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Analog Devices Inc. LT3581IMSE#TRPBF
- Part No.:
- LT3581IMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3581IMSE#TRPBF.pdf
- Description:
- IC REG BST CHARG PUMP ADJ 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,524
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Product details
Overview
LT3581IMSE#TRPBF from Analog Devices (formerly Linear Technology) is a 3.3A, 42V dual-switch PWM DC/DC converter IC configured as a boost/inverting regulator with integrated fault protection. It features master/slave NPN switches (1.9A/1.4A), 2.5MHz max switching frequency, output short-circuit protection, and programmable undervoltage lockout. It delivers 12V at 830mA or –12V at 625mA from a 5V input in compact MSOP-16 packaging.
For engineers reviewing the LT3581IMSE#TRPBF datasheet, LT3581IMSE#TRPBF pinout, LT3581IMSE#TRPBF application, or LT3581IMSE#TRPBF equivalent, key selection considerations include its combined 3.3A current limit with SW1+SW2 tie-together capability, 2.5MHz synchronization-ready oscillator, fault-protected GATE-driven PMOS disconnect, and MSE package thermal performance (θJA = 45°C/W).
Technical Context
The LT3581IMSE#TRPBF employs constant-frequency current-mode control with internal ramp compensation and dual NPN power switches. Its master/slave architecture enables flexible topologies-boost, SEPIC, inverting, or flyback-and supports high-voltage charge-pump configurations when SW1 and SW2 are tied together.
Fault detection includes overcurrent (SW1 >1.9A or SW1+SW2 >3.3A), input overvoltage (>22V), switch overvoltage (>42V), and overtemperature (>165°C). The FAULT pin is bidirectional and actively pulls low during faults, disabling switching, CLKOUT, and enabling soft-start timeout recovery.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Configuration | Dual NPN: 1.9A master (SW1) + 1.4A slave (SW2); combined 3.3A limit when tied |
| Input Voltage Range | 2.5V to 22V operating; 40V transient tolerance - supports wide automotive and industrial rails |
| Switching Frequency | 200kHz–2.5MHz adjustable via RT resistor or external SYNC clock - enables EMI optimization and small magnetics |
| Feedback Reference | 1.215V (positive) / 9mV (negative) - precise regulation for boost or inverting outputs |
| Protection Features | Output short-circuit, VIN OVLO (22.1–25V), SW overvoltage (42V), overtemperature (165°C), and fault-activated GATE pull-down |
| Soft-Start Control | SS pin charges via 250kΩ internal current source; 0–2.1V ramp controls current limit and GATE drive slew rate |
| Package & Thermal | 16-Lead MSOP (MSE); θJA = 45°C/W, θJC = 10°C/W; exposed pad must be soldered to PCB ground |
Pinout & Package
LT3581IMSE#TRPBF is housed in a 16-lead plastic MSOP (MSE) package with an exposed thermal pad (Pin 17) that must be soldered to the PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB (Pin 1) | Positive/Negative Feedback Input | Accepts 1.215V (boost) or 9mV (inverting) reference; bias current 83.3µA - sets output voltage via single resistor |
| VC (Pin 2) | Error Amplifier Output | Drives external compensation network (R-C-RC) - determines loop stability and transient response |
| GATE (Pin 3) | PMOS Gate Drive Output | Pull-down current source (up to 933µA); linearly controlled by SS voltage - enables soft-started output disconnect |
| FAULT (Pin 4) | Bidirectional Fault Indicator | Active-low open-collector; pulled low internally on fault or externally to trigger shutdown - initiates SS timeout sequence |
| VIN (Pin 5) | Main Input Supply | 2.5V–22V operation; 40V absolute max - requires local ceramic bypass (≥4.7µF) |
| SW1 (Pins 6,7,8) | Master Switch Collector | 1.9A rated NPN collector; minimize trace area to reduce EMI - connects to inductor/transformer primary |
| SW2 (Pins 9,10,11) | Slave Switch Collector | 1.4A rated NPN collector; shares current with SW1 when tied - enables higher-power topologies |
| CLKOUT (Pin 12) | Synchronized Clock Output | Buffered oscillator output (2.1Vpp, 42% duty cycle); drives ≤50pF load - synchronizes other regulators or monitors die temperature |
| SHDN (Pin 13) | Shutdown/UVLO Input | High-gain comparator with 1.33V typical threshold and 30mV hysteresis - enables slow-ramping enable/disable and configurable UVLO |
| RT (Pin 14) | Oscillator Timing Input | Resistor-to-ground sets free-running frequency (200kHz–2.5MHz); no external capacitor required |
| SS (Pin 15) | Soft-Start Control | Charged by 250kΩ current source to 2.1V; controls current limit ramp and GATE drive activation - prevents inrush and enables hot-swap |
| SYNC (Pin 16) | External Clock Input | Accepts 0.4V–1.3V logic levels; overrides internal oscillator - allows system-level clock domain alignment |
