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Analog Devices Inc. LT3579IUFD-1#TRPBF
- Part No.:
- LT3579IUFD-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LT3579IUFD-1#TRPBF.pdf
- Description:
- IC REG BST CHARGE PUMP ADJ 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,972
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Product details
Overview
LT3579IUFD-1#TRPBF 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, 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 LT3579IUFD-1#TRPBF datasheet, LT3579IUFD-1#TRPBF pinout, LT3579IUFD-1#TRPBF application, or LT3579IUFD-1#TRPBF equivalent, key selection considerations include its 20-pin 4mm × 5mm QFN package, 200kHz–2.5MHz programmable switching frequency, CLKOUT phase-inverted synchronization capability for multiphase operation, and integrated soft-start/frequency foldback for controlled startup under heavy load.
Technical Context
The LT3579IUFD-1#TRPBF implements constant-frequency current-mode control with dual NPN power switches optimized for combined 6A peak current delivery. Its master/slave architecture enables precise current sharing (ISW2/ISW1 = 0.78 A/A) and supports dual-phase interleaved operation via 180° out-of-phase CLKOUT output with fixed ~50% duty cycle.
Fault management includes five independent detection paths: SW1/SW2 overcurrent (>3.4A / >6A), VIN overvoltage (>16.2V), SW overvoltage (>42V), junction temperature (>165°C), and external FAULT assertion. Recovery uses a timed SS pin charge/discharge sequence with automatic GATE high-impedance transition to disconnect external PMOS during fault events.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Configuration | Dual NPN master/slave (3.4A/2.6A); combined 6A peak current limit enables high-power Boost/Inverting designs without external current sharing circuitry. |
| Input Voltage Range | 2.5V to 16V operating; 40V transient rating allows direct connection to 12V automotive rails with surge margin. |
| Switching Frequency | 200kHz–2.5MHz adjustable via RT resistor or external SYNC clock; supports EMI optimization and compact magnetics selection. |
| CLKOUT Output | Inverted 180° phase, ~50% duty cycle; enables synchronized dual-phase operation with matched timing across multiple LT3579IUFD-1#TRPBF units. |
| Protection Features | Integrated output short-circuit, VIN/SW overvoltage, overtemperature, and external FAULT pin assertion - all trigger automatic shutdown, GATE disable, and SS timeout recovery. |
| Package & Thermal | 20-pin 4mm × 5mm QFN with exposed thermal pad; θJA = 34°C/W enables 125°C junction operation in constrained PCB layouts. |
| Soft-Start Control | SS pin charges to 1.8V then 2.1V; controls ramp rate of switch current and GATE pull-down current (0–933µA) to limit inrush and enable hot-plug capability. |
Pinout & Package
LT3579IUFD-1#TRPBF is housed in a 20-pin 4mm × 5mm plastic QFN package with exposed thermal pad (Pin 21) soldered to PCB ground for thermal performance. Pin numbering follows standard QFN top-view orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (Pin 1) | Positive/Negative Feedback Input | Accepts voltage divider from VOUT to regulate +12V (1.215V reference) or –12V (9mV reference); bias current 83.3µA enables high-impedance feedback networks. |
| VC (Pin 2) | Error Amplifier Output | Drives external compensation network (RC/CC) to stabilize loop response; connects to A1/A2 op-amp output in regulation path. |
| GATE (Pin 3) | PMOS Gate Drive Output | Sinks up to 933µA linearly with SS voltage; drives external PMOS for output disconnect during fault - impedance drops to 2kΩ when SS > 500mV and VGATE < 2V. |
| FAULT (Pin 4) | Bidirectional Fault Indicator | Active-low open-drain output; pulled low internally on fault or externally asserted; requires 100kΩ pull-up to exceed 1V for fault clearance. |
| VIN (Pin 5) | Main Input Supply | 2.5V–16V input rail; must be locally bypassed; internal UVLO disables chip below 2.3V (typical). |
| SW1 (Pins 6–10) | Master Switch Collector | Handles ≥3.4A peak current; connects to inductor in Boost/SEPIC or transformer primary in Flyback; minimize trace area for EMI reduction. |
| GND (Pin 21) | Power Ground | Exposed thermal pad; must be soldered to PCB ground plane for thermal conduction and noise control. |
| SW2 (Pins 11–15) | Slave Switch Collector | Handles ≥2.6A peak current; tied to SW1 for combined 6A operation; shares same voltage stress limits (42V max). |
| CLKOUT (Pin 16) | Synchronization Clock Output | Outputs inverted oscillator signal at ~50% duty cycle; usable as temperature monitor (duty cycle ∝ TJ) or for multiphase sync. |
| SHDN (Pin 17) | Shutdown/UVLO Control | Enables chip above 1.33V (typical); hysteresis prevents glitch-induced toggling; supports resistor-divider UVLO configuration. |
| RT (Pin 18) | Frequency Set Resistor | Connects to ground to set free-running frequency (200kHz–2.5MHz); no floating allowed. |
