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Analog Devices Inc. LT8315IFE#TRPBF
- Part No.:
- LT8315IFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-TSSOP (0.173", 4.40mm Width), 16 Leads, Exposed Pad
- Datasheet:
-
LT8315IFE#TRPBF.pdf
- Description:
- IC REG FLYBACK 800MA 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:6,579
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Product details
Overview
LT8315IFE#TRPBF from Analog Devices (formerly Linear Technology) is a high-voltage isolated flyback controller IC with integrated 630V/300mA power switch, enabling opto-isolator-free regulation via tertiary-winding voltage sampling. It operates from 18V to 560V input, delivers up to 15W output, and features quasi-resonant boundary-mode control for high efficiency and tight load regulation in telecom and industrial off-line supplies.
For engineers reviewing the LT8315IFE#TRPBF datasheet, LT8315IFE#TRPBF pinout, LT8315IFE#TRPBF application, or LT8315IFE#TRPBF equivalent, key selection considerations include its 630V drain rating, 70μA quiescent current in Burst Mode, constant-current/constant-voltage regulation capability, TSSOP-20 package with high-voltage spacing, and temperature-compensated feedback architecture for stable 12V output across automotive and medical operating ranges.
Technical Context
The LT8315IFE#TRPBF implements boundary-mode (critical conduction) control using a sample-and-hold circuit triggered by dV/dt detection on the DCM pin, ensuring zero-current switching and eliminating subharmonic oscillation. Its internal 630V depletion-mode startup FET charges INTVCC at power-up without external components.
Regulation relies on sampling the flyback pulse from a transformer's tertiary winding at near-zero secondary current, referenced to a 1.22V internal bandgap with ±4.1mV/°C PTAT compensation via the TC pin - directly correcting diode forward-voltage drift. The VC pin controls both peak current limit and switching frequency through a transconductance error amplifier (75–125μS).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 18V to 560V - supports universal AC rectified inputs and high-voltage DC bus applications without pre-regulation. |
| Integrated Switch | 630V/300mA N-channel MOSFET - eliminates external HV switch and enables compact, high-reliability flyback designs. |
| Quiescent Current | 70μA in Burst Mode - enables ultra-low standby power for housekeeping supplies in always-on systems. |
| FB Regulation Voltage | 1.22V ±30mV - precise reference for output voltage programming via resistor divider on tertiary winding. |
| Switching Frequency Range | 3.5kHz–140kHz (boundary mode), down to 220Hz in Standby Mode - balances efficiency, EMI, and light-load performance. |
| Current Limit Threshold | 110–130mV on SOURCE pin - sets maximum switch current with 80% design margin for robust overcurrent protection. |
| TC Pin Tempco | +4.1mV/°C - matches output diode VF drift to maintain ±5% output accuracy over −40°C to 125°C. |
Pinout & Package
The LT8315IFE#TRPBF is housed in a thermally enhanced 20-pin TSSOP package (FE grade) with four pins removed (pins 4–7) to ensure ≥8mm creepage/clearance for 560V operation. Exposed pad (pin 21) must be soldered to PCB ground plane for thermal management (θJA = 38°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DRAIN (1,2,3) | Drain of 630V power switch & startup FET | Connects to primary winding; handles full HV input; requires minimized trace area to reduce EMI spikes. |
| SOURCE (18) | Source of power switch | Current-sensing node; voltage drop across RSNS sets peak current limit (100mV threshold). |
| EN/UVLO (17) | Enable and undervoltage lockout input | 1.22V threshold with 65mV hysteresis; enables/disable control and input brownout protection. |
| FB (12) | Feedback input | Samples tertiary-winding flyback pulse; regulated to 1.22V reference for isolated output voltage control. |
| VC (13) | Voltage-controlled oscillator input | Controls switching frequency and peak current via transconductance amplifier output current. |
