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Analog Devices Inc. LT8315EFE#TRPBF
- Part No.:
- LT8315EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-TSSOP (0.173", 4.40mm Width), 16 Leads, Exposed Pad
- Datasheet:
-
LT8315EFE#TRPBF.pdf
- Description:
- IC REG FLYBACK 800MA 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,726
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Product details
Overview
LT8315EFE#TRPBF from Analog Devices (formerly Linear Technology) is a high-voltage, micropower, no-opto isolated flyback controller IC with integrated 630V/300mA power switch. It delivers up to 15W output power, operates from 18V to 560V input, and achieves constant-voltage/constant-current regulation using quasi-resonant boundary-mode control-enabling compact, low-EMI telecom and industrial off-line supplies.
For engineers reviewing the LT8315EFE#TRPBF datasheet, LT8315EFE#TRPBF pinout, LT8315EFE#TRPBF application, or LT8315EFE#TRPBF equivalent, this page provides verified technical context, real-world design meaning for key specs, validated pin functions, confirmed alternatives, and supply-chain support details specific to the LT8315EFE#TRPBF temperature-grade variant.
Technical Context
The LT8315EFE#TRPBF implements boundary-mode (critical conduction) control via a DCM pin that detects dV/dt on a transformer tertiary winding, enabling precise output voltage sampling at near-zero secondary current. Its internal 630V depletion-mode startup FET charges INTVCC without external components, and its GM transconductance amplifier (75–125μS) drives VC to regulate both switching frequency and peak current limit.
It supports dual-loop regulation: FB pin controls constant-voltage mode by comparing sampled tertiary voltage to a 1.22V reference, while IREG/SS pin sets constant-current threshold via a 10μA sink current. Temperature compensation is implemented via TC pin's PTAT voltage (+4.1mV/°C), which offsets diode forward-voltage drift when connected through RTC to FB.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 18V to 560V - supports direct connection to rectified AC mains or high-voltage DC bus without pre-regulation. |
| Integrated Switch | 630V/300mA MOSFET - eliminates need for external HV switch; enables single-chip isolated flyback up to 15W. |
| Quiescent Current | 70μA in Burst Mode - enables ultra-low standby power for housekeeping rails in always-on systems. |
| FB Regulation Voltage | 1.22V ±30mV - defines output voltage setpoint via RFB1/RFB2 divider; accuracy directly impacts CV regulation tolerance. |
| Switching Frequency Range | 3.5kHz–140kHz - variable boundary-mode operation improves efficiency and reduces transformer size vs fixed-frequency CCM. |
| Operating Junction Temp | −40°C to 125°C - E-grade rating suitable for industrial and automotive under-hood auxiliary supplies. |
| Package | 20-pin TSSOP with 4 pins removed - high-voltage creepage spacing between DRAIN pins meets reinforced insulation requirements. |
Pinout & Package
The LT8315EFE#TRPBF is housed in a thermally enhanced 20-pin plastic TSSOP (FE package) with pins 4, 5, 6, and 7 omitted to ensure ≥8mm creepage distance between high-voltage DRAIN pins (1, 2, 3) and low-voltage circuitry. The exposed pad (Pin 21) is GND and must be soldered to PCB for thermal management (θJC = 10°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 compact layout to minimize EMI and voltage spikes. |
| SOURCE (18) | Source of power switch | Current-sense node; voltage across RSNS sets peak current limit (100mV threshold); ties to GND via sense resistor. |
| EN/UVLO (17) | Enable / undervoltage lockout input | 1.22V threshold with 65mV hysteresis; enables/disables regulation; can be driven by logic or resistor divider from VIN. |
| FB (12) | Feedback input | Samples tertiary winding flyback pulse; regulated to 1.22V reference; determines output voltage via RFB1/RFB2 divider. |
| VC (13) | Voltage-controlled oscillator input | Loop compensation node; internal GM amplifier outputs error current here; sets switching frequency and current limit. |
| IREG/SS (14) | Current regulation / soft-start | 10μA sink current sets CC threshold; capacitor here implements soft-start; resistor to GND programs current limit. |
| TC (11) | Temperature compensation | PTAT voltage (1.22V @ 25°C, +4.1mV/°C); connects to FB via RTC to compensate output diode VF drift. |
| DCM (10) | Discontinuous conduction mode detector | Detects dV/dt of tertiary winding; triggers sample-and-hold for accurate zero-current voltage sampling. |
