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Analog Devices Inc. LT3581EMSE#TRPBF
- Part No.:
- LT3581EMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3581EMSE#TRPBF.pdf
- Description:
- IC REG BST CHARG PUMP ADJ 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:620
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Product details
Overview
LT3581EMSE#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 output short-circuit protection, 200kHz–2.5MHz programmable switching frequency, and integrated fault detection for overvoltage, overtemperature, and overcurrent conditions - used in TFT-LCD bias supplies and automotive ECU local power rails.
For engineers reviewing the LT3581EMSE#TRPBF datasheet, LT3581EMSE#TRPBF pinout, LT3581EMSE#TRPBF application, or LT3581EMSE#TRPBF equivalent, key selection criteria include its dual-switch current sharing (1.9A/1.4A), 250mV typical VCE(SAT) at 2.75A, user-configurable undervoltage lockout via SHDN pin, and compatibility with external clock synchronization through SYNC/CLKOUT pins.
Technical Context
The LT3581EMSE#TRPBF employs constant-frequency current-mode control with internal ramp compensation and dual NPN power switches (SW1/SW2) capable of combined 3.3A current limiting. Its fault protection architecture includes real-time sampling mode for output short detection, frequency foldback during startup, and bidirectional FAULT pin logic that disables switching, pulls GATE high-impedance, and initiates SS pin timeout sequencing upon overvoltage (>22V VIN), overtemperature (>165°C), or overcurrent events.
It integrates a precision 1.215V positive feedback reference and 9mV negative reference for boost/inverting configurations, supports soft-start via external capacitor on SS pin with 250kΩ internal charge current, and provides buffered clock output (CLKOUT) with temperature-proportional duty cycle for system-level thermal monitoring and multi-regulator synchronization.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency Range | 200kHz to 2.5MHz - enables compact magnetics and EMI optimization via RT resistor or external SYNC clock. |
| Combined Switch Current Limit | 3.3A min - achieved by tying SW1 (1.9A min) and SW2 (1.4A min) with 78% current sharing ratio. |
| VCE(SAT) (SW1+SW2) | 250mV typ at 2.75A - reduces conduction loss and thermal stress in high-current boost/flyback designs. |
| Input Voltage Range | 2.5V to 22V operating, 40V transient - supports wide-input industrial and automotive supply rails. |
| Feedback Reference Voltage | 1.215V ±15mV (positive), 9mV ±6mV (negative) - enables accurate regulation in both boost and inverting modes. |
| Fault Detection Thresholds | VIN OVLO ≥22.1V, TJ ≥165°C, SW overvoltage ≥42V - autonomous protection without external circuitry. |
| Quiescent Current | 2.3mA typ (active), 1µA max (shutdown) - minimizes standby power in battery-sensitive applications. |
Pinout & Package
LT3581EMSE#TRPBF is housed in a 16-lead plastic MSOP package (4.0mm × 3.0mm × 1.1mm) with exposed thermal pad (Pin 17 = GND). The package supports high-power density layouts and requires soldering of the exposed pad to PCB ground for thermal management (θJA = 45°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (Pin 1) | Positive/Negative Feedback Input | Connects to output via resistor divider; sets regulation point at 1.215V (boost) or 9mV (inverting); bias current 83.3µA. |
| VC (Pin 2) | Error Amplifier Output | Drives external compensation network (capacitor + resistor + capacitor) to stabilize loop response. |
| GATE (Pin 3) | PMOS Gate Drive Output | Pull-down current source (max 933µA) for external PMOS disconnect switch; ramps with SS voltage. |
| FAULT (Pin 4) | Bidirectional Fault Indicator | Active-low open-drain output; pulled low internally on fault or externally to trigger shutdown sequence. |
| VIN (Pin 5) | Main Input Supply | Accepts 2.5V–22V; requires local ceramic bypass (≥4.7µF) near pin; 40V absolute max rating. |
| SW1 (Pins 6,7,8) | Master NPN Switch Collector | Handles up to 1.9A; minimize trace area to reduce EMI; rated for 42V breakdown. |
| SW2 (Pins 9,10,11) | Slave NPN Switch Collector | Shares current with SW1 at 78% ratio; enables 3.3A combined limit when tied together. |
| CLKOUT (Pin 12) | Synchronization Clock Output | Buffered oscillator output (1.9–2.3V high, <200mV low); drives ≤50pF load; duty cycle tracks junction temperature. |
| SHDN (Pin 13) | Shutdown/UVLO Control | High-gain input; activates at >1.33V (typ), deactivates at <1.24V (typ); supports slow-ramping signals and configurable UVLO. |
| RT (Pin 14) | Frequency Setting Input | Resistor-to-ground sets free-running frequency (e.g., 43.2kΩ → 2MHz); no floating allowed. |
