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Analog Devices Inc. LTC3803IS6#TRMPBF
- Part No.:
- LTC3803IS6#TRMPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- SOT-23-6 Thin, TSOT-23-6
- Datasheet:
-
LTC3803IS6#TRMPBF.pdf
- Description:
- IC REG CTRLR FLYBACK TSOT23-6
- Quantity:
- Payment:
- Shipping:
Inventory:4,463
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Product details
Overview
LTC3803IS6#TRMPBF from Analog Devices (formerly Linear Technology) is a constant-frequency current-mode flyback DC/DC controller optimized for driving external N-channel MOSFETs in high-input-voltage telecom and industrial power supplies. It delivers ±1.5% output voltage accuracy, 200kHz fixed switching frequency, 240μA quiescent current, and operates across –40°C to +125°C junction temperature. Its ground-referenced current sensing enables input voltages beyond its own VCC rating - ideal for nonisolated 5V housekeeping rails in 36–72V telecom systems.
For engineers reviewing the LTC3803IS6#TRMPBF datasheet, LTC3803IS6#TRMPBF pinout, LTC3803IS6#TRMPBF application, or LTC3803IS6#TRMPBF equivalent, key selection criteria include its programmable slope compensation, internal soft-start (1.4ms), VCC shunt regulator (9.5V clamp), undervoltage lockout with 3.0V hysteresis (VTURNON = 8.7V / VTURNOFF = 5.7V), and SOT-23-6 ThinSOT™ package compatibility with space-constrained board layouts.
Technical Context
The LTC3803IS6#TRMPBF implements current-mode control using an internal 200kHz oscillator, peak-current comparator, and RS latch to regulate output voltage via ITH/RUN pin voltage-directly setting the current threshold. Its error amplifier (200–500 μA/V transconductance) drives ITH/RUN to close the loop, while slope compensation is injected as a 5μA linear ramp from the SENSE pin across an external resistor (RSL).
Startup relies on micropower hysteretic UVLO (8.7V turn-on / 5.7V turn-off) and a 0.3μA internal pull-up on ITH/RUN; shutdown occurs when ITH/RUN falls below 0.28V. The VCC pin integrates a shunt regulator (clamped at 9.5V @ 25mA), enabling direct high-VIN biasing through a single resistor without external LDOs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 200 kHz fixed - ensures predictable EMI profile and simplifies filter design across load range. |
| Output Voltage Accuracy | ±1.5% - achieved via 800 mV internal reference with <0.05 mV/V line regulation. |
| Quiescent Current | 240 μA - enables high-efficiency operation at light loads in always-on telecom housekeeping rails. |
| VCC UVLO Thresholds | VTURNON = 8.7 V, VTURNOFF = 5.7 V (3.0 V hysteresis) - supports reliable bootstrap start-up from bias winding. |
| Peak Sense Voltage | 100 mV typical - sets current limit with minimal power loss in RSENSE. |
| Slope Compensation Current | 5 μA peak - programmable via external RSL to stabilize duty cycles >50% in flyback designs. |
| Soft-Start Time | 1.4 ms - prevents inrush current and output overshoot during power-up. |
| Operating Temperature | –40°C to +125°C (junction) - qualified for industrial and telecom environments. |
Pinout & Package
Package: 6-lead TSOT-23 (ThinSOT™), 1 mm profile, RoHS-compliant, moisture sensitivity level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ITH/RUN (Pin 1) | Error amplifier output & shutdown control | Sets current comparator threshold (0.7–1.9 V); <0.28 V forces shutdown; hosts RC compensation network. |
| GND (Pin 2) | Analog and power ground reference | Common return for VFB, SENSE, and VCC bypass; must be low-impedance connection to minimize noise coupling. |
| VFB (Pin 3) | Feedback input | Compares output divider voltage to 800 mV reference; max 50 nA input bias enables high-value resistors for low quiescent loss. |
| SENSE (Pin 4) | Current sense & slope compensation injection | Monitors RSENSE voltage (0–100 mV); sources 5 μA ramp for duty-cycle-dependent slope compensation. |
| VCC (Pin 5) | Supply input with integrated shunt regulator | Internally clamped to ~9.5 V; accepts up to 25 mA sink current; requires ≥10 μF local ceramic bypass. |
