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Analog Devices Inc. LT8315IFE#PBF
- Part No.:
- LT8315IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-TSSOP (0.173", 4.40mm Width), 16 Leads, Exposed Pad
- Datasheet:
-
LT8315IFE#PBF.pdf
- Description:
- IC REG FLYBACK 800MA 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:385
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Product details
Overview
LT8315IFE#PBF from Analog Devices (formerly Linear Technology) is a high-voltage, micropower isolated flyback controller IC with integrated 630V/300mA power MOSFET. It enables opto-isolator–free regulation by sampling the output voltage from a transformer tertiary winding, supports quasi-resonant boundary-mode operation, delivers up to 15W, and operates from 18V to 560V input. It is used in isolated housekeeping supplies for telecom, industrial, and EV battery stack monitoring systems.
For engineers reviewing the LT8315IFE#PBF datasheet, LT8315IFE#PBF pinout, LT8315IFE#PBF application, or LT8315IFE#PBF equivalent, key selection considerations include its 630V integrated switch rating, 70μA quiescent current in Burst Mode, ±4.1mV/°C TC pin temperature compensation, programmable constant-current/constant-voltage regulation, and thermally enhanced 20-pin TSSOP package with high-voltage spacing.
Technical Context
The LT8315IFE#PBF implements quasi-resonant boundary-mode control using a DCM pin that detects negative dV/dt on the tertiary winding to trigger sampling of the FB pin at near-zero secondary current-eliminating load-regulation error from ESR drops. Its internal 630V depletion-mode startup FET charges INTVCC during startup, then disables once bias is established from the tertiary winding.
It integrates dual regulation loops: a voltage error amplifier (GM = 100μS, VFB = 1.22V) for CV mode and a current regulation loop referenced to IREG/SS (10μA sink), enabling seamless transition between constant-voltage and constant-current operation. Standby Mode (via SMODE pin) reduces minimum switching frequency to 220Hz for ultralow no-load power draw.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 18V to 560V - supports direct off-line and high-voltage DC bus applications without pre-regulation. |
| Integrated Switch | 630V/300mA MOSFET - eliminates external HV switch and enables compact, single-chip isolated flyback designs. |
| Quiescent Current | 70μA in Burst Mode - enables <10mW no-load power consumption for energy-sensitive systems. |
| FB Regulation Voltage | 1.22V ±30mV - precise internal reference enabling tight output voltage tolerance with resistor divider programming. |
| Switching Frequency Range | 3.5kHz–140kHz (Burst/Standby) or 138–142kHz (normal) - adaptive boundary-mode control minimizes EMI and improves efficiency across load range. |
| TC Pin Tempco | +4.1mV/°C PTAT voltage - compensates output diode forward-voltage drift to maintain stable output over temperature. |
| Current Limit Threshold | 120mV at SOURCE pin - sets peak switch current via external sense resistor; supports programmable CC regulation. |
Pinout & Package
The LT8315IFE#PBF is housed in a thermally enhanced 20-lead plastic TSSOP package (FE grade) with four pins removed (pins 4–7) to ensure ≥8mm creepage/clearance for high-voltage isolation. The exposed pad (Pin 21) is GND and must be soldered to a PCB ground plane for thermal management (θJC = 10°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DRAIN (1,2,3) | Drain of 630V power MOSFET & startup FET | Connects directly to primary winding; carries full HV switching current; requires short, low-inductance layout. |
| INTVCC (8) | Internal gate driver bias supply | Charged to ~12V at startup via DRAIN; regulated to 10V during operation; bypass with ≥2.2μF ceramic capacitor. |
| BIAS (9) | Unregulated IC power input | Derives operating power from transformer tertiary winding; bypass locally to reduce noise coupling. |
| DCM (10) | Discontinuous conduction mode detector | Samples dV/dt of tertiary winding to detect valley and trigger FB sampling-enables opto-free regulation. |
| TC (11) | Temperature compensation reference | Provides +4.1mV/°C PTAT voltage to offset diode VF drift; connected via RTC resistor to FB for stable output. |
| FB (12) | Feedback input | Sampled voltage regulated to 1.22V; connected to resistor divider from tertiary winding to set output voltage. |
| VC (13) | Voltage control loop compensation | Output of transconductance error amp; sets switching frequency and peak current limit; requires R-C network for stability. |
| IREG/SS (14) | Current regulation / soft-start | 10μA current sink; voltage determines CC setpoint; capacitor here implements controlled startup ramp. |
| SMODE (16) | Standby mode enable | Tie to INTVCC to reduce min frequency to 220Hz; tie to GND for normal 3.5kHz min frequency. |
