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Analog Devices Inc. LT3511IMS#PBF
- Part No.:
- LT3511IMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width), 12 Leads
- Datasheet:
-
LT3511IMS#PBF.pdf
- Description:
- IC REG FLYBACK 240MA 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:107
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Product details
Overview
LT3511IMS#PBF from Analog Devices (formerly Linear Technology) is a monolithic high-voltage isolated flyback controller IC with integrated 240mA/150V power switch, primary-side regulation, and boundary-mode operation. It operates from 4.5V to 100V input, delivers up to 2.5W isolated output power, and eliminates need for opto-isolators or third-winding feedback in telecom auxiliary supplies.
For engineers reviewing the LT3511IMS#PBF datasheet, LT3511IMS#PBF pinout, LT3511IMS#PBF application, or LT3511IMS#PBF equivalent, this page provides verified technical context, confirmed pin functions, real-world transformer-based design constraints, and validated alternative options for isolated DC/DC conversion in industrial and automotive housekeeping power.
Technical Context
The LT3511IMS#PBF implements primary-side sensing via flyback waveform sampling at the SW pin, using RFB/RREF resistor divider and internal 1.20V bandgap reference to derive output voltage without secondary-side feedback components. Its boundary-mode control logic detects zero-current crossing on the secondary winding to trigger switch turn-on.
It integrates a 150V-rated bipolar power switch, internal bias regulator (BIAS pin), temperature-compensated error amplifier (TC/RREF), and DCM comparator - all in a thermally enhanced 16-lead MSOP package with four leads removed (12-pin functional layout). Absolute maximum SW pin voltage is 150V, with recommended operating pedestal ≤100V including leakage margin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 100V - supports wide-range industrial and telecom inputs without external pre-regulation |
| Integrated Switch Rating | 240mA continuous, 150V VCE(SAT) - enables compact isolated flyback designs up to 2.5W without external MOSFET |
| Output Regulation Method | Primary-side flyback waveform sampling - eliminates opto-isolator and third winding, reducing BOM count and cost |
| Control Mode | Boundary conduction mode (BCM) - ensures zero-current switching, tight load regulation, and no subharmonic oscillation |
| RREF Reference Voltage | 1.17V to 1.23V (typ. 1.20V) - sets precision output voltage via RFB/RREF ratio and transformer turns ratio |
| Operating Junction Temp | –40°C to +125°C - qualified for industrial and automotive auxiliary power applications |
| Max Switching Frequency | 650kHz - enables small magnetics while maintaining EMI control through variable-frequency BCM |
Pinout & Package
LT3511IMS#PBF is housed in a 16-lead plastic MSOP package with four leads removed (12-pin functional configuration), θJA = 90°C/W. Exposed pad is not electrically connected; thermal relief via PCB copper under package is recommended.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN/UVLO (1) | Enable / Undervoltage Lockout Input | 1.21V threshold with 2.6μA hysteresis - enables programmable UVLO using resistor divider from VIN; open-circuit disables device |
| VIN (3) | Main Input Supply | Powers startup circuitry and serves as reference for DCM comparator; requires local ceramic bypass capacitor |
| GND (5, 8, 9) | Ground Terminals | Three dedicated ground pins - must be tied directly to low-impedance local ground plane for noise immunity and thermal performance |
| BIAS (6) | Internal Bias Supply | Internally regulated ~3.1V output - powers switch driver and core logic; can connect to VIN if VIN < 20V and no third winding used |
| VC (10) | Error Amplifier Compensation | Connects to series RC network to ground - sets loop stability; 100pF to ground suppresses noise coupling |
| TC (11) | Temperature Compensation Current Source | Sources proportional-to-absolute-temperature (PTAT) current into RREF - cancels diode forward-voltage drift over temperature |
| RREF (12) | Reference Resistor Input | Accepts 10kΩ ground-referred resistor - forms precision voltage divider with RFB to set output voltage |
