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Analog Devices Inc. LT3579IFE#PBF
- Part No.:
- LT3579IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3579IFE#PBF.pdf
- Description:
- IC REG BST CHRG PUMP ADJ 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,088
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Product details
Overview
LT3579IFE#PBF from Analog Devices is a 6A, 42V dual-switch PWM DC/DC converter supporting boost, inverting, SEPIC, and flyback topologies. It integrates master (3.4A) and slave (2.6A) NPN switches, output short-circuit protection, input overvoltage lockout (16.2V min), and temperature monitoring via CLKOUT duty cycle. It delivers 12V at 1.7A from 5V input in boost mode for local power supply applications.
For engineers reviewing the LT3579IFE#PBF datasheet, LT3579IFE#PBF pinout, LT3579IFE#PBF application, or LT3579IFE#PBF equivalent, this page provides verified functional identity, validated TSSOP-20 package mapping, confirmed 6A combined current limit, real-world fault response behavior, and two rigorously cross-checked alternative parts with documented technical and application differences.
Technical Context
The LT3579IFE#PBF implements constant-frequency current-mode control with integrated 42V/3.4A master and 42V/2.6A slave NPN switches-tied together for 6A total current limit. Its switching frequency is programmable from 200kHz to 2.5MHz via RT resistor or external SYNC signal, and it drives CLKOUT with temperature-proportional duty cycle (LT3579 variant) or fixed 50% duty cycle (LT3579-1).
Fault protection includes internal detection of SW overcurrent (>3.4A SW1 or >6A combined), VIN overvoltage (>16.2V), SW overvoltage (>42V), and die temperature (>165°C), triggering FAULT pin assertion, switch disable, GATE high-impedance state, and SS-based timeout sequence. The SHDN pin supports configurable UVLO and accepts slowly ramping enable signals with 30mV hysteresis.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Configuration | Dual NPN: 3.4A master + 2.6A slave, tied for 6A peak current capability in boost/inverting/SEPIC/flyback |
| Input Voltage Range | 2.5V to 16V operating; 40V transient rating - supports wide-input industrial and automotive rails |
| Switch Voltage Rating | 42V collector-emitter max per switch - enables 36V-output boost or ±15V inverting supplies |
| Feedback Reference | 1.215V positive FB threshold (boost/SEPIC); 9mV negative FB threshold (inverting) - sets precise output regulation points |
| Switch VCE(SAT) | 250mV typical at 5.5A combined current - minimizes conduction loss and thermal rise in high-current paths |
| Operating Temperature | –40°C to +125°C junction - qualified for under-hood automotive and industrial environments |
| Package | 20-lead TSSOP with exposed pad (Pin 21 = GND) - provides low θJA = 38°C/W for thermal management |
Pinout & Package
LT3579IFE#PBF is housed in a 20-lead plastic TSSOP package with exposed thermal pad (Pin 21 = GND), requiring soldering to PCB ground plane for thermal and electrical integrity. θJA = 38°C/W, θJC = 10°C/W.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| FB (Pin 20) | Positive/Negative Feedback Input | Accepts 1.215V reference for boost/SEPIC or 9mV for inverting configuration; bias current ~83.3µA determines RFB value |
| VC (Pin 19) | Error Amplifier Output | Drives external compensation network (RC/CC) to stabilize loop response and prevent oscillation |
| GATE (Pin 1) | PMOS Gate Drive Output | Pull-down current source (up to 933µA) for external PMOS disconnect switch; ramps with SS voltage for soft-started turn-on |
| FAULT (Pin 2) | Bidirectional Fault Indicator | Active-low open-collector output; pulled low internally on overcurrent/overvoltage/overtemperature or externally to force shutdown |
| VIN (Pin 3) | Main Input Supply | 2.5V–16V operating range; internal UVLO disables chip below 2.3V; 40V absolute max withstand |
| SW1 (Pins 4–7) | Master Switch Collector | 3.4A minimum peak current handling; connects to inductor/diode node in boost or transformer primary in flyback |
| GND (Pins 8,9,21) | Power & Signal Ground | Multiple low-inductance ground connections including exposed pad; mandatory for EMI control and thermal dissipation |
| SW2 (Pins 10–13) | Slave Switch Collector | 2.6A minimum peak current; tied to SW1 for 6A operation or used independently in multiphase or charge-pump topologies |
| CLKOUT (Pin 14) | Temperature-Compensated Clock Output | Oscillates at fSW; duty cycle varies linearly with junction temperature - usable as analog thermal monitor |
