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Analog Devices Inc. LT8303IS5#TRMPBF
- Part No.:
- LT8303IS5#TRMPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- SOT-23-5 Thin, TSOT-23-5
- Datasheet:
-
LT8303IS5#TRMPBF.pdf
- Description:
- IC REG FLYBCK ADJ 450MA TSOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,130
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Product details
Overview
LT8303IS5#TRMPBF from Analog Devices (formerly Linear Technology) is a micropower high-voltage isolated flyback controller IC with integrated 150V/450mA DMOS power switch, operating from 5.5V to 100V input and delivering up to 5W isolated output power. It regulates output voltage via primary-side flyback waveform sampling-eliminating opto-isolators and third windings-and uses a single external resistor (RFB) for output programming. Designed for auxiliary/housekeeping supplies in industrial and telecom systems.
For engineers reviewing the LT8303IS5#TRMPBF datasheet, LT8303IS5#TRMPBF pinout, LT8303IS5#TRMPBF application, or LT8303IS5#TRMPBF equivalent, key selection criteria include its 150V SW pin rating, boundary mode + low-ripple Burst Mode operation, 70µA sleep-mode quiescent current, –40°C to 125°C operating junction temperature, and TSOT-23-5 package compatibility with space-constrained isolated DC/DC designs.
Technical Context
The LT8303IS5#TRMPBF implements current-mode control in boundary conduction mode (BCM) at heavy loads and transitions to discontinuous conduction mode (DCM) with frequency clamping below 350kHz typical. Its flyback pulse sense circuit and sample-and-hold error amplifier enable accurate isolated output regulation without secondary-side feedback components.
It integrates internal compensation, soft-start, EN/UVLO with 1.223V threshold and 2.5µA hysteresis current, and a 12.23kΩ internal reference. The 150V-rated SW pin supports high-input-voltage flyback topologies while requiring careful transformer turns ratio selection to keep reflected voltage plus leakage spikes below 150V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5.5V to 100V - supports wide-range industrial, telecom, and automotive input rails without external pre-regulation. |
| Integrated Switch | 150V/450mA DMOS - eliminates external high-voltage MOSFET; enables compact isolated flyback with ≤5W output. |
| Quiescent Current | 70µA in Sleep Mode - enables ultra-low-power standby operation in always-on auxiliary supplies. |
| Output Regulation Method | Primary-side sampling from SW pin flyback pulse - removes opto-isolator and third winding, reducing BOM count and cost. |
| Switching Modes | Boundary mode (heavy load), DCM (mid-load), low-ripple Burst Mode® (light load) - balances efficiency, EMI, and output ripple across full load range. |
| Operating Temp Range | –40°C to 125°C junction - qualified for industrial and extended-temperature embedded applications. |
| Package | 5-Lead TSOT-23 - surface-mount, thermally enhanced package suitable for high-density PCB layouts. |
Pinout & Package
LT8303IS5#TRMPBF is housed in a 5-lead ThinSOT™ (TSOT-23) plastic package with exposed pad for thermal performance. Pin 1 = EN/UVLO, Pin 2 = GND, Pin 3 = RFB, Pin 4 = SW, Pin 5 = VIN.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN/UVLO (Pin 1) | Enable and input undervoltage lockout input | Shuts down IC when pulled below 0.3V; 1.223V threshold enables precise VIN UVLO programming with resistor divider. |
| GND (Pin 2) | Power and signal ground reference | Must connect directly to local ground plane to minimize noise coupling into sensitive analog blocks. |
| RFB (Pin 3) | Feedback current input for output voltage setting | 100µA regulation current flows through external RFB; sets VOUT = (100µA × RFB)/NPS − VF, where NPS is transformer turns ratio. |
| SW (Pin 4) | Drain of internal 150V DMOS power switch | Carries high dv/dt switching node; requires minimized trace area and careful layout to suppress EMI and voltage spikes. |
| VIN (Pin 5) | Main input supply and reference for RFB circuitry | Supplies internal regulators; must be locally bypassed with ceramic capacitor to ensure stable operation under transient loads. |
Key Features
| Feature | Design Value |
|---|---|
