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Analog Devices Inc. LTC3803IS6-3#TRPBF
- Part No.:
- LTC3803IS6-3#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- SOT-23-6 Thin, TSOT-23-6
- Datasheet:
-
LTC3803IS6-3#TRPBF.pdf
- Description:
- IC REG CTRLR FLYBACK TSOT23-6
- Quantity:
- Payment:
- Shipping:
Inventory:3,734
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Product details
Overview
LTC3803IS6-3#TRPBF from Analog Devices (formerly Linear Technology) is a constant-frequency current-mode flyback DC/DC controller in a 6-lead ThinSOT™ package, optimized for driving N-channel MOSFETs in high-input-voltage telecom and automotive housekeeping supplies. It delivers ±1.5% output voltage accuracy, 300 kHz fixed switching frequency, 240 μA quiescent current, and operates across –40°C to 125°C junction temperature.
For engineers reviewing the LTC3803IS6-3#TRPBF datasheet, LTC3803IS6-3#TRPBF pinout, LTC3803IS6-3#TRPBF application, or LTC3803IS6-3#TRPBF equivalent, key selection considerations include its ground-referenced current sensing architecture, programmable slope compensation via external resistor, internal soft-start (1.4 ms), VCC shunt regulator (9.5 V clamp), and undervoltage lockout with 1 V hysteresis (7.5 V turn-on / 5.7 V turn-off).
Technical Context
The LTC3803IS6-3#TRPBF implements a current-mode control loop where the ITH/RUN pin sets the current comparator threshold, directly modulating peak switch current in proportion to output error. Its 300 kHz oscillator drives an RS latch that controls NGATE, with duty cycle limited to 8–80% and blanking to suppress noise during MOSFET turn-on.
It features dual power-up mechanisms: micropower hysteretic start-up using a bias winding and trickle-charge resistor, or direct high-VIN supply via internal VCC shunt regulator (clamp voltage 9.5 V at 1 mA). The SENSE pin injects a linear 5 μA ramp (0–80% duty cycle) for slope compensation, while VFB references an 800 mV internal bandgap with ±1.5% accuracy over temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 300 kHz fixed - enables predictable EMI filtering and stable light-load operation without burst mode noise. |
| Output Voltage Accuracy | ±1.5% - ensures tight regulation for sensitive telecom housekeeping rails without post-regulation. |
| Quiescent Current | 240 μA - minimizes standby power loss in always-on auxiliary supplies. |
| VCC Turn-On/Off Threshold | 7.5 V / 5.7 V - wide UVLO hysteresis supports reliable bootstrap start-up from flyback bias windings. |
| Peak Current Sense Voltage | 100 mV (typ) - low-sense threshold reduces I²R losses and enables high-efficiency, low-RDS(on) MOSFET selection. |
| Soft-Start Time | 1.4 ms - prevents inrush current and transformer saturation during power-up. |
| Operating Temperature | –40°C to 125°C - qualified for industrial and automotive under-hood auxiliary power applications. |
Pinout & Package
The LTC3803IS6-3#TRPBF is housed in a 6-lead plastic TSOT-23 (ThinSOT™) package, 1 mm profile, with exposed pad not electrically connected. Pin 1 is ITH/RUN (error amp compensation + shutdown control), Pin 2 is GND, Pin 3 is VFB (feedback input referenced to 800 mV), Pin 4 is SENSE (current sense + slope compensation injection), Pin 5 is VCC (supply with internal 9.5 V shunt clamp), and Pin 6 is NGATE (N-MOSFET gate driver, 0 V to VCC swing).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ITH/RUN (Pin 1) | Error amplifier output & shutdown control | Sets current comparator threshold (0.7–1.9 V range); pulled low to force shutdown; internal 0.3 μA current source biases pin toward VCC. |
| GND (Pin 2) | Power and signal reference | Common return for VCC bypass, current sense resistor, and feedback divider; must be low-impedance connection. |
| VFB (Pin 3) | Feedback input | Compares external resistive divider output to internal 800 mV reference; <50 nA input current minimizes divider loading error. |
| SENSE (Pin 4) | Current sensing & slope compensation injection | Monitors voltage across external RSENSE; sources 5 μA linear ramp (0–80% duty cycle) into RSL for subharmonic oscillation suppression. |
