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Analog Devices Inc. LT3581HDE#TRPBF
- Part No.:
- LT3581HDE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LT3581HDE#TRPBF.pdf
- Description:
- IC REG BST CHARGE PUMP ADJ 14DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,294
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Product details
Overview
LT3581HDE#TRPBF from Analog Devices (formerly Linear Technology) is a 3.3A, 42V combined master/slave PWM DC/DC converter IC designed for boost, inverting, SEPIC, and flyback topologies. 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#TRPBF datasheet, LT3581HDE#TRPBF pinout, LT3581HDE#TRPBF application, or LT3581HDE#TRPBF equivalent, key selection criteria include its dual-switch current sharing (1.9A/1.4A), fault-protected operation under VIN overvoltage (>22V), SW overvoltage (>42V), overtemperature (>165°C), and integrated soft-start with SS-controlled GATE pull-down for external PMOS disconnect.
Technical Context
The LT3581HDE#TRPBF implements constant-frequency current-mode control with internal 1.215V positive FB reference and 9mV negative FB reference, enabling precise regulation in both boost and inverting configurations. Its master/slave NPN switch architecture supports tied-collector operation with guaranteed 3.3A combined current limit and 250mV VCE(SAT) at 2.75A.
Fault detection is implemented via dedicated FAULT pin with bidirectional logic: internally pulled low on SW overcurrent, VIN OVLO (>22V), SW overvoltage (>42V), or die temperature >165°C; externally asserted by pulling FAULT below 750mV. Soft-start is managed through SS pin voltage ramping (0–2.1V), which linearly controls GATE pull-down current up to 933µA and enables controlled PMOS turn-on.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 22V operating; 40V transient tolerance - supports wide industrial input rails including automotive battery variations. |
| Switch Current Limit | 1.9A (SW1) / 1.4A (SW2) master/slave; 3.3A combined - enables high-power local bias supplies without external current sensing. |
| Switching Frequency | 200kHz to 2.5MHz, RT-programmable or external SYNC - allows EMI optimization and compact magnetics in space-constrained designs. |
| Feedback Reference | 1.215V (positive) / 9mV (negative) - provides accurate output regulation across boost and inverting topologies with minimal external components. |
| Junction Temperature Range | –40°C to +150°C - qualified for under-hood automotive and high-ambient industrial applications requiring extended thermal robustness. |
| Quiescent Current | 2.3mA (active), <1µA (shutdown) - ensures low standby power in always-on systems such as ECU wake-up circuits. |
| Output Short Protection | Dedicated FAULT pin with hysteresis (750mV/1000mV thresholds) - enables system-level fault signaling and automatic power-path isolation via external PMOS. |
Pinout & Package
LT3581HDE#TRPBF is housed in a 14-pin 4mm × 3mm plastic DFN package with exposed pad (Pin 15) soldered to PCB ground for thermal and electrical integrity. Pin count and layout match the DE package variant specified in Linear Technology's official documentation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW1 (Pins 6,7) | Master NPN collector | Primary high-current switching node; must minimize trace area to reduce EMI and parasitic inductance. |
| SW2 (Pins 8,9) | Slave NPN collector | Secondary switch enabling current sharing; tied to SW1 for 3.3A total limit or used independently in multi-rail topologies. |
| FB (Pin 1) | Feedback input | Accepts 1.215V (boost) or 9mV (inverting) reference; determines output voltage via single resistor divider. |
| FAULT (Pin 4) | Bidirectional fault indicator | Pulled low internally on overcurrent/overvoltage/overtemperature; pulls external PMOS gate high via RGATE to disconnect VOUT. |
| GATE (Pin 3) | PMOS gate drive | Sink current up to 933µA, linearly scaled by SS voltage - enables soft-turn-on of external PMOS for inrush limiting and hot-swap capability. |
| SS (Pin 13) | Soft-start control | Charged by internal 250kΩ resistor; ramps 0–2.1V to control GATE current and enable CLKOUT after 1.8V threshold. |
| CLKOUT (Pin 10) | Synchronization output | Drives capacitive loads ≤50pF; provides clock signal for multi-regulator synchronization and junction temperature monitoring via duty cycle. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated fault protection | Detects and responds to output shorts, VIN overvoltage (>22V), SW overvoltage (>42V), and die temperature >165°C - eliminates need for discrete protection circuitry. |
