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Analog Devices Inc. LTC3803IS6#TRPBF
- Part No.:
- LTC3803IS6#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- SOT-23-6 Thin, TSOT-23-6
- Datasheet:
-
LTC3803IS6#TRPBF.pdf
- Description:
- IC REG CTRLR FLYBACK TSOT23-6
- Quantity:
- Payment:
- Shipping:
Inventory:6,159
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Product details
Overview
LTC3803IS6#TRPBF from Analog Devices (formerly Linear Technology) is a constant-frequency current-mode flyback DC/DC controller optimized for driving N-channel MOSFETs in high-input-voltage telecom and industrial power supplies. It delivers ±1.5% output voltage accuracy, 200 kHz fixed switching frequency, 240 μA quiescent current, and operates across –40°C to 125°C. Used in nonisolated 5 V/2 A housekeeping supplies with 36–72 V input.
For engineers reviewing the LTC3803IS6#TRPBF datasheet, LTC3803IS6#TRPBF pinout, LTC3803IS6#TRPBF application, or LTC3803IS6#TRPBF equivalent, key selection criteria include VCC UVLO thresholds (7.7 V turn-on / 5.7 V turn-off), programmable slope compensation via SENSE pin, internal soft-start (1.4 ms), ground-referenced current sensing, and compatibility with high-VIN bias winding schemes.
Technical Context
The LTC3803IS6#TRPBF implements peak current-mode control with a 200 kHz free-running oscillator, 6–80% duty cycle range, and integrated slope compensation current source (5 μA). Its error amplifier features 200–500 μA/V transconductance and drives the ITH/RUN pin to set the current comparator threshold.
Startup relies on micropower hysteretic UVLO (VTURNON = 7.7 V, VTURNOFF = 5.7 V, VHYST = 2.0 V) and an internal 0.3 μA pull-up on ITH/RUN. The VCC shunt regulator clamps at 9.4 V (typ) under 25 mA load, enabling direct high-VIN resistor-fed operation without external regulators.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 200 kHz fixed - ensures predictable EMI profile and simplifies filter design across load range. |
| Output Voltage Accuracy | ±1.5% - enables tight regulation for sensitive telecom housekeeping rails without post-regulation. |
| Quiescent Current | 240 μA - supports ultra-low standby power in always-on auxiliary supplies. |
| VCC UVLO Thresholds | Turn-on: 7.7 V, Turn-off: 5.7 V - wide hysteresis enables reliable startup from bias windings in flyback topologies. |
| Peak Current Sense Voltage | 100 mV (typ) - sets precise overcurrent limit with minimal I²R loss in sense resistor. |
| Soft-Start Time | 1.4 ms - prevents inrush current stress on transformer, MOSFET, and output capacitors. |
| Error Amplifier gm | 200–500 μA/V - provides stable loop compensation margin with standard RC networks on ITH/RUN. |
Pinout & Package
Package: 6-lead TSOT-23 (ThinSOT™), 1 mm profile, rated for –40°C to 125°C junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ITH/RUN (1) | Error amplifier output & shutdown control | Sets current comparator threshold; pulled up internally (0.3 μA); <0.28 V forces shutdown. |
| GND (2) | Power and signal reference | Ground return for all internal circuits and external current sense resistor. |
| VFB (3) | Feedback input | Compares divided output voltage against 0.8 V internal reference; 10 nA input bias minimizes divider error. |
| SENSE (4) | Current sense & slope ramp injection | Monitors MOSFET source voltage; sources 5 μA linear ramp for slope compensation when RSL is present. |
| VCC (5) | Supply input with shunt regulator | Internally regulated to ~9.4 V; accepts 7.7–9.5 V input; sinks up to 25 mA for resistor-fed operation. |
| NGATE (6) | N-MOSFET gate driver | Push-pull output swinging 0 V to VCC; 40 ns rise/fall into 3000 pF; drives logic-level MOSFETs directly. |
Key Features
| Feature | Design Value |
|---|---|
| Constant-frequency current-mode control | Maintains 200 kHz operation down to zero load - eliminates low-frequency beat notes in audio-sensitive systems. |
| Ground-referenced current sensing | Enables high-side primary-side sensing without level-shifting; supports input voltages far exceeding IC's 8 V absolute max rating. |
| Programmable slope compensation | 5 μA ramp injected via SENSE pin - stabilizes duty cycles >50% without external op-amps or timing components. |
| Internal VCC shunt regulator | Clamps VCC to 9.4 V (typ) - allows direct connection to 36–72 V telecom rails via single series resistor, eliminating external LDOs. |
| Micropower hysteretic start-up | 0.3 μA ITH/RUN pull-up + 2.0 V UVLO hysteresis - enables self-starting from bias windings with minimal external components. |
Applications
| Telecom Housekeeping Supply | Automotive 42 V Auxiliary Rail |
|---|---|
Use Scenario: Generating 5 V/2 A nonisolated bias for FPGA, PHY, and management ICs in 48 V telecom line cards. IC Role / Device Role / Timing Role: Flyback controller regulating output via optocoupler-free feedback; sets MOSFET on-time using sensed primary current and 200 kHz clock. Use Value: Eliminates need for isolated feedback components; ±1.5% accuracy ensures reliable digital IC operation across temperature. |
Use Scenario: Powering infotainment microcontrollers and CAN transceivers from 42 V battery systems in commercial vehicles. IC Role / Device Role / Timing Role: High-input-voltage flyback controller with UVLO hysteresis tuned for cold-crank resilience (5.7 V dropout hold). Use Value: Operates continuously down to 36 V input while maintaining regulation - avoids brownouts during engine cranking. |
| Power over Ethernet (PoE) PD Interface | Industrial 12 V Auxiliary Converter |
Use Scenario: Deriving 3.3 V/1 A auxiliary power from PoE Class 4 (57 V) input for PD-side monitoring circuitry. IC Role / Device Role / Timing Role: Constant-frequency flyback controller managing primary-side current limiting and soft-start during hot-swap insertion. Use Value: 240 μA quiescent current meets IEEE 802.3af/at no-load requirements; 1.4 ms soft-start prevents inrush into PoE interface capacitors. |
