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Analog Devices Inc. LT3579EUFD-1#PBF
- Part No.:
- LT3579EUFD-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LT3579EUFD-1#PBF.pdf
- Description:
- IC REG BST CHARGE PUMP ADJ 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:146
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Product details
Overview
LT3579EUFD-1#PBF from Analog Devices is a dual-phase capable 6A, 42V PWM DC/DC converter with integrated master/slave NPN switches (3.4A/2.6A), fault protection (output short, input overvoltage, overtemperature), and configurable undervoltage lockout. It supports Boost, SEPIC, Inverting, and Flyback topologies - delivering 12V at 1.7A or –12V at 1.2A from 5V input - and is used in automotive ECU power supplies requiring robust transient handling and thermal resilience.
For engineers reviewing the LT3579EUFD-1#PBF datasheet, LT3579EUFD-1#PBF pinout, LT3579EUFD-1#PBF application, or LT3579EUFD-1#PBF equivalent, key selection considerations include its 20-pin 4mm × 5mm QFN package, 200kHz–2.5MHz programmable switching frequency, dual-phase synchronization capability via CLKOUT/SYNC, and integrated fault detection with automatic timeout recovery.
Technical Context
The LT3579EUFD-1#PBF implements constant-frequency current-mode control with dual NPN power switches: SW1 rated for ≥3.4A peak collector current and SW2 for ≥2.6A, sharing current at 0.78A/A ratio when tied. Its internal oscillator supports free-running (RT-set) or external synchronization (SYNC pin), with CLKOUT providing a buffered, phase-inverted (180°) clock output at ~50% duty cycle - essential for interleaved multiphase operation.
Fault management includes five independent FAULT1 triggers (SW overcurrent, VIN >16.2V, SW voltage >42V, die temperature >165°C) and FAULT2 (external pull-down), initiating state-machine-driven shutdown, GATE high-impedance transition, CLKOUT disable, and SS pin–based timeout sequencing. Soft-start ramps switch current linearly with SS voltage and enables controlled PMOS gate turn-on via GATE pin current (0–933µA).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Configuration | Dual-phase capable master/slave NPN switches (SW1: ≥3.4A, SW2: ≥2.6A); combined current limit ≥6A for high-power boost/inverting designs. |
| Input Voltage Range | 2.5V to 16V operating range; 40V absolute max transient rating - supports automotive cold-crank and industrial 12V/24V rails. |
| Switching Frequency | 200kHz to 2.5MHz programmable via RT resistor or external SYNC signal - enables EMI optimization and compact magnetics. |
| Feedback Reference | 1.215V positive FB reference (Boost/SEPIC) or 9mV negative FB reference (Inverting) - ensures precise output regulation across topologies. |
| Fault Protection | Integrated detection of output short circuit, VIN overvoltage (>16.2V), SW overvoltage (>42V), overtemperature (>165°C), and external FAULT assertion - triggers automatic shutdown and timeout recovery. |
| Package & Thermal | 20-pin 4mm × 5mm QFN with exposed thermal pad (θJA = 34°C/W); rated for –40°C to +125°C junction temperature. |
Pinout & Package
LT3579EUFD-1#PBF is housed in a 20-lead (4mm × 5mm) plastic QFN package with exposed thermal pad (Pin 21) soldered to PCB ground for thermal management. The package supports high-current routing and low-inductance layout critical for switching regulator stability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (Pin 1) | Positive/Negative Feedback Input | Accepts regulated voltage feedback: 1.215V reference for Boost/SEPIC, 9mV for Inverting; bias current 83.3µA enables single-resistor output setting. |
| VC (Pin 2) | Error Amplifier Output | Drives external compensation network (capacitor/resistor) to stabilize loop response and prevent oscillation. |
| GATE (Pin 3) | PMOS Gate Drive Output | Sinks 0–933µA linearly with SS voltage; enables soft-started external PMOS for output disconnect during fault events. |
| FAULT (Pin 4) | Bidirectional Fault Indicator | Active-low open-collector output; pulled low internally on fault or externally asserted; requires external pull-up (e.g., 100kΩ) to clear fault state. |
| VIN (Pin 5) | Main Input Supply | 2.5V–16V input rail; must be locally bypassed with low-ESR capacitor to suppress switching noise and supply transients. |
| SW1 (Pins 6–10) | Master Switch Collector | Internal NPN collector node rated ≥3.4A peak; connects to inductor/diode in Boost or transformer primary in Flyback. |
| GND (Exposed Pad Pin 21) | Power Ground Reference | Thermal and electrical ground plane connection; mandatory soldering required for thermal dissipation and noise control. |
| SW2 (Pins 11–15) | Slave Switch Collector | Internal NPN collector node rated ≥2.6A peak; tied to SW1 for 6A combined current or used independently in dual-phase configurations. |
| CLKOUT (Pin 16) | Synchronized Clock Output | Buffered oscillator output at same frequency as internal clock or SYNC input; 180° out-of-phase and ~50% duty cycle for LT3579-1 variant - enables interleaved multiphase operation. |
| SHDN (Pin 17) | Shutdown Control Input | High-impedance enable pin with 1.33V typical turn-on threshold and 30mV hysteresis; supports user-configurable UVLO via resistor divider. |