| NGATE (Pin 6) | N-MOSFET gate driver output | 0 V to VCC swing; 40 ns rise/fall times into 3000 pF; drives external high-side switch in flyback topology. |
Key Features
| Feature | Design Value |
|---|---|
| Constant-frequency current-mode control | Enables stable regulation and predictable EMI without minimum load requirement - critical for variable telecom loads. |
| Programmable slope compensation | 5 μA ramp injected via SENSE pin allows precise tuning of compensation slope to prevent subharmonic oscillation at high duty cycles. |
| Internal VCC shunt regulator | Clamps VCC to 9.5 V, permitting direct high-VIN biasing through a single resistor - eliminates need for external LDO or auxiliary supply. |
| Micropower hysteretic start-up | 0.3 μA ITH/RUN pull-up and wide UVLO hysteresis (3.0 V) enable robust self-starting from transformer bias winding in flyback converters. |
| Ground-referenced current sensing | Allows primary-side sensing with RSENSE tied to source - supports high-input-voltage operation where controller ground is isolated from high-side switch node. |
Applications
| Telecom Housekeeping Power | Automotive Auxiliary Supply |
|---|---|
Use Scenario: Generating 5V/2A nonisolated auxiliary rail from 36–72V telecom battery backup bus. IC Role / Device Role / Timing Role: Flyback controller regulating output via primary-side current sensing and feedback divider; 200kHz timing sets transformer size and filter component values. Use Value: Eliminates need for isolated DC/DC module - reduces BOM cost and board area while maintaining ±1.5% regulation across full input range. |
Use Scenario: Providing stable 12V auxiliary supply from 42V automotive main bus for infotainment microcontrollers. IC Role / Device Role / Timing Role: Constant-frequency current-mode controller managing N-MOSFET switch in boost-derived flyback; internal soft-start prevents cold-cranking inrush. Use Value: 240μA quiescent current and –40°C to +125°C rating ensure reliable operation during engine-off battery drain and under-hood thermal stress. |
| Power over Ethernet (PoE) PD | Industrial Sensor Node Supply |
Use Scenario: Deriving 3.3V/1A regulated output from PoE Class 4 (57V) input for powered device logic and PHY. IC Role / Device Role / Timing Role: Primary-side regulated flyback controller with VCC powered from bias winding; 200kHz frequency balances efficiency and magnetics size. Use Value: Adjustable slope compensation and no-minimum-load operation support dynamic PoE load profiles without output instability. |
Use Scenario: Compact 12V-to-5V conversion in DIN-rail mounted PLC I/O modules with limited PCB real estate. IC Role / Device Role / Timing Role: High-voltage flyback controller enabling direct 12–48V input handling; SOT-23-6 footprint minimizes layout area. Use Value: Ground-referenced sensing and internal VCC clamp allow safe operation with input transients exceeding 60V - reducing need for front-end TVS protection. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3748IMS#PBF | Isolated flyback controller with integrated transformer drive; no external MOSFET required; higher VIN rating (100V). | Designed for isolated outputs; includes primary-side sensing and opto-couplerless regulation - not suitable for nonisolated housekeeping rails. | Select LT3748 only when isolation is mandatory; LTC3803IS6#TRMPBF remains preferred for cost-sensitive, nonisolated telecom rails. |
| UCC28740DR | Variable-frequency quasi-resonant controller; lower IQ (120μA); no internal VCC shunt regulator - requires external bias supply. | Optimized for high-efficiency AC/DC adapters; lacks programmable slope compensation and fixed-frequency EMI control. | Choose UCC28740 for ultra-low standby power in AC/DC; LTC3803IS6#TRMPBF better suits fixed-frequency, high-VIN telecom systems needing simplicity and robustness. |
Compared with LT3748IMS#PBF and UCC28740DR, the LTC3803IS6#TRMPBF uniquely combines fixed 200kHz operation, internal VCC shunt regulation, and ground-referenced sensing - making it optimal for compact, nonisolated, high-input-voltage flyback supplies where layout simplicity and predictable EMI are prioritized over ultra-low IQ or isolation.
