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Analog Devices Inc. LT8315HFE#TRPBF
- Part No.:
- LT8315HFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-TSSOP (0.173", 4.40mm Width), 16 Leads, Exposed Pad
- Datasheet:
-
LT8315HFE#TRPBF.pdf
- Description:
- IC REG FLYBACK 800MA 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,796
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Product details
Overview
LT8315HFE#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 across 18V–560V input range, enables constant-voltage and constant-current regulation, and operates in quasi-resonant boundary mode for high efficiency and tight load regulation-used in telecom housekeeping supplies and EV battery stack monitoring.
For engineers reviewing the LT8315HFE#TRPBF datasheet, LT8315HFE#TRPBF pinout, LT8315HFE#TRPBF application, or LT8315HFE#TRPBF equivalent, key selection considerations include its 150°C junction-rated TSSOP-20 package, 70μA quiescent current in Burst Mode, 1.22V FB reference accuracy, programmable current limit via SOURCE pin, and absence of optocoupler requirement for isolated feedback.
Technical Context
The LT8315HFE#TRPBF implements boundary-mode (critical conduction) control using a sample-and-hold circuit that captures the flyback voltage from a transformer tertiary winding when secondary current approaches zero-enabling precise isolated output regulation without optocouplers. Its internal 630V depletion-mode startup FET charges INTVCC at power-up, eliminating external bleeder resistors.
It integrates a transconductance error amplifier (GM = 100μS), temperature-compensated reference (TC pin: +4.1mV/°C PTAT), and dual-loop CV/CC regulation. Switching frequency ranges from 3.5kHz (Burst Mode) to 140kHz (DCM-limited), with programmable soft-start and current limit via IREG/SS and SOURCE pins.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 18V to 560V - supports direct off-line and high-voltage DC bus applications including EV battery stacks and industrial HV rails. |
| Integrated Switch | 630V/300mA MOSFET - eliminates external HV switch; rated for ≥510V drain swing with 120V spike margin per datasheet Figure 1–4. |
| Quiescent Current | 70μA in Burst Mode - enables ultra-low standby power for always-on isolated supplies in telecom and medical systems. |
| FB Regulation Voltage | 1.22V ±3mV (−40°C to 150°C) - high-accuracy reference enabling ±5% output regulation across board population with proper RFB1/RFB2 selection. |
| Operating Junction Temp | −40°C to 150°C - H-grade qualification ensures reliability in under-hood automotive, industrial control, and high-ambient medical enclosures. |
| Switching Frequency Range | 3.5kHz to 140kHz - adaptive boundary/DCM operation maintains efficiency >85% across 5mA–440mA load (VIN ≥250V) per TA01b curve. |
| Current Limit Threshold | 110–130mV at SOURCE pin - sets peak switch current; combined with 300mA max switch rating, defines safe operating area for transformer design. |
Pinout & Package
LT8315HFE#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) is GND and must be soldered to PCB thermal plane for θJC = 10°C/W performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DRAIN (1,2,3) | Drain of 630V power switch & startup FET | High-side switching node; connects to primary winding; carries full HV input current and flyback spikes-requires compact layout and snubbing. |
| SOURCE (18) | Source of internal power switch | Current-sense node; voltage across RSNS sets peak current limit (110–130mV threshold); referenced to GND for accurate CC regulation. |
| FB (12) | Feedback input for output voltage sampling | Accepts scaled flyback pulse from tertiary winding; regulated to 1.22V reference; enables no-opto isolation with <±5% system accuracy. |
| TC (11) | Temperature compensation reference | PTAT voltage (+4.1mV/°C) used to offset diode VF drift; connected via RTC resistor to FB to stabilize VOUT over −40°C to 150°C. |
| IREG/SS (14) | Current regulation / soft-start control | 10μA sink current sets CC threshold; RC network here provides programmable soft-start ramp and current limit adjustment. |
| EN/UVLO (17) | Enable and undervoltage lockout input | 1.22V threshold with 65mV hysteresis; allows VIN-referenced UVLO or logic-level enable-critical for safe startup in HV systems. |
| GND (15,20,21) | Power and signal ground | Three dedicated GND pins plus exposed pad (Pin 21) for low-inductance return path and thermal dissipation-mandatory for 15W operation. |
Key Features
| Feature | Design Value |
|---|---|
| No-opto isolated regulation | Eliminates optocoupler, TL431, and associated bias networks-reduces BOM count by ≥4 components and improves long-term stability vs. aging optos. |
| Quasi-resonant boundary mode | Zero-current switching reduces EMI and transformer core loss; enables smaller magnetics than CCM while avoiding subharmonic oscillation. |
| Integrated 630V depletion-mode startup FET | Charges INTVCC capacitor directly from DRAIN at startup-removes need for external HV bleeder resistor and associated power loss. |
| Constant-current + constant-voltage regulation | Dual-loop control supports battery charging, LED drivers, and telecom bias supplies where both voltage and current limits are required. |
| 150°C junction-rated TSSOP-20 | H-grade qualification enables deployment in high-ambient environments (e.g., engine compartments, industrial cabinets) without derating. |
Applications
| Telecom Housekeeping Supply | EV Battery Stack Monitor |
|---|---|
Use Scenario: Providing isolated 12V/100mA bias to supervisory ICs and ADCs across 400–800V battery strings in electric vehicles. IC Role / Device Role / Timing Role: Primary-side flyback controller regulating isolated output from HV DC bus without optocoupler feedback. Use Value: Enables compact, high-reliability auxiliary supply with 70μA quiescent current-minimizing parasitic drain on traction battery during sleep mode. |
Use Scenario: Powering isolated CAN transceivers and cell voltage monitors in modular battery management systems (BMS). IC Role / Device Role / Timing Role: High-voltage flyback controller delivering stable 5V/200mA output from 200–560V intermediate rail. Use Value: Supports 150°C operation and withstands 560V input transients-meeting ASIL-B functional safety requirements for automotive BMS. |
| Industrial Off-Line Sensor Interface | Medical Isolated Auxiliary Supply |
