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Analog Devices Inc. LT1424CS8-5#PBF
- Part No.:
- LT1424CS8-5#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1424CS8-5#PBF.pdf
- Description:
- IC REG FLYBACK 5V 400MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:300
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Product details
Overview
LT1424CS8-5#PBF from Analog Devices (formerly Linear Technology) is a monolithic isolated flyback switching regulator IC with integrated 5V output, primary-side sensing, and no optoisolator or third-winding requirement. It delivers up to 400mA at 5V from 3V–20V input, operates at 285kHz, maintains regulation into discontinuous conduction mode, and features load compensation for ±0.5% load regulation over 0–400mA.
For engineers reviewing the LT1424CS8-5#PBF datasheet, LT1424CS8-5#PBF pinout, LT1424CS8-5#PBF application, or LT1424CS8-5#PBF equivalent, key selection considerations include primary-side feedback accuracy, 8-pin SOIC package compatibility, shutdown current of 20µA, fixed 5V output architecture, and design support for 1:1 transformers in space-constrained isolated supplies.
Technical Context
The LT1424CS8-5#PBF implements a current-mode control architecture with a proprietary flyback error amplifier that samples the primary-side flyback pulse waveform to infer isolated secondary voltage-eliminating optocouplers and auxiliary windings. Its internal bandgap reference (5.30V typ) and RREF/RFB thin-film resistor network enable precise 5V output programming without external dividers.
It integrates a 1.6A peak-current switch with 0.85V saturation voltage, 285kHz oscillator with ±15kHz tolerance, and dynamic timing controls including 180ns minimum flyback enable time and 150ns enable delay to reject transformer leakage spikes. Load compensation via RCCOMP pin adjusts target voltage based on sensed switch current to counteract output impedance droop.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 5V nominal; derived from internal RREF/RFB ratio and flyback pulse sampling-no external feedback resistors needed. |
| Input Voltage Range | 3V to 20V; includes undervoltage lockout at 2.8V to prevent erratic startup or brownout operation. |
| Switch Current Limit | 1.6A typical; sets maximum deliverable power and enables short-circuit protection without external sensing. |
| Operating Frequency | 285kHz typical; fixed-frequency operation simplifies EMI filtering and transformer design for 1:1 isolation. |
| Quiescent Current | 7mA typical; enables high efficiency at light loads and supports low-power standby modes. |
| Shutdown Current | 20µA typical; reduces system standby power when SHDN pin is pulled low. |
| Load Regulation | ±0.5% over 0–400mA; achieved via integrated load compensation circuitry referenced to RCCOMP pin. |
| Package | 8-lead SOIC (SO-8); RoHS-compliant, surface-mount, thermal resistance θJA = 110°C/W. |
Pinout & Package
LT1424CS8-5#PBF is housed in an 8-lead plastic SOIC (SO-8) package with standard 1.27mm pitch, exposed pad not present, and JEDEC MS-012AC compliant dimensions. Thermal resistance is 110°C/W (junction-to-ambient), suitable for industrial ambient temperatures up to +85°C with minimal heatsinking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SHDN (Pin 1) | Shutdown control input | Logic-compatible active-low enable; floating = operational, <0.9V = shutdown (20µA IQ). |
| VC (Pin 2) | Feedback amplifier output / current comparator input | Integrates loop compensation capacitor; voltage sets peak switch current threshold in current-mode control. |
| SYNC (Pin 3) | External oscillator synchronization input | Accepts 330–450kHz square wave (10–90% duty); overrides internal 285kHz oscillator for EMI reduction. |
| SGND (Pin 4) | Signal ground reference | Low-noise analog ground for internal reference and feedback amplifier-must be separated from PGND. |
| PGND (Pin 5) | Power ground return | Emitter connection of internal NPN switch; carries high pulsed currents-requires direct low-inductance PCB plane tie. |
| VSW (Pin 6) | Switch collector node | High-voltage, high-current switching node; connects directly to transformer primary and snubber components. |
| VIN (Pin 7) | Main supply input | 3–20V DC input; requires ≥10µF local ceramic bypass to suppress ripple and ensure stable UVLO behavior. |
| RCCOMP (Pin 8) | Load compensation filter terminal | Connects external 0.1µF ceramic capacitor to implement load-dependent VREF adjustment for improved regulation. |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side output voltage sensing | Eliminates optoisolators and third-winding transformers-reduces BOM count, cost, and board area in isolated 5V supplies. |
| Discontinuous mode regulation | Maintains ±1% output accuracy down to ~1mA load via collapse-detect timing and minimum enable time control. |
| Integrated load compensation | Adjusts target VREF in real time using sensed switch current to cancel secondary-side ESR-induced droop. |
| Fixed 5V output configuration | Factory-trimmed RREF/RFB/ROCOMP thin-film resistors eliminate external feedback network-ensures production consistency. |
| Thermal shutdown protection | Internal junction temperature cutoff at 145°C prevents damage during overload or poor heatsinking conditions. |
| Synchronization capability | Allows frequency alignment with system clock or adjacent converters to avoid beat frequencies and simplify EMI compliance. |
Applications
| Industrial Sensor Isolation | Medical Patient Monitoring |
|---|---|
Use Scenario: Providing galvanically isolated 5V power to analog front-end sensors in PLC I/O modules where ground loops must be broken. IC Role / Device Role / Timing Role: Primary-side flyback controller generating regulated 5V output without optocoupler-enabling compact, low-cost isolation in DIN-rail mounted equipment. Use Value: Achieves <±1% output stability across –40°C to +85°C while reducing transformer footprint by eliminating auxiliary winding requirements. | Use Scenario: Powering isolated ADCs and digital isolators in bedside vital sign monitors requiring reinforced insulation per IEC 60601-1. IC Role / Device Role / Timing Role: Fixed-output isolated DC/DC controller delivering certified 5V/400mA with inherent creepage/clearance advantages of primary-side sensing. Use Value: Enables Class II (double-insulated) design without optocoupler aging concerns-supporting 10-year device lifetime and reduced calibration drift. |