| SS (Pin 15) | Soft-Start Timing Node | Charged by 250kΩ internal current source; controls ramp-up of switch current and GATE pull-down current. |
| SYNC (Pin 16) | External Clock Input | Accepts 0.4V–1.3V logic levels; overrides internal oscillator; enables multi-IC synchronization. |
| GND (Pin 17, Exposed Pad) | Power and Signal Ground | Thermal and electrical reference; must be soldered to PCB ground plane for thermal performance and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Master/Slave Switch Pair | Enables 3.3A total current capability with matched thermal behavior and automatic current sharing (78% SW2/SW1 ratio). |
| Output Short-Circuit Protection | Uses sample-mode current sensing every cycle to detect overcurrent before damage occurs; triggers FAULT pin and disables switches within microseconds. |
| Configurable Undervoltage Lockout | SHDN pin accepts external resistor divider to set precise VIN turn-on threshold (e.g., 8V or 12V), independent of internal 2.3V UVLO. |
| Frequency Foldback During Startup | Reduces fSW to 1/6 nominal when FB voltage is between 350mV–900mV, improving inductor current control and preventing peak current overshoot. |
| CLKOUT Temperature Monitoring | Duty cycle varies linearly with junction temperature (≈42% at 25°C, decreasing ~0.1%/°C), enabling passive thermal telemetry without extra sensors. |
Applications
| TFT-LCD Bias Supply | Vacuum Fluorescent Display (VFD) Bias |
|---|---|
Use Scenario: Generating stable ±15V to ±30V rails for LCD gate/source drivers and VCOM adjustment from a 5V or 12V system rail. IC Role / Device Role / Timing Role: Configured as inverting or SEPIC converter; uses dual switches to deliver high-voltage, low-noise outputs with tight regulation. Use Value: Eliminates need for discrete high-voltage charge pumps; achieves >85% efficiency at 625mA while maintaining output short protection. | Use Scenario: Providing isolated high-voltage anode bias (e.g., +40V to +120V) and grid bias (e.g., –10V to –30V) for vacuum fluorescent tube displays in automotive instrument clusters. IC Role / Device Role / Timing Role: Operated in flyback or charge-pump-aided topology; leverages SW1/SW2 tie configuration for high-voltage step-up with minimal component count. Use Value: Reduces bill-of-materials by 30% vs. traditional transformer-based solutions; maintains fault immunity during filament surge events. |
| Automotive Engine Control Unit (ECU) Local Power | Industrial Sensor Signal Conditioning |
Use Scenario: Generating 12V or –12V auxiliary rails from a noisy 5V microcontroller domain supply in engine control modules subjected to load dump transients. IC Role / Device Role / Timing Role: Used in boost configuration with external PMOS disconnect (driven by GATE pin); monitors FAULT pin for system-level diagnostics. Use Value: Survives 40V transients; shuts down within 10µs on output short; supports hot-plug operation via controlled soft-start. | Use Scenario: Powering precision op-amps, ADC references, and isolated interface ICs requiring clean, low-noise dual-rail supplies in factory automation I/O modules. IC Role / Device Role / Timing Role: Configured as SEPIC to maintain regulation during input dips (e.g., 3.3V–24V); uses CLKOUT to synchronize multiple converters and suppress beat frequencies. Use Value: Achieves <10mVpp output ripple at full load; eliminates cross-talk between adjacent signal chains via synchronized switching. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3873EMS#TRPBF | Single 60V N-channel MOSFET controller (no integrated switches); requires external FETs; supports up to 10A output. | Used in higher-current, higher-efficiency synchronous buck applications - not suitable for inverting or charge-pump topologies. | Select when designing >3A non-isolated buck regulators with external FET optimization; not a drop-in replacement. |
| LT8330EMSE#TRPBF | Single 60V monolithic boost converter (1.5A switch); lacks slave switch, fault protection, and dual-mode feedback. | Targeted at simpler boost-only applications without short-circuit or overvoltage protection requirements. | Choose for cost-sensitive, lower-current boost designs where fault robustness is secondary. |
Compared with LTC3873EMS#TRPBF and LT8330EMSE#TRPBF, the LT3581EMSE#TRPBF uniquely integrates dual 42V NPN switches with coordinated current limiting, comprehensive fault detection (including output short), and native support for inverting/SEPIC/flyback topologies - making it the only option among the three for high-reliability, multi-topology local power conversion in space-constrained environments.
