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Analog Devices Inc. LT3512EMS#PBF
- Part No.:
- LT3512EMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width), 12 Leads
- Datasheet:
-
LT3512EMS#PBF.pdf
- Description:
- IC REG FLYBACK 420MA 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:383
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Product details
Overview
LT3512EMS#PBF from Analog Devices (formerly Linear Technology) is a monolithic high-voltage isolated flyback controller IC integrating a 420mA/150V internal power switch, primary-side regulation 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 4.5W isolated output power, and eliminates opto-isolators or third-winding feedback - enabling compact telecom auxiliary supplies and industrial housekeeping rails.
For engineers reviewing the LT3512EMS#PBF datasheet, LT3512EMS#PBF pinout, LT3512EMS#PBF application, or LT3512EMS#PBF equivalent, key selection considerations include its 150V SW pin rating, 1.21V EN/UVLO threshold with hysteresis, boundary-mode operation for tight load regulation, RREF/RFB resistor-based output programming, and BIAS pin self-supply capability down to 4.5V input.
Technical Context
The LT3512EMS#PBF implements primary-side sensing via flyback waveform sampling at the SW pin, using a dedicated flyback error amplifier referenced to a 1.20V internal bandgap. It employs boundary conduction mode (BCM) control - turning on the switch precisely when secondary current reaches zero - eliminating load-regulation errors from ESR and enabling smaller magnetics.
Its architecture integrates temperature compensation via the TC pin (0.55V reference sourcing proportional-to-absolute-temperature current into RREF), compensating diode forward-voltage drift. The VC pin provides traditional current-mode compensation, while the BIAS pin supplies internal driver and bias circuitry - configurable for self-bias or third-winding supply.
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 | 420mA, 150V NPN transistor - eliminates external high-voltage switch and reduces BOM count for isolated flyback designs. |
| Switching Frequency Range | 40kHz to 650kHz - variable-frequency boundary mode enables stable operation across line/load while avoiding subharmonic oscillation. |
| RREF Reference Voltage | 1.17V to 1.23V (typ 1.20V) - precise internal bandgap sets output voltage accuracy via RFB/RREF ratio and transformer turns ratio. |
| EN/UVLO Threshold | 1.15V to 1.27V (typ 1.21V) with 2.6µA hysteresis - enables accurate undervoltage lockout programming using a simple resistor divider from VIN. |
| BIAS Pin Regulation | 3.0V to 3.2V - internally regulated supply for gate driver and control logic; supports direct connection to VIN if ≤20V. |
| Operating Junction Temp | –40°C to 125°C - qualified for extended industrial temperature range, matching LT3512E grade specification. |
Pinout & Package
LT3512EMS#PBF is housed in a 16-lead plastic MSOP package with four leads removed (12-pin functional layout), featuring θJA = 90°C/W and exposed pad thermal enhancement. The package supports high-voltage isolation and compact PCB layout for flyback converters.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN/UVLO (Pin 1) | Enable / Undervoltage Lockout Input | Starts or shuts down converter; 1.21V threshold with hysteresis enables programmable UVLO using resistor divider from VIN. |
| VIN (Pin 3) | Main Input Supply | Supplies startup circuitry and serves as reference for DCM comparator; requires local bypass capacitor. |
| GND (Pins 5, 8, 9) | Ground Return Paths | Three dedicated ground pins minimize ground loop impedance and improve noise immunity in high-dv/dt flyback operation. |
| BIAS (Pin 6) | Internal Bias Supply | Provides regulated ~3.1V supply for switch driver and internal logic; can be tied to VIN if ≤20V or driven by third winding. |
| VC (Pin 10) | Error Amplifier Compensation | Connect series RC to ground for loop stability; 100pF to ground suppresses noise coupling into control loop. |
| TC (Pin 11) | Temperature Compensation Input | Sources proportional-to-absolute-temperature current into RREF to cancel diode VF drift over temperature. |
| RREF (Pin 12) | Reference Resistor Connection | Ground-referenced node for 10kΩ resistor; forms feedback divider with RFB to set output voltage via bandgap reference. |
| RFB (Pin 14) | Feedback Resistor Connection | Connected to SW node; ratio RFB/RREF × 1.20V defines reflected output voltage before transformer turns ratio scaling. |
| SW (Pin 16) | Switch Collector Output | Drives primary winding of flyback transformer; rated to 150V transients; requires minimized trace area for EMI control. |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side regulation | Eliminates opto-isolator and third winding - reduces component count, cost, and board space while improving reliability and dynamic response. |
| Boundary conduction mode (BCM) | Enables zero-current switching each cycle, minimizing ESR-induced load regulation error and allowing smaller transformer size vs CCM. |
| Integrated 150V/420mA switch | Reduces external component count and simplifies layout; eliminates need for discrete HV transistor and associated gate drive circuitry. |
| Self-biased BIAS pin | Supports operation down to 4.5V input without external start-up resistor or auxiliary winding - simplifies low-input designs. |
| Temperature-compensated feedback | TC pin current cancels diode forward-voltage drift, maintaining ±1% output voltage accuracy over –40°C to 125°C junction range. |
Applications
| Isolated Telecom Auxiliary Supply | Industrial Housekeeping Rail |
|---|---|
|
Use Scenario: Providing isolated 5V/0.5A bias for DSPs, FPGAs, and interface ICs in 48V telecom systems with strict space constraints. IC Role / Device Role / Timing Role: Primary-side flyback controller managing energy transfer, regulation, and safety isolation without optocoupler feedback path. Use Value: Enables single-chip isolated DC/DC conversion meeting IEC 60950 creepage/clearance requirements while reducing bill-of-materials by 30% vs opto-based solutions. |
Use Scenario: Generating isolated ±15V rails for analog front-ends and sensor signal conditioning in factory automation PLCs operating from 24V DC bus. IC Role / Device Role / Timing Role: Boundary-mode controller delivering tightly regulated dual outputs using center-tapped secondary and single LT3512EMS#PBF. Use Value: Achieves <±2% load regulation across 10–100% load with no opto aging drift, supporting 15-year field life in unattended industrial equipment. |