| EN/UVLO (17) | Enable / undervoltage lockout | 1.22V threshold with 65mV hysteresis; enables chip only above VIN threshold; configurable via resistor divider. |
| SOURCE (18) | Power switch source terminal | Used for peak current sensing; connects to RSNS resistor to GND for programmable current limiting. |
| GND (15,20,21) | Signal and power ground | Pins 15/20 are signal GND; Pin 21 is exposed thermal pad-must be soldered to large copper area for heat dissipation. |
Key Features
| Feature | Design Value |
|---|---|
| No-opto isolated regulation | Eliminates optocoupler, TL431, and associated compensation components-reduces BOM cost, board space, and aging-related drift. |
| Quasi-resonant boundary-mode control | Ensures zero-current switching at turn-on, minimizing EMI and improving efficiency vs. fixed-frequency CCM flyback. |
| Integrated 630V/300mA switch | Enables single-chip 15W isolated flyback design without external HV MOSFET or gate driver-simplifies layout and reliability validation. |
| Low-ripple Burst Mode® operation | Maintains <1% output ripple at light loads while drawing only 70μA-critical for always-on industrial and telecom housekeeping rails. |
| Programmable CV/CC regulation | Supports dual-loop regulation for battery charging, LED drivers, or fault-tolerant supplies where both voltage and current limits matter. |
| Temperature-compensated output | TC pin + external RTC resistor actively corrects for output diode VF drift-achieves ±3% output stability over –40°C to 125°C. |
Applications
| Telecom Housekeeping Supply | Industrial PLC Isolated Auxiliary Rail |
|---|---|
|
Use Scenario: Providing isolated 12V/200mA auxiliary power for control logic and communication interfaces in 48V–380V telecom rectifier shelves. IC Role / Device Role / Timing Role: Primary-side flyback controller regulating output via tertiary winding sampling-no secondary-side feedback components required. Use Value: Reduces component count by 6+ parts (opto, shunt ref, bias resistors, compensation caps) and improves long-term stability vs. optocoupler aging. |
Use Scenario: Generating isolated 5V/500mA supply for microcontroller, I/O isolators, and analog front-end in harsh industrial PLC backplanes. IC Role / Device Role / Timing Role: High-voltage flyback controller with 630V switch and boundary-mode control-enables direct connection to 240VAC-derived DC bus. Use Value: Achieves >85% efficiency at full load and <10mW no-load power, meeting stringent IEC 61000-3-2 harmonic and energy-efficiency requirements. |
| EV Battery Stack Monitor Supply | Medical Isolated Sensor Interface |
|
Use Scenario: Powering isolated ADCs and CAN transceivers across 100–800V battery strings in electric vehicle battery management systems. IC Role / Device Role / Timing Role: Micropower flyback controller with 560V max input and 70μA quiescent current-supports ultra-low standby power per cell monitor. Use Value: Enables <100μA per-cell standby current budget while maintaining 12V rail stability across wide temperature and input voltage variation. |
Use Scenario: Delivering reinforced-isolation 3.3V/100mA power for patient-connected sensor front-ends in portable diagnostic devices. IC Role / Device Role / Timing Role: Isolated flyback controller with certified creepage (≥8mm) and low EMI boundary-mode operation-meets IEC 60601-1 2×MOPP requirements. Use Value: Eliminates optocoupler certification burden and supports Class III leakage current compliance (<10μA) without additional filtering. |
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 |
|---|---|---|---|
| UCC28740DR | 650V/300mA switch; 75μA IQ; no integrated TC pin; requires external opto or auxiliary winding feedback for regulation. | Lacks built-in temperature compensation and true no-opto architecture-requires more external components for same accuracy. | Choose UCC28740DR only if TI's ecosystem preference or existing design reuse outweighs LT8315IFE#PBF's integrated TC and simpler no-opto implementation. |
| MAX17690ATP+ | 65V max input (not HV); external 600V MOSFET required; 100μA IQ; supports ZVS but no TC pin or tertiary-winding sampling. | Not suitable for direct 560V input; requires HV gate driver and external switch-increases complexity and footprint vs. LT8315IFE#PBF. | Select MAX17690ATP+ only for lower-input-voltage isolated supplies (<100V) where its ZVS capability provides measurable efficiency gain. |
Compared with UCC28740DR and MAX17690ATP+, the LT8315IFE#PBF uniquely combines 560V input capability, integrated 630V switch, no-opto tertiary-winding regulation, and active temperature compensation-delivering the lowest component count and highest accuracy for high-voltage isolated flyback designs.