| Communications Interface Isolation | Test & Measurement Equipment |
Use Scenario: Supplying isolated 5V rails for RS-485 transceivers and CAN bus nodes in factory automation networks. IC Role / Device Role / Timing Role: Flyback controller operating at 285kHz to generate noise-immune 5V power synchronized to master clock via SYNC pin. Use Value: Reduces conducted EMI in multi-node bus systems and eliminates optocoupler CMTI limitations in high-speed data links. | Use Scenario: Powering isolated analog signal chains in portable oscilloscopes and multimeters where size and thermal performance are critical. IC Role / Device Role / Timing Role: Compact 8-pin SOIC-based isolated supply delivering clean 5V at up to 400mA with <20µA shutdown current for battery-backed operation. Use Value: Supports >10-hour battery life in handheld instruments while maintaining ±0.5% load regulation across varying measurement loads. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated flyback regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3748IMS#PBF | Requires external optocoupler feedback; supports adjustable output (0.8V–24V); higher 100V switch rating. | Used where variable output or higher input voltage (>20V) is required; lacks primary-side sensing simplicity. | Select LT3748IMS#PBF only if output programmability or >20V VIN capability is mandatory-adds complexity and cost. |
| UCC28911DR | Primary-side sensing like LT1424CS8-5#PBF but uses QR topology; fixed 5V output; lower 700mA max output current. | Targets ultra-low-power AC/DC adapters (<5W); lacks load compensation and discontinuous-mode optimization. | Choose UCC28911DR for cost-sensitive, low-power AC-input designs-not for wide-VIN DC-fed industrial isolation. |
Compared with LT3748IMS#PBF and UCC28911DR, the LT1424CS8-5#PBF uniquely combines fixed 5V output, primary-side sensing, load compensation, and robust discontinuous-mode regulation-making it optimal for space-constrained, high-reliability DC-fed isolated supplies where simplicity and precision outweigh programmability needs.
Availability
LT1424CS8-5#PBF is available at Aetrix Electronics and suitable for industrial sensor isolation, medical patient monitoring, communications interface isolation, and test & measurement equipment requiring stable component supply and long-term obsolescence management.
Supply support for LT1424CS8-5#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 LT1424CS8-5#PBF belongs to Linear's legacy isolated power controller family, designed specifically for compact, low-component-count 5V isolated flyback supplies in safety-critical and space-constrained applications.
FAQ
What is the maximum output current supported by the LT1424CS8-5#PBF?
The LT1424CS8-5#PBF delivers up to 400mA at 5V under typical conditions with proper thermal management and a 1:1 transformer. Peak switch current is internally limited to 1.6A, and output capability depends on transformer design, input voltage, and ambient temperature. At 20V input and 85°C ambient, sustained 400mA requires adequate PCB copper area for heat dissipation.
Does the LT1424CS8-5#PBF require an external feedback resistor network?
No, the LT1424CS8-5#PBF does not require external feedback resistors. It integrates factory-trimmed thin-film RREF, RFB, and ROCOMP resistors to configure the 5V output and load compensation function. Only an external 0.1µF capacitor on the RCCOMP pin is needed for full functionality.
Can the LT1424CS8-5#PBF operate with non-1:1 transformers?
The LT1424CS8-5#PBF is optimized for use with 1:1 transformers as specified in its datasheet and typical applications. While operation with other turns ratios is theoretically possible, output voltage accuracy degrades due to fixed internal resistor ratios and flyback pulse interpretation assumptions-designs requiring non-1:1 ratios should use the general-purpose LT1425 instead.
How does the LT1424CS8-5#PBF achieve regulation without an optoisolator?
The LT1424CS8-5#PBF achieves regulation by sampling the amplitude of the primary-side flyback voltage pulse, which correlates directly with secondary output voltage minus diode drop and leakage effects. Its proprietary flyback error amplifier converts this pulse into a feedback current referenced to an internal bandgap, enabling closed-loop control without secondary-side components.
What is the purpose of the RCCOMP pin on the LT1424CS8-5#PBF?
The RCCOMP pin on the LT1424CS8-5#PBF connects to an external 0.1µF capacitor to implement load compensation. This circuit senses average switch current and dynamically adjusts the internal reference voltage to counteract output voltage droop caused by secondary-side ESR-delivering ±0.5% load regulation from 0 to 400mA.
LT1424CS8-5#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:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1424CS8-5#PBF FAQ
1.How can I place an order for LT1424CS8-5#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1424CS8-5#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 LT1424CS8-5#PBF reliable?
The price and inventory of LT1424CS8-5#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1424CS8-5#PBF is usually 5 days.
3.What payment methods are accepted for LT1424CS8-5#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1424CS8-5#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1424CS8-5#PBF?
LT1424CS8-5#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1424CS8-5#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 LT1424CS8-5#PBF?
For technical support, including LT1424CS8-5#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1424CS8-5#PBF requirements.
6.How does Aetrix verify that LT1424CS8-5#PBF is sourced from the original manufacturer or authorized distributors?
All LT1424CS8-5#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 LT1424CS8-5#PBF meets industry standards.
7.What is the process for return or replacement of LT1424CS8-5#PBF?
All LT1424CS8-5#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1424CS8-5#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 LT1424CS8-5#PBF part is unused and in its original packaging.
Return procedure for LT1424CS8-5#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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