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Analog Devices Inc. LTC3803ES6-5#TRPBF
- Part No.:
- LTC3803ES6-5#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- SOT-23-6 Thin, TSOT-23-6
- Datasheet:
-
LTC3803ES6-5#TRPBF.pdf
- Description:
- IC REG CTRLR FLYBACK TSOT23-6
- Quantity:
- Payment:
- Shipping:
Inventory:8,503
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Product details
Overview
LTC3803ES6-5#TRPBF from Analog Devices (formerly Linear Technology) is a constant-frequency current-mode flyback DC/DC controller in a 6-lead SOT-23 (ThinSOT™) package, optimized for driving N-channel MOSFETs in high-input-voltage applications. It operates from 5V to 50V input, delivers ±1.5% output voltage accuracy, maintains 200kHz fixed switching frequency down to light loads, and consumes only 240μA quiescent current. It is used in isolated telecom housekeeping supplies and automotive auxiliary power rails.
For engineers reviewing the LTC3803ES6-5#TRPBF datasheet, LTC3803ES6-5#TRPBF pinout, LTC3803ES6-5#TRPBF application, or LTC3803ES6-5#TRPBF equivalent, key selection criteria include its ground-referenced current sensing architecture, programmable slope compensation via external resistor, internal 4.8V undervoltage lockout, 0.7–1.9V ITH/RUN control range, and compatibility with wide VIN/VOUT designs limited only by external components.
Technical Context
The LTC3803ES6-5#TRPBF implements a peak-current-mode control loop with an internal 200kHz oscillator, error amplifier with 200–500μA/V transconductance, and current comparator referenced to the ITH/RUN pin voltage. Its SENSE pin provides dual functionality: sensing MOSFET source current through an external resistor and injecting a 5μA linear ramp for slope compensation.
Startup and shutdown are managed via two independent mechanisms: VCC undervoltage lockout (4.8V turn-on, 4.0V turn-off) and ITH/RUN forced shutdown (0.08–0.47V threshold depending on grade). Internal soft-start clamps ITH/RUN for ~0.7ms at power-up, while the VCC shunt regulator self-biases from high VIN via a series resistor, regulating VCC to ~8.1V at up to 25mA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 200kHz fixed (170–230kHz over temp); enables predictable EMI filtering and stable operation across load range. |
| Output Voltage Accuracy | ±1.5% over temperature; ensures tight regulation for sensitive downstream circuitry without trimming. |
| Quiescent Current | 240μA typical; minimizes no-load power loss in always-on auxiliary supplies. |
| VCC UVLO Threshold | 4.8V turn-on / 4.0V turn-off (hysteresis = 0.05–0.8V); prevents erratic gate drive during brownout conditions. |
| Reference Voltage | 0.788–0.812V (E-grade, –40°C to 125°C); sets feedback divider ratio for precise output voltage setting. |
| Peak Sense Voltage | 100mV typical (85–120mV over temp/grade); defines current limit threshold at SENSE pin. |
| Gate Drive Rise/Fall Time | 40ns each (CL = 3000pF); supports fast MOSFET switching with low switching losses. |
Pinout & Package
Package: 6-lead low-profile (1mm height) TSOT-23 (ThinSOT™), JEDEC MO-193 compliant, –40°C to 125°C operating junction temperature (E-grade).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ITH/RUN (Pin 1) | Error amplifier output & run/shutdown control | Sets current comparator threshold (0.7–1.9V range); sinking/sourcing current adjusts duty cycle; <0.28V forces shutdown. |
| GND (Pin 2) | Analog and power ground reference | Common return for feedback, sense, and VCC bypass; must be low-impedance connection to minimize noise coupling. |
| VFB (Pin 3) | Feedback input | Compares divided output voltage against 0.8V internal reference; 10nA max input bias enables high-resistor-divider designs. |
| SENSE (Pin 4) | Current sense & slope compensation injection | Monitors MOSFET source voltage; injects 5μA linear ramp (6.5–80% duty cycle) for stability in continuous conduction mode. |
| VCC (Pin 5) | Supply input with internal shunt regulator | Accepts 5–50V input; internal clamp regulates to ~8.1V at up to 25mA; requires local 10μF ceramic bypass. |