| SYNC (Pin 20) | External Clock Input | Accepts 0.4V–1.3V logic levels; overrides internal oscillator; reverts to RT-set frequency when driven <0.4V. |
| SS (Pin 19) | Soft-Start Timing | Charges via internal 250kΩ resistor; controls ramp rate of switch current and GATE drive; initiates timeout sequence during fault. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-phase synchronization support | CLKOUT provides 180° out-of-phase, fixed 50% duty cycle signal enabling interleaved operation with matched timing across multiple LT3579IUFD-1#TRPBF units. |
| Integrated fault recovery sequence | SS pin executes timed charge-to-1.8V then discharge-to-50mV cycle upon fault, ensuring minimum stress duration on power components and external PMOS. |
| Configurable undervoltage lockout | SHDN pin accepts resistor divider from VIN to set custom turn-on threshold (e.g., 9V UVLO), supplementing internal 2.3V lockout for system-level brownout protection. |
| Low VCE(SAT) power switches | 250mV typical saturation voltage at 5.5A combined current reduces conduction loss and improves efficiency in high-current Boost/Inverting applications. |
| Sample Mode short-circuit detection | Forces Q1/Q2 on every cycle when FB is out of regulation (45mV < FB < 1.17V), enabling reliable detection of output shorts before full current ramp-up. |
Applications
| Automotive Engine Control Unit (ECU) Power | Vacuum Fluorescent Display (VFD) Bias Supply |
|---|---|
Use Scenario: Provides isolated +12V and –12V rails from 12V vehicle battery for microcontroller, sensors, and actuators in engine bay environments with wide temperature swings and load dump transients. IC Role / Device Role / Timing Role: Dual-rail DC/DC controller with fault protection ensures uninterrupted operation during cranking, cold start, and load dump events; CLKOUT synchronizes auxiliary regulators. Use Value: 40V transient rating, –40°C to 125°C operation, and integrated overvoltage/overtemperature protection eliminate need for external TVS or thermal sensors. | Use Scenario: Generates high-voltage AC bias (±30V to ±100V) for vacuum fluorescent display anodes and grids using charge-pump-augmented topology from 5V/12V input. IC Role / Device Role / Timing Role: Configured in high-efficiency charge-pump topology leveraging dual switches to reduce component count vs. traditional discrete pump circuits. Use Value: Combined 6A switch current and 42V rating enable single-chip generation of high-voltage bias with fewer external capacitors and diodes than conventional solutions. |
| TFT-LCD Panel Bias Supply | Industrial Local Power Supply |
Use Scenario: Supplies regulated AVDD (+15V), VGH (+25V), and VGL (–10V) rails for TFT-LCD source/gate drivers in medical imaging and industrial HMI displays. IC Role / Device Role / Timing Role: Operates in Boost and Inverting configurations simultaneously; uses FB pin's dual-reference capability (1.215V/+12V or 9mV/–12V) for rail-specific feedback. Use Value: Single IC replaces multiple converters; soft-start and frequency foldback prevent overshoot during panel power-up sequences. | Use Scenario: Powers FPGA I/O banks, ADC references, and isolated communication interfaces in programmable logic controllers (PLCs) and motor drives where board space and reliability are critical. IC Role / Device Role / Timing Role: Functions as local point-of-load regulator with output short-circuit protection and thermal shutdown - eliminating risk of cascading failure in dense PCB layouts. Use Value: Exposed-pad QFN package delivers low thermal resistance (θJA = 34°C/W), enabling full 6A output in compact industrial enclosures without forced air cooling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3891EFE#TRPBF | Single-channel 60V synchronous buck controller; no integrated switches; requires external MOSFETs; supports 4–60V input. | Targeted at high-input-voltage step-down only; lacks inverting/SEPIC capability and integrated fault protection logic. | Select when higher input voltage (>16V) or synchronous rectification efficiency is required; not drop-in for LT3579IUFD-1#TRPBF's integrated switch or dual-rail topologies. |
| LT8330EMSE#TRPBF | Single-switch 40V boost/SEPIC/inverting controller; 4A switch; no slave switch or dual-phase CLKOUT; smaller 16-pin MSOP package. | Lower current capacity and no multiphase support; simpler fault handling (no sample mode or dual overvoltage thresholds). | Choose for cost-sensitive, lower-power (<4A) Boost/Inverting designs where dual-phase sync and full 6A protection are unnecessary. |
Compared with LTC3891EFE#TRPBF and LT8330EMSE#TRPBF, the LT3579IUFD-1#TRPBF uniquely integrates dual NPN switches with coordinated current limiting, 180° CLKOUT for multiphase operation, and comprehensive fault detection/recovery - making it optimal for space-constrained, high-reliability dual-rail power systems where protection autonomy matters.