| GND (Exposed Pad) | Power & Signal Ground | Thermal and electrical reference; mandatory solder connection to PCB ground plane - critical for θJC = 10°C/W performance |
Key Features
| Feature | Design Value |
|---|---|
| Combined 3.3A Power Switch | SW1+SW2 tied configuration delivers 3.3A total current limit with guaranteed 78% current sharing - enables high-current boost/inverting designs without external MOSFETs |
| Programmable UVLO with SHDN Pin | Configurable turn-on threshold using external resistor divider on SHDN - supports custom input voltage sequencing and brown-in/out behavior |
| Sample Mode Fault Detection | Forces Q1/Q2 on every cycle when FB is out of regulation (>3.7%) - detects output shorts before catastrophic current rise, enabling fast fault response |
| Frequency Foldback | Reduces fSW to 1/6 normal when FB = 350–900mV - lowers minimum duty cycle to improve start-up control under heavy loads or low VIN |
| CLKOUT Temperature Monitoring | CLKOUT duty cycle varies linearly with junction temperature - provides non-invasive thermal feedback without additional sensors or pins |
| Low VCE(SAT) Switches | 250mV typical saturation voltage at 2.75A (SW1+SW2 tied) - minimizes conduction loss and improves efficiency at full load |
Applications
| Automotive Engine Control Unit (ECU) Power | Vacuum Fluorescent Display (VFD) Bias Supplies |
|---|---|
|
Use Scenario: Generating isolated ±12V rails from a 12V battery supply in engine bay environments with wide temperature swings and load dump transients. IC Role / Device Role / Timing Role: Dual-switch boost/inverting controller providing regulated high-voltage bias with fault protection against shorted display segments or wiring faults. Use Value: Eliminates need for discrete protection circuitry; withstands 40V transients; operates from –40°C to 125°C; reduces BOM count by integrating dual switches and fault logic. |
Use Scenario: Driving VFD anode and grid supplies requiring stable +20V and –20V outputs from a 5V microcontroller rail in instrument clusters. IC Role / Device Role / Timing Role: Inverting converter generating negative bias while boosting positive rail, with synchronized switching to minimize EMI near sensitive analog circuits. Use Value: Achieves 20V@200mA and –20V@150mA simultaneously; 2.5MHz operation allows <1µH inductors; GATE-controlled PMOS isolates faults to prevent display burn-in. |
| TFT-LCD Bias Supplies | Local Power Supply for Industrial Sensors |
|
Use Scenario: Providing AVDD (+15V), VGH (+25V), and VGL (–10V) for TFT panel drivers in medical imaging displays where reliability and low noise are critical. IC Role / Device Role / Timing Role: Configured in multi-output flyback or charge-pump topology to generate multiple high-voltage rails with tight regulation and fast transient response. Use Value: Single-chip solution replaces three discrete converters; fault protection prevents damage from LCD panel arcing; CLKOUT synchronization avoids beat frequencies with display timing clocks. |
Use Scenario: Powering isolated analog front-ends and signal conditioners in factory automation nodes where input voltage varies between 3.3V and 24V. IC Role / Device Role / Timing Role: Wide-input boost regulator delivering stable 5V or 3.3V to precision ADCs and op-amps, with undervoltage lockout preventing erratic behavior during brownouts. Use Value: Operates down to 2.5V input - supports backup battery operation; soft-start prevents sensor reset glitches; 45°C/W thermal resistance sustains full load at 70°C ambient. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-switch DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3573EMSE#TRPBF | Single 3.3A switch (no slave), 40V rating, no GATE pin, no sample mode - lacks dual-switch flexibility and output disconnect capability | Suitable only for basic boost/SEPIC; cannot implement inverting or fault-isolated topologies | Select when cost and footprint are prioritized over fault resilience and topology versatility |
| LM5122MMX/NOPB | 3.5A synchronous buck-boost controller (external FETs), 65V rating, no integrated switches - requires 4 external MOSFETs and gate drivers | Supports wider VIN range (3.5–65V) and higher power, but increases layout complexity and component count | Select for >22V input or >3.3A continuous output where discrete FET optimization is needed |
Compared with LT3573EMSE#TRPBF and LM5122MMX/NOPB, the LT3581IMSE#TRPBF uniquely integrates dual NPN switches with coordinated fault handling, GATE-driven PMOS disconnect, and sample-mode short-circuit detection - making it optimal for space-constrained, safety-critical bias supply designs where reliability trumps raw voltage range or peak current.
