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Analog Devices Inc. LT3581HDE#PBF
- Part No.:
- LT3581HDE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LT3581HDE#PBF.pdf
- Description:
- IC REG BST CHARGE PUMP ADJ 14DFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,965
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Product details
Overview
LT3581HDE#PBF from Analog Devices (formerly Linear Technology) is a 3.3A, 42V combined master/slave PWM DC/DC converter IC optimized for boost, inverting, SEPIC, and flyback configurations. It delivers 12V at 830mA or –12V at 625mA from a 5V input, features output short-circuit protection, 200kHz–2.5MHz programmable switching frequency, and operates across –40°C to +150°C junction temperature.
For engineers reviewing the LT3581HDE#PBF datasheet, LT3581HDE#PBF pinout, LT3581HDE#PBF application, or LT3581HDE#PBF equivalent, this page provides verified functional specifications, thermal-rated package details, fault-protection behavior, and validated alternative options for high-reliability local power supply designs.
Technical Context
The LT3581HDE#PBF implements constant-frequency current-mode control with integrated 1.9A master (SW1) and 1.4A slave (SW2) NPN switches-tied together for 3.3A total current limit. Its fault detection includes VIN overvoltage (>22V), SW overvoltage (>42V), die temperature (>165°C), and overcurrent on SW1 or combined SW1+SW2 paths.
It supports external synchronization via SYNC pin (1.3V high threshold, 0.4V low), drives CLKOUT for multi-IC timing coordination, and uses SS pin voltage to linearly modulate GATE pull-down current (up to 933µA) for controlled PMOS turn-on during soft-start and fault recovery.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency Range | 200kHz to 2.5MHz - enables compact magnetics and EMI optimization in space-constrained applications. |
| Combined Switch Current Limit | 3.3A (min) - supports high-power boost/inverting topologies without external current-sense amplifiers. |
| Input Voltage Range | 2.5V to 22V operating, 40V transient - accommodates wide-input industrial and automotive supplies. |
| Output Short Protection | Active fault response with internal FAULT pin pull-down and GATE high-impedance - isolates downstream circuitry within microseconds. |
| Junction Temperature Range | –40°C to +150°C - qualified for under-hood automotive and high-ambient industrial environments. |
| Feedback Reference Voltage | 1.215V (positive), 9mV (negative) - enables precise regulation in both boost and inverting configurations. |
| Quiescent Current | 2.3mA (typical, active), <1µA (shutdown) - minimizes standby power loss in battery-backed systems. |
Pinout & Package
LT3581HDE#PBF is housed in a 14-pin 4mm × 3mm plastic DFN package with exposed thermal pad (Pin 15 = GND). The package supports high-power dissipation (θJC = 4.3°C/W) and requires soldering of the exposed pad to PCB ground for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW1 (Pins 6,7) | Master switch collector | Handles up to 1.9A continuous; primary current path in boost/flyback; minimized trace area required for EMI control. |
| SW2 (Pins 8,9) | Slave switch collector | Shares current with SW1 (78% ratio); enables 3.3A combined limit when tied externally; same voltage rating (42V). |
| FB (Pin 1) | Feedback input | Accepts positive (1.215V ref) or negative (9mV ref) feedback; determines output regulation mode and voltage setpoint. |
| FAULT (Pin 4) | Bidirectional fault indicator | Pulled low internally on overvoltage/overcurrent/overtemperature; can be asserted externally to force shutdown and initiate recovery sequence. |
| GATE (Pin 3) | PMOS gate drive | Sinks up to 933µA; current scales linearly with SS voltage; used for output disconnect during faults or hot-plug sequencing. |
| CLKOUT (Pin 10) | Clock output | Drives capacitive loads ≤50pF; provides synchronized clock for other regulators; duty cycle varies linearly with junction temperature for thermal monitoring. |
| SHDN (Pin 11) | Enable/shutdown control | High-impedance input with 1.33V typical turn-on threshold and 30mV hysteresis; supports configurable UVLO using resistor divider from VIN. |
| RT (Pin 12) | Frequency programming | Resistor-to-ground sets free-running oscillator frequency; supports 200kHz–2.5MHz range with ±10% tolerance. |
| SS (Pin 13) | Soft-start control | Charged by internal 250kΩ resistor; controls ramp rate of switch current and GATE pull-down; initiates timeout sequence during fault recovery. |
| VIN (Pin 5) | Main input supply | 2.5V–22V operating range; bypass capacitor required locally; internal UVLO disables operation below 2.3V. |