Availability
LT3581EMSE#TRPBF is available at Aetrix Electronics and suitable for TFT-LCD bias supplies, automotive ECU local power, and industrial sensor signal conditioning requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT3581EMSE#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 technical and manufacturing continuity for all Linear power products, including rigorous AEC-Q200-aligned reliability testing and extended temperature grade support.
The LT3581EMSE#TRPBF belongs to Linear's high-integration PWM DC/DC converter family designed specifically for fault-tolerant local power generation in automotive, industrial, and display systems where output reliability under abnormal conditions is critical.
FAQ
What is the maximum combined output current achievable with LT3581EMSE#TRPBF in boost configuration?
The LT3581EMSE#TRPBF supports a guaranteed minimum combined switch current limit of 3.3A when SW1 and SW2 are tied together - enabling up to 830mA at 12V (boost) or 625mA at –12V (inverting) from a 5V input. Actual output current depends on layout, inductor selection, and thermal management; derating is required above 85°C ambient.
Does LT3581EMSE#TRPBF require external components for output short-circuit protection?
No. The LT3581EMSE#TRPBF implements autonomous output short-circuit protection via its internal sample-mode current sensing circuitry, which monitors SW1 current every switching cycle. When overcurrent is detected, it pulls the FAULT pin low, disables switching, and initiates SS pin timeout sequencing - all without external comparators or sense resistors.
Can LT3581EMSE#TRPBF be synchronized to an external clock source?
Yes. The LT3581EMSE#TRPBF accepts TTL/CMOS-compatible clock signals on its SYNC pin (thresholds: <0.4V low, >1.3V high) to override its internal oscillator. The CLKOUT pin simultaneously provides a buffered copy of the synchronized frequency, enabling deterministic phase alignment across multiple LT3581EMSE#TRPBF or compatible regulators.
What is the purpose of the GATE pin on LT3581EMSE#TRPBF and how is it used?
The GATE pin on LT3581EMSE#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 ramps linearly with SS pin voltage, enabling soft turn-on of the PMOS to limit inrush current - a key feature for hot-plug-capable power rails in automotive and industrial systems.
How does the LT3581EMSE#TRPBF handle overtemperature conditions?
The LT3581EMSE#TRPBF includes integrated overtemperature protection that triggers a FAULT1 event when junction temperature exceeds 165°C (min). Upon detection, it pulls the FAULT pin low, disables switching, sets GATE pin to high impedance, and initiates SS pin timeout sequencing - allowing thermal recovery before automatic restart, ensuring safe operation without external thermal sensors.
LT3581EMSE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width) 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:
- 16-MSOP-EP
LT3581EMSE#TRPBF FAQ
1.How can I place an order for LT3581EMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3581EMSE#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 LT3581EMSE#TRPBF reliable?
The price and inventory of LT3581EMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3581EMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3581EMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3581EMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3581EMSE#TRPBF?
LT3581EMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3581EMSE#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 LT3581EMSE#TRPBF?
For technical support, including LT3581EMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3581EMSE#TRPBF requirements.
6.How does Aetrix verify that LT3581EMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3581EMSE#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 LT3581EMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3581EMSE#TRPBF?
All LT3581EMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3581EMSE#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 LT3581EMSE#TRPBF part is unused and in its original packaging.
Return procedure for LT3581EMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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