Availability
LT3581IMSE#TRPBF is available at Aetrix Electronics and suitable for automotive ECU power, VFD bias supplies, TFT-LCD bias generation, and industrial sensor local power requiring stable component supply across extended temperature ranges.
Supply support for LT3581IMSE#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 its legacy of high-performance analog and power management ICs with rigorous qualification and long-term product support.
The LT3581IMSE#TRPBF belongs to Linear's high-reliability DC/DC converter family designed for fault-tolerant local power in automotive, industrial, and display systems - emphasizing integrated protection, thermal robustness, and topology flexibility over basic conversion efficiency.
FAQ
What is the maximum switching frequency supported by the LT3581IMSE#TRPBF?
The LT3581IMSE#TRPBF supports a maximum switching frequency of 2.5MHz when configured with an appropriate RT resistor (e.g., 34kΩ to ground). This high-frequency capability enables use of sub-1µH inductors and compact ceramic output capacitors, reducing board area and improving transient response in space-constrained applications like TFT-LCD bias supplies.
How does the LT3581IMSE#TRPBF protect against output short circuits?
The LT3581IMSE#TRPBF uses Sample Mode fault detection: when FB voltage deviates >3.7% from regulation (e.g., due to short), it forces both SW1 and SW2 on each cycle to sample inductor current. If sampled current exceeds 1.9A (SW1) or 3.3A (combined), the FAULT pin pulls low, disabling switching and activating the GATE pin to turn off an external PMOS - physically disconnecting the output within microseconds.
Can the LT3581IMSE#TRPBF be used in inverting configurations?
Yes, the LT3581IMSE#TRPBF is explicitly designed for inverting operation. With FB referenced to 9mV (not 1.215V), it regulates negative outputs such as –12V at 625mA from a 5V input. The datasheet provides dedicated inverting design equations, feedback resistor calculation, and layout guidance - confirming full support for this topology in the LT3581IMSE#TRPBF's specification set.
What is the purpose of the GATE pin on the LT3581IMSE#TRPBF?
The GATE pin on the LT3581IMSE#TRPBF is a programmable pull-down current source (0–933µA) that drives the gate of an external PMOS transistor. During normal operation, it remains high-impedance; during fault events, it activates to pull the PMOS gate low, disconnecting the output path. Its linear control by the SS pin also enables soft-started turn-on, limiting inrush current in hot-plug scenarios.
Does the LT3581IMSE#TRPBF require external compensation components?
Yes, the LT3581IMSE#TRPBF requires external compensation on the VC pin. A standard Type II network (resistor + capacitor + series RC) is used to stabilize the current-mode control loop. The datasheet provides design equations and example values (e.g., 10kΩ, 1nF, 10.5kΩ+0.1µF) based on selected inductor and output capacitor - omitting these components will cause instability or poor transient response.
LT3581IMSE#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
LT3581IMSE#TRPBF FAQ
1.How can I place an order for LT3581IMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3581IMSE#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 LT3581IMSE#TRPBF reliable?
The price and inventory of LT3581IMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3581IMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3581IMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3581IMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3581IMSE#TRPBF?
LT3581IMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3581IMSE#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 LT3581IMSE#TRPBF?
For technical support, including LT3581IMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3581IMSE#TRPBF requirements.
6.How does Aetrix verify that LT3581IMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3581IMSE#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 LT3581IMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3581IMSE#TRPBF?
All LT3581IMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3581IMSE#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 LT3581IMSE#TRPBF part is unused and in its original packaging.
Return procedure for LT3581IMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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