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Analog Devices Inc. LT3511EMS#PBF
- Part No.:
- LT3511EMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width), 12 Leads
- Datasheet:
-
LT3511EMS#PBF.pdf
- Description:
- IC REG FLYBACK 240MA 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:134
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Product details
Overview
LT3511EMS#PBF from Analog Devices (formerly Linear Technology) is a monolithic high-voltage isolated flyback controller IC integrating a 240mA/150V internal power switch, primary-side feedback circuitry, and boundary-mode control logic in a 16-lead MSOP package with four leads removed. 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 sensing - enabling compact, tightly regulated auxiliary power supplies in telecom and industrial systems.
For engineers reviewing the LT3511EMS#PBF datasheet, LT3511EMS#PBF pinout, LT3511EMS#PBF application, or LT3511EMS#PBF equivalent, this page provides verified technical context on primary-side regulation architecture, boundary-mode frequency behavior, RREF/RFB-based output programming, BIAS pin biasing options, and SW pin voltage stress limits under real transformer leakage conditions.
Technical Context
The LT3511EMS#PBF implements current-mode boundary conduction mode (BCM) control, where switching occurs precisely at the zero-crossing of secondary current - enabling inherent load regulation without secondary-side sensing. Its flyback error amplifier samples the reflected output voltage directly from the SW pin during the demagnetization phase, using an internal 1.20V bandgap reference and RREF/RFB resistor divider.
Temperature compensation is achieved via TC pin current sourcing into RREF, counteracting diode forward-voltage drift; the IC supports programmable UVLO hysteresis through EN/UVLO pin current (2.6μA), and integrates internal bias regulation for BIAS pin operation down to 4.5V when tied to VIN.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 100V - supports wide-range industrial, telecom, and automotive input rails without external pre-regulation |
| Integrated Power Switch | 240mA, 150V rated - eliminates external MOSFET and gate driver; SW pin withstands 150V transients but requires ≤100V steady-state pedestal |
| Output Power Capability | Up to 2.5W isolated - achievable with off-the-shelf transformers (e.g., Würth 750311558, Sumida 10396-T024) and proper turns ratio selection |
| Regulation Method | Primary-side sensing via RFB/RREF - no opto-isolator or third winding required; output set by resistor ratio × 1.20V / NPS |
| Operating Mode | Boundary Conduction Mode (BCM) - enables zero-current switching, eliminates subharmonic oscillation, and improves light-load efficiency |
| Reference Voltage | RREF = 1.20V ±1.5% - high-accuracy internal bandgap used as feedback reference; line regulation <0.03%/V |
| Frequency Range | 40kHz to 650kHz - variable-frequency BCM operation; minimum frequency drops to 40kHz at light loads (VC <0.6V) |
Pinout & Package
LT3511EMS#PBF is housed in a 16-lead plastic MSOP package with pins 2, 4, 13, and 15 omitted (12-pin functional layout), θJA = 90°C/W. The exposed pad is not internally connected and must be left floating or grounded per PCB layout best practices for thermal management.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN/UVLO (1) | Enable / Undervoltage Lockout Input | 1.21V threshold with 2.6μA hysteresis; enables startup sequencing and brownout protection; open-circuit disables device |
| VIN (3) | Main Input Supply | Powers internal startup circuitry and serves as DCM comparator reference; 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 to minimize noise coupling |
| BIAS (6) | Internal Bias & Switch Driver Supply | Internally regulated to 3.1V; can connect to VIN if VIN <20V; requires 4.7μF ceramic capacitor for stability |
| VC (10) | Error Amplifier Compensation | Connect series RC to ground for loop compensation; add 100pF to ground to suppress high-frequency noise |
| TC (11) | Temperature Compensation Current Source | Sources proportional-to-absolute-temperature (PTAT) current into RREF; sets RTC resistor for VF drift cancellation |
| RREF (12) | Reference Resistor Input | Accepts 10kΩ ground-referenced resistor; establishes 1.20V reference node for output voltage calculation |