| IREG/SS (14) | Current regulation / soft-start | 10μA sink current sets CC regulation point; capacitor adds soft-start ramp to limit inrush. |
| TC (11) | Temperature compensation | PTAT voltage (1.22V @ 25°C, +4.1mV/°C) compensates diode VF drift in CV/CC regulation. |
| GND (15,20,21) | Power and signal ground | Pins 15/20 are signal GND; exposed pad (21) is thermal GND - must be soldered to large copper pour. |
Key Features
| Feature | Design Value |
|---|---|
| No-opto isolated regulation | Eliminates optocoupler, reducing BOM cost, aging drift, and dynamic response lag in 12V telecom supplies. |
| Quasi-resonant boundary mode | Enables zero-current turn-on, improving efficiency >90% at 12V/440mA and allowing smaller magnetics vs CCM. |
| Integrated 630V/300mA switch | Reduces component count and layout complexity for 15W isolated flyback converters up to 560VIN. |
| Low-ripple Burst Mode® | Maintains <1% output ripple at light loads (3mA) while holding 70μA quiescent current for battery-backed systems. |
| Programmable CV/CC regulation | Simultaneously regulates output voltage and current - essential for LED drivers and battery charging circuits. |
Applications
| Isolated Telecom Housekeeping Supply | Industrial Off-Line Sensor Power |
|---|---|
Use Scenario: Providing 12V/200mA auxiliary power to FPGA configuration circuitry and monitoring ICs in 48VDC telecom shelves. IC Role / Device Role / Timing Role: Primary-side flyback controller regulating isolated output via tertiary winding sampling - no optocoupler required. Use Value: Enables compact, long-life 12V supply meeting GR-1089 immunity requirements with <±1.5% line/load regulation over −40°C to 85°C. | Use Scenario: Generating 12V/150mA isolated bias for analog front-end sensors in factory automation PLC modules powered from 240VAC mains. IC Role / Device Role / Timing Role: High-voltage flyback controller implementing boundary-mode switching to meet IEC 61000-4-5 surge immunity. Use Value: Delivers stable 12V output with <50mV ripple under 10–100% load steps, supporting precision ADC references and isolated RS-485 transceivers. |
| Electric Vehicle Battery Stack Monitor | Medical Isolated Patient Monitoring |
Use Scenario: Supplying 12V/100mA isolated power to cell voltage measurement ICs across 100+ series-connected EV battery cells (up to 560V total stack). IC Role / Device Role / Timing Role: Flyback controller with 630V drain rating and high-voltage TSSOP spacing enabling direct connection to intermediate taps. Use Value: Achieves <±3% output accuracy over −40°C to 105°C with TC pin compensation - critical for accurate cell voltage reporting. | Use Scenario: Powering isolated analog signal conditioning and microcontroller subsystems in Class II medical devices requiring 2×MOPP isolation. IC Role / Device Role / Timing Role: Safety-certified flyback controller delivering reinforced isolation via transformer design - no optocoupler creepage path needed. Use Value: Meets IEC 60601-1 2×MOPP requirements with 8mm creepage (TSSOP-20 FE package) and <10μA leakage current at 560VDC. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage isolated flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCC28911DR | 650V/300mA switch; fixed 132kHz frequency; no TC pin or CV/CC regulation | Lacks temperature compensation and dual-loop regulation - less suitable for wide-temp medical or EV battery monitoring | Prefer LT8315IFE#TRPBF when ±5% output stability over −40°C to 125°C is required. |
| LNK3206P | 725V switch; integrated 725V diode; no DCM pin or boundary-mode control - operates in DCM only | Higher voltage rating but lower efficiency (<85%) and no quasi-resonant zero-current switching | Choose LT8315IFE#TRPBF for >90% efficiency at 12V/440mA and reduced transformer size. |
Compared with UCC28911DR and LNK3206P, the LT8315IFE#TRPBF provides superior thermal stability via TC pin compensation, higher light-load efficiency via Burst Mode®, and tighter regulation through boundary-mode control - making it optimal for precision 12V isolated supplies in demanding environments.