| VCC (Pin 5) | Supply input with shunt regulator | Internally clamped to ~9.5 V; accepts up to 25 mA sink current; requires ≥1 μF ceramic bypass capacitor adjacent to pin. |
| NGATE (Pin 6) | N-channel MOSFET gate driver | Drives external high-side N-MOSFET; 40 ns rise/fall time into 3000 pF; peak output current 1 A for <10 μs. |
Key Features
| Feature | Design Value |
|---|---|
| Ground-referenced current sensing | Enables high-side primary-side sensing without level-shifting circuitry; allows input voltage beyond IC's absolute maximum ratings. |
| Programmable slope compensation | 5 μA linear ramp injected at SENSE pin enables stable operation at >50% duty cycle without external op-amp networks. |
| Micropower hysteretic start-up | 240 μA operating current and <90 μA shutdown current allow efficient bootstrapping from low-current bias windings. |
| Internal VCC shunt regulator | Clamps VCC to ~9.5 V, permitting direct high-VIN supply via single dropping resistor - eliminates need for external LDO. |
| No minimum load requirement | Constant-frequency operation maintained down to zero load - avoids audible noise and output voltage drift in lightly loaded telecom systems. |
Applications
| Telecom Housekeeping Supply | Automotive 42V Auxiliary Rail |
|---|---|
Use Scenario: Nonisolated 5 V/2 A power rail for base station control logic, monitoring ICs, and interface circuitry fed from 36–72 V telecom battery backup. IC Role / Device Role / Timing Role: Constant-frequency flyback controller regulating output via primary-side current sensing and VFB feedback. Use Value: Eliminates need for optocoupler or secondary-side sensing; ±1.5% accuracy maintains MCU reset thresholds across temperature. |
Use Scenario: Auxiliary 5 V supply for infotainment microcontrollers and CAN transceivers in 42 V stop-start vehicle systems. IC Role / Device Role / Timing Role: High-input-voltage flyback controller with UVLO hysteresis tolerating cold-crank dips and load-dump transients. Use Value: 300 kHz switching enables compact magnetics; –40°C to 125°C rating ensures reliability under hood. |
| Power over Ethernet (PoE) PD | Industrial PLC Auxiliary Power |
Use Scenario: 5 V/1 A isolated auxiliary supply for PoE-powered devices (e.g., IP cameras, VoIP phones) accepting 37–57 V input. IC Role / Device Role / Timing Role: Primary-side regulated flyback controller with internal soft-start and programmable slope compensation. Use Value: 1.4 ms soft-start prevents inrush into downstream capacitors; ground-referenced sensing simplifies transformer design. |
Use Scenario: 5 V housekeeping rail for programmable logic controllers powered from 24 V or 48 V industrial bus. IC Role / Device Role / Timing Role: Current-mode controller enabling fast transient response to step-load changes from I/O modules. Use Value: Excellent line/load transient response due to current-mode architecture; no minimum load required for factory test modes. |
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 275 kHz frequency; 1.5 V VREF; no internal VCC shunt regulator; requires external bias supply. | Lacks integrated VCC clamp and programmable slope compensation; needs external startup circuitry for high-VIN. | Choose UCC28C43DR only if external bias supply is already present and cost sensitivity outweighs design simplicity. |
| MAX17595ATP+T | 300 kHz frequency; 0.8 V VREF; includes integrated high-side gate driver and valley-current sensing; no VCC shunt. | Supports synchronous rectification but requires higher gate drive voltage; lacks ground-referenced sensing flexibility. | Select MAX17595ATP+T when synchronous flyback topology is preferred and board space permits additional gate-drive components. |
Compared with UCC28C43DR and MAX17595ATP+T, the LTC3803IS6-3#TRPBF uniquely combines internal VCC shunt regulation, ground-referenced current sensing, and programmable slope compensation in a 6-pin ThinSOT package-enabling simpler, more robust high-input-voltage flyback designs without external bias or level-shift circuitry.
