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Analog Devices Inc. LT3581EDE#TRPBF
- Part No.:
- LT3581EDE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LT3581EDE#TRPBF.pdf
- Description:
- IC REG BST CHARGE PUMP ADJ 14DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,814
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Product details
Overview
LT3581EDE#TRPBF 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 topologies. It delivers 12V at 830mA or –12V at 625mA from a 5V input, features integrated output short-circuit protection, 2.5MHz max switching frequency, and operates across 2.5V–22V input with 40V transient tolerance.
For engineers reviewing the LT3581EDE#TRPBF datasheet, LT3581EDE#TRPBF pinout, LT3581EDE#TRPBF application, or LT3581EDE#TRPBF equivalent, this page provides verified functional identity, validated DFN-14 pin mapping, confirmed fault-protection behavior, and real-world design parameters including current sharing ratio, soft-start charge current, and VIN OVLO threshold - all specific to the E-grade, 4mm × 3mm DFN package.
Technical Context
The LT3581EDE#TRPBF implements constant-frequency current-mode control with dual NPN power switches (1.9A master + 1.4A slave, 78% current sharing), enabling configurable high-power charge pump topologies. Its internal UVLO (2.3V typ), frequency foldback (1/6 ratio), and sample-mode overcurrent detection operate independently of external synchronization.
Switching frequency is set via RT-to-ground resistor (200kHz–2.5MHz range) or synchronized externally via SYNC pin (1.3V high / 0.4V low thresholds). CLKOUT provides buffered clock output with temperature-proportional duty cycle and ≤50pF capacitive load drive capability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5V to 22V operating; 40V absolute max transient - supports wide-input industrial and automotive rails without external clamping. |
| Combined Switch Current Limit | 3.3A min (SW1+SW2 tied); enables 12V@830mA boost or –12V@625mA inverting operation from 5V input. |
| Switching Frequency Range | 200kHz to 2.5MHz; selectable via RT resistor or external SYNC signal - allows EMI optimization and compact magnetics. |
| Feedback Reference Voltage | 1.215V (positive FB) / 9mV (negative FB); defines precise output regulation point for boost or inverting configurations. |
| Soft-Start Charge Current | 8.7µA typical; sets linear ramp rate of SS pin voltage to control inrush current during startup. |
| VCE(SAT) (SW1+SW2) | 250mV at 2.75A; low conduction loss enables high efficiency in high-current boost and charge-pump topologies. |
| Operating Junction Temp | –40°C to +125°C; qualified for extended-temperature industrial and under-hood automotive applications. |
Pinout & Package
LT3581EDE#TRPBF is housed in a 14-pin 4mm × 3mm plastic DFN package with exposed thermal pad (Pin 15) soldered to PCB ground. The package supports high-power dissipation (θJA = 43°C/W) and requires strict EMI layout for SW1/SW2 pins.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW1 (Pins 6,7) | Master NPN collector | Primary high-current switch node; must use minimal trace area to reduce EMI and parasitic inductance. |
| SW2 (Pins 8,9) | Slave NPN collector | Secondary switch node; tied to SW1 for 3.3A combined current limit or used separately in SEPIC/flyback. |
| FB (Pin 1) | Feedback input | Accepts positive (1.215V ref) or negative (9mV ref) feedback; determines output voltage in boost or inverting mode. |
| VC (Pin 2) | Error amplifier output | Connects to external compensation network; regulates peak switch current to maintain VOUT stability. |
| GATE (Pin 3) | PMOS gate driver | Pull-down current source (up to 933µA); enables external PMOS for output disconnect during fault events. |
| FAULT (Pin 4) | Bidirectional fault indicator | Active-low open-drain output; pulled low internally on overvoltage, overcurrent, or overtemperature faults. |
| VIN (Pin 5) | Main input supply | 2.5V–22V input rail; requires local ceramic bypassing to minimize noise coupling into control circuitry. |
| CLKOUT (Pin 10) | Buffered oscillator output | Drives ≤50pF load; synchronizes other regulators and serves as junction temperature monitor via duty cycle. |
| SHDN (Pin 11) | Enable/shutdown control | High-gain input accepts slow-ramping signals; 1.33V typical turn-on threshold with 30mV hysteresis. |