| No opto-isolator or third winding required | Reduces bill-of-materials, board area, and long-term reliability risk from opto aging and nonlinear response. |
| Low-ripple Burst Mode® operation | Maintains <1% output voltage ripple at light loads while achieving >80% efficiency down to 0.5% full-load current. |
| Internal compensation and soft-start | Eliminates external compensation network and startup inrush current limiting components. |
| Accurate EN/UVLO with hysteresis | Enables robust input rail sequencing and brown-out protection with programmable 1.223V threshold and 2.5µA hysteresis current. |
| Boundary mode operation | Ensures zero-current switching on secondary side each cycle, improving load regulation and enabling smaller magnetics vs CCM. |
Applications
| Industrial PLC I/O Modules | Telecom Line Cards |
|---|---|
Use Scenario: Isolated 5V housekeeping supply powering microcontrollers, ADCs, and digital isolators in modular I/O backplanes with 24–48V DC input rails. IC Role / Device Role / Timing Role: Primary-side flyback controller providing galvanically isolated 5V/0.65A output with no secondary feedback components. Use Value: Reduces component count by eliminating opto-isolator and third winding; maintains ±3% output regulation across –40°C to 85°C ambient. | Use Scenario: Auxiliary 3.3V supply for FPGA configuration and management ICs on telecom line cards with 48V nominal input and strict EMI limits. IC Role / Device Role / Timing Role: Micropower isolated flyback controller operating in low-ripple Burst Mode® to meet <10mVpp output ripple requirement at 1mA load. Use Value: Achieves 70µA sleep-mode IQ and <500ns minimum off-time compliance, enabling reliable start-up during hot-swap events. |
| Automotive Body Control Units | Medical Sensor Interfaces |
Use Scenario: Isolated 12V auxiliary supply for CAN transceivers and EEPROMs in 12V/24V battery-powered body control modules with cold-crank tolerance. IC Role / Device Role / Timing Role: High-input-voltage flyback controller supporting 5.5V–100V operation and 150V SW pin rating for direct connection to unregulated battery rails. Use Value: Withstands 100V transients per ISO 7637-2; delivers stable 12V/0.25A output using Wurth 750315828 (2:1) transformer. | Use Scenario: Patient-isolated 5V supply for analog front-end sensors and low-noise LDOs in portable diagnostic devices requiring reinforced insulation per IEC 60601-1. IC Role / Device Role / Timing Role: Safety-certifiable isolated power controller enabling creepage/clearance compliance via transformer-based isolation instead of optocouplers. Use Value: Eliminates opto drift and lifetime degradation; supports 5kVRMS isolation with certified transformers like Sumida PS15-109. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3748EMSE#PBF | Requires external MOSFET; supports up to 100V input but no integrated switch; higher BOM count and layout complexity. | Used where higher output power (>5W) or custom switch selection is needed; lacks primary-side sensing simplicity. | Select LT3748EMSE#PBF only when >5W output or discrete switch optimization is required; not drop-in compatible. |
| UCC28740DR | TI part with integrated 700V MOSFET; uses different primary-sensing architecture (VCS-based); 100µA typical IQ in burst mode. | Better suited for universal AC input (85–265VAC) offline applications; less optimal for 12–100VDC industrial inputs. | Choose UCC28740DR for AC/DC flyback; LT8303IS5#TRMPBF remains preferred for DC/DC isolated auxiliary supplies with tight space constraints. |
Compared with LT3748EMSE#PBF and UCC28740DR, the LT8303IS5#TRMPBF offers lowest system-level component count for ≤5W DC/DC isolated supplies due to its integrated 150V switch and single-resistor output programming-reducing design time, footprint, and long-term calibration drift risk.
Availability
LT8303IS5#TRMPBF is available at Aetrix Electronics and suitable for industrial automation, telecom infrastructure, and automotive electronics requiring stable component supply, extended temperature operation, and long-lifecycle support.
Supply support for LT8303IS5#TRMPBF 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 and maintains full product support, documentation, and manufacturing continuity for all Linear parts including the LT8303 series.