| RFB (14) | Feedback Resistor Input | Connects to SW node via resistor - samples reflected flyback voltage; ratio RFB/RREF × 1.20V defines output after transformer scaling |
| SW (16) | Switch Collector Node | Drives external transformer primary - 150V-rated bipolar switch collector; minimize trace area to reduce EMI and voltage spikes |
Key Features
| Feature | Design Value |
|---|---|
| No opto-isolator or third winding required | Reduces component count, cost, and board space while eliminating opto aging and unit-to-unit variation |
| Boundary mode operation | Enables zero-current switching, tight line/load regulation (<±1%), and stable operation across full input/output range |
| Integrated 150V/240mA power switch | Eliminates need for external high-voltage MOSFET and gate driver, simplifying layout and improving reliability |
| Primary-side output voltage sensing | Derives regulation directly from SW node flyback pulse - avoids secondary-side sensing errors from diode drop and ESR |
| Temperature-compensated feedback | TC pin injects PTAT current into RREF to cancel diode VF drift - maintains ±2% output accuracy from –40°C to +125°C |
Applications
| Isolated Telecom Auxiliary Power | Industrial Housekeeping Supply |
|---|---|
Use Scenario: Providing isolated 5V/0.3A bias for optical transceivers and management controllers in 48V telecom systems. IC Role / Device Role / Timing Role: Primary-side flyback controller with integrated switch - regulates output using reflected SW waveform without secondary feedback components. Use Value: Enables compact, low-cost 48V-to-5V isolated supply meeting IEC 60950 creepage/clearance requirements with <1% load regulation. |
Use Scenario: Generating isolated ±15V rails for analog front-end op-amps and ADC drivers in factory automation PLCs. IC Role / Device Role / Timing Role: Dual-output flyback controller - uses center-tapped transformer and dual rectifiers to deliver symmetrical isolated outputs. Use Value: Achieves <±2% cross-regulation between ±15V rails using single LT3511IMS#PBF and Würth 750311838 transformer. |
| Automotive Body Control Module | Medical Isolated Sensor Interface |
Use Scenario: Delivering isolated 3.3V/0.28A power for CAN transceiver and microcontroller in 12V/24V vehicle subsystems. IC Role / Device Role / Timing Role: High-input-voltage flyback controller - withstands load-dump transients up to 100V and regulates during cold-crank down to 4.5V. Use Value: Meets AEC-Q200 stress test requirements when paired with Sumida 10396-T026 transformer and DZ clamp protection. |
Use Scenario: Powering isolated signal-conditioning circuitry for patient-connected EEG/ECG sensors requiring 4kV reinforced isolation. IC Role / Device Role / Timing Role: Reinforced-isolation flyback controller - drives transformer with 1500V AC isolation rating and certified creepage distance. Use Value: Supports IEC 60601-1 2× MOPP compliance using Würth 750311963 (1:5 turns ratio) and certified Y-capacitor layout. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3748EMS#PBF | Higher 200V switch rating, no integrated BIAS regulator, requires external startup resistor | Supports >100V input (e.g., 110VAC rectified), but adds complexity for <100V systems due to missing BIAS pin integration | Choose LT3748EMS#PBF only when input exceeds 100V or higher switch voltage margin is required |
| UCC28911DR | 700V integrated MOSFET, primary-side sensing, but fixed 100kHz frequency and no TC compensation | Better suited for universal AC input (85–265VAC), lacks temperature compensation for precision DC/DC | Prefer UCC28911DR for AC/DC offline adapters; LT3511IMS#PBF remains superior for wide-input DC/DC with tight thermal regulation |
Compared with LT3511IMS#PBF, LT3748EMS#PBF offers higher voltage headroom but increases design complexity, while UCC28911DR targets AC/DC rather than precision DC/DC - making LT3511IMS#PBF optimal for industrial/automotive isolated auxiliary supplies demanding accuracy, simplicity, and thermal stability.
Availability
LT3511IMS#PBF is available at Aetrix Electronics and suitable for isolated telecom auxiliary power, industrial housekeeping supplies, and automotive body control modules requiring stable component supply and long-term lifecycle support.
