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Analog Devices Inc. LT3579EFE#PBF
- Part No.:
- LT3579EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3579EFE#PBF.pdf
- Description:
- IC REG BST CHRG PUMP ADJ 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,252
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Product details
Overview
LT3579EFE#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, programmable undervoltage lockout, and 200kHz–2.5MHz switching frequency. It delivers 12V at 1.7A or –12V at 1.2A from a 5V input and is used in TFT-LCD bias supplies and automotive ECU power rails.
For engineers reviewing the LT3579EFE#PBF datasheet, LT3579EFE#PBF pinout, LT3579EFE#PBF application, or LT3579EFE#PBF equivalent, key selection criteria include combined 6A current limit, fault-protected operation under output shorts/overvoltage/overtemperature, TSSOP-20 package thermal performance (θJA = 38°C/W), and dual-phase capability via LT3579-1 variant compatibility.
Technical Context
The LT3579EFE#PBF employs constant-frequency current-mode control with integrated error amplifier (70V/V gain, 250µmhos transconductance), frequency foldback for startup stability, and sample-mode overcurrent detection triggered when FB deviates >3.7% from regulation. Its dual NPN switch architecture enables configurable current sharing (ISW2/ISW1 = 0.78 A/A) and total 6A peak current handling with 250mV VCE(SAT) at 5.5A.
Switching frequency is set by RT-to-ground resistor (200kHz–2.5MHz range) or synchronized externally via SYNC pin (1.3V high threshold, 0.4V low). CLKOUT provides buffered clock output (1.9–2.3V high, 100–200mV low) with temperature-proportional duty cycle (LT3579) or fixed 50% duty cycle (LT3579-1), enabling multi-IC synchronization and junction temperature monitoring.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Configuration | Dual NPN: master (3.4A min) + slave (2.6A min), combined 6A peak current limit |
| Input Voltage Range | 2.5V to 16V operating; 40V transient tolerance - supports wide automotive and industrial supply rails |
| Switch Voltage Rating | 42V max on SW1/SW2 - enables 36V system-level designs with margin |
| Feedback Reference | 1.215V ±15mV (positive mode); 9mV ±6mV (inverting mode) - sets precise output regulation points |
| Quiescent Current | 2.4mA typical (active); 1µA max (shutdown) - minimizes standby power loss |
| Thermal Performance | TSSOP-20 package: θJA = 38°C/W, TJMAX = 125°C - defines PCB copper requirements for 125°C ambient operation |
| Protection Features | Output short-circuit, VIN overvoltage (>16.2V), SW overvoltage (>42V), overtemperature (>165°C) - autonomous fault response without external circuitry |
Pinout & Package
LT3579EFE#PBF is housed in a 20-lead plastic TSSOP package (FE) with exposed thermal pad (Pin 21) soldered to PCB ground. Package dimensions: 6.5mm × 4.4mm × 1.1mm. Thermal resistance: θJA = 38°C/W, θJC = 10°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (Pin 20) | Positive/Negative Feedback Input | Accepts 1.215V reference for boost/SEPIC or 9mV for inverting; bias current 83.3µA - sets output voltage via single resistor |
| VC (Pin 19) | Error Amplifier Output | Drives external compensation network (RC/CC) - stabilizes loop response across topologies |
| GATE (Pin 1) | PMOS Gate Drive Output | Pull-down current source (933µA max); linear with SS voltage - controls external PMOS for output disconnect during fault |
| FAULT (Pin 2) | Bidirectional Fault Indicator | Active-low open-collector; pulled low internally on fault or externally to trigger shutdown - enables system-level fault coordination |
| VIN (Pin 3) | Main Input Supply | 2.5V–16V operating range; 40V absolute max - requires local ceramic bypassing for noise immunity |
| SW1 (Pins 4–7) | Master Switch Collector | Handles 3.4A min peak current; 42V rating - primary power path in dual-switch configurations |
| GND (Pins 8,9,21) | Power & Signal Ground | Exposed pad (Pin 21) must be soldered to PCB ground plane - critical for thermal dissipation and EMI reduction |
| SW2 (Pins 10–13) | Slave Switch Collector | Handles 2.6A min peak current; tied to SW1 for 6A combined limit - enables high-power charge-pump topologies |
| CLKOUT (Pin 14) | Clock Output / Temp Monitor | Buffered oscillator output; duty cycle varies linearly with junction temperature - synchronizes other regulators or monitors die temp |