Use Scenario: Generating isolated 12V/50mA for analog front-ends and isolation amplifiers in factory automation I/O modules. IC Role / Device Role / Timing Role: No-opto flyback controller implementing boundary-mode switching for low-noise, low-EMI sensor power. Use Value: Achieves >85% efficiency at light loads via Burst Mode-reducing thermal stress in sealed enclosures without forced air cooling. |
Use Scenario: Delivering isolated 12V/150mA to patient-connected monitoring circuits requiring reinforced insulation per IEC 60601-1. IC Role / Device Role / Timing Role: Primary-side regulated flyback controller eliminating optocoupler failure modes in long-life medical devices. Use Value: Meets creepage/clearance requirements via TSSOP-20 with removed pins-enabling certified 4kV isolation without custom transformer shielding. |
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; 105°C max junction temp; requires external LDO for bias; no integrated TC compensation. | Lacks 150°C rating and PTAT-based diode temp compensation-less suitable for automotive under-hood or high-ambient industrial use. | Select UCC28740DR only if operating ambient ≤105°C and output diode temp drift is mitigated externally. |
| MAX17690ATP+T | 650V/350mA switch; 125°C max junction temp; includes active burst mode but no depletion-mode startup FET. | Requires external startup circuitry; lacks integrated TC pin-needs additional op-amp compensation network for VOUT stability over temperature. | Choose MAX17690ATP+T when higher peak current (350mA) is needed and startup complexity is acceptable. |
Compared with UCC28740DR and MAX17690ATP+T, the LT8315HFE#TRPBF uniquely combines 150°C operation, depletion-mode startup, and integrated PTAT temperature compensation-reducing component count and improving thermal robustness in demanding isolated supply designs.
Availability
LT8315HFE#TRPBF is available at Aetrix Electronics and suitable for telecom housekeeping supplies, EV battery stack monitors, and industrial off-line sensor interfaces requiring stable component supply across extended temperature and high-voltage operating conditions.
Supply support for LT8315HFE#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 industrial, automotive, communications, and healthcare markets.
The LT8315HFE#TRPBF belongs to Analog Devices' high-voltage isolated power controller product line, designed specifically for no-opto flyback topologies in applications demanding wide input range, high reliability, and minimal component count.
FAQ
What is the maximum continuous output power achievable with the LT8315HFE#TRPBF?
The LT8315HFE#TRPBF supports up to 15W of continuous output power, as confirmed in the Typical Application section and validated across input voltages from 20V to 450V in the datasheet's efficiency curves (TA01a/b). This assumes proper transformer design, thermal management via the exposed pad, and operation within the 150°C junction limit. Output power scales with input voltage and transformer turns ratio-e.g., 12V/440mA at VIN >250V.
Does the LT8315HFE#TRPBF require an optocoupler for isolated output regulation?
No, the LT8315HFE#TRPBF does not require an optocoupler. It achieves isolated regulation by sampling the flyback voltage from a third (tertiary) winding on the transformer-capturing the waveform when secondary current approaches zero. This no-opto architecture eliminates optocoupler aging, nonlinearity, and dynamic response limitations while reducing BOM cost and size.
How does the TC pin on the LT8315HFE#TRPBF improve output voltage stability?
The TC pin on the LT8315HFE#TRPBF provides a buffered PTAT voltage (+4.1mV/°C) matched to the internal 1.22V reference. When connected via RTC resistor to the FB pin, it compensates for the negative temperature coefficient of the output rectifier diode (typically −1.5mV/°C). This correction reduces VOUT drift from ±200–400mV to <±25mV over −40°C to 150°C, critical for precision medical and telecom supplies.
What is the purpose of the depletion-mode startup FET in the LT8315HFE#TRPBF?
The depletion-mode startup FET in the LT8315HFE#TRPBF is an internal transistor that is normally on. At power-up, it draws current from the DRAIN pin to charge the INTVCC capacitor to ~12V-providing initial bias for the controller before the transformer's BIAS winding becomes active. This eliminates the need for external HV bleeder resistors, reducing standby power loss and component count.
Can the LT8315HFE#TRPBF operate in constant-current mode for battery charging applications?
Yes, the LT8315HFE#TRPBF supports true constant-current regulation via its dual-loop architecture. The IREG/SS pin sinks a precise 10μA current; the resulting voltage sets the current limit threshold. When output current reaches this point, the controller transitions from constant-voltage to constant-current mode-making it suitable for lead-acid, LiFePO₄, and supercapacitor charging in isolated systems.
LT8315HFE#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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP-EP
LT8315HFE#TRPBF FAQ
1.How can I place an order for LT8315HFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8315HFE#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 LT8315HFE#TRPBF reliable?
The price and inventory of LT8315HFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8315HFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8315HFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8315HFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8315HFE#TRPBF?
LT8315HFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8315HFE#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 LT8315HFE#TRPBF?
For technical support, including LT8315HFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8315HFE#TRPBF requirements.
6.How does Aetrix verify that LT8315HFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8315HFE#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 LT8315HFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8315HFE#TRPBF?
All LT8315HFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8315HFE#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 LT8315HFE#TRPBF part is unused and in its original packaging.
Return procedure for LT8315HFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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