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Analog Devices Inc. LT8303HS5#TRMPBF
- Part No.:
- LT8303HS5#TRMPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- SOT-23-5 Thin, TSOT-23-5
- Datasheet:
-
LT8303HS5#TRMPBF.pdf
- Description:
- IC REG FLYBCK ADJ 450MA TSOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,127
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Product details
Overview
LT8303HS5#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 in boundary or low-ripple Burst Mode. It regulates output voltage via primary-side flyback pulse sampling-eliminating opto-isolators and third windings-and uses a single external resistor for VOUT programming. Used in telecom auxiliary supplies and industrial isolated bias rails.
For engineers reviewing the LT8303HS5#TRMPBF datasheet, LT8303HS5#TRMPBF pinout, LT8303HS5#TRMPBF application, or LT8303HS5#TRMPBF equivalent, key selection considerations include its –40°C to 150°C guaranteed junction temperature rating, 70µA sleep-mode quiescent current, 150V SW pin absolute maximum rating, boundary mode operation for tight load regulation, and TSOT-23-5 package compatibility with space-constrained isolated DC/DC designs.
Technical Context
The LT8303HS5#TRMPBF implements current-mode control with a novel flyback pulse sense circuit and sample-and-hold error amplifier that samples the reflected output voltage at zero secondary current-enabling precise regulation without secondary-side feedback components. Its boundary conduction mode (BCM) operation ensures consistent zero-current switching across load range, while internal frequency clamping limits max switching frequency to 350kHz to prevent excessive losses at light loads.
It integrates soft-start, internal loop compensation, accurate EN/UVLO with 1.223V threshold and 2.5µA hysteresis current, and a 12.23kΩ trimmed internal reference. The device transitions seamlessly between BCM at heavy loads, discontinuous conduction mode (DCM) under frequency clamp, and low-ripple Burst Mode at ultra-light loads-maintaining >85% efficiency from 3mA to full load across 12V–72V inputs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 5.5V to 100V - supports wide-input industrial, automotive, and telecom supply rails without external pre-regulation. |
| Max Output Power | 5W - enables compact isolated bias supplies for gate drivers, sensors, and communication interfaces. |
| Internal Switch Rating | 150V/450mA DMOS - eliminates external high-voltage switch; withstands flyback spikes up to 150V with proper transformer leakage control. |
| Quiescent Current | 70µA in Sleep Mode - minimizes standby power loss in always-on isolated systems. |
| Operating Junction Temp | –40°C to 150°C - qualified for harsh-environment applications including under-hood automotive and industrial motor controls. |
| Switching Frequency Range | 5kHz to 380kHz - auto-adjusts between boundary mode (variable f), DCM (clamped f ≤350kHz), and Burst Mode (fmin ≈7kHz) for optimal efficiency across load. |
| VOUT Programming | Single RFB resistor - sets output using IRFB = 100µA × RFB, enabling rapid design iteration without secondary feedback networks. |
Pinout & Package
LT8303HS5#TRMPBF is housed in a 5-lead ThinSOT™ (TSOT-23) package with exposed pad for thermal enhancement. Pin 1 is EN/UVLO, Pin 2 is GND, Pin 3 is RFB, Pin 4 is SW (drain of internal DMOS), and Pin 5 is VIN. The package measures 2.9mm × 1.6mm × 0.9mm and supports reflow soldering per JEDEC J-STD-020.
| 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 allows precise VIN UVLO setting with resistor divider. |
| GND (Pin 2) | Power and signal ground reference | Must connect directly to local ground plane to minimize noise coupling into sensitive feedback path. |
| RFB (Pin 3) | Feedback current input for output voltage programming | Accepts 100µA regulation current; connects externally to SW node via RFB to set VOUT = 100µA × RFB/NPS − VF. |
| SW (Pin 4) | Drain of internal 150V/450mA DMOS switch | Carries high dv/dt flyback waveform; requires minimized trace area and careful layout to suppress EMI and voltage overshoot. |
| VIN (Pin 5) | Main input supply and reference for RFB circuitry | Supplies internal regulators; must be locally bypassed with ≥1µF ceramic capacitor to ensure stable operation during transients. |
Key Features
| Feature | Design Value |
|---|---|
| Primary-side sensing architecture | Eliminates opto-isolator and third winding-reducing BOM count, cost, and board area while improving long-term reliability vs. aging optos. |
| Boundary conduction mode (BCM) | Enables zero-current switching every cycle, delivering ±3% load regulation without external compensation or load-sense resistors. |
| Low-ripple Burst Mode | Maintains <15mVPP output ripple at light loads (e.g., 3mA) while achieving >80% efficiency-critical for noise-sensitive analog circuits. |
| Integrated soft-start and compensation | Reduces external component count by two capacitors and one resistor versus discrete controller solutions. |
| 150°C high-temp grade | Guaranteed operation up to 150°C junction temperature-enables placement near heat sources in motor drives and power converters. |
Applications
| Industrial Isolated Sensor Bias | Automotive Auxiliary Power |
|---|---|
Use Scenario: Providing isolated 5V/100mA bias to current-sense amplifiers and isolated ADCs in motor control inverters. IC Role / Device Role / Timing Role: Primary-side flyback controller generating regulated isolated output without secondary feedback components. Use Value: Enables compact, high-reliability isolation in space-constrained engine bay modules where opto-isolator lifetime degradation is unacceptable. | Use Scenario: Generating 3.3V/200mA isolated housekeeping power for CAN transceivers and microcontrollers in 12V/24V vehicle architectures. IC Role / Device Role / Timing Role: Micropower flyback controller delivering stable output across cold-crank (5.5V) to load-dump (100V) conditions. Use Value: Maintains system uptime during extreme input transients while consuming only 70µA in sleep mode-extending battery life in always-on ECUs. |
| Telecom Datacom Isolation | Medical Equipment Auxiliary Supply |