| BIAS (9) | Unregulated IC power input | Derives operating power from tertiary winding post-startup; bypass with ≥10μF ceramic capacitor. |
| INTVCC (8) | Internal gate driver bias | 10V LDO output; powers gate driver and logic; bypass with ≥2.2μF ceramic capacitor. |
| GND (15,20,21) | Ground reference | Three ground connections including exposed thermal pad (Pin 21); all must connect to low-impedance ground plane. |
| SMODE (16) | Standby mode enable | Tie to INTVCC to reduce min. frequency to 220Hz for ultralow quiescent power; tie to GND to disable. |
Key Features
| Feature | Design Value |
|---|---|
| No opto-isolator required | Output voltage regulation derived from tertiary winding flyback waveform - eliminates optocoupler cost, aging, and bandwidth limitations. |
| Quasi-resonant boundary-mode operation | Zero-current switching reduces EMI and losses; enables smaller magnetics and tighter load regulation without output current sensing. |
| Integrated 630V/300mA switch | Single-chip solution for 15W isolated flyback - removes external HV MOSFET, driver, and associated gate-drive components. |
| Low ripple Burst Mode® at light loads | Maintains tight output regulation down to mA-level loads with <1% ripple - ideal for always-on housekeeping supplies. |
| Programmable CC/CV regulation | Independent loops for voltage and current control - supports battery charging, LED drivers, and programmable lab supplies. |
Applications
| Telecom Housekeeping Supply | Industrial Off-Line Sensor Power |
|---|---|
Use Scenario: Providing isolated 12V/100mA auxiliary power for FPGA configuration, PHY interface, or MCU reset circuitry in 48V telecom systems. IC Role / Device Role / Timing Role: Primary-side flyback controller regulating isolated output without optocoupler; samples tertiary winding during boundary-mode valley. Use Value: Eliminates optocoupler BOM cost and lifetime drift; 70μA quiescent current extends system uptime during brownout conditions. | Use Scenario: Generating 5V/200mA isolated power for analog sensor front-ends in factory automation PLCs operating from 240VAC mains. IC Role / Device Role / Timing Role: High-voltage flyback controller with 560V input rating and 125°C junction temp - withstands industrial line surges and ambient heat. Use Value: Integrated 630V switch avoids external HV MOSFET derating; boundary-mode operation maintains >85% efficiency across 10–100% load range. |
| Electric Vehicle Battery Stack Monitor | Medical Isolated Auxiliary Rail |
Use Scenario: Powering isolated ADCs and communication isolators across 400–800V EV battery cell stacks for cell voltage monitoring. IC Role / Device Role / Timing Role: No-opto flyback controller sampling tertiary winding - enables galvanic isolation without signal latency or gain drift. Use Value: 18–560V input range accommodates wide battery SOC swing; TC pin compensation ensures <±2% output stability over −40°C to 105°C. | Use Scenario: Delivering 3.3V/150mA isolated power to patient-connected ECG front-end amplifiers requiring reinforced insulation per IEC 60601-1. IC Role / Device Role / Timing Role: Safety-certifiable flyback controller with creepage-enhanced TSSOP package and no optocoupler failure mode. Use Value: Omitted pins (4,5,6,7) provide ≥8mm creepage; 125°C rating supports sealed enclosure thermal design; low EMI simplifies EMC testing. |
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; 18–450V input; no integrated TC compensation; requires external opto for tight CV regulation | Lacks PTAT-based diode temp compensation; lower max input voltage; optimized for cost-sensitive consumer adapters | Select UCC28740DR only if TC compensation is unnecessary and input stays ≤450V; verify opto loop stability for medical/industrial use. |
| MAX17690ATP+T | 650V/300mA switch; 18–550V input; includes integrated VREF temp compensation but no TC pin; uses different DCM detection method | Supports same HV range but lacks dedicated TC pin for diode VF correction; higher typical quiescent current (120μA) | Choose MAX17690ATP+T when board space allows external compensation network; confirm DCM timing matches transformer design. |
Compared with UCC28740DR and MAX17690ATP+T, the LT8315EFE#TRPBF uniquely integrates a dedicated TC pin with +4.1mV/°C PTAT voltage for direct diode-VF compensation, delivers lowest quiescent current (70μA), and supports highest input voltage (560V), making it optimal for precision, high-reliability isolated supplies where thermal drift and wide VIN range are critical.