| SHDN (Pin 15) | Shutdown Control | 1.33V typical turn-on threshold; 30mV hysteresis - supports slow-ramping enable signals and user-configurable UVLO |
| RT (Pin 16) | Frequency Set Resistor | Connects to ground to set free-running frequency (200kHz–2.5MHz); no floating allowed - determines minimum on/off times |
| SYNC (Pin 17) | External Clock Input | Accepts 0.4V–1.3V logic levels; reverts to internal oscillator if <0.4V - enables precise multi-phase timing alignment |
| SS (Pin 18) | Soft-Start Capacitor Node | Charged by 250kΩ internal resistor to 2.1V; controls ramp rate of switch current and GATE drive - prevents inrush and enables hot-plug operation |
Key Features
| Feature | Design Value |
|---|---|
| 6A Combined Power Switch | Master (3.4A) + slave (2.6A) NPN switches tied together - eliminates need for external current-sharing components in high-current boost/inverting designs |
| Output Short-Circuit Protection | Autonomous shutdown triggered by FB out-of-regulation sampling - protects downstream loads without external sense resistors or controllers |
| Programmable Undervoltage Lockout | SHDN pin accepts resistor divider from VIN to set custom turn-on voltage (e.g., 9V UVLO) - replaces discrete UVLO ICs in battery-powered systems |
| Configurable Topology Support | Single IC supports boost, inverting, SEPIC, and flyback via external component selection - reduces BOM count across multiple power rail requirements |
| CLKOUT Synchronization & Temp Monitoring | Buffered clock output with temperature-proportional duty cycle - enables daisy-chained regulator timing and real-time thermal diagnostics |
| Low VCE(SAT) Switches | 250mV typical at 5.5A combined current - reduces conduction losses and thermal stress in high-current applications |
Applications
| TFT-LCD Bias Supply | Automotive ECU Power Rail |
|---|---|
Use Scenario: Generating ±15V bias voltages for LCD gate/source drivers in automotive infotainment displays. IC Role / Device Role / Timing Role: Dual-output inverting/boost controller delivering regulated positive and negative rails with fault isolation. Use Value: Integrated 6A switches eliminate external MOSFETs; output short protection prevents display damage during connector mating/unmating. | Use Scenario: Local 12V-to-5V/3.3V conversion for microcontroller, CAN transceiver, and sensor power in engine control units. IC Role / Device Role / Timing Role: High-efficiency, fault-tolerant DC/DC converter operating across cold-crank (4.5V) to load-dump (40V) conditions. Use Value: 40V transient rating and VIN overvoltage lockout (>16.2V) ensure continuous operation during automotive load-dump events. |
| Vacuum Fluorescent Display (VFD) Supply | Industrial Programmable Logic Controller (PLC) I/O Module |
Use Scenario: Providing 30–60V anode supply and –10V grid bias for VFD segments in industrial HMIs and instrumentation panels. IC Role / Device Role / Timing Role: High-voltage boost converter with adjustable UVLO to match VFD turn-on thresholds. Use Value: 42V switch rating and programmable SHDN enable reliable start-up at low battery voltage while preventing overvoltage damage. | Use Scenario: Isolated auxiliary power for digital I/O conditioning circuits requiring robust fault containment in noisy factory environments. IC Role / Device Role / Timing Role: Fault-protected local regulator with GATE-driven PMOS disconnect for field-side power isolation. Use Value: Bidirectional FAULT pin allows PLC backplane to coordinate shutdown across multiple modules during overcurrent events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3789EFE#PBF | 4-switch synchronous buck-boost controller; requires external MOSFETs; no integrated switches | Higher efficiency at >3A loads; supports wider VIN range (4V–36V); lacks integrated fault protection | Select when efficiency >92% and input >16V are required; add external fault management circuitry |
| LT8330EFE#PBF | Single-switch boost converter; 5A switch; no slave switch or dual-phase support | Simpler layout; lower cost; limited to boost-only topology; no inverting/SEPIC capability | Select for cost-sensitive boost-only designs below 5A; omit when dual-switch redundancy or topology flexibility is needed |
Compared with LTC3789EFE#PBF and LT8330EFE#PBF, the LT3579EFE#PBF uniquely combines integrated dual 42V/6A switches, autonomous fault protection, and multi-topology configurability - making it optimal for space-constrained, safety-critical bias supplies where reliability trumps peak efficiency.