The LT8303IS5#TRMPBF belongs to Linear's isolated power controller family, designed specifically to simplify and miniaturize isolated DC/DC conversion in space- and efficiency-constrained applications such as auxiliary supplies and sensor interfaces.
FAQ
What is the maximum output power achievable with LT8303IS5#TRMPBF?
The LT8303IS5#TRMPBF delivers up to 5W of isolated output power depending on input voltage, transformer turns ratio, and efficiency. At VIN = 48V with a 6:1 transformer and 5V output, it sustains ~4.35W; at VIN = 30V, output drops to ~2.95W. Peak power is limited by the 450mA switch current limit and 150V SW pin rating, requiring careful transformer selection to avoid exceeding 150V under worst-case leakage conditions.
Does LT8303IS5#TRMPBF require an opto-isolator for regulation?
No, the LT8303IS5#TRMPBF does not require an opto-isolator. It samples the isolated output voltage directly from the primary-side flyback waveform at the SW pin using an internal flyback pulse sense circuit and sample-and-hold error amplifier. This architecture eliminates opto-isolators and third transformer windings, reducing component count, cost, and long-term reliability concerns associated with opto aging and nonlinearity.
What is the purpose of the RFB pin on LT8303IS5#TRMPBF?
The RFB pin on LT8303IS5#TRMPBF accepts a single external resistor that sets the regulated output voltage via a 100µA internal regulation current. The relationship is VOUT ≈ (100µA × RFB)/NPS − VF, where NPS is the transformer primary-to-secondary turns ratio and VF is the output diode forward voltage. This simplifies design versus traditional feedback networks requiring multiple resistors and compensation components.
Can LT8303IS5#TRMPBF operate with input voltages below 5.5V?
No, LT8303IS5#TRMPBF has a specified minimum input voltage of 5.5V per its Absolute Maximum Ratings and Electrical Characteristics tables. Operation below 5.5V may result in failure to start, unstable regulation, or undefined behavior. For sub-5.5V input applications, alternative controllers such as the LT3999 or discrete solutions must be considered.
How does LT8303IS5#TRMPBF handle light-load efficiency?
The LT8303IS5#TRMPBF employs low-ripple Burst Mode® operation at light loads, alternating between active switching cycles and sleep mode to reduce effective quiescent current to 70µA. Unlike conventional burst modes, it maintains minimal output voltage ripple (<10mVpp typical) by enforcing minimum switch-on and switch-off times, ensuring stable regulation even at loads as low as 0.5% of full-scale output current.
LT8303IS5#TRMPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- SOT-23-5 Thin, TSOT-23-5
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Flyback
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 5.5V
- Voltage - Input (Max):
- 100V
- Voltage - Output (Min/Fixed):
- -
- Voltage - Output (Max):
- -
- Current - Output:
- 450mA
- Frequency - Switching:
- 7kHz ~ 350kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TSOT-23-5
LT8303IS5#TRMPBF FAQ
1.How can I place an order for LT8303IS5#TRMPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8303IS5#TRMPBF 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 LT8303IS5#TRMPBF reliable?
The price and inventory of LT8303IS5#TRMPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8303IS5#TRMPBF is usually 5 days.
3.What payment methods are accepted for LT8303IS5#TRMPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8303IS5#TRMPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8303IS5#TRMPBF?
LT8303IS5#TRMPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8303IS5#TRMPBF 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 LT8303IS5#TRMPBF?
For technical support, including LT8303IS5#TRMPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8303IS5#TRMPBF requirements.
6.How does Aetrix verify that LT8303IS5#TRMPBF is sourced from the original manufacturer or authorized distributors?
All LT8303IS5#TRMPBF 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 LT8303IS5#TRMPBF meets industry standards.
7.What is the process for return or replacement of LT8303IS5#TRMPBF?
All LT8303IS5#TRMPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8303IS5#TRMPBF, 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 LT8303IS5#TRMPBF part is unused and in its original packaging.
Return procedure for LT8303IS5#TRMPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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