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Analog Devices Inc. LT3575EFE#TRPBF
- Part No.:
- LT3575EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3575EFE#TRPBF.pdf
- Description:
- IC REG FLYBACK 2.5A 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,762
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Product details
Overview
LT3575EFE#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 regulation without optocoupler or third winding. 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 LT3575EFE#TRPBF datasheet, LT3575EFE#TRPBF pinout, LT3575EFE#TRPBF application, or LT3575EFE#TRPBF equivalent, key selection criteria include its 16-lead TSSOP package with exposed thermal pad, programmable current limit via RILIM, temperature-compensated feedback via TC pin, and boundary-mode operation enabling compact transformer design and stable regulation across –40°C to 125°C.
Technical Context
The LT3575EFE#TRPBF implements primary-side sensing by sampling the flyback pulse waveform at the SW pin during zero-current detection on the secondary side. Its boundary-mode control architecture eliminates subharmonic oscillation and enables fixed-off-time operation with variable frequency, improving light-load efficiency and reducing EMI.
It integrates a high-gain error amplifier referenced to a 1.23V bandgap, a DCM comparator for zero-current detection, and a temperature-compensation current source tied to the TC pin to offset diode forward-voltage drift. The VC pin provides direct control of peak switch current, while RFB/RREF resistor ratio sets output voltage in conjunction with transformer turns ratio.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 40V - supports wide-input industrial and automotive supply rails without external pre-regulation. |
| Integrated Switch | 2.5A, 60V NPN - eliminates need for external power transistor; SW pin voltage must stay ≤50V during off-time. |
| Output Power | Up to 14W - achievable with off-the-shelf transformers and no optocoupler, simplifying isolation compliance. |
| Switching Frequency | 40kHz to 1000kHz - variable boundary-mode frequency adapts to load, improving regulation and minimizing transformer size. |
| RREF Voltage | 1.21V to 1.26V - precision internal reference used with external RFB/RREF resistors to set output voltage. |
| Operating Temp Range | –40°C to 125°C - qualified for harsh environments including automotive under-hood and industrial control cabinets. |
| Package | 16-Lead TSSOP with exposed thermal pad (Pin 17 = GND) - enables efficient heat dissipation in space-constrained PCB layouts. |
Pinout & Package
LT3575EFE#TRPBF is housed in a thermally enhanced 16-lead plastic TSSOP package (FE grade) with an exposed GND pad (Pin 17) that must be soldered to the PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pins 3, 4) | Collector node of integrated NPN switch | Carries high di/dt switching current; requires short, low-inductance routing to minimize EMI and voltage spikes. |
| BIAS (Pin 5) | Internal bias supply and switch driver rail | Must be bypassed locally; can connect to VIN if ≤15V and no third winding is used. |
| SHDN/UVLO (Pin 6) | Shutdown and undervoltage lockout input | Resistor divider from VIN sets turn-on threshold (~1.22V); provides 2.8μA hysteresis current for stable UVLO behavior. |
| RILIM (Pin 8) | Programmable switch current limit adjust | Ground-referenced resistor sets peak current (2.8A–4.2A typical); 10kΩ yields full 2.5A capability. |
| VC (Pin 9) | Error amplifier compensation node | Connect series RC to GND for loop stability; 100pF parallel cap suppresses noise coupling into feedback path. |
| RFB (Pin 10) | Primary-side feedback input | Samples flyback pulse amplitude; average current ≈200μA during flyback period; determines output voltage with RREF and turns ratio. |
| RREF (Pin 11) | Reference resistor connection | Ground-referred resistor (typically 6.04kΩ) sets gain for feedback loop; trimmed for accuracy at this value. |
| TC (Pin 12) | Temperature compensation current source | Current sourced into RREF to cancel diode VF temperature drift; RTC = 0.55V / ITC. |
| TEST (Pin 13) | Factory test terminal | Must be connected to GND for normal operation; floating or high-impedance state disables device. |
| GND (Pins 14, 17) | Power and signal ground | Exposed pad (Pin 17) is electrically and thermally GND; requires multiple vias to inner ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side regulation | Eliminates optocoupler and third winding - reduces BOM cost, improves long-term reliability, and avoids opto aging/nonlinearity issues. |
| Boundary-mode operation | Enables zero-current switching per cycle - improves load regulation, allows smaller magnetics, and prevents subharmonic oscillation without slope compensation. |
| Programmable soft-start | Capacitor on SS pin controls output ramp rate and inrush current - prevents overshoot and stress during startup. |
| Temperature-compensated feedback | TC pin injects PTAT current into RREF - offsets diode forward-voltage drift over temperature, maintaining ±1% output accuracy from –40°C to 125°C. |
| Thermally enhanced package | 16-lead TSSOP with exposed GND pad (θJC = 10°C/W) - supports 14W operation in compact layouts without heatsink. |
Applications
| Industrial Isolated DC-DC Supply | Automotive Body Control Module |
|---|---|
Use Scenario: 24V vehicle battery powers isolated 5V/1.4A rail for microcontroller and CAN transceiver in body control unit. IC Role / Device Role / Timing Role: Primary-side flyback controller regulating isolated output without optocoupler; handles 12V–28V input transients. Use Value: Eliminates optocoupler aging and timing drift, ensuring stable 5V rail over 15-year automotive lifecycle. | Use Scenario: 12V/24V industrial PLC I/O module requires isolated 3.3V/3A supply for field-side logic and ADC interface. IC Role / Device Role / Timing Role: Boundary-mode flyback controller delivering 10W+ output using 3:1 transformer and standard RFB/RREF values. Use Value: Achieves <±1.5% load regulation across 0–3A with no secondary-side components, reducing footprint by 35% vs. opto-based designs. |