| RT (Pin 18) | Frequency Timing Input | Resistor-to-ground sets free-running switching frequency (200kHz–2.5MHz); no floating allowed. |
| SYNC (Pin 20) | External Clock Input | Accepts 0.4V–1.3V logic-level clock; overrides RT setting to synchronize multiple regulators and reduce beat frequencies. |
| SS (Pin 19) | Soft-Start Control | Charged by internal 250kΩ resistor to 2.1V; controls ramp rate of switch current and GATE drive - prevents inrush and enables hot-swap capability. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-phase synchronization support | CLKOUT provides 180° phase-shifted, 50% duty-cycle clock enabling interleaved operation with matched LT3579-1 devices - reduces input/output ripple and EMI. |
| Integrated fault protection suite | Detects five distinct fault conditions (SW overcurrent, VIN OV, SW OV, overtemperature, external FAULT) and executes deterministic state-machine recovery - eliminates need for external monitoring ICs. |
| Configurable undervoltage lockout | SHDN pin accepts resistor divider from VIN to set custom turn-on threshold (e.g., 8V or 10V), complementing internal 2.3V UVLO - ensures stable startup under weak battery conditions. |
| Output short-circuit resilient topology | Sample Mode forces periodic switch conduction to detect inductor current exceeding 3.4A (SW1) or 6A (combined), triggering immediate shutdown before damage occurs. |
| Low VCE(SAT) power switches | 250mV typical saturation voltage at 5.5A combined current - minimizes conduction loss and improves efficiency in high-current boost/inverting applications. |
Applications
| Automotive Engine Control Unit (ECU) Power | Vacuum Fluorescent Display (VFD) Bias Supply |
|---|---|
Use Scenario: Provides isolated 12V/–12V rails from vehicle 12V battery to power microcontrollers, sensors, and actuators in engine bay environments with wide temperature swings and load dump transients. IC Role / Device Role / Timing Role: Primary DC/DC controller implementing Boost and Inverting topologies; manages fault recovery during cranking and alternator surge events. Use Value: 40V transient tolerance, –40°C to +125°C operation, and integrated overvoltage/overtemperature protection eliminate need for external TVS and thermal sensors. | Use Scenario: Generates high-voltage AC bias (±30V to ±100V) for vacuum fluorescent display anodes and grids using charge-pump–aided flyback configuration. IC Role / Device Role / Timing Role: Dual-switch controller enabling efficient high-voltage charge pump topologies with fewer external components than traditional discrete solutions. Use Value: Master/slave switch coordination and 42V switch rating allow direct generation of >40V outputs without cascaded stages - reducing BOM count and board area. |
| TFT-LCD Bias Supplies | Industrial Local Power Supply |
Use Scenario: Delivers regulated ±15V and +5V rails for TFT-LCD source/gate drivers and timing controllers in medical imaging and industrial HMI panels. IC Role / Device Role / Timing Role: Configured in SEPIC and Inverting modes to maintain regulation during input dips; uses frequency foldback for stable startup into large capacitive loads. Use Value: 200kHz–2.5MHz frequency range allows optimization for low-noise (low-f) or compact (high-f) designs; soft-start prevents inrush into large display capacitance. | Use Scenario: Powers FPGA I/O banks, ADC references, and isolated communication interfaces in programmable logic controllers and data acquisition systems. IC Role / Device Role / Timing Role: Local point-of-load regulator supporting multiple topologies; leverages GATE pin to drive external PMOS for hot-swap and reverse-polarity protection. Use Value: GATE pin's linear current ramp (0–933µA) enables controlled PMOS turn-on - limiting inrush current and enabling safe field-replacement without system shutdown. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3891EUF#PBF | Single-channel synchronous step-down controller; no integrated switches; supports up to 60V input; requires external MOSFETs. | Used where higher efficiency at >3A loads is needed and board space allows discrete FETs; lacks integrated fault protection and dual-phase sync. | Select LTC3891EUF#PBF when designing high-efficiency buck converters with external FETs and no requirement for integrated switches or fault recovery automation. |
| LT8330EFE#PBF | Single-switch 60V boost/SEPIC/inverting controller; integrated 4A switch; no slave switch or dual-phase capability; lower max current (4A vs 6A). | Suitable for cost-sensitive, lower-current applications (<4A) where dual-phase interleaving is unnecessary; lacks CLKOUT phase inversion for multiphase sync. | Select LT8330EFE#PBF for simpler, lower-cost boost/inverting supplies up to 4A where dual-phase operation and advanced fault sequencing are not required. |
Compared with LTC3891EUF#PBF and LT8330EFE#PBF, the LT3579EUFD-1#PBF uniquely integrates dual NPN switches with coordinated current sharing, built-in fault state machine recovery, and 180° phase-shifted CLKOUT - making it optimal for space-constrained, high-reliability multiphase boost/inverting supplies demanding autonomous fault handling.
