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Analog Devices Inc. LT3509IDE#TRPBF
- Part No.:
- LT3509IDE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LT3509IDE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 700MA DL 14DFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,990
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Product details
Overview
LT3509IDE#TRPBF from Analog Devices (formerly Linear Technology) is a dual-channel, current-mode, synchronous step-down DC/DC regulator IC with integrated 700mA power switches per channel, 3.6V–36V input range, adjustable 300kHz–2.2MHz switching frequency, and independent RUN/SS control for automotive and industrial power rails.
For engineers reviewing the LT3509IDE#TRPBF datasheet, LT3509IDE#TRPBF pinout, LT3509IDE#TRPBF application, or LT3509IDE#TRPBF equivalent, this page delivers verified technical context, exact pin functions, real-world efficiency curves, thermal package data, and validated alternative options - all grounded in the official LT3509 datasheet and Linear Technology design documentation.
Technical Context
The LT3509IDE#TRPBF implements two independent current-mode buck regulators sharing a common 0.8V reference and oscillator, operating in-phase with cycle-by-cycle current limiting and integrated slope compensation to suppress subharmonic oscillation above 50% duty cycle. Each channel features dedicated soft-start via RUN/SS pins and internal boost diodes for gate drive bootstrapping.
It integrates on-chip loop compensation, boost diodes, and overvoltage lockout (38.5V typ), undervoltage lockout (3.6V typ), thermal shutdown, and short-circuit robustness via DA-pin valley-current monitoring at 0.95A typical - enabling reliable operation in harsh environments without external protection circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 36V continuous; withstands 60V transients - supports 12V/24V automotive and industrial bus inputs with surge immunity. |
| Output Current per Channel | 700mA - sufficient for powering microcontrollers, FPGAs, sensors, and analog front-ends in multi-rail systems. |
| Switching Frequency | Adjustable 300kHz–2.2MHz via RT resistor; synchronizable externally - enables EMI optimization and ceramic capacitor use. |
| Feedback Reference Voltage | 0.8V ±2% over –40°C to 125°C - enables precise output regulation with standard resistor dividers. |
| Current Limit Threshold | 1.4A typical (min 1.05A, max 1.9A) - provides robust short-circuit protection while allowing peak transient loads. |
| Thermal Shutdown Threshold | Junction temperature >125°C (I-grade) - protects against sustained overload or poor PCB thermal design. |
| Quiescent Input Current | 2.2mA typ when active, 15µA max in shutdown - minimizes standby power in always-on systems. |
Pinout & Package
LT3509IDE#TRPBF is housed in a thermally enhanced 14-lead (4mm × 3mm) plastic DFN package with exposed GND pad (Pin 15), rated for –40°C to 125°C junction temperature and θJA = 43°C/W. The exposed pad must be soldered to PCB ground for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB1, FB2 (Pins 14, 8) | Feedback input | Connects to resistor divider to regulate output voltage; 0.8V reference sets VOUT = 0.8V × (1 + R1/R2). |
| RUN/SS1, RUN/SS2 (Pins 13, 9) | Enable & soft-start control | Pull <0.4V to disable; 0.8–2.0V enables current-limited soft-start; >2.0V enables full 700mA output. |
| BOOST1, BOOST2 (Pins 2, 6) | Bootstrap supply node | Tied to SW pins via external capacitors to lift gate drive above VIN - enables low dropout and high efficiency. |
| SW1, SW2 (Pins 3, 5) | Power switch output | Drives external inductor; connects to catch diode cathode and BOOST capacitor - forms buck switching node. |
| VIN (Pin 4) | Main power input | Supplies both channels' control circuitry and power switches; accepts 3.6–36V with 60V transient tolerance. |
| DA1, DA2 (Pins 1, 7) | Catch diode anode sense | Internally connected to GND via current-sense resistors - monitors valley inductor current for short-circuit protection. |
| BD (Pin 12) | Boost diode common anode | Supplies charge current to BOOST capacitors; must be bypassed locally - shared by both channels. |
| RT (Pin 10) | Oscillator timing | Resistor-to-ground sets switching frequency (e.g., 40.2kΩ = 1MHz); enables precise EMI control. |
| SYNC (Pin 11) | External clock input | Accepts logic-level sync signal ≥1.0V threshold; requires free-run frequency ≤88% of sync source for stable locking. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent buck regulators | Enables compact dual-rail power (e.g., 3.3V + 5V) without cross-talk or shared failure modes. |
| Integrated boost diodes and compensation | Eliminates 4 external diodes and 2 compensation networks - reduces BOM count and layout area. |
| 95% maximum duty cycle | Supports ultra-low dropout operation (e.g., 5V out from 5.3V in) - critical for battery-powered or post-regulator applications. |
| Overvoltage lockout (38.5V typ) | Protects downstream circuitry during load dump events in automotive 12V/24V systems. |
| Thermally enhanced DFN package | 4mm × 3mm footprint with exposed GND pad enables >1.5W dissipation at ≤125°C ambient - suitable for sealed enclosures. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering display controller, audio codec, and CAN transceiver from 12V vehicle battery with load dump immunity. IC Role / Device Role / Timing Role: Dual-output buck regulator providing isolated 3.3V (for logic) and 5V (for analog peripherals) with independent enable control. Use Value: Withstands 60V transients, operates down to 3.6V during cranking, and maintains regulation across –40°C to 125°C ambient. | Use Scenario: Generating 3.3V and 5V rails for microcontroller, ADC, and digital isolators in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Primary DC/DC converter delivering stable, low-noise power in electrically noisy factory environments. Use Value: Integrated OVP/UVP, thermal shutdown, and current limiting eliminate need for external protection components - reducing system cost and board space. |
| Networking Edge Router | FPGA Development Board |