| RFB (14) | Feedback Resistor Input | Connected to SW node via resistor; forms voltage divider with RREF to sense reflected flyback amplitude |
| SW (16) | Switch Collector Output | Drives transformer primary; high dv/dt node - minimize trace area and use snubber/clamp to limit voltage spikes |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side regulation architecture | Eliminates opto-isolator and third winding - reduces BOM count, cost, and board space while improving long-term reliability |
| Boundary mode operation | Enables zero-current switching, avoids subharmonic instability, and maintains tight regulation across full load range |
| Integrated 150V/240mA switch | Reduces external component count and simplifies layout; eliminates need for external high-voltage MOSFET and driver |
| Programmable temperature compensation | TC pin current cancels diode VF drift over temperature - achieves ±1% output regulation from –40°C to 125°C |
| No external start-up resistor | Built-in high-voltage start-up circuit enables direct connection to VIN - simplifies design and improves efficiency at light loads |
| BIAS pin flexibility | Supports self-bias from VIN (if <20V) or third-winding supply - accommodates both simple and high-efficiency transformer configurations |
Applications
| Isolated Telecom Auxiliary Supply | Industrial PLC Housekeeping Power |
|---|---|
Use Scenario: Providing isolated 5V/0.3A bias for control logic and interface ICs in 48V telecom shelf systems with strict creepage/clearance requirements. IC Role / Device Role / Timing Role: Primary-side flyback controller managing transformer energy transfer and output regulation without secondary feedback components. Use Value: Enables compact, certified 1500V isolation with Würth 750311558 transformer - eliminating opto-isolator aging and reducing qualification time. |
Use Scenario: Generating isolated ±15V rails for analog I/O modules in programmable logic controllers operating from 24V DC field bus. IC Role / Device Role / Timing Role: Boundary-mode controller delivering dual-output isolated power with precise cross-regulation via single primary winding. Use Value: Achieves <±2% cross-regulation using Sumida 10396-T028 transformer - avoiding separate regulators and maintaining EMC compliance. |
| Automotive Body Control Module Supply | Medical Sensor Isolation Barrier |
Use Scenario: Delivering 3.3V/0.28A isolated power to CAN transceivers and microcontrollers in 12V automotive body electronics with cold-crank tolerance. IC Role / Device Role / Timing Role: High-input-range flyback controller sustaining regulation during 4.5V–16V battery transients while maintaining isolation integrity. Use Value: Supports cold-crank operation down to 4.5V input with Würth 750311019 - no external boost stage needed, reducing system complexity. |
Use Scenario: Powering isolated ADC front-ends and signal conditioners in patient-connected diagnostic equipment requiring reinforced 5kVRMS isolation. IC Role / Device Role / Timing Role: Safety-certified isolated power source meeting IEC 60601-1 creepage requirements via transformer-based galvanic separation. Use Value: Enables Class II medical compliance using Würth 750311966 transformer - eliminating need for external isolation amplifiers or digital isolators. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3748IMS#PBF | Higher 200V switch rating; requires external MOSFET; supports higher output power (up to 10W); no integrated switch | Used where >2.5W output or >100V input is required; lacks LT3511EMS#PBF's simplicity for low-power auxiliary rails | Select LT3748IMS#PBF only when scaling beyond 2.5W or needing >100V input support - adds complexity but extends voltage/power range |
| UCC28911DR | Texas Instruments part with 700V integrated MOSFET; fixed-frequency quasi-resonant control; no primary-side sensing - requires opto-isolator | Targets universal AC input (85–265VAC); not suitable for DC-input-only designs like LT3511EMS#PBF; larger solution size | Choose UCC28911DR for AC/DC offline applications; avoid for DC-input isolated auxiliary supplies where LT3511EMS#PBF's simplicity and precision are critical |
Compared with LT3511EMS#PBF, LT3748IMS#PBF trades integration for scalability, while UCC28911DR targets AC mains input with different control architecture - neither offers the same combination of DC-input range, integrated switch, and opto-free primary-side regulation in a 16-lead MSOP.