| VC (Pin 2) | Error amplifier output | Connects to external compensation network (RC, CC); sets loop stability and transient response in regulation mode. |
| SYNC (Pin 14) | External clock input | Accepts 0.4V–1.3V logic levels; overrides internal oscillator; enables phase-aligned multi-regulator operation. |
| GND (Pin 15) | Power and signal ground | Exposed thermal pad; must be soldered to PCB ground plane for thermal management and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated dual-switch architecture | Eliminates need for external current-sharing components in high-current boost/inverting designs. |
| Programmable undervoltage lockout (UVLO) | Configurable via SHDN pin resistor divider - enables precise input voltage turn-on thresholds independent of internal 2.3V UVLO. |
| Frequency foldback | Reduces switching frequency to 1/6 nominal when FB is between 350mV–900mV - improves start-up control and prevents inductor saturation. |
| Sample Mode fault detection | Forces Q1/Q2 conduction every cycle when FB is out of regulation by >3.7% - enables fast, accurate short-circuit detection without additional sensing circuitry. |
| Thermal-grade packaging | H-grade qualification (–40°C to +150°C) with exposed pad - ensures reliability in engine control units and industrial motor drives. |
Applications
| Automotive Engine Control Unit (ECU) Power | Vacuum Fluorescent Display (VFD) Bias Supplies |
|---|---|
Use Scenario: Generating isolated 12V and –12V rails from a 5V microcontroller supply in under-hood ECU modules exposed to ambient temperatures up to 125°C. IC Role / Device Role / Timing Role: Dual-rail DC/DC converter with integrated fault protection; regulates output voltage while detecting load shorts and overtemperature events. Use Value: Enables single-chip solution for dual-polarity bias generation with guaranteed operation up to 150°C junction temperature and automatic fault isolation. | Use Scenario: Providing stable, low-noise –24V to –30V bias for VFD anode drivers in instrumentation panels where rapid startup and short-circuit resilience are critical. IC Role / Device Role / Timing Role: Inverting converter configured with external PMOS disconnect; uses Sample Mode to detect filament shorts before full power delivery. Use Value: Delivers regulated negative output with sub-50µs fault response time and no external current-sense resistors or comparators required. |
| TFT-LCD Bias Supplies | Local Power Supply |
Use Scenario: Generating AVDD (+15V) and VGH (+25V) rails from a 3.3V or 5V system rail in portable medical displays requiring compact, low-EMI power solutions. IC Role / Device Role / Timing Role: Boost converter with 2MHz switching frequency; uses CLKOUT to synchronize adjacent regulators and reduce beat frequencies. Use Value: Achieves >85% efficiency at 600mA load while meeting CISPR-22 Class B EMI limits due to fixed-frequency operation and minimal external component count. | Use Scenario: Replacing discrete buck-boost solutions in FPGA I/O bank power supplies where board space is constrained and thermal margin is limited. IC Role / Device Role / Timing Role: Configurable SEPIC converter supporting input voltages above and below output; integrates soft-start, UVLO, and fault reporting into one IC. Use Value: Reduces BOM count by 7 components versus discrete implementation and eliminates risk of layout-induced oscillation through integrated compensation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3589EUF#PBF | Quad-output PMIC with integrated LDOs; lower max switch current (1.2A per channel); no combined master/slave topology. | Targeted at multi-rail portable systems; lacks 42V switch rating and inverting capability. | Choose LTC3589EUF#PBF only when multiple regulated outputs and ultra-low quiescent current (<10µA) are prioritized over high-voltage, high-current conversion. |
| LM5122MH/NOPB | Single-channel synchronous boost controller; external MOSFETs; supports up to 65V input; no integrated switches or fault protection logic. | Requires external current-sense, protection ICs, and gate drivers; suited for >10A applications with custom thermal design. | Choose LM5122MH/NOPB when scalability beyond 3.3A, higher efficiency at >1A loads, or 65V input capability outweighs integration and fault-protection benefits of LT3581HDE#PBF. |
Compared with LTC3589EUF#PBF and LM5122MH/NOPB, the LT3581HDE#PBF uniquely combines 42V integrated switches, dual-rail configurability, and autonomous fault response in a thermally robust 4mm × 3mm DFN - making it optimal for space-limited, high-reliability boost/inverting supplies where protection and simplicity are design priorities.
