579EUFD#PBF.pdf
- Description:
- IC REG BST CHARGE PUMP ADJ 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,276
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Product details
Overview
LT3579EUFD#PBF from Analog Devices is a 6A, 42V dual-switch PWM DC/DC converter IC configured as a boost/inverting regulator with integrated fault protection. It features master/slave NPN switches (3.4A/2.6A), 200kHz–2.5MHz programmable switching frequency, and operates from 2.5V to 16V input to generate ±12V outputs. It is used in TFT-LCD bias supplies requiring short-circuit and overvoltage protection.
For engineers reviewing the LT3579EUFD#PBF datasheet, LT3579EUFD#PBF pinout, LT3579EUFD#PBF application, or LT3579EUFD#PBF equivalent, key selection criteria include combined 6A current limit, 42V switch rating, QFN-20 (4mm × 5mm) package thermal performance, and fault-handling behavior during output shorts or overtemperature events.
Technical Context
The LT3579EUFD#PBF implements constant-frequency current-mode control with internal 1.215V positive and 9mV negative feedback references for boost and inverting configurations. Its dual-switch architecture supports tied-collector operation for 6A total current limit and independent SW1/SW2 current sharing (0.78A/A ratio).
It integrates frequency foldback (1/6× nominal fOSC), soft-start with 250kΩ internal ramp, and bidirectional FAULT pin logic that disables switching, pulls CLKOUT low, and initiates SS-based timeout sequencing upon overcurrent (≥3.4A SW1 or ≥6A combined), VIN >16.2V, SW >42V, or TJ >165°C detection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 16V operating; withstands 40V transients - enables direct connection to automotive 12V rails with transient immunity. |
| Switch Rating | 42V collector voltage, 3.4A SW1 / 2.6A SW2 (min); 6A combined when tied - supports high-voltage boost and inverting topologies up to ~40V output. |
| Switch VCE(SAT) | 250mV at 5.5A (typical) - reduces conduction loss and thermal stress in high-current power stages. |
| Switching Frequency | 200kHz to 2.5MHz, adjustable via RT resistor or external SYNC clock - allows EMI optimization and compact magnetics selection. |
| Fault Protection | Detects output short, VIN overvoltage (>16.2V), SW overvoltage (>42V), and overtemperature (>165°C) - triggers automatic shutdown and SS-based recovery timeout. |
| Package Thermal Resistance | θJA = 34°C/W, θJC = 2.7°C/W (UFD QFN) - enables high-power operation with minimal PCB copper area vs. TSSOP. |
| Operating Temperature | –40°C to +125°C junction - qualified for under-hood automotive and industrial embedded power applications. |
Pinout & Package
LT3579EUFD#PBF is housed in a 20-lead, 4mm × 5mm plastic QFN package with exposed thermal pad (Pin 21 = GND). The package provides low thermal resistance (θJA = 34°C/W) and requires soldering of the exposed pad to the PCB ground plane for optimal thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (Pin 1) | Positive/Negative Feedback Input | Accepts 1.215V reference for boost/SEPIC or 9mV for inverting regulation; bias current 83.3µA enables single-resistor VOUT setting. |
| VC (Pin 2) | Error Amplifier Output | Drives external compensation network (RC/CC) to stabilize loop response across load and line variations. |
| GATE (Pin 3) | PMOS Gate Drive Output | Sinks up to 933µA (linear with SS voltage) to control external PMOS for output disconnect during fault conditions. |
| FAULT (Pin 4) | Bidirectional Fault Indicator | Active-low open-drain output; pulled low internally on fault or externally to force shutdown - enables system-level fault coordination. |
| VIN (Pin 5) | Main Input Supply | Accepts 2.5V–16V input; includes internal UVLO (2.3V turn-on) and overvoltage lockout (16.2V threshold). |
| SW1 (Pins 6–10) | Master Switch Collector | Internal 3.4A NPN collector; tied to SW2 for 6A combined current path - requires minimized trace area for EMI control. |
| GND (Pins 8,9,21) | Power and Signal Ground | Multiple ground connections including exposed pad (Pin 21) - mandatory soldering ensures thermal dissipation and noise immunity. |
| SW2 (Pins 11–15) | Slave Switch Collector | Internal 2.6A NPN collector; shares current with SW1 at 0.78A/A ratio when tied - enables scalable high-power designs. |
| CLKOUT (Pin 16) | Buffered Clock Output | Drives compatible regulators at same frequency; duty cycle varies linearly with junction temperature - usable as on-die thermal monitor. |