| NGATE (Pin 6) | N-channel MOSFET gate driver output | 0V to VCC swing; 1A peak pulsed current; drives gate capacitance directly without external buffer in most designs. |
Key Features
| Feature | Design Value |
|---|---|
| Ground-referenced current sensing | Enables high-side primary-side sensing without level-shifting circuits; simplifies layout and reduces component count. |
| Adjustable slope compensation | External RSL sets ramp magnitude (e.g., 5.9kΩ yields 30mV drop at 80% duty cycle); eliminates subharmonic oscillation in CCM flyback. |
| Internal soft-start | ~0.7ms ITH/RUN voltage ramp at startup; prevents inrush current and output overshoot in isolated converters. |
| No minimum load requirement | Stable regulation from zero load to full load due to constant-frequency current-mode architecture. |
| VCC shunt regulator | Self-biases from high VIN via single resistor; eliminates need for dedicated bias winding or LDO in flyback topologies. |
Applications
| Telecom Housekeeping Supply | Automotive Auxiliary Power |
|---|---|
Use Scenario: Isolated 10V/100mA auxiliary rail for base station control logic and monitoring ICs from 36–75V telecom input. IC Role / Device Role / Timing Role: Flyback controller managing primary-side switching, current sensing, and voltage regulation without optocoupler feedback. Use Value: Enables compact, low-noise, high-efficiency isolated supply using only passive magnetics and standard MOSFETs-no third-winding or opto-isolator required. |
Use Scenario: 12V/1.2A isolated auxiliary supply for infotainment head unit from 6–50V automotive battery input. IC Role / Device Role / Timing Role: Constant-frequency current-mode controller ensuring stable regulation across cold-crank (6V) and load-dump (50V) transients. Use Value: Delivers ±1.5% output accuracy and 240μA quiescent current to meet automotive standby power budgets and EMC requirements. |
| Power over Ethernet (PoE) Interface | Industrial Sensor Node Power |
Use Scenario: 5V/0.3A isolated secondary-side supply derived from PoE midspan (48V) input for Ethernet PHY and microcontroller. IC Role / Device Role / Timing Role: Primary-side flyback controller with programmable slope compensation enabling stable operation at high duty cycles (>70%) needed for 48V-to-5V conversion. Use Value: Fixed 200kHz frequency simplifies EMI filter design; ground-referenced sensing avoids isolation barrier complications in PoE PD implementations. |
Use Scenario: 3.3V/1.5A isolated supply for wireless sensor node powered from wide-range industrial 18–72V DC bus. IC Role / Device Role / Timing Role: High-input-voltage flyback controller supporting 4:1 input range with internal UVLO hysteresis to withstand line sags and surges. Use Value: Eliminates need for pre-regulator stage; ±1.5% reference accuracy ensures reliable ADC reference and RF transceiver operation across temperature. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3805ES6-5#TRPBF | Adjustable frequency (100–600kHz), higher max duty cycle (90%), no internal shunt regulator - requires external bias. | Better suited for designs needing EMI spread-spectrum tuning or higher power density; less suitable for ultra-low-component-count high-VIN biasing. | Choose LTC3805ES6-5#TRPBF when frequency flexibility or higher peak current capability is required; avoid if VCC self-biasing from VIN is essential. |
| LTC3873ES6-5#TRPBF | No external current sense resistor needed (No RSENSE™ architecture); higher quiescent current (600μA); same 200kHz fixed frequency. | Reduces BOM count and PCB area in cost-sensitive designs; trades off efficiency at light load due to higher ICC. | Choose LTC3873ES6-5#TRPBF when minimizing external components outweighs quiescent current penalty; verify thermal performance at full load. |
Compared with LTC3803ES6-5#TRPBF, LTC3805ES6-5#TRPBF offers frequency adjustability but removes integrated VCC regulation, while LTC3873ES6-5#TRPBF eliminates the sense resistor but increases no-load power consumption - making LTC3803ES6-5#TRPBF optimal for simple, low-quiescent, self-biased flyback designs.
