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Analog Devices Inc. LT3509HMSE#PBF
- Part No.:
- LT3509HMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3509HMSE#PBF.pdf
- Description:
- IC REG BUCK ADJ 700MA DL 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:538
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Product details
Overview
LT3509HMSE#PBF from Analog Devices (formerly Linear Technology) is a dual-channel, current-mode, 36V-input, 700mA step-down DC/DC regulator IC with integrated power switches, internal compensation, and boost diodes. It delivers independent 3.3V and 5V outputs in automotive and industrial power systems requiring robust transient protection up to 60V and operation to 150°C junction temperature.
For engineers reviewing the LT3509HMSE#PBF datasheet, LT3509HMSE#PBF pinout, LT3509HMSE#PBF application, or LT3509HMSE#PBF equivalent, key selection considerations include its –40°C to 150°C H-grade MSOP package, adjustable 300kHz–2.2MHz switching frequency via RT resistor, independent RUN/SS soft-start control per channel, and overvoltage lockout at 38.5V typical.
Technical Context
The LT3509HMSE#PBF implements constant-frequency current-mode control with shared oscillator and reference across two independent channels operating in-phase. Each channel features cycle-by-cycle current limiting, thermal shutdown, and overvoltage/undervoltage protection-enabling reliable multi-rail regulation in harsh environments.
Its boost architecture uses internal Schottky diodes (BD pin) and external capacitors to drive switch bases above VIN, enabling >95% duty cycle and low dropout operation. Synchronization capability (SYNC pin) and RT-resistor programmability support EMI-sensitive designs and multi-converter coordination without frequency beating.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 36V continuous; withstands 60V transients - enables direct connection to 24V/36V automotive or industrial rails. |
| Output Current per Channel | 700mA - supports powering microcontrollers, FPGAs, and analog circuitry from each rail. |
| Switching Frequency | 300kHz to 2.2MHz (RT-programmable); synchronizable - avoids AM band interference and allows small ceramic output caps. |
| Feedback Reference Voltage | 0.800V ±2% - sets precise output voltage via resistor divider; stable over –40°C to 150°C. |
| Junction Temperature Range | –40°C to +150°C - qualified for under-hood automotive and high-ambient industrial use. |
| Overvoltage Lockout Threshold | 38.5V typical - protects internal switches and downstream loads during load-dump events. |
| Shutdown Current | 9µA max - minimizes battery drain in always-on systems when both channels disabled. |
Pinout & Package
LT3509HMSE#PBF is housed in a thermally enhanced 16-lead Plastic MSOP with exposed pad (pin 17 = GND), optimized for high-power density and thermal dissipation in space-constrained automotive modules.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DA1, DA2 (Pins 1, 8) | Catch diode anode sense | Internally connected to GND via current-sense resistors; monitors valley inductor current for short-circuit protection. |
| BOOST1, BOOST2 (Pins 2, 7) | Bootstrap capacitor node | Drives switch base above VIN via external capacitor; requires ≥2V above SW for full efficiency. |
| SW1, SW2 (Pins 3, 6) | Power switch output | Drives external inductors; connects to catch diode cathodes and BOOST capacitors. |
| VIN (Pins 4, 5) | Main input supply | Dual pins must be tied together; supplies control circuitry and internal switches; requires local ceramic bypass. |
| FB1, FB2 (Pins 16, 9) | Output voltage feedback | Compares output divider voltage to 0.8V reference; determines regulated output level per channel. |
| RUN/SS1, RUN/SS2 (Pins 15, 10) | Enable & soft-start control | 0.4–0.8V disables; 0.8–2.0V enables with current-limited soft-start; >2.0V enables full 700mA output. |
| RT (Pin 11) | Oscillator timing input | Sets switching frequency via resistor to GND; 40.2kΩ yields ~1MHz nominal. |
| SYNC (Pin 12) | External clock input | Accepts logic-level sync signal ≥1.0V threshold; free-run frequency must be ≥12% below sync source. |
| BD (Pin 13) | Boost diode common anode | Supplies charge current to both BOOST capacitors; must be locally bypassed with ceramic cap. |
| AGND (Pin 14) | Analog ground reference | Separate low-noise return for control circuitry; must connect to main GND plane but not sole ground path. |
| Exposed Pad (Pin 17) | Thermal & power ground | Electrically GND; must be soldered to PCB ground plane with thermal vias for 4.3°C/W θJC. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent regulators | Enables simultaneous 3.3V/5V or other dual-rail generation without external sequencing components. |
| Integrated boost diodes and compensation | Reduces BOM count by 4 diodes and 2 compensation networks; simplifies layout and validation. |
| 95% maximum duty cycle | Supports ultra-low dropout operation down to VIN ≈ VOUT + 0.5V, critical for cold-crank automotive scenarios. |
| 60V transient tolerance on VIN | Withstands ISO 7637-2 Pulse 5a load-dump events without external TVS, lowering system cost and footprint. |
| Independent RUN/SS pins | Allows staggered startup, fault-isolated shutdown, and dynamic current limiting per rail in real-time systems. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering DSP, display controller, and audio codec in head-unit under varying battery conditions (6V–16V), including cold-crank and load-dump transients. IC Role / Device Role / Timing Role: Dual-output DC/DC regulator providing isolated, sequenced 3.3V and 5V rails with built-in OVP and thermal protection. Use Value: Eliminates need for external TVS and sequencing ICs; 150°C rating ensures reliability in sealed enclosures near engine compartments. | Use Scenario: Generating stable 3.3V logic and 5V sensor interface rails in DIN-rail mounted controllers exposed to 40°C–85°C ambient and 36V field wiring. IC Role / Device Role / Timing Role: High-voltage dual buck converter delivering regulated outputs from unregulated 24V industrial supply. Use Value: Wide 3.6V–36V input range accommodates brownouts and surges; exposed-pad MSOP aids convection cooling in fanless enclosures. |