| Automotive Body Control Module Supply | Medical Isolated Sensor Interface |
|
Use Scenario: Delivering isolated 3.3V/0.3A power for CAN transceivers and microcontrollers in 12V/24V vehicle body control units 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 galvanic isolation. Use Value: Supports ASIL-B compatible designs via inherent fault detection (UVLO, thermal shutdown) and elimination of opto failure modes. |
Use Scenario: Powering isolated ADCs and current-sense amplifiers in patient-connected medical devices requiring 4000VRMS reinforced isolation per IEC 60601-1. IC Role / Device Role / Timing Role: Primary-side regulated flyback IC enabling certified isolation barrier without optocoupler certification overhead. Use Value: Reduces time-to-certification by eliminating opto qualification testing and supports long-term calibration stability via temperature-compensated feedback. |
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; no integrated switch; requires external MOSFET; supports wider frequency range (100kHz–1MHz). | Better suited for >10W designs or where higher efficiency at light load is critical; lacks self-bias BIAS pin functionality. | Select LT3748IMS#PBF when output power exceeds 4.5W or when external MOSFET selection is required for thermal management. |
| UCC28911DR | Texas Instruments part; 700V integrated MOSFET; primary-side sensing; fixed 50kHz frequency; no TC or RREF pins. | Targeted at universal AC input (85–265VAC) offline flyback; lacks precision temperature compensation and programmable UVLO hysteresis. | Choose UCC28911DR for cost-sensitive AC/DC adapters; avoid for precision DC-input isolated supplies requiring <±1% regulation over temperature. |
Compared with LT3512EMS#PBF, LT3748IMS#PBF offers higher voltage headroom but increases system complexity, while UCC28911DR targets AC mains input and sacrifices temperature stability and UVLO flexibility - making LT3512EMS#PBF optimal for precision DC-input isolated flyback up to 4.5W.
Availability
LT3512EMS#PBF is available at Aetrix Electronics and suitable for isolated telecom auxiliary supplies, industrial housekeeping rails, and automotive body control module power conversion requiring stable component supply and long-term production continuity.
Supply support for LT3512EMS#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3512EMS#PBF belongs to Linear's high-voltage isolated power controller product line, designed specifically to simplify and miniaturize primary-side regulated flyback converters for DC-input applications demanding safety isolation and precision regulation.
FAQ
What is the maximum isolated output power achievable with LT3512EMS#PBF?
The LT3512EMS#PBF delivers up to 4.5W of isolated output power under typical conditions. This assumes proper transformer selection (e.g., Würth 750311559, 4:1 turns ratio), 100V SW pin voltage limit, and 50V margin for leakage spikes. At 72V input and 5V/0.5A output, measured performance reaches 2.5–3.0W depending on efficiency and layout; higher power requires careful thermal design and clamp optimization.
Does LT3512EMS#PBF require an external start-up resistor?
No, the LT3512EMS#PBF does not require an external start-up resistor. Its BIAS pin supports self-bias operation when connected directly to VIN (if VIN ≤20V), enabling reliable start-up from as low as 4.5V input. This eliminates a common external component in flyback controllers and improves efficiency at light loads.
How does LT3512EMS#PBF achieve regulation without an opto-isolator?
The LT3512EMS#PBF samples the reflected flyback voltage at the SW pin during the off-time, when secondary current reaches zero. Its dedicated flyback error amplifier compares this sampled voltage - scaled by RFB/RREF and transformer turns ratio - against a 1.20V internal bandgap reference. This primary-side sensing eliminates opto-isolator latency, aging, and nonlinearity.
What is the function of the TC pin on LT3512EMS#PBF?
The TC pin on LT3512EMS#PBF sources a proportional-to-absolute-temperature (PTAT) current (ITC = 0.55V / RTC) into the RREF node. This current compensates for the negative temperature coefficient of the output rectifier diode's forward voltage drop, maintaining stable output voltage across –40°C to 125°C operating junction temperature.
Can LT3512EMS#PBF operate with a 1:1 transformer turns ratio?
Yes, LT3512EMS#PBF can operate with a 1:1 transformer turns ratio, particularly for higher-output-voltage applications (e.g., 12V or 24V outputs from 24V–48V inputs). However, for low-output-voltage designs like 5V or 3.3V, higher step-down ratios (e.g., 4:1 or 6:1) maximize power delivery and ensure SW pin voltage remains within the 150V absolute maximum rating.
LT3512EMS#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
LT3512EMS#PBF FAQ
1.How can I place an order for LT3512EMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3512EMS#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 LT3512EMS#PBF reliable?
The price and inventory of LT3512EMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3512EMS#PBF is usually 5 days.
3.What payment methods are accepted for LT3512EMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3512EMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3512EMS#PBF?
LT3512EMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3512EMS#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 LT3512EMS#PBF?
For technical support, including LT3512EMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3512EMS#PBF requirements.
6.How does Aetrix verify that LT3512EMS#PBF is sourced from the original manufacturer or authorized distributors?
All LT3512EMS#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 LT3512EMS#PBF meets industry standards.
7.What is the process for return or replacement of LT3512EMS#PBF?
All LT3512EMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3512EMS#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 LT3512EMS#PBF part is unused and in its original packaging.
Return procedure for LT3512EMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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