| Configurable UVLO | SHDN pin accepts external resistor divider to set custom input turn-on voltage - supports battery-powered systems with precise brown-in/brown-out thresholds. |
| Frequency foldback | Reduces switching frequency when FB is between 350mV–900mV - improves start-up control and prevents inductor saturation during light-load transients. |
| High-gain SHDN input | Accepts slowly ramping signals with 30mV hysteresis - enables clean enable/disable sequencing without external Schmitt triggers. |
| Sample mode operation | Forces Q1/Q2 conduction every cycle when FB is out of regulation by >3.7% - enables reliable short-circuit detection independent of load dynamics. |
Applications
| Vacuum Fluorescent Display (VFD) Bias Supply | TFT-LCD Panel Bias Supply |
|---|---|
Use Scenario: Generating +30V and –30V bias rails from a 5V or 12V supply for VFD segment/anode/grid drivers in automotive instrument clusters. IC Role / Device Role / Timing Role: LT3581HDE#TRPBF operates in inverting configuration with dual feedback to regulate negative rail, while master/slave switches handle peak currents up to 3.3A during display refresh bursts. Use Value: Integrated short-circuit protection prevents latch-up during VFD filament faults; 150°C rating ensures reliability in sealed, thermally constrained dash environments. | Use Scenario: Providing AVDD (+15V), VGH (+25V), and VGL (–10V) for TFT-LCD source/gate drivers in industrial HMIs and medical displays. IC Role / Device Role / Timing Role: LT3581HDE#TRPBF configured as stacked boost/inverting converters; CLKOUT synchronizes multiple regulators to suppress beat frequencies in sensitive analog video paths. Use Value: 2.5MHz max switching frequency enables use of small 1.5µH inductors and 4.7µF ceramic output caps - reduces board area by >40% vs legacy 500kHz solutions. |
| Automotive Engine Control Unit (ECU) Local Power | Industrial Programmable Logic Controller (PLC) I/O Module Supply |
Use Scenario: Generating isolated 5V or 3.3V auxiliary rails from 12V battery input for microcontroller, CAN transceiver, and sensor interface circuitry in engine bay ECUs. IC Role / Device Role / Timing Role: LT3581HDE#TRPBF used in SEPIC configuration to maintain regulation during cold-crank (4.5V) and load-dump (40V) transients; FAULT pin signals MCU on overvoltage events. Use Value: 40V absolute max VIN and 150°C operating range meet AEC-Q100 Grade 1 requirements; integrated UVLO avoids false resets during battery voltage sags. | Use Scenario: Delivering 24V-to-12V/5V local supplies for digital I/O conditioning, relay drivers, and isolated communication interfaces in DIN-rail mounted PLC modules. IC Role / Device Role / Timing Role: LT3581HDE#TRPBF configured as boost converter with external PMOS disconnect; GATE pin soft-start prevents inrush into large 1000µF bulk capacitance during hot-swap insertion. Use Value: 3.3A current capability supports simultaneous powering of 8+ digital outputs; exposed DFN pad ensures thermal stability at full load in 70°C ambient enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3891EFE#PBF | Single 60V N-channel MOSFET controller; requires external FETs; no integrated slave switch or FAULT pin logic. | Used in higher-efficiency, higher-current (>5A) synchronous buck applications; lacks integrated short-circuit protection. | Select when efficiency >95% and layout flexibility outweigh need for integrated fault response and compact footprint. |
| MAX17595ATP+T | 40V, 3A synchronous step-up controller; includes integrated gate drivers but no dual-switch architecture or sample-mode short detection. | Targeted at high-density consumer power supplies; rated only to 125°C junction temperature. | Select for cost-sensitive, non-automotive applications where 150°C operation and robust fault handling are not required. |
Compared with LTC3891EFE#PBF and MAX17595ATP+T, the LT3581HDE#TRPBF uniquely integrates master/slave NPN switches with coordinated current limiting, dedicated FAULT signaling with PMOS gate control, and sample-mode short-circuit detection - making it optimal for space-constrained, fault-critical industrial and automotive bias supplies where reliability trumps marginal efficiency gains.