Availability
LT3579EFE#PBF is available at Aetrix Electronics and suitable for TFT-LCD bias supplies, automotive ECU power rails, and industrial PLC I/O modules requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3579EFE#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 LT3579 product line delivers fault-protected, multi-topology DC/DC conversion for demanding local power applications including display bias, automotive electronics, and industrial control - emphasizing reliability, integration, and design flexibility over raw efficiency.
FAQ
What is the maximum switching frequency supported by the LT3579EFE#PBF?
The LT3579EFE#PBF supports a switching frequency range of 200kHz to 2.5MHz. This is set either by the resistor connected from the RT pin to ground (e.g., 34kΩ yields 2.5MHz) or by synchronizing to an external clock via the SYNC pin. The part maintains stable current-mode operation across this full range, enabling optimization for size (higher fSW) or efficiency (lower fSW). The LT3579EFE#PBF's minimum on-time (55ns) and off-time (45ns) support reliable operation even at 2.5MHz.
How does the LT3579EFE#PBF protect against output short circuits?
The LT3579EFE#PBF detects output shorts using Sample Mode: when FB voltage falls outside regulation (e.g., <45mV for inverting or >1.17V for boost), the IC forces both SW1 and SW2 to conduct briefly each cycle to sample inductor current. If sampled current exceeds 3.4A (SW1) or 6A (combined), the FAULT pin pulls low, disabling switches, CLKOUT, and GATE drive. An external PMOS controlled by the GATE pin then disconnects the output, providing hardware-level isolation. This all occurs autonomously without external components.
Can the LT3579EFE#PBF be used in inverting converter configurations?
Yes, the LT3579EFE#PBF is explicitly designed for inverting configurations. Its FB pin uses a 9mV reference (±6mV) in inverting mode, allowing precise negative output regulation (e.g., –12V at 1.2A from 5V input). The datasheet provides dedicated equations for RFB calculation and includes inverting application schematics. The dual-switch architecture simplifies inverting designs by eliminating the need for external synchronous rectifiers or complex gate-drive timing.
What is the role of the GATE pin on the LT3579EFE#PBF?
The GATE pin on the LT3579EFE#PBF is a programmable pull-down current source (0–933µA) that drives the gate of an external PMOS transistor. During normal operation, it remains high-impedance. During fault conditions, it actively pulls the PMOS gate low to disconnect the output path - providing hardware-level output isolation. Its current ramps linearly with SS pin voltage, enabling soft turn-on of the PMOS to limit inrush current during startup or recovery.
Does the LT3579EFE#PBF support synchronization with other switching regulators?
Yes, the LT3579EFE#PBF supports bidirectional synchronization. Its CLKOUT pin provides a buffered copy of its internal oscillator or SYNC input signal, which can synchronize other compatible regulators (including additional LT3579EFE#PBF devices). Conversely, the SYNC pin accepts external clocks (0.4V–1.3V logic levels) to align LT3579EFE#PBF switching with system-wide timing domains - essential for reducing EMI in multi-rail power systems.
LT3579EFE#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
LT3579EFE#PBF FAQ
1.How can I place an order for LT3579EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3579EFE#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 LT3579EFE#PBF reliable?
The price and inventory of LT3579EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3579EFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3579EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3579EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3579EFE#PBF?
LT3579EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3579EFE#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 LT3579EFE#PBF?
For technical support, including LT3579EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3579EFE#PBF requirements.
6.How does Aetrix verify that LT3579EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3579EFE#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 LT3579EFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3579EFE#PBF?
All LT3579EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3579EFE#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 LT3579EFE#PBF part is unused and in its original packaging.
Return procedure for LT3579EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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