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Analog Devices Inc. LT1424IS8-5#PBF
- Part No.:
- LT1424IS8-5#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1424IS8-5#PBF.pdf
- Description:
- IC REG FLYBACK 5V 400MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:548
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Product details
Overview
LT1424IS8-5#PBF from Analog Devices (formerly Linear Technology) is a monolithic isolated flyback switching regulator IC designed for primary-side sensing of 5V isolated outputs without optoisolators or third-winding feedback. It integrates a 1.6A peak-current switch, 285kHz oscillator, current-mode control, load compensation, and shutdown functionality. It delivers up to 400mA at 5V using standard 1:1 transformers in industrial power supplies.
For engineers reviewing the LT1424IS8-5#PBF datasheet, LT1424IS8-5#PBF pinout, LT1424IS8-5#PBF application, or LT1424IS8-5#PBF equivalent, key selection considerations include primary-side regulation accuracy under light-load discontinuous conduction mode, integrated load compensation for <±1% load regulation, and SO-8 package thermal performance at 110°C/W junction-to-ambient.
Technical Context
The LT1424IS8-5#PBF implements a proprietary flyback error amplifier that samples the primary-side flyback pulse waveform to infer secondary output voltage-eliminating optoisolators and auxiliary windings. Its collapse-detect comparator and minimum-enable-time logic maintain regulation down to ~1–2mA output current.
It uses current-mode control with cycle-by-cycle peak current limiting (1.6A typical), internal 2.6V bias regulator, and externally compensated VC loop via RCCOMP capacitor. The SYNC pin supports external frequency synchronization from 330kHz to 450kHz, while SHDN reduces quiescent current to 20µA in standby.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5V nominal; regulated via primary-side flyback sampling-no secondary feedback components required. |
| Switching Frequency | 285kHz typical; enables compact magnetics and EMI filtering; adjustable ±15% via SYNC pin. |
| Peak Switch Current | 1.6A typical; sets maximum deliverable output power (~400mA at 5V with typical efficiency). |
| Input Voltage Range | 3V to 20V; supports wide-input industrial rails; includes 2.8V undervoltage lockout. |
| Quiescent Current | 7mA typical; drops to 20µA in shutdown-critical for low-power standby operation. |
| Load Regulation | Improved by integrated load compensation circuitry; achieves <±1% variation from no-load to full 400mA. |
| Reference Voltage | 5.30V at VSW pin (TYP); accounts for diode drop and leakage-enables accurate 5V output calibration. |
Pinout & Package
LT1424IS8-5#PBF is housed in an 8-pin SOIC (SO-8) package with 110°C/W θJA, optimized for surface-mount industrial power supply designs requiring thermal reliability and board-space efficiency.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SHDN (Pin 1) | Shutdown control input | Logic-high (>0.9V) disables switching and reduces VIN current to ~20µA; floating = active. |
| VC (Pin 2) | Feedback amplifier output / current comparator input | Integrates loop compensation via external capacitor to ground; sets peak current threshold. |
| SYNC (Pin 3) | External oscillator synchronization input | Accepts 10–90% duty-cycle logic signal; locks internal 285kHz oscillator to 330–450kHz range. |
| SGND (Pin 4) | Signal ground reference | Low-noise ground for internal bandgap and feedback amplifier; must be isolated from PGND currents. |
| PGND (Pin 5) | Power ground / switch emitter | High-current return path for internal NPN switch; requires direct connection to ground plane. |
| VSW (Pin 6) | Switch collector node | Connects to transformer primary; carries high dv/dt switching current-requires short, low-inductance routing. |
| VIN (Pin 7) | Main supply input | 3–20V input; bypassed with ≥10µF capacitor; triggers UVLO below 2.8V. |
| RCCOMP (Pin 8) | Load compensation filter terminal | Connects external 0.1µF ceramic capacitor to enable dynamic adjustment of output voltage vs. load current. |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side output sensing | Eliminates optoisolator and third-winding-reduces BOM count, cost, and footprint while improving long-term stability. |
| Discontinuous mode regulation | Maintains tight 5V regulation down to ~1–2mA output via collapse-detect timing and minimum-enable logic. |
| Integrated load compensation | Corrects for output impedance error (diode drop, ESR) using average switch current feedback-enables <±1% load regulation. |
| Current-mode control with cycle-by-cycle limiting | Provides inherent line/load transient response and overcurrent protection without external sense resistors. |
| Thermal shutdown protection | Internal overtemperature circuit disables switching if die temperature exceeds safe limit-prevents damage under overload or poor heatsinking. |
Applications
| Industrial Isolated Sensors | Medical Instrumentation Supplies |
|---|---|
Use Scenario: Powering isolated analog front-ends in PLC I/O modules where galvanic separation from field-side transients is mandatory. IC Role / Device Role / Timing Role: Primary-side flyback controller generating clean, regulated 5V for ADCs, op-amps, and isolated UART interfaces. Use Value: Eliminates optoisolator aging drift and transformer winding complexity-ensures stable 5V rail over 10+ year field life with <±1% total output variation. | Use Scenario: Providing patient-isolated 5V power to ECG/EEG signal conditioning circuits in diagnostic equipment. IC Role / Device Role / Timing Role: Safety-certified isolated DC-DC converter meeting IEC 60601 creepage/clearance requirements via 1:1 transformer design. Use Value: Achieves reinforced isolation without optocouplers-reducing failure modes and simplifying safety validation for Class II medical devices. |
| Industrial Communication Gateways | Factory Automation IO Controllers |