Availability
LT8315EFE#TRPBF is available at Aetrix Electronics and suitable for telecom housekeeping, industrial off-line sensor power, electric vehicle battery monitor supplies, and medical isolated auxiliary rails requiring stable component supply across extended temperature and high-voltage stress conditions.
Supply support for LT8315EFE#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, Inc. (ADI) acquired Linear Technology in 2017 and maintains its high-performance power management portfolio, emphasizing reliability, precision, and high-voltage capability for mission-critical applications.
The LT8315EFE#TRPBF belongs to ADI's LT® high-voltage flyback controller family, designed specifically for isolated power conversion in telecom, industrial, automotive, and medical systems where optocoupler-free regulation, wide input range, and thermal stability are essential.
FAQ
What is the maximum input voltage supported by the LT8315EFE#TRPBF?
The LT8315EFE#TRPBF supports an absolute maximum input voltage of 560V, 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 integrated 630V power switch provides 120V margin above the 560V max input for leakage inductance spikes, ensuring robust operation under transient overvoltage conditions.
Does the LT8315EFE#TRPBF require an optocoupler for output voltage regulation?
No, the LT8315EFE#TRPBF does not require an optocoupler. It regulates the isolated output voltage by sampling the flyback pulse on a transformer tertiary winding - eliminating optocoupler cost, aging, nonlinearity, and bandwidth limitations. The LT8315EFE#TRPBF uses a sample-and-hold circuit triggered by DCM pin dV/dt detection at near-zero secondary current to achieve ±5% output accuracy without external isolation components.
How does the TC pin on the LT8315EFE#TRPBF improve output voltage stability?
The TC pin on the LT8315EFE#TRPBF provides a buffered PTAT voltage (1.22V at 25°C, +4.1mV/°C) that compensates for the negative temperature coefficient of the output diode's forward voltage (VF). When connected via RTC resistor to the FB pin, it counteracts VF drift (≈−1.5mV/°C), reducing output voltage variation from ±400mV to <±2% over −40°C to 125°C - a critical feature for medical and industrial applications where thermal stability is mandated.
What is the purpose of the SMODE pin on the LT8315EFE#TRPBF?
The SMODE pin on the LT8315EFE#TRPBF enables Standby Mode: when tied to INTVCC, it reduces the minimum switching frequency from 3.5kHz to 220Hz, lowering quiescent current and extending hold-up time in ultralow-power housekeeping applications. This mode maintains regulation while minimizing energy loss during light-load or standby conditions - essential for always-on systems like telecom base stations or EV battery monitors.
Can the LT8315EFE#TRPBF deliver constant-current output for battery charging applications?
Yes, the LT8315EFE#TRPBF supports true constant-current (CC) regulation via the IREG/SS pin. A 10μA current sinks from this pin; the resulting voltage across an external resistor to GND sets the CC threshold. When output current exceeds this point, the controller transitions from constant-voltage to constant-current mode - enabling reliable single-chip Li-ion, lead-acid, or supercapacitor charging without additional current-sense amplifiers or microcontrollers.
LT8315EFE#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
LT8315EFE#TRPBF FAQ
1.How can I place an order for LT8315EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8315EFE#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 LT8315EFE#TRPBF reliable?
The price and inventory of LT8315EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8315EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8315EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8315EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8315EFE#TRPBF?
LT8315EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8315EFE#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 LT8315EFE#TRPBF?
For technical support, including LT8315EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8315EFE#TRPBF requirements.
6.How does Aetrix verify that LT8315EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8315EFE#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 LT8315EFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8315EFE#TRPBF?
All LT8315EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8315EFE#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 LT8315EFE#TRPBF part is unused and in its original packaging.
Return procedure for LT8315EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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