| Medical Patient Monitoring Equipment | Industrial Ethernet Gateway |
Use Scenario: Isolated 5V/2A supply for analog front-end and isolated ADC in portable ECG monitor requiring 4kV reinforced isolation. IC Role / Device Role / Timing Role: Flyback controller implementing creepage/clearance-compliant transformer design with primary-only feedback. Use Value: Meets IEC 60601-1 creepage requirements without secondary-side feedback circuitry, simplifying safety certification. | Use Scenario: DIN-rail mounted gateway with dual isolated 3.3V/1.5A rails for Ethernet PHY and RS-485 transceivers. IC Role / Device Role / Timing Role: Dual-output flyback controller (using two LT3575EFE#TRPBF) providing independent regulation for high-noise interfaces. Use Value: Enables simultaneous isolation of multiple data interfaces with <1% cross-regulation, eliminating shared ground noise coupling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCC28740DR | Fixed-frequency quasi-resonant controller; no integrated switch; requires external MOSFET. | Supports higher power (>25W); needs more external components; lacks primary-side temperature compensation. | Choose UCC28740DR when >15W output or higher efficiency at light load is required; accept added complexity and layout area. |
| MAX17690ATP+ | Current-mode flyback controller with integrated 0.5Ω/100V MOSFET; lower current rating (1.2A), different pinout. | Optimized for 5V/1A–2A outputs; limited to 6W max; no TC pin or programmable soft-start. | Choose MAX17690ATP+ for cost-sensitive, low-power (<6W) isolated supplies where thermal margin is ample and temperature drift is less critical. |
Compared with UCC28740DR and MAX17690ATP+, the LT3575EFE#TRPBF uniquely combines integrated 2.5A/60V NPN switch, boundary-mode control, and TC-pin temperature compensation - enabling compact, reliable 5–14W isolated supplies without optocouplers or secondary-side components.
Availability
LT3575EFE#TRPBF is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and medical monitoring equipment requiring stable component supply, long-lifecycle support, and certified isolation compliance.
Supply support for LT3575EFE#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 (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 LT3575 product line was developed specifically for primary-side regulated isolated flyback converters targeting space-constrained, high-reliability applications where optocoupler elimination and thermal robustness are critical design requirements.
FAQ
What is the maximum output power achievable with LT3575EFE#TRPBF?
The LT3575EFE#TRPBF delivers up to 14W output power with no external power switch, as confirmed in the datasheet's Typical Application section. This assumes proper transformer selection (e.g., Würth 750311303, 3:1 turns ratio), adequate PCB thermal design, and operation within the 3V–40V input range. Output power scales with input voltage and transformer turns ratio but must keep SW pin voltage below 50V to avoid breakdown.
Does LT3575EFE#TRPBF require an optocoupler for regulation?
No, the LT3575EFE#TRPBF does not require an optocoupler. It achieves isolated output regulation by directly sensing the flyback pulse waveform at the SW pin on the primary side, using boundary-mode zero-current detection. This eliminates optocoupler-related aging, nonlinearity, and dynamic response limitations while reducing BOM count and board area.
How is output voltage set on LT3575EFE#TRPBF?
Output voltage on LT3575EFE#TRPBF is set using two external resistors - RFB connected between SW and RREF pins, and RREF connected between RREF pin and GND - in combination with the transformer's primary-to-secondary turns ratio (NPS) and diode forward voltage (VF). The nominal relationship is VOUT ≈ (VREF × RFB / RREF) × NPS – VF, with optional TC-pin compensation for temperature drift.
What is the function of the TC pin on LT3575EFE#TRPBF?
The TC (Temperature Compensation) pin on LT3575EFE#TRPBF sources a proportional-to-absolute-temperature (PTAT) current into the RREF node to counteract the negative temperature coefficient of the output rectifier diode's forward voltage. A resistor from TC to GND sets the compensation current (ITC = 0.55V / RTC), enabling stable output voltage regulation across –40°C to 125°C without secondary-side components.
Can LT3575EFE#TRPBF operate with a 1:1 transformer?
Yes, LT3575EFE#TRPBF supports 1:1 transformers, as validated in Table 1 of the datasheet for 3.3V, 5V, 12V, 15V, and 20V outputs. However, 1:1 operation limits maximum output power and requires careful attention to SW pin voltage stress - especially at high input voltages - since VSW(MAX) = VIN(MAX) + VOUT + VF must remain ≤50V to protect the internal NPN switch.
LT3575EFE#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
LT3575EFE#TRPBF FAQ
1.How can I place an order for LT3575EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3575EFE#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 LT3575EFE#TRPBF reliable?
The price and inventory of LT3575EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3575EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3575EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3575EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3575EFE#TRPBF?
LT3575EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3575EFE#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 LT3575EFE#TRPBF?
For technical support, including LT3575EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3575EFE#TRPBF requirements.
6.How does Aetrix verify that LT3575EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3575EFE#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 LT3575EFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3575EFE#TRPBF?
All LT3575EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3575EFE#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 LT3575EFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3575EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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