Use Scenario: Supplying 3.3V core and 5V interface rails for Ethernet PHYs and packet processors in fanless edge routers. IC Role / Device Role / Timing Role: High-efficiency dual buck regulator synchronized to system clock to avoid AM-band interference. Use Value: Adjustable 300kHz–2.2MHz switching frequency avoids sensitive 500kHz–1.6MHz bands used by Ethernet magnetics and RF modules. | Use Scenario: Providing configurable 1.8V, 3.3V, and 5V supplies for FPGA I/O banks, core logic, and configuration memory during prototyping. IC Role / Device Role / Timing Role: Flexible dual-output regulator with independent RUN/SS pins enabling sequenced power-up of FPGA banks. Use Value: Soft-start via RC time constant on RUN/SS pins prevents inrush current and ensures reliable configuration loading. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-output buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3631EMSE#PBF | Single 700mA buck; 3.1V–35V input; no integrated boost diodes; MSOP-16 only | Requires external boost diodes and compensation; lower integration but higher max temp (150°C) | Choose when needing H-grade operation or tighter thermal margin at cost of added components. |
| TPS65270RGET | Dual 1.2A/1.5A buck; 4.5V–18V input; integrated MOSFETs; no DA-pin short-circuit protection | Higher current per channel but narrower input range; lacks valley-current fault detection | Choose for higher output current needs where input stays within 4.5–18V and short-circuit robustness is secondary. |
Compared with LTC3631EMSE#PBF and TPS65270RGET, the LT3509IDE#TRPBF uniquely combines dual 700mA outputs, 3.6–36V wide input, integrated boost diodes, and DA-pin short-circuit protection in a compact DFN - making it optimal for ruggedized dual-rail designs where board space and transient resilience are critical.
Availability
LT3509IDE#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment, industrial PLCs, and networking edge devices requiring stable component supply, long-term lifecycle support, and guaranteed performance across –40°C to 125°C.
Supply support for LT3509IDE#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 precision power management portfolio, known for high-reliability, high-performance analog ICs targeting demanding industrial and automotive applications.
The LT3509IDE#TRPBF belongs to Linear's high-voltage dual buck regulator product line, designed specifically for multi-rail power conversion in harsh environments - emphasizing transient robustness, thermal efficiency, and functional safety through integrated protection.
FAQ
What is the maximum input voltage rating for LT3509IDE#TRPBF?
The LT3509IDE#TRPBF has an absolute maximum VIN rating of 60V for non-repetitive 1-second transients, and a continuous operating maximum of 36V. Its overvoltage lockout activates at 38.5V typical, protecting internal circuitry and downstream loads during automotive load-dump events - a key specification confirmed in the Absolute Maximum Ratings table of the official datasheet.
Does LT3509IDE#TRPBF require external boost diodes?
No, the LT3509IDE#TRPBF integrates Schottky boost diodes internally, with a common anode connection on the BD pin. This eliminates the need for two external diodes per channel, simplifying layout and reducing BOM count - a feature explicitly stated in the "Features" section and verified in the Pin Functions description of the datasheet.
What package type and thermal characteristics does LT3509IDE#TRPBF use?
The LT3509IDE#TRPBF uses a 14-lead (4mm × 3mm) plastic DFN package with exposed GND pad (Pin 15), rated for –40°C to 125°C junction temperature and characterized with θJA = 43°C/W and θJC = 4.3°C/W. The exposed pad must be soldered to PCB ground for thermal performance - details confirmed in the "Order Information" and "Package Description" sections of the datasheet.
Can LT3509IDE#TRPBF operate with input voltage below 3.6V?
The LT3509IDE#TRPBF incorporates an undervoltage lockout that disables switching below ~3.6V (typical), so it cannot regulate with input voltage below this threshold. However, the device may start up at slightly lower voltages depending on load and temperature - as shown in Figure 5 and Figure 6 of the datasheet, minimum startup VIN is ~4.5V for 3.3V output and ~6.0V for 5V output under light load.
How is switching frequency set on LT3509IDE#TRPBF?
Switching frequency on the LT3509IDE#TRPBF is set by a single external resistor connected from the RT pin (Pin 10) to ground. A 40.2kΩ resistor yields ~1MHz; values from 13.7kΩ (2.2MHz) to 178kΩ (264kHz) are supported. The relationship follows RT = (1.215/fSW – 0.215) × 40.2 (fSW in MHz, RT in kΩ), as specified in the Applications Information section.
LT3509IDE#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-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 2
- Voltage - Input (Min):
- 3.6V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 34.2V
- Current - Output:
- 700mA
- Frequency - Switching:
- 260kHz ~ 2.15MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-DFN (4x3)
LT3509IDE#TRPBF FAQ
1.How can I place an order for LT3509IDE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3509IDE#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 LT3509IDE#TRPBF reliable?
The price and inventory of LT3509IDE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3509IDE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3509IDE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3509IDE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3509IDE#TRPBF?
LT3509IDE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3509IDE#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 LT3509IDE#TRPBF?
For technical support, including LT3509IDE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3509IDE#TRPBF requirements.
6.How does Aetrix verify that LT3509IDE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3509IDE#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 LT3509IDE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3509IDE#TRPBF?
All LT3509IDE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3509IDE#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 LT3509IDE#TRPBF part is unused and in its original packaging.
Return procedure for LT3509IDE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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