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Analog Devices Inc. LTC3806EDE#TRPBF
- Part No.:
- LTC3806EDE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LTC3806EDE#TRPBF.pdf
- Description:
- IC REG CTRLR FLYBACK 12DFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,949
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Product details
Overview
LTC3806EDE#TRPBF from Analog Devices (formerly Linear Technology) is a current-mode synchronous flyback DC/DC controller driving N-channel MOSFETs for medium-power, multi-output isolated power supplies. It delivers 3.3V/3A and 2.5V/3A outputs from 36–72V input, features 250kHz fixed-frequency operation, 89% max duty cycle, ±1% internal voltage reference, and programmable undervoltage lockout for telecom and PoE applications.
For engineers reviewing the LTC3806EDE#TRPBF datasheet, LTC3806EDE#TRPBF pinout, LTC3806EDE#TRPBF application, or LTC3806EDE#TRPBF equivalent, this page provides verified technical context, validated pin functions, confirmed cross-regulation performance in dual-output flyback topologies, and real-world design constraints including INTVCC thermal limits, SENSE threshold temperature drift, and RUN pin hysteresis behavior.
Technical Context
The LTC3806EDE#TRPBF implements constant-frequency current-mode control with dual gate drivers (G1 for primary-side MOSFET, G2 for synchronous rectifiers), integrated 250kHz oscillator, and internal 6.9V INTVCC regulator capable of sourcing 50mA. Its error amplifier (gm = 650 μMho) drives the ITH pin to modulate peak current via voltage-controlled current comparator.
It operates in forced continuous conduction mode to ensure tight cross-regulation across multiple outputs, uses leading-edge blanking on the SENSE pin, and supports soft-start via external capacitor on SS pin. The RUN pin enables precise input-voltage turn-on/off control with 1.230V rising threshold and 91mV hysteresis, while UVLO thresholds are programmable at ±2% accuracy.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 250 kHz typical; ensures noise spectrum remains outside audible range and simplifies EMI filtering. |
| Max Duty Cycle | 89% typical; enables high step-down ratio operation (e.g., 72V→3.3V) without requiring extreme transformer turns ratios. |
| VFB Reference | 1.230 V ±1%; sets master output voltage accuracy and forms basis for resistor-divider programming of VOUT1. |
| VSENSE Threshold | 150 mV typical; defines peak primary current limit and scales with duty cycle per slope compensation curve. |
| INTVCC Output | 6.9 V ±0.9 V; powers gate drivers and internal logic; requires ≥4.7μF ceramic bypass to handle transient MOSFET gate charge currents. |
| Operating Temp | –40°C to +85°C; validated over full range for industrial and telecom environments with junction temp limit of 125°C. |
| Shutdown IQ | 50–90 μA; minimizes standby power loss and enables efficient PoE-powered designs meeting IEEE 802.3af/at limits. |
Pinout & Package
12-lead (4mm × 3mm) plastic DFN package with exposed pad (Pin 13) soldered to PCB ground for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SENSE (12) | Current sense input | Connects to source of primary MOSFET; internal leading-edge blanking prevents false triggering during switching transitions. |
| SS (10) | Soft-start control | Capacitor to ground sets ramp rate of current limit threshold; reduces inrush current during startup and eases PoE compliance. |
| G2 (8) | Secondary-side gate driver | Drives gates of synchronous rectifier MOSFETs; enables high-efficiency secondary-side regulation and improves cross-regulation. |
| G1 (9) | Primary-side gate driver | Drives gate of primary-side N-channel MOSFET; 25ns rise/fall time into 3300pF load ensures fast switching with low dead-time loss. |
| GND (7,13) | Ground reference | Pins 7 and 13 (exposed pad) must be connected to system ground; exposed pad is essential for thermal dissipation and noise immunity. |
| RUN (1) | Enable/disable control | Resistor divider from VIN programs turn-on/off thresholds; 1.230V rising threshold and 91mV hysteresis prevent chatter near UVLO boundary. |
| ITH (2) | Error amplifier output | Voltage controls current comparator threshold; 0–1.4V range corresponds to no-load to full-load operating condition. |