| Networking Equipment PoE PD | FPGA Core & Auxiliary Power |
Use Scenario: Secondary regulation stage in IEEE 802.3af/at powered device, stepping down 37–57V PoE input to 3.3V/5V for MAC/PHY and management MCU. IC Role / Device Role / Timing Role: Input-transient-hardened dual buck regulator handling PoE voltage ripple and surge while maintaining tight output regulation. Use Value: 60V VIN absolute max and 38.5V OVP prevent latch-up during PoE classification and detection phases. | Use Scenario: Supplying 1.8V core and 3.3V I/O rails for Xilinx Artix-7 FPGA in test equipment, where clean, low-noise, and fast transient response are critical. IC Role / Device Role / Timing Role: Dual-channel synchronous buck controller with independent soft-start and current limiting per rail. Use Value: Independent RUN/SS pins enable controlled FPGA configuration sequencing; 2.2MHz max frequency allows <1µH inductors and minimal output capacitance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-output step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3631EMSE#PBF | Single-channel, 36V, 1A buck; no dual output or BD pin; requires external diodes. | Lacks independent second rail and integrated boost diodes - suitable only if single-rail design suffices. | Select only when dual output is unnecessary and board area permits external diodes and compensation. |
| TPS54240DGQR | Single-channel, 40V, 2.5A buck; no integrated boost diodes; external compensation required. | Higher current but no dual regulation - needs two ICs for same functionality; no 150°C grade available. | Choose only for higher-current single-rail needs; not a functional substitute for dual-rail LT3509HMSE#PBF. |
Compared with LTC3631EMSE#PBF and TPS54240DGQR, the LT3509HMSE#PBF uniquely integrates dual 700mA regulators, boost diodes, and 150°C operation in one MSOP package-reducing component count, layout complexity, and thermal derating risk in compact automotive and industrial systems.
Availability
LT3509HMSE#PBF is available at Aetrix Electronics and suitable for automotive infotainment, industrial PLCs, and networking equipment requiring stable component supply across extended temperature and high-reliability environments.
Supply support for LT3509HMSE#PBF 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 power management ICs for demanding applications.
The LT3509 product line was designed specifically for ruggedized dual-rail DC/DC conversion in automotive, industrial, and telecom infrastructure-emphasizing transient robustness, wide temperature operation, and integration of protection and bias circuitry.
FAQ
What is the maximum allowable voltage on the VIN pin of the LT3509HMSE#PBF?
The LT3509HMSE#PBF has an absolute maximum VIN rating of 60V for non-repetitive 1-second transients, and 36V for continuous operation. Its overvoltage lockout activates at 38.5V typical to halt switching and protect internal circuitry during sustained overvoltage events such as automotive load dump.
Does the LT3509HMSE#PBF require external boost diodes?
No, the LT3509HMSE#PBF integrates Schottky boost diodes connected to the BD pin, eliminating the need for external diodes in standard configurations. The BD pin serves as the common anode for both channels' boost circuits, and must be locally bypassed with a ceramic capacitor for optimal performance.
How is the switching frequency set on the LT3509HMSE#PBF?
The switching frequency of the LT3509HMSE#PBF is set using a single resistor from the RT pin to ground. For example, a 40.2kΩ resistor yields ~1MHz; values from 13.7kΩ (2.2MHz) to 178kΩ (264kHz) cover the full programmable range. External synchronization via the SYNC pin is also supported.
What is the purpose of the AGND pin on the LT3509HMSE#PBF?
The AGND pin (Pin 14) on the LT3509HMSE#PBF provides a dedicated analog ground reference for the control circuitry, reducing noise coupling into the feedback and oscillator paths. It must be connected to the main PCB ground plane but should not serve as the sole ground return path-especially for high-current load-side components.
Can the LT3509HMSE#PBF operate with input voltage below 3.6V?
The LT3509HMSE#PBF incorporates an undervoltage lockout that disables switching below ~3.3V (typical). While the device may start regulating at slightly lower voltages depending on load and temperature, reliable operation is specified from 3.6V to 36V; operation below this risks instability or failure to maintain regulation.
LT3509HMSE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tube
- 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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LT3509HMSE#PBF FAQ
1.How can I place an order for LT3509HMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3509HMSE#PBF 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 LT3509HMSE#PBF reliable?
The price and inventory of LT3509HMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3509HMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3509HMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3509HMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3509HMSE#PBF?
LT3509HMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3509HMSE#PBF 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 LT3509HMSE#PBF?
For technical support, including LT3509HMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3509HMSE#PBF requirements.
6.How does Aetrix verify that LT3509HMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3509HMSE#PBF 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 LT3509HMSE#PBF meets industry standards.
7.What is the process for return or replacement of LT3509HMSE#PBF?
All LT3509HMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3509HMSE#PBF, 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 LT3509HMSE#PBF part is unused and in its original packaging.
Return procedure for LT3509HMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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