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Analog Devices Inc. LT3509IMSE#TRPBF
- Part No.:
- LT3509IMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3509IMSE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 700MA DL 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,570
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Product details
Overview
LT3509IMSE#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, 3.6V–36V input range, and independent RUN/SS control per channel - designed for automotive and industrial multi-rail power systems requiring robust transient immunity up to 60V and constant-frequency operation above the AM band.
For engineers reviewing the LT3509IMSE#TRPBF datasheet, LT3509IMSE#TRPBF pinout, LT3509IMSE#TRPBF application, or LT3509IMSE#TRPBF equivalent, key selection considerations include its dual 700mA output capability, adjustable 300kHz–2.2MHz switching frequency via RT resistor, internal boost diodes and compensation, thermal shutdown, overvoltage lockout (38.5V typ), and MSOP-16 package with exposed pad for enhanced thermal performance.
Technical Context
The LT3509IMSE#TRPBF implements a dual, phase-aligned, current-mode control architecture with shared oscillator and reference but independent error amplifiers, soft-start, and shutdown logic per channel. Each regulator uses cycle-by-cycle peak current limiting and valley current monitoring via DA pins to enable short-circuit robustness.
Its BOOST circuit employs internal Schottky diodes (BD pin) and external capacitors to drive switch bases above VIN, enabling >95% duty cycle and low dropout operation. Switching frequency is set by RT (264kHz–2.2MHz) or synchronized externally via SYNC pin with ≥12% margin below external clock.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 36V continuous; withstands 60V transients - enables direct connection to automotive battery rails with load dump protection. |
| Output Current per Channel | 700mA - sufficient for powering core logic rails of microcontrollers, FPGAs, and DSPs in compact multi-rail designs. |
| Switching Frequency | Adjustable 300kHz–2.2MHz via RT resistor; synchronizable externally - avoids AM-band interference and supports small ceramic capacitors & low-profile inductors. |
| Feedback Reference Voltage | 0.800V ±2% over –40°C to 125°C - enables precise output regulation (e.g., 3.3V, 5V, 1.8V) using standard resistor dividers. |
| Overvoltage Lockout Threshold | 38.5V typical - disables switching during 60V transients to protect internal switches and downstream circuitry. |
| Thermal Shutdown | Activates at junction temperature >150°C (H-grade) or >125°C (I-grade); LT3509IMSE#TRPBF is I-grade - ensures safe operation under sustained overload or poor PCB thermal design. |
| Package | 16-Lead MSOP with exposed thermal pad - θJA = 43°C/W; requires soldered GND pad and thermal vias for reliable 700mA operation at high ambient temperatures. |
Pinout & Package
LT3509IMSE#TRPBF is housed in a 16-lead plastic MSOP package with exposed pad (Pin 17 = GND), optimized for thermal dissipation in space-constrained industrial and automotive applications. The exposed pad must be soldered to a PCB ground plane with multiple thermal vias.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| DA1, DA2 (Pins 1, 8) | Catch diode anode sense terminals | Internally connected to GND via current-sense resistors; monitor valley inductor current for short-circuit detection and current limiting. |
| BOOST1, BOOST2 (Pins 2, 7) | Bootstrap capacitor connection points | Accept charge from BD pin to elevate switch base voltage above VIN - critical for low RDS(on) conduction and <95% max duty cycle operation. |
| SW1, SW2 (Pins 3, 6) | Internal power switch outputs | Drive external inductors and catch diodes; require low-inductance layout to minimize EMI and voltage spikes during switching transitions. |
| VIN (Pins 4, 5) | Main power input | Dual-pin configuration mandates tying together; supplies both control circuitry and power switches - demands local 10µF+ ceramic input capacitance. |
| FB1, FB2 (Pins 16, 9) | Output voltage feedback inputs | Compare regulated output to 0.8V internal reference; resistor divider ratio sets VOUT - R2 ≤20kΩ recommended to minimize bias current error. |
| RUN/SS1, RUN/SS2 (Pins 15, 10) | Channel enable & soft-start control | 0.4–0.8V = shutdown; 0.8–2.0V = current-limited soft-start; >2.0V = full 700mA operation - supports sequenced power-up and fault recovery. |
| RT (Pin 11) | Oscillator timing resistor connection | Single external resistor sets free-running frequency (e.g., 40.2kΩ = 1MHz); enables precise EMI management and layout optimization. |