| SHDN (Pin 15) | Shutdown/UVLO Control | Enables chip above 1.33V (typ); shuts down below 0.3V; supports resistor-divider UVLO configuration with 30mV hysteresis |
| RT (Pin 16) | Frequency Programming | Resistor-to-ground sets free-running fSW from 200kHz to 2.5MHz; tolerance affects accuracy of timing |
| SYNC (Pin 17) | External Clock Input | Accepts 0.4V–1.3V logic levels; synchronizes LT3579IFE#PBF to external clock or reverts to RT-set frequency when <0.4V |
| SS (Pin 18) | Soft-Start Timing | Charged by internal 250kΩ resistor; controls ramp rate of switch current and GATE pull-down current to limit inrush |
Key Features
| Feature | Design Value |
|---|---|
| 6A Combined Switch Current Limit | Guaranteed 6A minimum peak current with SW1+SW2 tied - enables high-power local supplies without external MOSFETs |
| Output Short-Circuit Protection | Sample-mode overcurrent detection triggers FAULT within microseconds and initiates SS-based timeout - prevents latch-up during sustained shorts |
| Configurable Undervoltage Lockout | SHDN pin accepts resistor divider from VIN to set custom turn-on threshold (e.g., 9V system start-up) with built-in hysteresis |
| CLKOUT Temperature Monitoring | CLKOUT duty cycle changes linearly with junction temperature - eliminates need for external thermal sensor in space-constrained designs |
| Frequency Foldback During Startup | Reduces fSW to 1/6 nominal when FB is between 350mV–900mV - improves control of inductor current during soft-start |
Applications
| Automotive Engine Control Unit (ECU) Power | Vacuum Fluorescent Display (VFD) Bias Supply |
|---|---|
|
Use Scenario: Generating isolated ±24V rails from 12V battery for ECU microcontroller, CAN transceiver, and sensor interfaces under cold-crank (6V) and load-dump (40V) conditions. IC Role / Device Role / Timing Role: Primary DC/DC controller implementing boost + inverting topology with fault-protected output disconnect via GATE-driven PMOS. Use Value: 40V transient rating and –40°C to +125°C operation ensure reliability across automotive temperature and voltage extremes; FAULT pin enables system-level fault logging. |
Use Scenario: Providing regulated +30V and –30V bias for vacuum fluorescent display anode and cathode drivers in industrial HMI panels. IC Role / Device Role / Timing Role: Inverting converter generating negative rail; dual-switch architecture allows efficient high-voltage generation without transformer. Use Value: 42V switch rating and 6A current capacity support fast VFD segment charging; soft-start prevents display flash during power-up. |
| TFT-LCD Bias Supplies | Industrial Local Power Supply |
|
Use Scenario: Generating AVDD (+15V), VGH (+25V), and VGL (–10V) for TFT-LCD column/row drivers in medical imaging displays. IC Role / Device Role / Timing Role: Configured as boost for AVDD/VGH and inverting for VGL; CLKOUT used for thermal monitoring near display driver ICs. Use Value: Single-chip solution reduces BOM count vs. discrete boost + inverter; 2.5MHz max switching enables compact magnetics. |
Use Scenario: Point-of-load conversion from 5V or 12V backplane to 3.3V/5V/12V rails for FPGA I/O banks, ADC references, and interface logic in programmable logic controllers. IC Role / Device Role / Timing Role: Flexible topology support allows reuse across multiple rail requirements; RT/SYNC pins enable synchronized multi-rail designs. Use Value: Pin-compatible upgrade path from LT3579EFE#PBF; guaranteed 6A current and fault protection simplify safety-critical design validation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3891EMSE#PBF | Single 60V N-channel MOSFET controller (no integrated switches); requires external FETs; supports 4-phase interleaving | Higher efficiency at >3A loads due to low-RDS(on) FETs; no integrated fault protection - needs external circuitry for short-circuit response | Select when efficiency >92% and layout flexibility outweigh integrated protection needs; not drop-in for LT3579IFE#PBF |
| LT8330EDD#PBF | Single 60V, 1.5A monolithic boost converter; no slave switch; no fault pin or GATE drive; 2MHz max fSW | Simpler design for ≤1.5A outputs; lacks output disconnect, thermal monitoring, and multiphase capability | Choose for cost-sensitive, lower-current applications where fault robustness and high-current capability are not required |
Compared with LTC3891EMSE#PBF and LT8330EDD#PBF, the LT3579IFE#PBF uniquely combines integrated 6A dual-NPN switches, bidirectional FAULT signaling, GATE-driven PMOS disconnect, and junction-temperature-sensing CLKOUT - making it optimal for space-constrained, fault-critical local power designs where external component count must be minimized.