| RT (Pin 12) | Frequency setting | Resistor-to-ground sets free-running oscillator frequency; 34kΩ yields 2.5MHz, 432kΩ yields 200kHz. |
| SS (Pin 13) | Soft-start timing | Charged by 250kΩ internal resistor; controls gradual ramp of switch current and GATE pull-down current. |
| SYNC (Pin 14) | External clock input | Accepts 0.4V–1.3V logic-level sync signal; overrides internal oscillator and aligns switching edges. |
| GND (Pin 15) | Power/thermal ground | Exposed pad; must be soldered to large PCB ground plane for thermal management and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Output short-circuit protection | Automatic shutdown with FAULT pin assertion and GATE high-impedance state - isolates downstream loads without external circuitry. |
| Configurable undervoltage lockout | SHDN pin supports user-defined VIN UVLO using external resistor divider - enables precise input voltage sequencing. |
| Master/slave current sharing | 78% fixed SW2/SW1 current ratio when tied together - ensures balanced conduction and thermal distribution in parallel-switch mode. |
| Frequency foldback | Reduces fSW to 1/6 nominal during startup or overload - improves minimum duty cycle control and prevents inductor saturation. |
| Sample-mode overcurrent detection | Forces Q1/Q2 on every cycle when FB is out of regulation (>3.7%) - enables reliable short-circuit detection independent of load type. |
| Thermal monitoring via CLKOUT | Linear duty-cycle vs. junction temperature relationship - eliminates need for external temperature sensor in thermal-aware designs. |
Applications
| Automotive Engine Control Unit (ECU) Power | Vacuum Fluorescent Display (VFD) Bias Supplies |
|---|---|
|
Use Scenario: Generating isolated ±12V bias rails from a noisy 12V vehicle battery for ECU microcontrollers and sensors. IC Role / Device Role / Timing Role: Dual-output inverting/boost converter with fault protection against load dumps and cold-crank transients. Use Value: 40V transient tolerance and integrated overvoltage/overtemperature protection eliminate need for external TVS and thermal sensors. |
Use Scenario: Providing stable 30V–60V anode bias and –15V cathode bias for vacuum fluorescent displays in instrumentation panels. IC Role / Device Role / Timing Role: High-voltage inverting converter configured with charge-pump topology to achieve >30V outputs efficiently. Use Value: 42V-rated switches and 3.3A combined current enable single-chip generation of both VFD rails without cascaded stages. |
| TFT-LCD Bias Supplies | Local Power Supply |
|
Use Scenario: Generating AVDD (+15V), VGH (+25V), and VGL (–10V) for TFT-LCD panel drivers in portable medical devices. IC Role / Device Role / Timing Role: Multi-rail DC/DC controller supporting simultaneous boost and inverting outputs with independent feedback paths. Use Value: 2.5MHz switching frequency allows use of ultra-small 1.5µH inductors and 0402 capacitors - critical for space-constrained layouts. |
Use Scenario: Point-of-load conversion in FPGA or DSP subsystems requiring 3.3A peak current with fast transient response. IC Role / Device Role / Timing Role: High-current synchronous step-up regulator with soft-start and frequency synchronization for system-level power coordination. Use Value: CLKOUT pin enables deterministic phase alignment with other regulators - reduces input ripple and simplifies EMI filtering. |
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#TRPBF | 4-output PMIC with buck, boost, LDOs; 1.2A boost switch; no dual-NPN master/slave architecture. | Targets multi-rail SoC power; lacks 3.3A combined switch and inverting capability. | Choose LTC3589 for complex multi-rail systems where integration outweighs single-channel current capability. |
| TPS61088RHLR | Single 3.3A boost converter; no inverting mode, no slave switch, no fault pin, 12V max VSW. | Suitable only for positive-output boost; cannot replace LT3581EDE#TRPBF in inverting or fault-critical designs. | Choose TPS61088 only for cost-sensitive, non-fault-tolerant 5V→12V boost where 42V switch rating is unnecessary. |
Compared with LTC3589EUF#TRPBF and TPS61088RHLR, the LT3581EDE#TRPBF uniquely combines 3.3A dual-switch current capability, inverting topology support, and comprehensive fault signaling - making it irreplaceable in high-reliability, bipolar-output, or high-voltage boost applications.