Availability
LTC3803IS6#TRMPBF is available at Aetrix Electronics and suitable for telecom housekeeping power, automotive auxiliary supplies, Power over Ethernet (PoE) powered devices, and industrial sensor node power conversion requiring stable component supply and long-term industrial temperature support.
Supply support for LTC3803IS6#TRMPBF 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#TRMPBF belongs to Linear's legacy high-voltage flyback controller family, designed specifically for nonisolated, high-input-voltage DC/DC conversion in telecom infrastructure, industrial automation, and automotive subsystems where reliability and layout simplicity are critical.
FAQ
What is the operating temperature range for the LTC3803IS6#TRMPBF?
The LTC3803IS6#TRMPBF is rated for a junction temperature range of –40°C to +125°C. This I-grade variant is fully specified and guaranteed across that range, making it suitable for industrial and telecom environments where ambient temperatures may exceed commercial limits. Derating guidelines apply above 125°C per manufacturer thermal data.
Does the LTC3803IS6#TRMPBF require an external MOSFET?
Yes, the LTC3803IS6#TRMPBF is a controller IC-not a converter IC-and requires an external N-channel MOSFET connected to its NGATE pin. It provides gate drive capability (1A peak, 40ns edges) but does not integrate power switches. This architecture allows designers to select MOSFETs optimized for voltage, current, and thermal requirements of their specific flyback design.
How is the LTC3803IS6#TRMPBF powered in high-input-voltage applications?
The LTC3803IS6#TRMPBF can be powered directly from high VIN (e.g., 48V or 72V) via a series resistor into its VCC pin, thanks to its internal shunt regulator clamped at ~9.5V. It sinks up to 25mA to maintain regulation, eliminating the need for an external LDO. Alternatively, a bias winding on the flyback transformer can supply VCC after startup, improving overall efficiency.
What is the purpose of the SENSE pin on the LTC3803IS6#TRMPBF?
The SENSE pin on the LTC3803IS6#TRMPBF serves two functions: (1) it monitors voltage across an external current-sense resistor (RSENSE) to implement peak-current-mode control, and (2) it sources a 5μA linear ramp current used for programmable slope compensation - injected into an external RSL to stabilize the control loop at high duty cycles.
Can the LTC3803IS6#TRMPBF be used in isolated flyback topologies?
Yes, the LTC3803IS6#TRMPBF is commonly used in isolated flyback designs. Its ground-referenced current sensing and VFB feedback architecture support both isolated and nonisolated configurations. For isolation, the feedback signal is typically delivered via optocoupler or auxiliary winding sensing - and the controller regulates based on secondary-side voltage referenced to its local ground.
LTC3803IS6#TRMPBF 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#TRMPBF FAQ
1.How can I place an order for LTC3803IS6#TRMPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3803IS6#TRMPBF 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#TRMPBF reliable?
The price and inventory of LTC3803IS6#TRMPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3803IS6#TRMPBF is usually 5 days.
3.What payment methods are accepted for LTC3803IS6#TRMPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3803IS6#TRMPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3803IS6#TRMPBF?
LTC3803IS6#TRMPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3803IS6#TRMPBF 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#TRMPBF?
For technical support, including LTC3803IS6#TRMPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3803IS6#TRMPBF requirements.
6.How does Aetrix verify that LTC3803IS6#TRMPBF is sourced from the original manufacturer or authorized distributors?
All LTC3803IS6#TRMPBF 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#TRMPBF meets industry standards.
7.What is the process for return or replacement of LTC3803IS6#TRMPBF?
All LTC3803IS6#TRMPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3803IS6#TRMPBF, 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#TRMPBF part is unused and in its original packaging.
Return procedure for LTC3803IS6#TRMPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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