Use Scenario: Supplying isolated 5V to RS-485 transceivers and CAN bus nodes in harsh factory environments. IC Role / Device Role / Timing Role: Flyback regulator powering isolated communication PHYs while rejecting common-mode noise on shared ground planes. Use Value: Maintains regulation during brownouts (down to 3V input) and load steps-ensuring uninterrupted serial data transmission under variable line conditions. | Use Scenario: Delivering 5V to microcontroller-based digital IO modules interfacing with 24V DC field buses. IC Role / Device Role / Timing Role: Compact, thermally robust isolated supply enabling dense PCB layouts in DIN-rail mounted controllers. Use Value: SO-8 package with 110°C/W θJA sustains 400mA output at 70°C ambient-avoids derating or heatsinks in enclosed enclosures. |
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 | Secondary-side feedback via optocoupler; higher integration (X-cap discharge, soft-start); 65kHz fixed frequency. | Requires optoisolator and TL431; better suited for high-efficiency, low-noise consumer adapters-not optimal for industrial simplicity. | Select UCC28740DR only when secondary regulation precision >0.5% is required and optocoupler BOM overhead is acceptable. |
| LT3748EMSE#PBF | Primary-side sensing like LT1424IS8-5#PBF but supports adjustable output (via resistor divider); wider input (4.5–100V); no integrated load compensation. | Enables flexible output voltages (e.g., 3.3V, 12V) but lacks built-in load compensation-requires external circuitry for <±1% regulation. | Choose LT3748EMSE#PBF for multi-voltage designs where 5V is not fixed; retain LT1424IS8-5#PBF for lowest-component-count 5V-only systems. |
Compared with UCC28740DR and LT3748EMSE#PBF, the LT1424IS8-5#PBF uniquely combines fixed 5V output, zero-opto primary-side sensing, and integrated load compensation-making it the most component-efficient solution for cost-sensitive, high-reliability industrial 5V isolated supplies.
Availability
LT1424IS8-5#PBF is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and isolated communication gateways requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.
Supply support for LT1424IS8-5#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 LT1424 family was developed specifically for cost-optimized, high-reliability isolated flyback power supplies in industrial and instrumentation applications-emphasizing primary-side regulation, minimal external components, and robust light-load performance.
FAQ
What is the primary function of the LT1424IS8-5#PBF in a power supply design?
The LT1424IS8-5#PBF serves as a monolithic isolated flyback controller that regulates a fixed 5V output using primary-side sensing-eliminating the need for optoisolators or auxiliary transformer windings. It integrates the power switch, oscillator, current-mode control, and load compensation circuitry, enabling compact, reliable, and low-BOM-count isolated DC-DC conversion in industrial applications.
Does the LT1424IS8-5#PBF require an external MOSFET or transistor?
No, the LT1424IS8-5#PBF does not require an external MOSFET or transistor. It contains an integrated high-current NPN bipolar switch rated for 1.6A peak current and 35V breakdown, capable of delivering up to 400mA at 5V directly from the IC-no external power devices are needed for its intended 5V/400mA application.
How does the LT1424IS8-5#PBF achieve regulation without an optoisolator?
The LT1424IS8-5#PBF achieves regulation by sampling the amplitude of the primary-side flyback voltage pulse across the transformer's main winding. Its proprietary flyback error amplifier converts this pulse into a feedback signal proportional to the isolated secondary output voltage-enabling precise 5V regulation without optoisolators, third windings, or secondary-side components.
What is the purpose of the RCCOMP pin on the LT1424IS8-5#PBF?
On the LT1424IS8-5#PBF, the RCCOMP pin connects to an external 0.1µF ceramic capacitor to implement the integrated load compensation function. This circuit dynamically adjusts the target output voltage based on average switch current, counteracting voltage droop caused by diode forward drop and secondary-side ESR-achieving <±1% load regulation from no-load to full 400mA.
Can the LT1424IS8-5#PBF operate with input voltages below 5V?
Yes, the LT1424IS8-5#PBF operates with input voltages as low as 3V (minimum specified), making it suitable for battery-backed or low-voltage industrial rails. Its undervoltage lockout activates below 2.8V, and it maintains regulation across the full 3V–20V range-enabling use in 3.3V system rails or degraded 12V/24V inputs with proper transformer turns ratio selection.
LT1424IS8-5#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive or Negative, Isolation Capable
- Topology:
- Flyback
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.8V
- Voltage - Input (Max):
- 20V
- Voltage - Output (Min/Fixed):
- 5V
- Voltage - Output (Max):
- -
- Current - Output:
- 400mA
- Frequency - Switching:
- 285kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1424IS8-5#PBF FAQ
1.How can I place an order for LT1424IS8-5#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1424IS8-5#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 LT1424IS8-5#PBF reliable?
The price and inventory of LT1424IS8-5#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1424IS8-5#PBF is usually 5 days.
3.What payment methods are accepted for LT1424IS8-5#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1424IS8-5#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1424IS8-5#PBF?
LT1424IS8-5#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1424IS8-5#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 LT1424IS8-5#PBF?
For technical support, including LT1424IS8-5#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1424IS8-5#PBF requirements.
6.How does Aetrix verify that LT1424IS8-5#PBF is sourced from the original manufacturer or authorized distributors?
All LT1424IS8-5#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 LT1424IS8-5#PBF meets industry standards.
7.What is the process for return or replacement of LT1424IS8-5#PBF?
All LT1424IS8-5#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1424IS8-5#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 LT1424IS8-5#PBF part is unused and in its original packaging.
Return procedure for LT1424IS8-5#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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