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Analog Devices Inc. LT3512IMS#PBF
- Part No.:
- LT3512IMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width), 12 Leads
- Datasheet:
-
LT3512IMS#PBF.pdf
- Description:
- IC REG FLYBACK 420MA 16MSOP
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LT3512IMS#PBF from Analog Devices (formerly Linear Technology) is a monolithic high-voltage isolated flyback controller IC with integrated 420mA/150V power switch, designed for primary-side regulated isolated DC/DC conversion. It operates from 4.5V to 100V input, delivers up to 4.5W output power, uses boundary-mode control, and eliminates need for optocoupler or third winding - enabling compact telecom and industrial auxiliary supplies.
For engineers reviewing the LT3512IMS#PBF datasheet, LT3512IMS#PBF pinout, LT3512IMS#PBF application, or LT3512IMS#PBF equivalent, key selection considerations include its 150V SW pin rating, internal RREF reference (1.20V), BIAS pin self-supply capability, EN/UVLO programmable threshold (1.21V), and MSOP-16(12) package with thermal performance (θJA = 90°C/W).
Technical Context
The LT3512IMS#PBF implements boundary-mode current-mode control, sampling the reflected flyback voltage at the SW pin when secondary current reaches zero to derive output voltage without isolation components. Its flyback error amplifier compares a resistor-divided representation of VFLBK against an internal 1.20V bandgap reference, enabling regulation accuracy independent of transformer leakage or diode VF drift.
Temperature compensation is achieved via TC pin current sourcing into RREF, counteracting diode forward-voltage temperature coefficient. The device integrates oscillator, latch, driver, bias regulator, and DCM comparator - all optimized for single-stage isolated flyback operation with no external sense resistor required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 100V - supports wide-input industrial, telecom, and automotive auxiliary rails without external pre-regulation. |
| Integrated Power Switch | 420mA, 150V rated NPN transistor - enables direct high-side switching in flyback topology with built-in overvoltage protection. |
| RREF Reference Voltage | 1.20V ±1.5% - stable bandgap reference used with RFB/RREF resistors to set output voltage without secondary feedback circuitry. |
| Switching Frequency Range | 40kHz to 650kHz - variable boundary-mode frequency adapts to load and line conditions while avoiding subharmonic oscillation. |
| EN/UVLO Threshold | 1.21V ±30mV - precise enable/undervoltage lockout with 2.6µA hysteresis current for reliable startup and brownout protection. |
| BIAS Pin Voltage | 3.1V typical - internally regulated supply for gate driver and control logic; supports direct connection to VIN if ≤20V. |
| Operating Junction Temp | –40°C to +125°C - specified performance across full industrial temperature range for reliable embedded power delivery. |
Pinout & Package
LT3512IMS#PBF is housed in a 16-lead plastic MSOP package with four leads removed (12-pin functional layout), featuring exposed pad for thermal enhancement and θJA = 90°C/W. Package dimensions: 4.0mm × 4.0mm × 1.1mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN/UVLO (1) | Enable / Undervoltage Lockout Input | Starts or shuts down converter; 1.21V threshold allows resistor-divider programming of input UVLO point. |
| VIN (3) | Main Input Supply | Supplies start-up current and serves as reference for DCM comparator and feedback circuitry; requires local bypass capacitor. |
| GND (5, 8, 9) | Ground Terminals | Three dedicated ground pins minimize ground impedance and improve noise immunity in high-dV/dt flyback operation. |
| BIAS (6) | Internal Bias Supply | Provides regulated ~3.1V for driver and internal circuitry; can be tied to VIN if <20V, eliminating need for auxiliary winding. |
| VC (10) | Error Amplifier Compensation | Connects external RC network to stabilize loop response; 100pF to ground suppresses noise coupling into control path. |
| TC (11) | Temperature Compensation Input | Sources proportional-to-absolute-temperature (PTAT) current into RREF to cancel diode VF drift over temperature. |
| RREF (12) | Reference Resistor Connection | Accepts 10kΩ ground-referenced resistor; sets gain for flyback voltage sensing and defines output regulation point. |
| RFB (14) | Feedback Resistor Connection | Connects to SW node via resistor; forms voltage divider with RREF to scale reflected flyback pulse for regulation. |