Availability
LTC3803ES6-5#TRPBF is available at Aetrix Electronics and suitable for telecom housekeeping supplies, automotive auxiliary power rails, and Power over Ethernet interface circuits requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC3803ES6-5#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 precision analog and power management portfolio with rigorous qualification and long-term product support.
The LTC3803-5 belongs to Linear's high-voltage flyback controller family, designed specifically for isolated DC/DC conversion in space-constrained, high-reliability applications where simplicity, low quiescent current, and robust input voltage handling are critical.
FAQ
What is the maximum input voltage the LTC3803ES6-5#TRPBF can handle?
The LTC3803ES6-5#TRPBF itself has no absolute maximum input voltage rating because it uses ground-referenced current sensing and does not require any pin to connect directly to high VIN. The practical input voltage limit is set by external components - primarily the breakdown voltage of the N-channel MOSFET and transformer insulation. Typical designs operate from 6V to 50V, with some applications extending beyond 72V using appropriately rated FETs and magnetics. The VCC pin is internally regulated to ~8.1V regardless of input.
Does the LTC3803ES6-5#TRPBF require an optocoupler for feedback in isolated flyback designs?
No, the LTC3803ES6-5#TRPBF does not require an optocoupler. It uses primary-side regulation: the output voltage is sensed indirectly via a resistive divider on the secondary, reflected back through the transformer to the VFB pin. This eliminates the need for optocouplers or third-winding sensing, reducing cost, size, and failure points while maintaining ±1.5% output accuracy across line and load variations.
How is slope compensation implemented on the LTC3803ES6-5#TRPBF?
Slope compensation on the LTC3803ES6-5#TRPBF is implemented by injecting a linear 5μA current ramp from the SENSE pin into an external resistor (RSL) connected between SENSE and the current sense resistor. This creates a voltage ramp that adds to the sensed current signal, stabilizing the control loop against subharmonic oscillation in continuous conduction mode. A typical value is 5.9kΩ, yielding ~30mV compensation at 80% duty cycle. Omitting RSL (shorting SENSE to RSENSE) disables slope compensation for discontinuous mode designs.
What is the purpose of the internal VCC shunt regulator in the LTC3803ES6-5#TRPBF?
The internal VCC shunt regulator in the LTC3803ES6-5#TRPBF allows direct powering from high input voltages (e.g., 48V telecom or 72V industrial rails) using only a single series resistor and local bypass capacitor. It clamps VCC to ~8.1V while sinking up to 25mA, eliminating the need for a separate bias winding, LDO, or auxiliary supply - significantly simplifying flyback converter design and reducing bill-of-materials count.
Can the LTC3803ES6-5#TRPBF be used in boost or SEPIC topologies?
Yes, the LTC3803ES6-5#TRPBF is explicitly specified for flyback, SEPIC, and boost converter applications per its datasheet. Its current-mode architecture, ground-referenced sensing, and flexible gate drive make it suitable for non-isolated topologies. For boost, the SENSE pin monitors switch current on the low-side path; for SEPIC, it senses current in the coupled inductor's series path. Layout and component selection must follow topology-specific guidelines, especially regarding current path routing and snubber design.
LTC3803ES6-5#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- SOT-23-6 Thin, TSOT-23-6
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Flyback
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 4V ~ 8.1V
- Frequency - Switching:
- 200kHz
- Duty Cycle (Max):
- 80%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TSOT-23-6
LTC3803ES6-5#TRPBF FAQ
1.How can I place an order for LTC3803ES6-5#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3803ES6-5#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 LTC3803ES6-5#TRPBF reliable?
The price and inventory of LTC3803ES6-5#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3803ES6-5#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3803ES6-5#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3803ES6-5#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3803ES6-5#TRPBF?
LTC3803ES6-5#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3803ES6-5#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 LTC3803ES6-5#TRPBF?
For technical support, including LTC3803ES6-5#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3803ES6-5#TRPBF requirements.
6.How does Aetrix verify that LTC3803ES6-5#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3803ES6-5#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 LTC3803ES6-5#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3803ES6-5#TRPBF?
All LTC3803ES6-5#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3803ES6-5#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 LTC3803ES6-5#TRPBF part is unused and in its original packaging.
Return procedure for LTC3803ES6-5#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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