Availability
LT3579IUFD-1#TRPBF is available at Aetrix Electronics and suitable for automotive ECU power, VFD bias supplies, TFT-LCD panel bias, and industrial local power supply designs requiring stable component supply, long-term lifecycle support, and guaranteed parametric compliance.
Supply support for LT3579IUFD-1#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, communications, and automotive markets.
The LT3579 product line delivers highly integrated PWM DC/DC controllers with built-in fault protection and flexible topology support - designed specifically for robust local power conversion in harsh environments like automotive engine compartments and industrial control cabinets.
FAQ
What is the maximum combined switch current supported by the LT3579IUFD-1#TRPBF?
The LT3579IUFD-1#TRPBF supports a guaranteed minimum combined peak current of 6A when SW1 and SW2 are tied together. Electrical characteristics specify a typical SW1+SW2 current limit of 7.5A and maximum of 9.4A under defined test conditions. This enables high-power Boost and Inverting configurations without external current sharing components.
How does the LT3579IUFD-1#TRPBF differ from the standard LT3579IUFD#TRPBF?
The LT3579IUFD-1#TRPBF includes dual-phase capability not present in the base LT3579IUFD#TRPBF. Specifically, its CLKOUT signal is 180° out of phase with the internal oscillator and maintains a fixed ~50% duty cycle - enabling synchronized interleaved operation with another LT3579IUFD-1#TRPBF unit. The standard version has variable CLKOUT duty cycle (~42%) and no phase inversion.
Can the LT3579IUFD-1#TRPBF be used in an inverting configuration, and what feedback reference applies?
Yes, the LT3579IUFD-1#TRPBF supports inverting configurations. In this mode, the FB pin uses a negative feedback reference of 9mV (not 1.215V). The feedback resistor is calculated as RFB = (|VOUT| + 9mV) / 83.3µA. This low-reference design enables precise regulation of negative output voltages such as –12V for LCD bias rails.
What thermal performance can be expected from the LT3579IUFD-1#TRPBF in its QFN package?
The LT3579IUFD-1#TRPBF 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. With the exposed pad (Pin 21) properly soldered to a PCB ground plane, it sustains continuous 125°C junction operation under full 6A load in typical industrial layouts - verified per manufacturer characterization data.
Does the LT3579IUFD-1#TRPBF require external components for fault recovery, or is it autonomous?
The LT3579IUFD-1#TRPBF implements fully autonomous fault recovery using its internal SS pin circuitry. Upon fault detection (e.g., output short), it automatically discharges the SS capacitor, holds FAULT low, disables switches and CLKOUT, then executes a timed charge/discharge sequence - all without external intervention. Only a pull-up resistor on the FAULT pin (typically 100kΩ) is required for normal operation.
LT3579IUFD-1#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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)
LT3579IUFD-1#TRPBF FAQ
1.How can I place an order for LT3579IUFD-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3579IUFD-1#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 LT3579IUFD-1#TRPBF reliable?
The price and inventory of LT3579IUFD-1#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3579IUFD-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3579IUFD-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3579IUFD-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3579IUFD-1#TRPBF?
LT3579IUFD-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3579IUFD-1#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 LT3579IUFD-1#TRPBF?
For technical support, including LT3579IUFD-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3579IUFD-1#TRPBF requirements.
6.How does Aetrix verify that LT3579IUFD-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3579IUFD-1#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 LT3579IUFD-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3579IUFD-1#TRPBF?
All LT3579IUFD-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3579IUFD-1#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 LT3579IUFD-1#TRPBF part is unused and in its original packaging.
Return procedure for LT3579IUFD-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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