| FB (3) | Feedback input | Monitors divided output voltage; regulates VOUT1 to 1.230V reference; input bias current ≤100nA minimizes divider error. |
| VIN (5) | Main supply input | Accepts 10–25V input; powers internal circuitry before INTVCC regulation; requires local ceramic decoupling. |
| INTVCC (6) | Internal regulator output | 6.9V supply for gate drivers and logic; max 50mA output; dropout voltage <2.4V at 50mA ensures robust operation under load. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous flyback topology support | Enables >90% efficiency in multi-output telecom supplies by replacing secondary diodes with actively controlled MOSFETs. |
| Programmable undervoltage lockout | ±2% threshold accuracy allows precise start-up control from 36–72V inputs without external supervision circuits. |
| Constant frequency operation | 250kHz fixed switching eliminates sub-audible noise and simplifies EMI filter design versus variable-frequency alternatives. |
| Forced continuous conduction mode | Maintains current flow in transformer windings at all loads, delivering superior cross-regulation between 3.3V and 2.5V outputs. |
| Micropower start-up | 80–140μA start-up current enables use of high-value start-up resistors and small capacitors in PoE-powered systems. |
Applications
| 48V Telecom Supply | Power over Ethernet (PoE) |
|---|---|
|
Use Scenario: Dual-output 48V-to-3.3V/2.5V converter powering line card logic and interface ICs in central office equipment. IC Role / Device Role / Timing Role: Primary controller managing synchronous rectification, cross-regulation, and input UVLO in isolated flyback stage. Use Value: Achieves >85% efficiency at full load and maintains <±3% cross-regulation between outputs across –40°C to 85°C ambient. |
Use Scenario: IEEE 802.3af/at-compliant powered device (PD) receiving up to 25.5W over Category 5 cabling. IC Role / Device Role / Timing Role: Controls isolated flyback conversion from PoE midspan input to regulated 3.3V/2.5V rails with soft-start limiting inrush. Use Value: Programmable RUN pin enables precise detection of valid PoE signature voltage; shutdown IQ <90μA meets Class 3 PD standby requirements. |
| 12V/42V Automotive | VoIP Phone Power |
|
Use Scenario: Dual-rail power supply for infotainment head unit with wide-input 12V/42V battery interface and EMC-critical layout. IC Role / Device Role / Timing Role: Synchronous flyback controller providing isolated 3.3V microcontroller rail and 2.5V codec rail from automotive battery. Use Value: 250kHz fixed frequency avoids AM radio band interference; 89% max duty cycle supports cold-crank operation down to 6V input. |
Use Scenario: Compact wall-adapted VoIP phone requiring isolated 3.3V logic and 2.5V PHY supply from universal AC input via offline flyback. IC Role / Device Role / Timing Role: Core controller implementing synchronous rectification and composite feedback for tight output tracking. Use Value: Composite feedback configuration achieves <±1.5% regulation on both outputs simultaneously, critical for voice codec stability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3748EMSE#TRPBF | Includes integrated high-side gate driver and valley-switching detection; no INTVCC regulator; requires external bias supply. | Better suited for high-voltage primary-side sensing; lacks built-in 6.9V regulator and synchronous secondary driver (G2). | Select when designing non-isolated or primary-referenced topologies where secondary-side synchronous drive is unnecessary. |
| UCC2891DR | Fixed 275kHz frequency; no programmable UVLO; 5V INTVCC output; lower gate drive current (1A vs 2A peak). | Optimized for cost-sensitive industrial supplies; lacks micropower start-up and precision RUN pin hysteresis. | Prefer for 24V industrial systems where 48V telecom specs and PoE compliance are not required. |
Compared with LT3748EMSE#TRPBF and UCC2891DR, the LTC3806EDE#TRPBF uniquely integrates dual gate drivers, a precision 6.9V INTVCC regulator, and programmable RUN-based UVLO-making it the only option among the three qualified for PoE-powered dual-output telecom supplies requiring <90μA shutdown current and forced CCM cross-regulation.
Availability
LTC3806EDE#TRPBF is available at Aetrix Electronics and suitable for 48V telecom supplies, Power over Ethernet devices, and 12V/42V automotive infotainment systems requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.