Use Scenario: Isolated 12V/200mA supply for Ethernet PHYs and PoE interface controllers in network switches. IC Role / Device Role / Timing Role: High-voltage flyback controller supporting 48V–72V input ranges common in telecom infrastructure. Use Value: Delivers 5W output with <±1% line/load regulation-meeting stringent timing margin requirements for gigabit Ethernet clocking. | Use Scenario: 24V/100mA isolated auxiliary rail powering isolated SPI isolators and patient-monitoring front-end sensors. IC Role / Device Role / Timing Role: Safety-certified isolated power controller meeting IEC 60601 creepage/clearance requirements via transformer-only isolation. Use Value: Eliminates opto-isolator drift and aging-ensuring long-term calibration stability required for Class II medical devices. |
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#TRPBF | Requires external MOSFET; supports up to 450V input; no integrated switch; higher component count. | Better suited for >10W outputs or ultra-high-input applications (e.g., 400VDC industrial bus). | Select when higher power or input voltage beyond 100V is required; not drop-in compatible due to different pinout and external FET drive. |
| UCC28740DR | TI part with integrated 700V MOSFET; fixed 65kHz frequency; no Burst Mode; higher IQ (220µA active). | Targets cost-sensitive consumer adapters; lacks high-temp grade and low-ripple Burst Mode optimization. | Consider for lower-cost, lower-performance applications where 150°C operation and <15mV ripple are not required. |
Compared with LT3748EMSE#TRPBF and UCC28740DR, the LT8303HS5#TRMPBF uniquely combines integrated 150V/450mA switching, –40°C to 150°C qualification, and low-ripple Burst Mode-making it optimal for compact, high-reliability, low-power isolated supplies where board space and thermal margin are critical.
Availability
LT8303HS5#TRMPBF is available at Aetrix Electronics and suitable for industrial sensor bias, automotive auxiliary power, and telecom datacom isolation requiring stable component supply, long-lifecycle support, and guaranteed high-temperature performance.
Supply support for LT8303HS5#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 LT parts.
The LT8303HS5#TRMPBF belongs to Linear's isolated flyback controller family, designed specifically to simplify high-voltage isolated DC/DC conversion by eliminating opto-isolators and third windings while maintaining precision regulation across wide input and temperature ranges.
FAQ
What is the maximum allowable SW pin voltage stress for LT8303HS5#TRMPBF?
The LT8303HS5#TRMPBF has an absolute maximum SW pin rating of 150V. To ensure reliability, the peak flyback voltage-including input voltage plus reflected output voltage and leakage inductance spike-must remain below this limit. Designers must select transformer turns ratio and snubber components to keep total SW voltage <150V under worst-case conditions, especially at maximum VIN and full load.
How does LT8303HS5#TRMPBF achieve regulation without an opto-isolator or third winding?
The LT8303HS5#TRMPBF samples the isolated output voltage directly from the primary-side flyback pulse on the SW pin when secondary current reaches zero. Its internal flyback pulse sense circuit converts this voltage into a precise 100µA regulation current flowing through the external RFB resistor-enabling accurate VOUT programming without secondary-side components or isolation barriers.
What is the minimum load requirement for stable operation of LT8303HS5#TRMPBF?
The LT8303HS5#TRMPBF specifies a typical minimum load of <0.5% of full output current. This low minimum load is enabled by its low-ripple Burst Mode operation, which maintains regulation down to ~3mA output while holding output ripple below 15mVPP-ideal for powering standby circuits and low-power microcontrollers.
Can LT8303HS5#TRMPBF be used with a 1:N transformer turns ratio?
While LT8303HS5#TRMPBF supports 1:N ratios for high-output-voltage applications, caution is required: such configurations increase parasitic capacitance multiplication and may cause switch turn-on ringing beyond the 160ns leading-edge blanking window-potentially inducing light-load instability. Any 1:N design must be fully validated with actual transformer, layout, and load conditions before deployment.
What is the purpose of the RFB pin on LT8303HS5#TRMPBF, and how is it used?
The RFB pin on LT8303HS5#TRMPBF accepts a constant 100µA regulation current that flows through an external resistor connected to the SW node. The resulting voltage drop sets the output voltage according to VOUT ≈ (100µA × RFB)/NPS − VF, where NPS is the transformer turns ratio and VF is the output diode forward voltage-enabling precise, single-resistor VOUT programming without secondary feedback components.
LT8303HS5#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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TSOT-23-5
LT8303HS5#TRMPBF FAQ
1.How can I place an order for LT8303HS5#TRMPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8303HS5#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 LT8303HS5#TRMPBF reliable?
The price and inventory of LT8303HS5#TRMPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8303HS5#TRMPBF is usually 5 days.
3.What payment methods are accepted for LT8303HS5#TRMPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8303HS5#TRMPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8303HS5#TRMPBF?
LT8303HS5#TRMPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8303HS5#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 LT8303HS5#TRMPBF?
For technical support, including LT8303HS5#TRMPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8303HS5#TRMPBF requirements.
6.How does Aetrix verify that LT8303HS5#TRMPBF is sourced from the original manufacturer or authorized distributors?
All LT8303HS5#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 LT8303HS5#TRMPBF meets industry standards.
7.What is the process for return or replacement of LT8303HS5#TRMPBF?
All LT8303HS5#TRMPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8303HS5#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 LT8303HS5#TRMPBF part is unused and in its original packaging.
Return procedure for LT8303HS5#TRMPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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