Availability
LT8315IFE#TRPBF is available at Aetrix Electronics and suitable for isolated telecom housekeeping, industrial sensor bias, electric vehicle battery monitoring, and medical patient-isolation power supplies requiring stable component supply and long-term lifecycle support.
Supply support for LT8315IFE#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 aerospace, industrial, automotive, and communications markets.
The LT8315IFE#TRPBF belongs to the LT® high-voltage power conversion product line, designed specifically for compact, reliable, opto-free isolated flyback supplies in space-constrained, safety-critical applications from 18V to 560V input.
FAQ
What is the maximum input voltage supported by the LT8315IFE#TRPBF?
The LT8315IFE#TRPBF supports an absolute maximum input voltage of 560V on the DRAIN pin, with guaranteed operation from 18V to 560V. This enables direct connection to rectified 400VAC mains or high-voltage DC bus systems without pre-regulation stages. The device's 630V-rated internal MOSFET provides 70V margin for leakage spike suppression, as confirmed in the Absolute Maximum Ratings table.
How does the LT8315IFE#TRPBF achieve regulation without an optocoupler?
The LT8315IFE#TRPBF samples the flyback pulse voltage from a dedicated tertiary winding on the transformer at the instant secondary current reaches zero - a point where parasitic resistive drops vanish. This sampled voltage is compared to the internal 1.22V reference at the FB pin. Because the sampling occurs during natural zero-current transitions, no optocoupler is needed, eliminating aging, nonlinearity, and bandwidth limitations inherent in opto-based feedback loops.
What is the purpose of the TC pin on the LT8315IFE#TRPBF?
The TC pin on the LT8315IFE#TRPBF provides a buffered proportional-to-absolute-temperature (PTAT) voltage (1.22V at 25°C, +4.1mV/°C) used to compensate for the negative temperature coefficient of the output rectifier diode's forward voltage. By connecting a resistor from TC to FB, the LT8315IFE#TRPBF counteracts diode VF drift, maintaining ±5% output voltage accuracy across −40°C to 125°C - critical for medical and automotive applications.
Can the LT8315IFE#TRPBF operate in constant-current mode?
Yes, the LT8315IFE#TRPBF supports true constant-current (CC) regulation via the IREG/SS pin. A 10μA current sinks from this pin, and the resulting voltage - set by an external resistor to GND - determines the CC regulation threshold. When output current exceeds this threshold, the controller reduces duty cycle to maintain constant current, enabling use in LED drivers and battery charging circuits alongside its standard constant-voltage (CV) operation.
What package type and thermal characteristics does the LT8315IFE#TRPBF use?
The LT8315IFE#TRPBF uses a 20-pin TSSOP package (FE grade) with pins 4–7 omitted to ensure ≥8mm creepage distance for 560V operation. Its exposed pad (pin 21) is internally connected to GND and must be soldered to a PCB ground plane. Thermal resistance is θJA = 38°C/W and θJC = 10°C/W, enabling 15W operation at ≤125°C junction temperature with proper copper pour design.
LT8315IFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width), 16 Leads, Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Flyback
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 18V
- Voltage - Input (Max):
- 560V
- Voltage - Output (Min/Fixed):
- -
- Voltage - Output (Max):
- -
- Current - Output:
- 800mA
- Frequency - Switching:
- 220Hz ~ 140kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP-EP
LT8315IFE#TRPBF FAQ
1.How can I place an order for LT8315IFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8315IFE#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 LT8315IFE#TRPBF reliable?
The price and inventory of LT8315IFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8315IFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8315IFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8315IFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8315IFE#TRPBF?
LT8315IFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8315IFE#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 LT8315IFE#TRPBF?
For technical support, including LT8315IFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8315IFE#TRPBF requirements.
6.How does Aetrix verify that LT8315IFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8315IFE#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 LT8315IFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8315IFE#TRPBF?
All LT8315IFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8315IFE#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 LT8315IFE#TRPBF part is unused and in its original packaging.
Return procedure for LT8315IFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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