Availability
LTC3803IS6-3#TRPBF is available at Aetrix Electronics and suitable for telecom housekeeping supplies, automotive 42V auxiliary rails, and Power over Ethernet powered devices requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature performance.
Supply support for LTC3803IS6-3#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 full product support, manufacturing, and qualification for all Linear-branded power management ICs.
The LTC3803 family was designed specifically for high-input-voltage, isolated and nonisolated flyback converters in space-constrained telecom, automotive, and industrial applications - emphasizing simplicity, efficiency, and ruggedness over wide temperature and input ranges.
FAQ
What is the operating temperature range of the LTC3803IS6-3#TRPBF?
The LTC3803IS6-3#TRPBF is rated for operation from –40°C to 125°C junction temperature. This grade (I-temp) is validated per the manufacturer's datasheet and supports deployment in automotive under-hood environments and industrial control cabinets without derating. The device uses the same die as the H- and MP-grade variants but is tested and binned to meet specifications across this extended range.
Does the LTC3803IS6-3#TRPBF require an external current sense resistor?
Yes, the LTC3803IS6-3#TRPBF requires an external current sense resistor (RSENSE) connected between the MOSFET source and ground. The SENSE pin monitors the voltage drop across this resistor to implement current-mode control. Typical values range from tens of milliohms to several ohms depending on desired peak current; the IC's 100 mV (typ) peak sense threshold enables low-loss, high-efficiency designs.
Can the LTC3803IS6-3#TRPBF be powered directly from a high input voltage like 48 V?
Yes, the LTC3803IS6-3#TRPBF can be powered directly from high input voltages such as 48 V using its internal VCC shunt regulator. A series dropping resistor feeds VCC, and the IC self-regulates VCC to ~9.5 V by sinking up to 25 mA. This eliminates the need for an external LDO or bias winding, though efficiency is lower than transformer-coupled biasing.
What is the purpose of the ITH/RUN pin on the LTC3803IS6-3#TRPBF?
The ITH/RUN pin on the LTC3803IS6-3#TRPBF serves two critical functions: it acts as the error amplifier output (setting the current comparator threshold) and as the run/shutdown control input. Pulling this pin below 0.28 V forces shutdown; during normal operation, its voltage (0.7–1.9 V) directly determines peak switch current. It also serves as the compensation node for the control loop when an RC network is connected to ground.
How does slope compensation work on the LTC3803IS6-3#TRPBF?
The LTC3803IS6-3#TRPBF injects a linear 5 μA current ramp from the SENSE pin starting at 8% duty cycle and peaking at 80%. When routed through an external resistor (RSL), this creates a voltage ramp that adds to the current sense signal - effectively reducing the current comparator threshold in proportion to duty cycle. This stabilizes the control loop against subharmonic oscillation in continuous conduction mode.
LTC3803IS6-3#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:
- 300kHz
- 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
LTC3803IS6-3#TRPBF FAQ
1.How can I place an order for LTC3803IS6-3#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3803IS6-3#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 LTC3803IS6-3#TRPBF reliable?
The price and inventory of LTC3803IS6-3#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3803IS6-3#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3803IS6-3#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3803IS6-3#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3803IS6-3#TRPBF?
LTC3803IS6-3#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3803IS6-3#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 LTC3803IS6-3#TRPBF?
For technical support, including LTC3803IS6-3#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3803IS6-3#TRPBF requirements.
6.How does Aetrix verify that LTC3803IS6-3#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3803IS6-3#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 LTC3803IS6-3#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3803IS6-3#TRPBF?
All LTC3803IS6-3#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3803IS6-3#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 LTC3803IS6-3#TRPBF part is unused and in its original packaging.
Return procedure for LTC3803IS6-3#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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