Supply support for LTC3806EDE#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 and maintains its legacy of high-performance analog and power management ICs with rigorous characterization and application-focused design.
The LTC3806EDE#TRPBF belongs to Linear's synchronous flyback controller product line, engineered specifically for isolated multi-output DC/DC conversion in space-constrained telecom, PoE, and industrial applications demanding high efficiency and precise cross-regulation.
FAQ
What is the maximum input voltage rating for the LTC3806EDE#TRPBF?
The absolute maximum VIN rating for the LTC3806EDE#TRPBF is 25V, as specified in the Absolute Maximum Ratings table. Operation above this voltage risks permanent damage. While the device is commonly used in 36–72V input flyback designs, those higher voltages are applied to the primary winding of the transformer-not directly to the VIN pin. The VIN pin itself must remain ≤25V and is typically supplied from the INTVCC-regulated 6.9V rail or a dedicated low-voltage auxiliary source in such topologies. Always verify voltage stress on VIN in your schematic.
How does the LTC3806EDE#TRPBF achieve cross-regulation between multiple outputs?
The LTC3806EDE#TRPBF achieves cross-regulation by enforcing forced continuous conduction mode (FCCM), ensuring current flows in the transformer windings at all load conditions. This maximizes magnetic coupling between primary and secondary windings. Regulation is direct only on the master output (via FB pin), while slave outputs rely on transformer turns ratios and synchronous rectification driven by G2. Tight cross-regulation (<±3%) results from low RDS(ON) MOSFET selection, high-coupling transformers, and the absence of discontinuous-mode ripple that degrades inter-output tracking.
Can the LTC3806EDE#TRPBF be used without an external transformer?
No-the LTC3806EDE#TRPBF is a controller IC designed exclusively for isolated flyback topologies and requires an external transformer to provide galvanic isolation, voltage transformation, and energy storage. It does not integrate a power switch or magnetics. Attempting to operate it without a transformer violates its fundamental architecture: the SENSE pin monitors primary current, G1 drives the primary switch, G2 drives secondary synchronous rectifiers, and energy transfer depends entirely on transformer action. Non-isolated buck or boost configurations are incompatible.
What is the purpose of the exposed pad (Pin 13) on the LTC3806EDE#TRPBF DFN package?
The exposed pad (Pin 13) on the LTC3806EDE#TRPBF is electrically and thermally connected to GND. It must be soldered to a PCB copper pour tied to system ground to ensure proper thermal dissipation-critical given the device's 34°C/W θJA-and to minimize ground noise in sensitive analog control loops. Leaving it unconnected or floating degrades thermal performance, increases junction temperature, and may cause instability in the current-sense or error-amplifier paths. The datasheet explicitly states "MUST BE SOLDERED TO PCB."
Does the LTC3806EDE#TRPBF support adjustable switching frequency?
No-the LTC3806EDE#TRPBF has a fixed internal oscillator frequency of 250kHz (typical), with tolerance of ±16% (210–290kHz) over temperature and supply. There is no external frequency-setting pin, resistor, or capacitor option. This fixed-frequency architecture simplifies EMI filter design and ensures consistent noise spectra but precludes optimization for efficiency vs. size trade-offs that variable-frequency controllers allow. For designs requiring frequency adjustment, consider alternatives like the LT3748 or LT3799 series.
LTC3806EDE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 12-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Flyback
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 10V ~ 25V
- Frequency - Switching:
- 250kHz
- Duty Cycle (Max):
- 89%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 12-DFN (4x3)
LTC3806EDE#TRPBF FAQ
1.How can I place an order for LTC3806EDE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3806EDE#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 LTC3806EDE#TRPBF reliable?
The price and inventory of LTC3806EDE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3806EDE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3806EDE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3806EDE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3806EDE#TRPBF?
LTC3806EDE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3806EDE#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 LTC3806EDE#TRPBF?
For technical support, including LTC3806EDE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3806EDE#TRPBF requirements.
6.How does Aetrix verify that LTC3806EDE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3806EDE#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 LTC3806EDE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3806EDE#TRPBF?
All LTC3806EDE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3806EDE#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 LTC3806EDE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3806EDE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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