Availability
LT3581HDE#PBF is available at Aetrix Electronics and suitable for automotive engine control units, vacuum fluorescent display bias supplies, TFT-LCD panel power, industrial sensor nodes, and high-temperature embedded controllers requiring stable component supply across extended temperature ranges.
Supply support for LT3581HDE#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 acquired Linear Technology in 2017 and maintains full technical and manufacturing continuity for all Linear power products. Linear Technology was renowned for high-performance analog and power management ICs with rigorous automotive and industrial qualification.
The LT3581HDE#PBF belongs to Linear's high-voltage monolithic DC/DC converter family, designed specifically for fault-resilient local power generation in harsh environments where input transients, load shorts, and elevated ambient temperatures are common.
FAQ
What is the maximum junction temperature rating for the LT3581HDE#PBF?
The LT3581HDE#PBF is rated for operation from –40°C to +150°C junction temperature. This H-grade qualification is explicitly confirmed in the Absolute Maximum Ratings table and Electrical Characteristics section of the official datasheet, distinguishing it from E-grade (–40°C to +125°C) and I-grade variants. Operation above 125°C requires derating per manufacturer guidelines to ensure long-term reliability.
Does the LT3581HDE#PBF support inverting converter configuration?
Yes, the LT3581HDE#PBF fully supports inverting topology. Its FB pin accepts a negative reference voltage of 9mV, enabling direct regulation of negative output voltages such as –12V at 625mA from a 5V input. The datasheet provides explicit equations for RFB calculation in inverting mode and includes a dedicated inverting configuration diagram in the Applications Information section.
How does the LT3581HDE#PBF implement output short-circuit protection?
The LT3581HDE#PBF detects output shorts via Sample Mode: when FB voltage deviates >3.7% from regulation (e.g., <45mV in inverting mode), it forces Q1/Q2 conduction each cycle to sample inductor current. If sampled current exceeds 1.9A (SW1) or 3.3A (combined), the FAULT pin pulls low, disabling switches and setting GATE to high impedance - physically disconnecting the output via external PMOS. This occurs autonomously without external components.
Can the LT3581HDE#PBF be synchronized to an external clock source?
Yes, the LT3581HDE#PBF supports external synchronization via its SYNC pin. A logic-level clock signal with high threshold ≥1.3V and low threshold ≤0.4V can override the internal oscillator. When synchronized, the LT3581HDE#PBF matches the external clock frequency and phase, and its CLKOUT pin mirrors that timing - enabling deterministic multi-regulator operation and EMI reduction in dense power systems.
What package type and thermal characteristics apply to the LT3581HDE#PBF?
The LT3581HDE#PBF uses a 14-pin 4mm × 3mm plastic DFN package with exposed thermal pad (Pin 15 = GND). Its thermal resistance is θJA = 43°C/W and θJC = 4.3°C/W. The exposed pad must be soldered to the PCB ground plane to achieve rated performance; failure to do so degrades thermal dissipation and may trigger overtemperature faults prematurely.
LT3581HDE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 14-WFDFN 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):
- 22V
- Voltage - Output (Min/Fixed):
- 1.215V
- Voltage - Output (Max):
- 42V (Switch)
- Current - Output:
- 3.3A (Switch)
- Frequency - Switching:
- 200kHz ~ 2.5MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-DFN (4x3)
LT3581HDE#PBF FAQ
1.How can I place an order for LT3581HDE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3581HDE#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 LT3581HDE#PBF reliable?
The price and inventory of LT3581HDE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3581HDE#PBF is usually 5 days.
3.What payment methods are accepted for LT3581HDE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3581HDE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3581HDE#PBF?
LT3581HDE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3581HDE#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 LT3581HDE#PBF?
For technical support, including LT3581HDE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3581HDE#PBF requirements.
6.How does Aetrix verify that LT3581HDE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3581HDE#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 LT3581HDE#PBF meets industry standards.
7.What is the process for return or replacement of LT3581HDE#PBF?
All LT3581HDE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3581HDE#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 LT3581HDE#PBF part is unused and in its original packaging.
Return procedure for LT3581HDE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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