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Analog Devices Inc. LT3575IFE#TRPBF
- Part No.:
- LT3575IFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3575IFE#TRPBF.pdf
- Description:
- IC REG FLYBACK 2.5A 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:5,596
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Product details
Overview
LT3575IFE#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic isolated flyback controller IC with integrated 2.5A/60V NPN power switch, designed for primary-side regulated flyback converters without optocouplers or third windings. It operates from 3V to 40V input, delivers up to 14W output power, and uses boundary-mode control for improved load regulation in industrial and medical isolated power supplies.
For engineers reviewing the LT3575IFE#TRPBF datasheet, LT3575IFE#TRPBF pinout, LT3575IFE#TRPBF application, or LT3575IFE#TRPBF equivalent, key selection considerations include its 16-lead TSSOP package with exposed thermal pad, programmable current limit via RILIM, primary-side feedback architecture, and –40°C to 125°C operating junction temperature range.
Technical Context
The LT3575IFE#TRPBF implements boundary-mode (BCM) current-mode control to eliminate need for optocoupler or auxiliary winding by sampling the isolated output voltage directly from the primary-side flyback waveform at zero-secondary-current instants. Its internal error amplifier compares a pseudo-DC representation of VOUT-derived from RFB/RREF resistor ratio and transformer turns ratio-to a 1.23V bandgap reference.
It integrates a 2.5A/60V NPN switch, soft-start circuitry (0.7V threshold), shutdown/UVLO with 1.22V rising threshold and 2.8μA hysteresis current, and temperature-compensated feedback via TC pin current sourcing into RREF. The VC pin provides loop compensation and controls peak switch current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 40V - supports wide-input industrial and automotive supply rails without external regulators |
| Integrated Power Switch | 2.5A, 60V NPN - eliminates external transistor, enables compact 14W isolated designs |
| Switching Frequency Range | 40kHz to 1000kHz - variable-frequency boundary mode improves light-load efficiency and reduces EMI |
| RREF Reference Voltage | 1.23V ±1% - high-accuracy internal bandgap sets output voltage precision with external resistors |
| Operating Junction Temp | –40°C to 125°C - qualified for harsh environments including automotive under-hood and industrial control |
| Package Thermal Resistance | θJC = 10°C/W - exposed pad (Pin 17) must be soldered to PCB ground plane for reliable thermal management |
| SHDN/UVLO Threshold | 1.22V rising, 2.8μA hysteresis - enables precise input undervoltage lockout and controlled enable sequencing |
Pinout & Package
LT3575IFE#TRPBF is housed in a thermally enhanced 16-lead plastic TSSOP package (FE grade) with exposed GND pad (Pin 17). The package requires soldering of the exposed pad to a PCB ground plane using multiple vias for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pins 3, 4) | Collector node of integrated NPN switch | High-current switching node; requires short, low-inductance layout to minimize EMI and voltage spikes |
| BIAS (Pin 5) | Internal bias supply and driver power rail | Must be bypassed locally; can connect to VIN if ≤15V and no third winding used |
| SHDN/UVLO (Pin 6) | Enable/disable and input UVLO sensing input | Resistor divider from VIN sets turn-on threshold; 2.8μA hysteresis ensures clean startup/shutdown |
| SS (Pin 7) | Soft-start capacitor connection | 0.7V threshold controls output ramp rate and limits inrush current during startup |
| RILIM (Pin 8) | Programmable switch current limit adjust | 10kΩ to GND sets full 3.5A typical current limit; enables overcurrent protection tuning |
| VC (Pin 9) | Error amplifier compensation node | Connect series RC to GND for loop stability; 100pF parallel cap suppresses noise |
| RFB (Pin 10) | Primary-side flyback feedback input | Samples SW node during flyback; average current ≈200μA determines output voltage with RREF |
| RREF (Pin 11) | Reference resistor connection for bandgap | 6.04kΩ nominal value; sets feedback gain and enables temperature compensation via TC pin |
| TC (Pin 12) | Temperature compensation current source | 0.55V/RTC current injected into RREF to cancel diode VF tempco for stable VOUT over temperature |
| TEST (Pin 13) | Factory test terminal | Must be connected to GND for normal operation; not user-accessible in functional design |
| GND (Pins 14, 17) | Power and signal ground reference | Exposed pad (Pin 17) is mandatory GND connection for thermal dissipation and electrical reference |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side regulation | Eliminates optocoupler and third winding - reduces BOM cost, board area, and long-term drift concerns |
| Boundary-mode operation | Enables zero-current switching each cycle - improves load regulation and allows smaller magnetics vs CCM |
| Programmable current limit | RILIM pin accepts resistor to set switch current from 400mA to 4.2A - supports flexible overcurrent protection |
| Integrated temperature compensation | TC pin sources proportional-to-absolute-temperature current into RREF - maintains ±1% VOUT accuracy from –40°C to 125°C |
| Thermally enhanced TSSOP | Exposed GND pad with θJC = 10°C/W - enables 14W operation without heatsink in standard PCB layouts |
Applications
| Industrial Isolated DC-DC | Automotive Body Control Module |
|---|---|
Use Scenario: 24V vehicle battery powers isolated 5V/1.4A rail for CAN transceiver and microcontroller in body control unit. IC Role / Device Role / Timing Role: Primary-side flyback controller regulating isolated output without optocoupler; handles input transients up to 40V. Use Value: Eliminates optocoupler aging and unit-to-unit variation, enabling stable 5V rail across 15-year automotive lifecycle. | Use Scenario: 12V/24V industrial PLC I/O module requires isolated 3.3V/3A supply for digital isolators and ADC front-end. IC Role / Device Role / Timing Role: Boundary-mode flyback controller delivering 14W with <±1% load regulation across –40°C to 85°C ambient. Use Value: Achieves tight regulation without secondary-side sensing, reducing component count and improving reliability in dusty/harsh environments. |
| Medical Patient Monitoring | Industrial Ethernet Gateway |