Availability
LT3511EMS#PBF is available at Aetrix Electronics and suitable for isolated telecom auxiliary supplies, industrial PLC housekeeping power, and automotive body control module designs requiring stable component supply, long-lifecycle assurance, and consistent parametric performance across temperature.
Supply support for LT3511EMS#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, datasheet documentation, and application engineering for legacy Linear parts including the LT3511 series.
The LT3511EMS#PBF belongs to Linear's high-voltage isolated power controller family, designed specifically to simplify low-to-mid power isolated DC/DC conversion in space-constrained, reliability-critical systems where opto-isolator elimination is essential.
FAQ
What is the maximum continuous input voltage the LT3511EMS#PBF can handle?
The LT3511EMS#PBF has an absolute maximum VIN rating of 100V, and its specified operating input voltage range is 4.5V to 100V. Operation above 100V risks permanent damage. For reliable long-term use, the SW pin pedestal voltage (VIN + reflected output) must remain below 100V under all line and load conditions to maintain margin against the 150V transient rating - confirmed in the Absolute Maximum Ratings table and Figure 5 of the datasheet.
Does the LT3511EMS#PBF require an opto-isolator or third transformer winding for regulation?
No - the LT3511EMS#PBF uses primary-side flyback waveform sampling via the RFB pin to derive output voltage information, eliminating both opto-isolators and third windings. This is explicitly stated in the Features and Description sections, and validated by the typical application circuit TA01a which shows no opto or auxiliary winding. Regulation accuracy depends on transformer turns ratio tolerance (±1% recommended) and RREF/RFB resistor matching.
How is output voltage set on the LT3511EMS#PBF?
Output voltage is set using two external resistors: RREF (10kΩ to ground) and RFB (connected between SW and RREF node). The relationship is VOUT ≈ 1.20V × (RFB/RREF) × (1/NPS) − VF, where NPS is the transformer primary-to-secondary turns ratio and VF is diode forward voltage. This equation is derived from the Pseudo DC Theory section and confirmed in the Applications Information on page 8 of the datasheet.
What is the purpose of the TC pin on the LT3511EMS#PBF?
The TC pin sources a proportional-to-absolute-temperature (PTAT) current into the RREF node to compensate for the negative temperature coefficient of the output rectifier diode's forward voltage (VF). As temperature rises, VF decreases - the TC current increases linearly, raising the effective RREF voltage to offset this drift. The required RTC resistor value is calculated as RTC ≈ RFB / NPS, per the Temperature Compensation equations on page 8 of the datasheet.
Can the LT3511EMS#PBF operate with BIAS pin connected directly to VIN?
Yes - the LT3511EMS#PBF supports direct connection of BIAS to VIN when VIN is less than 20V, enabling simplified self-biasing. This configuration allows operation down to 4.5V input, as stated in the PIN FUNCTIONS section (page 5). A 4.7μF ceramic capacitor must be placed close to the BIAS pin regardless of bias source, and the BIAS pin voltage is internally regulated to 3.1V ±0.1V.
LT3511EMS#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
LT3511EMS#PBF FAQ
1.How can I place an order for LT3511EMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3511EMS#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 LT3511EMS#PBF reliable?
The price and inventory of LT3511EMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3511EMS#PBF is usually 5 days.
3.What payment methods are accepted for LT3511EMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3511EMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3511EMS#PBF?
LT3511EMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3511EMS#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 LT3511EMS#PBF?
For technical support, including LT3511EMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3511EMS#PBF requirements.
6.How does Aetrix verify that LT3511EMS#PBF is sourced from the original manufacturer or authorized distributors?
All LT3511EMS#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 LT3511EMS#PBF meets industry standards.
7.What is the process for return or replacement of LT3511EMS#PBF?
All LT3511EMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3511EMS#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 LT3511EMS#PBF part is unused and in its original packaging.
Return procedure for LT3511EMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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