Availability
LT3579EUFD-1#PBF is available at Aetrix Electronics and suitable for automotive ECU power, VFD bias supplies, TFT-LCD bias generation, and industrial local power supply designs requiring stable component supply, long-term lifecycle support, and guaranteed performance across –40°C to +125°C.
Supply support for LT3579EUFD-1#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 LT3579 product line delivers highly integrated PWM DC/DC controllers with fault protection and multi-topology flexibility - designed specifically for robust local power conversion in harsh environments where reliability, thermal resilience, and autonomous fault recovery are critical.
FAQ
What is the maximum combined switch current rating for LT3579EUFD-1#PBF?
The LT3579EUFD-1#PBF has a guaranteed minimum combined SW1 + SW2 current limit of 6A at all duty cycles, with typical performance reaching 7.5A and absolute maximum rating of 9.4A. This rating applies when both switches are tied together in parallel configurations for high-current Boost or Inverting topologies, and is validated across the full –40°C to +125°C operating junction temperature range.
How does the LT3579EUFD-1#PBF differ from the standard LT3579EUFD#PBF?
The LT3579EUFD-1#PBF includes dual-phase synchronization capability absent in the base LT3579EUFD#PBF: its CLKOUT pin delivers a fixed ~50% duty cycle and is 180° out of phase with the internal oscillator or SYNC input - enabling precise interleaving with other LT3579-1 devices. The standard version has variable CLKOUT duty cycle (~42%) and no guaranteed phase relationship, limiting multiphase use.
Can LT3579EUFD-1#PBF be used in an inverting configuration, and what feedback reference applies?
Yes, the LT3579EUFD-1#PBF supports Inverting configurations. In this mode, the FB pin uses a 9mV negative feedback reference voltage (not 1.215V), and the feedback resistor is calculated as RFB = (|VOUT| + 9mV) / 83.3µA. This low-reference architecture enables precise regulation of negative output voltages such as –12V or –15V from a 5V or 12V input.
What thermal performance can be expected from the LT3579EUFD-1#PBF in its QFN package?
The LT3579EUFD-1#PBF in the 20-pin 4mm × 5mm QFN package has a junction-to-ambient thermal resistance (θJA) of 34°C/W and junction-to-case (θJC) of 2.7°C/W when the exposed pad (Pin 21) is properly soldered to a PCB ground plane. This enables reliable operation at full 6A load up to +125°C ambient with appropriate copper area and airflow, and supports continuous operation within its –40°C to +125°C junction temperature specification.
Does LT3579EUFD-1#PBF require external components for fault recovery, or is it autonomous?
The LT3579EUFD-1#PBF implements fully autonomous fault recovery: upon FAULT detection (e.g., output short), it disables switches, pulls FAULT low, disables CLKOUT, and initiates an SS pin–based timeout sequence - charging SS to 1.8V then discharging to 50mV - before attempting restart. No external timer IC or microcontroller intervention is required; only a pull-up resistor on FAULT (e.g., 100kΩ) is needed to signal fault clearance.
LT3579EUFD-1#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-1#PBF FAQ
1.How can I place an order for LT3579EUFD-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3579EUFD-1#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-1#PBF reliable?
The price and inventory of LT3579EUFD-1#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-1#PBF is usually 5 days.
3.What payment methods are accepted for LT3579EUFD-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3579EUFD-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3579EUFD-1#PBF?
LT3579EUFD-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3579EUFD-1#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-1#PBF?
For technical support, including LT3579EUFD-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3579EUFD-1#PBF requirements.
6.How does Aetrix verify that LT3579EUFD-1#PBF is sourced from the original manufacturer or authorized distributors?
All LT3579EUFD-1#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-1#PBF meets industry standards.
7.What is the process for return or replacement of LT3579EUFD-1#PBF?
All LT3579EUFD-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3579EUFD-1#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-1#PBF part is unused and in its original packaging.
Return procedure for LT3579EUFD-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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