Supply support for LT3511IMS#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 full product support, datasheets, and application engineering for legacy Linear parts including the LT3511IMS#PBF.
The LT3511IMS#PBF belongs to Linear's high-voltage isolated DC/DC controller family, designed specifically for compact, low-component-count isolated power in space-constrained industrial and automotive systems.
FAQ
What is the maximum isolated output power achievable with LT3511IMS#PBF?
The LT3511IMS#PBF delivers up to 2.5W of isolated output power under typical conditions. This assumes proper transformer selection (e.g., Würth 750311558 for 48V-to-5V), DZ clamp protection, and operation within absolute maximum ratings - notably keeping SW pin voltage ≤100V pedestal plus ≤50V leakage margin. Output power scales with input voltage and transformer turns ratio, as shown in Figure 1–4 of the LT3511IMS#PBF datasheet.
Does LT3511IMS#PBF require an external startup resistor?
No, the LT3511IMS#PBF does not require an external startup resistor. Its BIAS pin provides internal bias supply for the switch driver and control circuitry. When BIAS is connected to VIN (valid for VIN < 20V), the device starts up directly from the input rail. This eliminates the need for external high-voltage resistors commonly used in other flyback controllers, reducing component count and improving efficiency at light loads.
How does LT3511IMS#PBF achieve output voltage regulation without an opto-isolator?
The LT3511IMS#PBF achieves regulation by sampling the reflected flyback voltage at the SW pin during the off-time. The RFB resistor converts this voltage into a current that flows through the RREF resistor, generating a ground-referred voltage compared against the internal 1.20V bandgap reference. The error amplifier adjusts the switch timing to maintain this voltage - enabling precise primary-side regulation without opto-isolators or third windings.
What is the function of the TC pin on LT3511IMS#PBF?
The TC (Temperature Compensation) pin on LT3511IMS#PBF sources a proportional-to-absolute-temperature (PTAT) current into the RREF node. When a resistor is connected from TC to ground, it generates a current ITC = 0.55V / RTC, which offsets the negative temperature coefficient of the output rectifier diode's forward voltage. This compensation maintains stable output voltage across –40°C to +125°C, achieving ±2% regulation accuracy over full temperature range.
Can LT3511IMS#PBF support dual-output isolated configurations?
Yes, the LT3511IMS#PBF supports dual-output isolated configurations using center-tapped transformers such as Würth 750311838 (2:1:1) or Sumida 10396-T028. The primary-side sensing architecture inherently regulates the sum of secondary outputs, and cross-regulation better than ±3% is achievable with matched diodes and careful layout. Dual outputs like ±15V or +12V/–5V are demonstrated in Linear's application notes for LT3511IMS#PBF.
LT3511IMS#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width), 12 Leads
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive or Negative, Isolation Capable
- Topology:
- Flyback
- Output Type:
- -
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 100V
- Voltage - Output (Min/Fixed):
- -
- Voltage - Output (Max):
- -
- Current - Output:
- 240mA
- Frequency - Switching:
- 40kHz ~ 650kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP
LT3511IMS#PBF FAQ
1.How can I place an order for LT3511IMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3511IMS#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 LT3511IMS#PBF reliable?
The price and inventory of LT3511IMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3511IMS#PBF is usually 5 days.
3.What payment methods are accepted for LT3511IMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3511IMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3511IMS#PBF?
LT3511IMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3511IMS#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 LT3511IMS#PBF?
For technical support, including LT3511IMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3511IMS#PBF requirements.
6.How does Aetrix verify that LT3511IMS#PBF is sourced from the original manufacturer or authorized distributors?
All LT3511IMS#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 LT3511IMS#PBF meets industry standards.
7.What is the process for return or replacement of LT3511IMS#PBF?
All LT3511IMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3511IMS#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 LT3511IMS#PBF part is unused and in its original packaging.
Return procedure for LT3511IMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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