| SHDN (Pin 17) | Shutdown Control Input | High-impedance input with 1.33V turn-on threshold and 30mV hysteresis - supports configurable UVLO using resistor divider from VIN. |
| RT (Pin 18) | Frequency Setting Input | Connects to ground via resistor to set free-running fOSC (200kHz–2.5MHz); no pull-up/pull-down required. |
| SYNC (Pin 20) | External Clock Input | Accepts 0.4V–1.3V logic levels to synchronize switching; reverts to internal oscillator when driven <0.4V. |
| SS (Pin 19) | Soft-Start Control | Charged by internal 250kΩ resistor to 2.1V; controls GATE current ramp and fault timeout timing - prevents inrush and enables hot-swap capability. |
Key Features
| Feature | Design Value |
|---|---|
| 6A Combined Switch Current Limit | Guaranteed minimum 6A peak current with SW1+SW2 tied - eliminates need for external current-sense resistors in high-power boost/inverting supplies. |
| Output Short-Circuit Protection | Sample-mode overcurrent detection triggers automatic shutdown and SS-based timeout - protects downstream circuitry without external sensing. |
| Configurable Undervoltage Lockout | SHDN pin accepts resistor divider from VIN to set custom turn-on threshold - enables precise brown-in/brown-out control for system sequencing. |
| CLKOUT Synchronization & Temp Monitoring | CLKOUT pin drives other regulators at identical frequency while providing linear duty-cycle vs. TJ - replaces discrete thermal sensor in space-constrained designs. |
| Low VCE(SAT) Switches | 250mV typical saturation voltage at 5.5A - reduces conduction losses by >30% vs. comparable 400mV devices, improving efficiency at full load. |
Applications
| TFT-LCD Bias Supply | Vacuum Fluorescent Display (VFD) Bias |
|---|---|
|
Use Scenario: Generating stable ±15V rails from 5V or 12V input for LCD panel gate/source drivers under variable load and temperature. IC Role / Device Role / Timing Role: Dual-switch DC/DC controller implementing inverting and boost topologies with integrated fault handling. Use Value: Eliminates discrete protection circuitry; 6A current headroom accommodates backlight dimming transients without dropout. |
Use Scenario: Providing isolated high-voltage bias (e.g., +30V, –30V) for VFD anode/grid drive in automotive instrument clusters. IC Role / Device Role / Timing Role: High-voltage inverting converter with 42V switch rating and overvoltage lockout. Use Value: Withstands 40V input transients common in vehicle battery systems; fault protection prevents display latch-up during ESD events. |
| Automotive Engine Control Unit (ECU) Power | Industrial Local Power Supply |
|
Use Scenario: Local 12V-to-±12V conversion for sensor signal conditioning and CAN transceiver bias in under-hood ECUs. IC Role / Device Role / Timing Role: Fault-tolerant dual-output regulator operating across –40°C to +125°C junction range. Use Value: Overtemperature shutdown at 165°C prevents thermal runaway; QFN package meets automotive vibration and thermal cycling requirements. |
Use Scenario: Compact, high-efficiency local supply for FPGA I/O banks or analog front-ends requiring regulated ±12V from 5V/12V bus. IC Role / Device Role / Timing Role: Programmable-frequency boost/inverting controller supporting SEPIC and flyback variants. Use Value: 200kHz–2.5MHz frequency range enables optimization for size (high-f) or efficiency (low-f); RT/SYNC flexibility simplifies multi-rail synchronization. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-switch DC/DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3780EFE#PBF | Single-switch synchronous buck-boost controller; no integrated switches; requires external MOSFETs. | Supports wider VIN range (4V–36V) but lacks built-in fault protection and dual-switch current sharing. | Select when higher efficiency at >3A loads is critical and board space permits external FETs and sense resistors. |
| LT8330EFE#PBF | Single-switch 6A boost controller with integrated 60V switch; no slave switch or inverting capability. | Offers higher 60V switch rating and lower quiescent current (2.8µA), but cannot implement inverting or SEPIC topologies. | Select for pure high-voltage boost applications where inverting output is unnecessary and 42V switch rating is sufficient. |
Compared with LTC3780EFE#PBF and LT8330EFE#PBF, the LT3579EUFD#PBF uniquely combines integrated dual NPN switches, inverting/boost/SEPIC/flyback configurability, and comprehensive fault protection - making it optimal for space-constrained, safety-critical bias supplies where component count and reliability are prioritized over maximum efficiency.