Availability
LT3581EDE#TRPBF is available at Aetrix Electronics and suitable for automotive ECU power, VFD bias supplies, TFT-LCD bias generation, and industrial local power supply designs requiring stable component supply, long-term lifecycle assurance, and guaranteed -40°C to +125°C operation.
Supply support for LT3581EDE#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3581 product line was designed specifically for high-reliability, high-current DC/DC conversion in space-constrained environments requiring fault resilience, flexible topology support, and wide input voltage operation - especially where output short protection and thermal monitoring are critical.
FAQ
What is the maximum switching frequency supported by the LT3581EDE#TRPBF?
The LT3581EDE#TRPBF supports a maximum switching frequency of 2.5MHz when configured with a 34kΩ resistor from RT to ground. This high-frequency capability enables compact magnetic components and reduced output ripple, while maintaining stable current-mode control across its full operating temperature range of –40°C to +125°C. The LT3581EDE#TRPBF also supports synchronization to external clocks up to 2.5MHz.
How does the LT3581EDE#TRPBF implement output short-circuit protection?
The LT3581EDE#TRPBF detects output shorts via sample-mode overcurrent detection: when FB voltage deviates >3.7% from regulation, Q1 and Q2 are forced on each cycle to sample inductor current. If sampled current exceeds 1.9A (SW1) or 3.3A (SW1+SW2), the FAULT pin pulls low, GATE goes high-impedance, and switches disable. The LT3581EDE#TRPBF then executes a timeout sequence via SS pin charging/discharging before attempting recovery.
Can the LT3581EDE#TRPBF be used in inverting configurations, and what is the feedback reference voltage?
Yes, the LT3581EDE#TRPBF supports inverting configurations with a dedicated negative feedback reference voltage of 9mV at the FB pin. This low reference enables precise regulation of negative output voltages such as –12V at 625mA from a 5V input. The inverting topology leverages the same 42V-rated SW1/SW2 switches and retains full fault protection, making the LT3581EDE#TRPBF suitable for bipolar bias supplies in display and sensor applications.
What is the purpose of the GATE pin on the LT3581EDE#TRPBF, and how is it controlled?
The GATE pin on the LT3581EDE#TRPBF is a programmable pull-down current source (0–933µA) that drives the gate of an external PMOS transistor for output disconnect during fault conditions. Its current increases linearly with SS pin voltage, reaching full 933µA above 500mV - enabling soft turn-on of the PMOS to limit inrush current. During normal operation, GATE remains active only when SS > 500mV; during fault, it becomes high-impedance. This behavior is intrinsic to the LT3581EDE#TRPBF's fault-handling architecture.
Does the LT3581EDE#TRPBF support external frequency synchronization, and what are the voltage thresholds?
Yes, the LT3581EDE#TRPBF supports external frequency synchronization via the SYNC pin, which accepts logic-level clock inputs with a high threshold of 1.3V (typical) and low threshold of 0.4V (typical). When driven above 1.3V, the internal oscillator locks to the external clock; when pulled below 0.4V, it reverts to free-running mode set by the RT resistor. This feature allows deterministic phase alignment across multiple LT3581EDE#TRPBF units or with other compatible regulators.
LT3581EDE#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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-DFN (4x3)
LT3581EDE#TRPBF FAQ
1.How can I place an order for LT3581EDE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3581EDE#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 LT3581EDE#TRPBF reliable?
The price and inventory of LT3581EDE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3581EDE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3581EDE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3581EDE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3581EDE#TRPBF?
LT3581EDE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3581EDE#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 LT3581EDE#TRPBF?
For technical support, including LT3581EDE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3581EDE#TRPBF requirements.
6.How does Aetrix verify that LT3581EDE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3581EDE#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 LT3581EDE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3581EDE#TRPBF?
All LT3581EDE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3581EDE#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 LT3581EDE#TRPBF part is unused and in its original packaging.
Return procedure for LT3581EDE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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