Availability
LT3579IFE#PBF is available at Aetrix Electronics and suitable for automotive engine control unit (ECU) power, vacuum fluorescent display (VFD) bias supplies, and industrial local power supply applications requiring stable component supply, extended temperature qualification, and long-term lifecycle continuity.
Supply support for LT3579IFE#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3579IFE#PBF belongs to Analog Devices' Power by Linear™ family of monolithic DC/DC converters, designed specifically for robust, high-current local power generation in harsh environments with integrated fault protection and thermal monitoring.
FAQ
What is the maximum switching frequency supported by the LT3579IFE#PBF?
The LT3579IFE#PBF supports a maximum switching frequency of 2.5MHz when configured with RT = 34kΩ to ground. This high-frequency capability allows use of smaller inductors and capacitors in space-constrained applications such as portable medical devices and compact industrial controllers. Frequency remains stable across temperature and load when synchronized to an external clock via the SYNC pin.
How does the LT3579IFE#PBF implement output short-circuit protection?
The LT3579IFE#PBF uses Sample Mode - forcing both SW1 and SW2 to turn on briefly every switching cycle when FB is out of regulation - to detect overcurrent. If sampled current exceeds 3.4A (SW1) or 6A (combined), the FAULT pin pulls low, switches disable, GATE goes high-impedance, and SS initiates a timeout sequence. This protects downstream components without requiring external current-sense resistors or comparators.
Can the LT3579IFE#PBF be used in a dual-phase configuration?
The standard LT3579IFE#PBF is not dual-phase capable; only the LT3579-1 variant (e.g., LT3579IFE-1#PBF) features 180° out-of-phase CLKOUT and fixed 50% duty cycle for multiphase synchronization. Using the base LT3579IFE#PBF in parallel requires external phase-shifting circuitry and does not guarantee current sharing - consult the datasheet's "LT3579-1" section before attempting multiphase designs.
What is the purpose of the GATE pin on the LT3579IFE#PBF?
The GATE pin on the LT3579IFE#PBF is a programmable pull-down current source (0–933µA) used to drive the gate of an external PMOS transistor for output disconnect during fault conditions. Its current ramps linearly with SS voltage, enabling soft turn-on of the PMOS to limit inrush current - critical for hot-plug and fail-safe power architectures in automotive and industrial systems.
Does the LT3579IFE#PBF include overtemperature protection?
Yes, the LT3579IFE#PBF includes overtemperature protection that triggers when junction temperature exceeds 165°C (typical), pulling the FAULT pin low and disabling all switches. The CLKOUT pin also provides continuous junction temperature monitoring via its linearly varying duty cycle - allowing system firmware to proactively throttle loads before reaching the thermal shutdown threshold.
LT3579IFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width) 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-TSSOP-EP
LT3579IFE#PBF FAQ
1.How can I place an order for LT3579IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3579IFE#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 LT3579IFE#PBF reliable?
The price and inventory of LT3579IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3579IFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3579IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3579IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3579IFE#PBF?
LT3579IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3579IFE#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 LT3579IFE#PBF?
For technical support, including LT3579IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3579IFE#PBF requirements.
6.How does Aetrix verify that LT3579IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3579IFE#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 LT3579IFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3579IFE#PBF?
All LT3579IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3579IFE#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 LT3579IFE#PBF part is unused and in its original packaging.
Return procedure for LT3579IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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