Availability
LT3579EUFD#PBF is available at Aetrix Electronics and suitable for TFT-LCD bias supplies, automotive ECU power, and industrial local power supply designs requiring stable component supply, extended temperature operation, and integrated fault protection.
Supply support for LT3579EUFD#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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3579EUFD#PBF belongs to Analog Devices' Power by Linear™ family of robust, fault-tolerant DC/DC controllers designed specifically for high-reliability local power generation in harsh environments.
FAQ
What is the maximum output voltage achievable with the LT3579EUFD#PBF in boost configuration?
The LT3579EUFD#PBF supports boost output voltages up to approximately 40V, constrained by its 42V switch rating and internal overvoltage protection thresholds. When configured with external components such as charge-pump aiding networks, higher voltages may be achieved, but standard boost operation remains limited to ≤40V to ensure reliable SW1/SW2 voltage margin and avoid triggering overvoltage faults.
Does the LT3579EUFD#PBF support synchronization with external clock sources?
Yes, the LT3579EUFD#PBF supports external synchronization via its SYNC pin (Pin 20), which accepts logic-level clocks between 200kHz and 2.5MHz. The high-level threshold is 1.3V and low-level threshold is 0.4V; driving SYNC below 0.4V reverts the device to its internal RT-set oscillator frequency.
How does the FAULT pin function during an overtemperature event on the LT3579EUFD#PBF?
During overtemperature (TJ >165°C), the LT3579EUFD#PBF pulls the FAULT pin low internally, disabling all switching activity, turning off the GATE driver, and halting CLKOUT. The SS pin then enters a timeout sequence-charging to 1.8V and discharging to 50mV-to enforce thermal recovery before automatic restart, preventing thermal runaway.
Can the LT3579EUFD#PBF be used in inverting converter topology?
Yes, the LT3579EUFD#PBF is explicitly designed for inverting operation using its negative feedback reference (9mV) at the FB pin. It generates regulated negative outputs such as –12V at 1.2A from a 5V input, with built-in short-circuit and overvoltage protection active in this configuration.
What is the purpose of the GATE pin on the LT3579EUFD#PBF?
The GATE pin (Pin 3) on the LT3579EUFD#PBF sinks up to 933µA to drive the gate of an external PMOS transistor. This enables output disconnect during fault conditions, limiting inrush current at startup and protecting downstream loads - functionality critical in hot-swap and safety-isolated applications.
LT3579EUFD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Boost, Charge Pump, Cuk, Flyback, SEPIC
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.5V
- Voltage - Input (Max):
- 16V
- Voltage - Output (Min/Fixed):
- 1.215V
- Voltage - Output (Max):
- 42V (Switch)
- Current - Output:
- 6A (Switch)
- Frequency - Switching:
- 200kHz ~ 2.5MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (4x5)
LT3579EUFD#PBF FAQ
1.How can I place an order for LT3579EUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3579EUFD#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 LT3579EUFD#PBF reliable?
The price and inventory of LT3579EUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3579EUFD#PBF is usually 5 days.
3.What payment methods are accepted for LT3579EUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3579EUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3579EUFD#PBF?
LT3579EUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3579EUFD#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 LT3579EUFD#PBF?
For technical support, including LT3579EUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3579EUFD#PBF requirements.
6.How does Aetrix verify that LT3579EUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3579EUFD#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 LT3579EUFD#PBF meets industry standards.
7.What is the process for return or replacement of LT3579EUFD#PBF?
All LT3579EUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3579EUFD#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 LT3579EUFD#PBF part is unused and in its original packaging.
Return procedure for LT3579EUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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