Availability
LT3581HDE#TRPBF is available at Aetrix Electronics and suitable for automotive ECU power, industrial HMI bias supplies, vacuum fluorescent display drivers, and programmable logic controller I/O modules requiring stable component supply across extended temperature ranges.
Supply support for LT3581HDE#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 acquired Linear Technology in 2017 and maintains full product support, datasheet archives, and application engineering for all LT parts including the LT3581 family.
The LT3581 product line was designed specifically for high-reliability local DC/DC conversion in harsh environments - emphasizing integrated fault protection, wide input range, and flexible topology support for automotive, industrial, and display power applications.
FAQ
What is the maximum operating junction temperature for the LT3581HDE#TRPBF?
The LT3581HDE#TRPBF is rated for continuous operation from –40°C to +150°C junction temperature, with derated lifetime above 125°C. This H-grade qualification makes it suitable for under-hood automotive and high-ambient industrial applications where standard E- or I-grade variants would fail thermally.
How does the LT3581HDE#TRPBF implement output short-circuit protection?
The LT3581HDE#TRPBF uses sample-mode detection: when FB voltage deviates >3.7% from regulation (e.g., <45mV in inverting mode), Q1 and Q2 are forced on 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 activating GATE to disconnect external PMOS - cutting VOUT within microseconds.
Can the LT3581HDE#TRPBF be synchronized to an external clock source?
Yes - the LT3581HDE#TRPBF accepts TTL/CMOS-compatible clock signals on the SYNC pin (high >1.3V, low <0.4V, duty cycle 20–80%). When driven, it locks its internal oscillator to the external frequency, and drives CLKOUT at the same rate. This enables deterministic EMI reduction and multi-regulator phase alignment in complex power systems.
What is the purpose of the GATE pin on the LT3581HDE#TRPBF?
The GATE pin on the LT3581HDE#TRPBF is a current-sinking driver for an external PMOS transistor used in the power path. Its sink current scales linearly with SS voltage (0–933µA), enabling soft-start of the PMOS to limit inrush current. During fault conditions, GATE goes high-impedance, allowing RGATE to pull the PMOS gate high and disconnect VOUT from VIN.
Does the LT3581HDE#TRPBF support both boost and inverting topologies?
Yes - the LT3581HDE#TRPBF is explicitly designed for configurable operation in boost, inverting, SEPIC, and flyback topologies. Its dual feedback references (1.215V for positive regulation, 9mV for negative) and independent SW1/SW2 pins allow direct implementation of all four configurations using standard external components per Linear Technology Application Note 128.
LT3581HDE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 14-WFDFN 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):
- 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#TRPBF FAQ
1.How can I place an order for LT3581HDE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3581HDE#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 LT3581HDE#TRPBF reliable?
The price and inventory of LT3581HDE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3581HDE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3581HDE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3581HDE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3581HDE#TRPBF?
LT3581HDE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3581HDE#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 LT3581HDE#TRPBF?
For technical support, including LT3581HDE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3581HDE#TRPBF requirements.
6.How does Aetrix verify that LT3581HDE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3581HDE#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 LT3581HDE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3581HDE#TRPBF?
All LT3581HDE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3581HDE#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 LT3581HDE#TRPBF part is unused and in its original packaging.
Return procedure for LT3581HDE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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