Use Scenario: Providing isolated 12 V/1.5 A for PLC I/O modules powered from 24–60 V industrial DC bus. IC Role / Device Role / Timing Role: Primary-side regulated flyback controller using third-winding bias and programmable slope compensation for stability at 75% duty cycle. Use Value: Adjustable slope compensation ensures stable operation across full input range without secondary-side feedback complexity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCC28C43DR | Fixed 200 kHz frequency, but only ±2% reference accuracy; no internal VCC shunt regulator - requires external bias supply. | Requires external 7–12 V bias rail; less suitable for resistor-fed high-VIN designs. | Choose UCC28C43DR only when external bias is already available and ±2% output tolerance is acceptable. |
| MAX5021ASA+ | Higher 250 kHz frequency; ±1% reference; includes built-in 7.5 V LDO - no shunt regulator, limited to ≤16 V VIN. | Not rated for >16 V VCC; incompatible with 36–72 V telecom inputs without pre-regulation. | Select MAX5021ASA+ for lower-profile 12 V systems where higher frequency reduces magnetics size, but avoid for high-VIN telecom use. |
Compared with UCC28C43DR and MAX5021ASA+, the LTC3803IS6#TRPBF uniquely combines ±1.5% accuracy, internal 9.4 V shunt regulation, and ground-referenced sensing - enabling simpler, more robust high-input-voltage flyback designs without auxiliary bias rails or pre-regulators.
Availability
LTC3803IS6#TRPBF is available at Aetrix Electronics and suitable for telecom housekeeping supplies, automotive 42 V auxiliary rails, and Power over Ethernet (PoE) powered device interfaces requiring stable component supply across extended temperature ranges.
Supply support for LTC3803IS6#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 high-performance analog and power management portfolio with rigorous automotive and industrial qualification standards.
The LTC3803IS6#TRPBF belongs to Linear's legacy high-voltage flyback controller family, designed specifically for telecom, industrial, and automotive auxiliary power supplies where simplicity, reliability, and high-input-voltage operation are critical.
FAQ
What is the operating temperature range of the LTC3803IS6#TRPBF?
The LTC3803IS6#TRPBF is specified for operation from –40°C to +125°C junction temperature. This industrial-grade rating makes it suitable for under-hood automotive auxiliary supplies and telecom equipment deployed in uncontrolled environments. The part marking "I" in LTC3803IS6 denotes the industrial temperature grade, distinct from the commercial (E), high-temp (H), or military (MP) variants.
Can the LTC3803IS6#TRPBF be powered directly from a 48 V input?
Yes - the LTC3803IS6#TRPBF can be powered directly from 48 V using a series current-limiting resistor and a minimum 10 μF VCC bypass capacitor. Its internal shunt regulator clamps VCC to ~9.4 V and sinks up to 25 mA, allowing simple resistor-fed operation without external regulators. This capability is explicitly validated in the datasheet's Figure 3 and Applications Information section.
How does slope compensation work on the LTC3803IS6#TRPBF?
The LTC3803IS6#TRPBF injects a linear 5 μA current ramp from the SENSE pin during 6–80% duty cycle, developing a voltage drop across an external resistor (RSL) to add slope compensation. This stabilizes current-mode control at duty cycles above 50%, preventing subharmonic oscillation. A typical RSL value is 5.9 kΩ, yielding ~30 mV compensation at 80% duty cycle - fully detailed in the Applications Information section.
What is the purpose of the ITH/RUN pin on the LTC3803IS6#TRPBF?
The ITH/RUN pin on the LTC3803IS6#TRPBF serves dual functions: it is the error amplifier output that sets the current comparator threshold, and it acts as the run/shutdown control input. Pulling ITH/RUN below 0.28 V (typ) forces shutdown; releasing it above this threshold - while VCC exceeds 7.7 V - initiates soft-start. Its 0.3 μA internal pull-up enables micropower bias-winding startup schemes.
Does the LTC3803IS6#TRPBF require an external current sense resistor?
Yes - the LTC3803IS6#TRPBF requires an external current sense resistor (RSENSE) connected between the MOSFET source and ground. It measures peak switch current by sensing the voltage across RSENSE, with a typical full-scale threshold of 100 mV. The value of RSENSE determines the current limit (e.g., 0.02 Ω for 5 A peak), and parasitic PCB resistance must be minimized to maintain accuracy - as emphasized in the Current Sense Resistor Considerations section.
LTC3803IS6#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):
- 5.7V ~ 8V
- 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
LTC3803IS6#TRPBF FAQ
1.How can I place an order for LTC3803IS6#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3803IS6#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 LTC3803IS6#TRPBF reliable?
The price and inventory of LTC3803IS6#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3803IS6#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3803IS6#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3803IS6#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3803IS6#TRPBF?
LTC3803IS6#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3803IS6#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 LTC3803IS6#TRPBF?
For technical support, including LTC3803IS6#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3803IS6#TRPBF requirements.
6.How does Aetrix verify that LTC3803IS6#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3803IS6#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 LTC3803IS6#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3803IS6#TRPBF?
All LTC3803IS6#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3803IS6#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 LTC3803IS6#TRPBF part is unused and in its original packaging.
Return procedure for LTC3803IS6#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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