| SW (16) | Switch Collector Output | Drives transformer primary; rated for 150V transients; requires minimized trace area to reduce EMI and voltage spikes. |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side regulation | Eliminates optocoupler and third winding - reduces BOM count, cost, and board space while improving long-term reliability. |
| Boundary-mode operation | Enables zero-current switching on secondary side each cycle, minimizing load regulation error from parasitic resistance and ESR. |
| No external current-sense resistor | Internal current limit sensing avoids power loss and PCB footprint of discrete sense resistor, simplifying layout and thermal design. |
| Self-biased operation | BIAS pin accepts direct VIN connection down to 4.5V, removing need for start-up resistor or auxiliary winding in low-input applications. |
| Integrated temperature compensation | TC pin current injection into RREF actively cancels diode forward-voltage drift, maintaining ±1% output regulation over –40°C to +125°C. |
Applications
| Isolated Telecom Power Supplies | Isolated Auxiliary/Housekeeping Power Supplies |
|---|---|
Use Scenario: Providing 5V/0.5A isolated bias for Ethernet PHY, PoE interface, or baseband processor in telecom infrastructure equipment operating from 36–72V DC input. IC Role / Device Role / Timing Role: Primary-side regulated flyback controller managing energy transfer, voltage sensing, and boundary-mode timing without secondary-side feedback components. Use Value: Enables compact, low-cost 4.5W isolated supply meeting IEC/EN 60950 creepage/clearance requirements using off-the-shelf transformers like Würth 750311559 (4:1). |
Use Scenario: Generating 12V/100mA isolated standby power for microcontroller reset circuitry and sensor bias in industrial PLC backplanes powered from 24V or 48V bus. IC Role / Device Role / Timing Role: Standalone isolated DC/DC controller delivering tightly regulated auxiliary rail with automatic light-load discontinuous mode entry below 0.6V VC. Use Value: Achieves <±1% load regulation across 10–100% load and <±2% line regulation from 4.5–100V input, reducing need for post-regulation LDOs. |
| Isolated Industrial Power Supplies | Isolated Medical Power Supplies |
Use Scenario: Delivering 3.3V/0.6A isolated power to isolated ADC front-ends and digital isolators in factory automation sensors operating from unregulated 12–48V field bus. IC Role / Device Role / Timing Role: Boundary-mode flyback controller providing primary-side feedback, adaptive frequency scaling, and robust EMI performance in noisy industrial environments. Use Value: Supports transformer turns ratios up to N:1 = 6:1 while maintaining SW pin stress <100V, enabling high-efficiency 3.3V outputs with Würth 750311573 (6:1:2). |
Use Scenario: Supplying ±15V/100mA isolated dual-rail power for analog front-end instrumentation amplifiers in portable medical devices requiring reinforced isolation per IEC 60601-1. IC Role / Device Role / Timing Role: Isolated flyback controller implementing primary-side regulation with TC-compensated RREF to maintain tight output tolerance across patient-room ambient temperature swings. Use Value: Meets 4kV AC reinforced isolation requirements using transformers like Würth 750311839 (2:1:1) and achieves <0.5% temperature-induced output drift from –20°C to +50°C. |
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 SW rating; supports up to 10W output; requires external MOSFET; no integrated switch. | Better suited for higher-power isolated supplies (>5W); needs external gate driver and MOSFET layout. | Select LT3748IMS#PBF when >5W output or >100V input is required; LT3512IMS#PBF remains optimal for ≤4.5W, integrated-switch simplicity. |
| UCC28911DR | 65V max SW rating; lower 100mA current limit; proprietary constant-on-time control; TI-specific ecosystem. | Limited to ≤30W input; not suitable for 72V telecom or 100V industrial inputs where LT3512IMS#PBF excels. | UCC28911DR may reduce BOM cost in low-voltage consumer applications, but LT3512IMS#PBF provides superior HV robustness and precision regulation for industrial designs. |
Compared with LT3748IMS#PBF and UCC28911DR, LT3512IMS#PBF uniquely combines 150V integrated switch, primary-side regulation, and boundary-mode control in a single MSOP-16 package - offering the highest integration level and smallest solution size for ≤4.5W isolated supplies across 4.5–100V input range.