| SYNC (Pin 12) | External clock synchronization input | Accepts logic-level clock (1.0V threshold); requires free-run frequency ≥12% lower than sync source - eliminates beat frequencies in multi-regulator systems. |
| BD (Pin 13) | Common anode of internal Schottky boost diodes | Supplies charge to BOOST1/BOOST2 capacitors; must be locally bypassed with 1µF ceramic to minimize AC impedance and ensure stable bootstrapping. |
| AGND (Pin 14) | Analog ground reference | Separate low-noise return for feedback and control circuitry - should connect to main GND plane only at single point near exposed pad to avoid noise coupling. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent 700mA regulators | Enables compact dual-rail solutions (e.g., 3.3V + 5V) without discrete controllers or external MOSFETs - reduces BOM count and board area. |
| Integrated boost diodes and compensation | Eliminates 4 external Schottky diodes and 2 RC compensation networks - simplifies layout, improves reliability, and accelerates time-to-market. |
| Overvoltage lockout (38.5V typ) and 60V transient tolerance | Protects against ISO 7637-2 Pulse 5a load dump events in automotive environments without external TVS clamping. |
| Independent RUN/SS pins with soft-start | Supports controlled power sequencing (e.g., core before I/O) and automatic recovery after overtemperature or overvoltage faults - enhances system robustness. |
| Thermally enhanced MSOP-16 with exposed pad | Delivers 700mA per channel at 125°C ambient when properly mounted - suitable for under-hood or enclosed industrial enclosures without forced airflow. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
|
Use Scenario: Powering 3.3V MCU core and 5V CAN transceiver from 12V vehicle battery with load dump transients. IC Role / Device Role / Timing Role: Dual-output step-down regulator providing isolated, sequenced, and transient-hardened rails. Use Value: Withstands 60V transients without external protection; independent RUN/SS allows MCU to enable CAN only after stable 3.3V rail is established. |
Use Scenario: Generating 5V sensor interface and 3.3V FPGA I/O rails in DIN-rail mounted programmable logic controller. IC Role / Device Role / Timing Role: Compact dual-buck converter delivering two independent, well-regulated supplies from wide-range 24V DC industrial bus. Use Value: 3.6V–36V input range accommodates brownouts and surges; thermally robust MSOP package operates reliably at 70°C ambient without derating. |
| Networking Equipment PoE PD | FPGA Core & Auxiliary Power |
|
Use Scenario: Converting 48V PoE midspan output to 3.3V logic and 5V PHY rails in IEEE 802.3af/at powered device. IC Role / Device Role / Timing Role: High-input-voltage dual buck regulator with fast transient response for Ethernet switch port power management. Use Value: Adjustable switching frequency avoids noise coupling into Gigabit Ethernet signal paths; internal compensation ensures stability across line/load variations. |
Use Scenario: Supplying 1.2V FPGA core and 2.5V I/O banks from 12V intermediate bus in embedded vision system. IC Role / Device Role / Timing Role: Dual-channel DC/DC controller supporting independent enable and soft-start for FPGA configuration sequencing. Use Value: 700mA per channel meets typical FPGA auxiliary rail requirements; SYNC pin enables deterministic switching alignment with system clock domain. |
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 |
|---|---|---|---|
| LT8609S | Silent Switcher® architecture; 2.5A per channel; 3V–42V input; integrated shielding reduces EMI by >40dB. | Better suited for noise-sensitive RF or medical applications where conducted emissions must meet CISPR 22 Class B. | Select LT8609S when ultra-low EMI is mandatory and higher current (>700mA) is required; not pin-compatible with LT3509IMSE#TRPBF. |
| TPS54290 | TI part; dual 2A channels; 4.5V–28V input; external compensation; no integrated boost diodes. | Requires 4 external Schottky diodes and 2 RC networks; wider input range unsuitable for 36V+ automotive transients. | Choose TPS54290 for cost-sensitive industrial applications with <28V input and available board space for discrete components. |
Compared with LT8609S and TPS54290, the LT3509IMSE#TRPBF offers optimal balance of integration (integrated boost diodes, compensation), automotive-grade transient tolerance (60V), and compact MSOP packaging - making it ideal for space- and reliability-constrained dual-rail designs where EMI is managed at system level.