Use Scenario: Isolated 5V/2A supply for patient-connected ECG front-end with reinforced insulation per IEC 60601-1. IC Role / Device Role / Timing Role: Flyback controller implementing creepage/clearance-compliant isolation via transformer; no optocoupler required. Use Value: Reduces risk of optocoupler failure-induced safety violation while maintaining 2×MOPP isolation integrity. | Use Scenario: DIN-rail mounted gateway converts 24VDC to isolated ±12V/0.5A for RS-485 transceivers and 3.3V/2A for ARM processor. IC Role / Device Role / Timing Role: Dual-output flyback controller (using center-tapped secondary) with independent RFB/RREF programming. Use Value: Enables single-transformer dual-rail solution with <2% cross-regulation, simplifying layout and certification. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCC28911DR | 65V MOSFET, 120kHz fixed frequency, no RILIM adjustment, no TC pin | Lacks temperature compensation and programmable current limit; lower max output power (~8W) | Choose UCC28911DR for cost-sensitive, lower-power (<8W), non-temperature-critical applications |
| MAX17690ATP+T | 65V MOSFET, 1MHz max frequency, integrated 5V LDO, no primary-side sensing | Requires optocoupler for regulation; higher component count and reduced long-term stability | Choose MAX17690ATP+T only when existing optocoupler-based design must be upgraded with minimal layout change |
Compared with UCC28911DR and MAX17690ATP+T, LT3575IFE#TRPBF uniquely combines primary-side regulation, programmable current limiting, and active temperature compensation in a single 16-pin TSSOP - enabling higher power, tighter regulation, and longer lifetime in mission-critical isolated supplies.
Availability
LT3575IFE#TRPBF is available at Aetrix Electronics and suitable for industrial power supplies, automotive body electronics, and medical monitoring equipment requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for LT3575IFE#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors for precision signal chain and power applications.
The LT3575IFE#TRPBF belongs to Linear's isolated power controller product line, engineered specifically for optocoupler-free flyback topologies in space-constrained, high-reliability systems where long-term regulation stability is critical.
FAQ
What is the maximum output power achievable with the LT3575IFE#TRPBF?
The LT3575IFE#TRPBF delivers up to 14W output power with no external power switch. This assumes optimal transformer selection (e.g., Würth 750311303, 3:1 turns ratio), 40V input, and proper thermal management via the exposed pad. Output power scales with input voltage and transformer turns ratio - for example, at 12V input with 3:1 ratio, typical output is ~8W at 5V/1.4A. Actual power depends on layout, transformer leakage, and ambient temperature.
Does the LT3575IFE#TRPBF require an optocoupler or third winding for regulation?
No, the LT3575IFE#TRPBF does not require an optocoupler or third winding. It achieves isolated output regulation by sampling the primary-side flyback waveform at zero-secondary-current instants. This primary-side sensing architecture eliminates optocoupler aging, nonlinearities, and unit-to-unit variation while reducing component count and board area - a core design advantage confirmed in the device's official datasheet and application notes.
How is output voltage set on the LT3575IFE#TRPBF?
Output voltage on the LT3575IFE#TRPBF is set using two external resistors: RFB connected between SW and RREF pins, and RREF connected between RREF pin and GND. The ratio RFB/RREF, combined with the internal 1.23V bandgap reference and transformer turns ratio (NPS), determines VOUT per the equation VOUT = (1.23V × RFB/RREF × NPS) − VF. Standard resistor values are provided in datasheet Tables 1–4 for common outputs (3.3V, 5V, 12V) and turns ratios (1:1 to 4:1).
What is the function of the TC pin on the LT3575IFE#TRPBF?
The TC pin on the LT3575IFE#TRPBF sources a temperature-proportional current (ITC = 0.55V / RTC) into the RREF node to compensate for the negative temperature coefficient of the output rectifier diode's forward voltage (VF). By connecting a resistor (e.g., 20.1kΩ for 5V/3:1 design) from TC to GND, the LT3575IFE#TRPBF maintains stable output voltage across –40°C to 125°C - a feature critical for medical and industrial applications where thermal drift must be minimized.
Can the LT3575IFE#TRPBF operate with input voltages below 3V?
No, the LT3575IFE#TRPBF has a minimum specified input voltage of 3V per Absolute Maximum Ratings and Electrical Characteristics tables. Operation below 3V is not guaranteed and may result in failure to start, unstable regulation, or undefined behavior. For sub-3V inputs, alternative controllers such as the LT3999 or discrete solutions with external biasing would be required - the LT3575IFE#TRPBF is not characterized or rated for such conditions.
LT3575IFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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):
- 3V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- -
- Voltage - Output (Max):
- -
- Current - Output:
- 2.5A
- Frequency - Switching:
- 40kHz ~ 1MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT3575IFE#TRPBF FAQ
1.How can I place an order for LT3575IFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3575IFE#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 LT3575IFE#TRPBF reliable?
The price and inventory of LT3575IFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3575IFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3575IFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3575IFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3575IFE#TRPBF?
LT3575IFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3575IFE#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 LT3575IFE#TRPBF?
For technical support, including LT3575IFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3575IFE#TRPBF requirements.
6.How does Aetrix verify that LT3575IFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3575IFE#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 LT3575IFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3575IFE#TRPBF?
All LT3575IFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3575IFE#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 LT3575IFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3575IFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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