Availability
LT3512IMS#PBF is available at Aetrix Electronics and suitable for isolated telecom power supplies, industrial auxiliary rails, and medical instrumentation requiring stable component supply with guaranteed long-term availability and full traceability.
Supply support for LT3512IMS#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 LT3512IMS#PBF.
The LT3512IMS#PBF belongs to Linear's high-voltage isolated power controller family, engineered specifically for primary-side regulated flyback converters targeting space-constrained, high-reliability auxiliary and housekeeping power applications.
FAQ
What is the maximum output power achievable with the LT3512IMS#PBF?
The LT3512IMS#PBF delivers up to 4.5W of isolated output power under typical conditions. This assumes proper transformer selection (e.g., Würth 750311559 for 48V→5V), 100V SW pin stress limit, and 50V margin for leakage spikes. At 72V input with 4:1 turns ratio, measured output is ~3.0W; at 36V input, it drops to ~2.5W due to boundary-mode frequency reduction and duty-cycle constraints.
Does the LT3512IMS#PBF require an optocoupler or third winding for regulation?
No, the LT3512IMS#PBF does not require an optocoupler or third winding. It achieves regulation by directly sensing the reflected flyback voltage at the SW pin during zero-secondary-current intervals. This primary-side sensing architecture eliminates isolation components, reduces cost and board area, and improves long-term stability versus optocoupler aging.
How is output voltage set on the LT3512IMS#PBF?
Output voltage is set using two external resistors: RFB connected between SW and RREF, and RREF connected between RREF pin and ground (typically 10kΩ). The ratio RFB/RREF, multiplied by the internal 1.20V reference and divided by the transformer turns ratio (NPS), determines VOUT. For example, with RFB = 57.6kΩ, RREF = 12.7kΩ, and 4:1 turns ratio, VOUT ≈ 5.0V.
What is the purpose of the TC pin on the LT3512IMS#PBF?
The TC pin on the LT3512IMS#PBF 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. A resistor from TC to ground (e.g., 53.6kΩ) sets the compensation current (~9.5µA), enabling <±1% output voltage stability over –40°C to +125°C junction temperature.
Can the LT3512IMS#PBF operate with input voltage below 10V?
Yes, the LT3512IMS#PBF operates from 4.5V to 100V input. When BIAS and VIN are shorted, startup is supported down to 4.5V. At low input voltages, the internal bias regulator maintains stable 3.1V for gate drive and control logic. Quiescent current remains ≤4.5mA across the full input range, ensuring efficiency in battery-backed or low-voltage auxiliary systems.
LT3512IMS#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:
- 420mA
- 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
LT3512IMS#PBF FAQ
1.How can I place an order for LT3512IMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3512IMS#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 LT3512IMS#PBF reliable?
The price and inventory of LT3512IMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3512IMS#PBF is usually 5 days.
3.What payment methods are accepted for LT3512IMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3512IMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3512IMS#PBF?
LT3512IMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3512IMS#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 LT3512IMS#PBF?
For technical support, including LT3512IMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3512IMS#PBF requirements.
6.How does Aetrix verify that LT3512IMS#PBF is sourced from the original manufacturer or authorized distributors?
All LT3512IMS#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 LT3512IMS#PBF meets industry standards.
7.What is the process for return or replacement of LT3512IMS#PBF?
All LT3512IMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3512IMS#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 LT3512IMS#PBF part is unused and in its original packaging.
Return procedure for LT3512IMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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