Availability
LT8315IFE#PBF is available at Aetrix Electronics and suitable for telecom housekeeping supplies, industrial PLC auxiliary rails, and EV battery stack monitor circuits requiring stable component supply, long-lifecycle support, and guaranteed lead-free compliance.
Supply support for LT8315IFE#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 precision instrumentation, industrial automation, and automotive markets.
The LT8315IFE#PBF belongs to Linear's high-voltage isolated power controller product line, designed specifically for compact, reliable, and certification-friendly off-line and high-bus-voltage isolated power conversion without optocouplers.
FAQ
What is the maximum input voltage supported by the LT8315IFE#PBF?
The LT8315IFE#PBF supports an absolute maximum input voltage of 560V on the DRAIN pin and operates continuously over an input range of 18V to 560V. This allows direct connection to high-voltage DC buses found in telecom rectifiers, EV battery stacks, and industrial 3-phase rectified supplies without pre-regulation stages.
Does the LT8315IFE#PBF require an optocoupler for regulation?
No, the LT8315IFE#PBF does not require an optocoupler. It achieves isolated output regulation by sampling the flyback pulse voltage from a dedicated tertiary winding on the transformer-eliminating optocoupler-related aging, nonlinearity, and component count while maintaining ±5% output accuracy across line, load, and temperature.
How is constant-current regulation implemented in the LT8315IFE#PBF?
The LT8315IFE#PBF implements constant-current regulation via its IREG/SS pin, which sinks a precise 10μA current. The voltage developed across an external resistor to GND sets the current limit threshold. When the SOURCE pin voltage reaches 120mV (over-current threshold), the part enters CC mode-making LT8315IFE#PBF suitable for LED drivers and battery charge controllers.
What is the purpose of the TC pin on the LT8315IFE#PBF?
The TC pin on the LT8315IFE#PBF provides a buffered proportional-to-absolute-temperature (PTAT) voltage (1.22V at 25°C, +4.1mV/°C) to compensate for the negative temperature coefficient of the output rectifier diode. Connecting an external resistor (RTC) from TC to FB cancels diode VF drift-enabling stable output voltage over –40°C to 125°C without trimming.
Can the LT8315IFE#PBF operate in standby mode, and how is it enabled?
Yes, the LT8315IFE#PBF supports Standby Mode to reduce no-load power consumption. It is enabled by connecting the SMODE pin to INTVCC, which lowers the minimum switching frequency from 3.5kHz to 220Hz. This extends the time between flyback pulses, reducing average current draw to <10μA while maintaining regulation integrity.
LT8315IFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width), 16 Leads, Exposed Pad
- Packaging:
- Tube
- 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#PBF FAQ
1.How can I place an order for LT8315IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8315IFE#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 LT8315IFE#PBF reliable?
The price and inventory of LT8315IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8315IFE#PBF is usually 5 days.
3.What payment methods are accepted for LT8315IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8315IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8315IFE#PBF?
LT8315IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8315IFE#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 LT8315IFE#PBF?
For technical support, including LT8315IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8315IFE#PBF requirements.
6.How does Aetrix verify that LT8315IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT8315IFE#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 LT8315IFE#PBF meets industry standards.
7.What is the process for return or replacement of LT8315IFE#PBF?
All LT8315IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8315IFE#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 LT8315IFE#PBF part is unused and in its original packaging.
Return procedure for LT8315IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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