Availability
LT3509IMSE#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment, industrial PLCs, networking PoE PDs, and FPGA power systems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT3509IMSE#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-Q100 stress testing for automotive-qualified variants.
The LT3509IMSE#TRPBF belongs to Linear's high-reliability monolithic DC/DC regulator family, engineered specifically for harsh-environment power conversion in automotive, industrial, and avionics applications where input transients, thermal stress, and long-term stability are critical.
FAQ
What is the maximum input voltage rating for LT3509IMSE#TRPBF?
The LT3509IMSE#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, disabling switching to protect internal circuitry during automotive load dump events. This makes LT3509IMSE#TRPBF suitable for direct connection to 12V and 24V vehicle batteries with transient immunity.
Does LT3509IMSE#TRPBF require external boost diodes?
No. The LT3509IMSE#TRPBF integrates Schottky boost diodes connected to the BD pin, eliminating the need for four external diodes typically required in bootstrap-based buck regulators. This integration reduces component count, PCB area, and potential failure points - a key differentiator versus alternatives like TPS54290 that require external diodes.
Can LT3509IMSE#TRPBF operate with only one channel enabled?
Yes. The LT3509IMSE#TRPBF supports independent channel control via RUN/SS1 and RUN/SS2 pins. Either channel can be disabled while the other remains active; when both are disabled, the common circuitry enters a low-current shutdown state (~9µA). This enables flexible power sequencing and partial-system sleep modes in battery-powered or energy-efficient designs.
What is the purpose of the AGND pin on LT3509IMSE#TRPBF?
The AGND pin (Pin 14) on LT3509IMSE#TRPBF provides a dedicated analog ground return for low-noise control circuitry - including the error amplifier, reference, and feedback network. It must be connected to the main system ground plane at a single point near the exposed thermal pad to prevent digital switching noise from corrupting regulation accuracy. It is not a substitute for the exposed pad GND connection.
How is switching frequency set on LT3509IMSE#TRPBF?
Switching frequency on LT3509IMSE#TRPBF is set by connecting a single resistor between the RT pin (Pin 11) and GND. Typical values range from 13.7kΩ (2.2MHz) to 178kΩ (264kHz). The relationship is defined by RT = (1.215/fSW − 0.215) × 40.2, where fSW is in MHz and RT in kΩ. For external synchronization, the free-run frequency must be ≥12% lower than the sync clock.
LT3509IMSE#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-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:
- 16-MSOP-EP
LT3509IMSE#TRPBF FAQ
1.How can I place an order for LT3509IMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3509IMSE#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 LT3509IMSE#TRPBF reliable?
The price and inventory of LT3509IMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3509IMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3509IMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3509IMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3509IMSE#TRPBF?
LT3509IMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3509IMSE#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 LT3509IMSE#TRPBF?
For technical support, including LT3509IMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3509IMSE#TRPBF requirements.
6.How does Aetrix verify that LT3509IMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3509IMSE#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 LT3509IMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3509IMSE#TRPBF?
All LT3509IMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3509IMSE#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 LT3509IMSE#TRPBF part is unused and in its original packaging.
Return procedure for LT3509IMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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