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Analog Devices Inc. LTC3803IS6-3#TRMPBF
- Part No.:
- LTC3803IS6-3#TRMPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- SOT-23-6 Thin, TSOT-23-6
- Datasheet:
-
LTC3803IS6-3#TRMPBF.pdf
- Description:
- IC REG CTRLR FLYBACK TSOT23-6
- Quantity:
- Payment:
- Shipping:
Inventory:1,440
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Product details
Overview
LTC3803IS6-3#TRMPBF from Analog Devices (formerly Linear Technology) is a constant-frequency current-mode flyback DC/DC controller optimized for high-input-voltage N-channel MOSFET drive in telecom and automotive auxiliary power supplies. It delivers 300 kHz fixed-frequency operation, ±1.5% output voltage accuracy, 240 μA quiescent current, internal soft-start, 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 LTC3803IS6-3#TRMPBF datasheet, LTC3803IS6-3#TRMPBF pinout, LTC3803IS6-3#TRMPBF application, or LTC3803IS6-3#TRMPBF equivalent, key selection criteria include VCC UVLO thresholds (7.5 V turn-on / 4.4 V turn-off), programmable slope compensation via SENSE pin, ground-referenced current sensing, 6-pin ThinSOT™ package compatibility, and bias-winding–enabled hysteretic start-up for high-VIN efficiency.
Technical Context
The LTC3803IS6-3#TRMPBF implements a current-mode control architecture with a 300 kHz free-running oscillator, peak-current sensing through the SENSE pin, and an error amplifier whose output modulates the current comparator threshold via the ITH/RUN node. Its internal shunt regulator clamps VCC to ~9.5 V, enabling direct high-VIN resistor-fed operation without external LDOs.
It features dual shutdown mechanisms: undervoltage lockout on VCC (7.5 V turn-on, 4.4 V turn-off) and forced shutdown via ITH/RUN pin voltage < 0.28 V. Internal soft-start limits ITH/RUN voltage ramp to ~1.4 ms, while adjustable slope compensation (5 μA ramp into external RSL) stabilizes duty cycles between 8% and 80%.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 300 kHz nominal - ensures predictable EMI profile and simplifies filter design for telecom-grade noise compliance. |
| Output Voltage Accuracy | ±1.5% over temperature - enables stable 5 V rail regulation without post-regulation in auxiliary power applications. |
| Quiescent Current | 240 μA - minimizes no-load power loss in always-on housekeeping supplies, extending system standby efficiency. |
| VCC UVLO Thresholds | Turn-on: 7.5 V; Turn-off: 4.4 V - provides 3.1 V hysteresis to support reliable bias-winding start-up in flyback converters. |
| Peak Sense Voltage | 100 mV typical - sets precise current limit with low-loss external sense resistors (e.g., 68 mΩ for 1.5 A peak). |
| Operating Temperature | –40°C to 125°C - qualified for under-hood automotive and industrial telecom environments without derating. |
| Gate Drive Capability | 1 A peak NGATE sink/source - directly drives medium-size N-MOSFETs (e.g., FDC2512) without external buffers. |
Pinout & Package
The LTC3803IS6-3#TRMPBF 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 output + shutdown control), Pin 2 is GND, Pin 3 is VFB (0.8 V reference feedback), Pin 4 is SENSE (current sense + slope ramp injection), Pin 5 is VCC (internally clamped to 9.5 V), and Pin 6 is NGATE (N-MOSFET gate driver).
| 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 (< 0.28 V) forces shutdown; internal 0.3 μA pull-up aids bias-winding start-up. |
| GND (Pin 2) | Power and signal reference | Ground return for VCC, SENSE, VFB, and NGATE; must be low-impedance to avoid current-sense measurement error. |
| VFB (Pin 3) | Feedback input | Compares divided output voltage against 0.8 V internal reference; 10 nA input bias enables high-resistor-divider designs. |
| SENSE (Pin 4) | Current sense & slope compensation node | Measures voltage across external RSENSE; injects 5 μA linear ramp (8–80% duty cycle) for stability-no separate slope pin required. |
| VCC (Pin 5) | Supply input with internal shunt regulator | Internally clamped to ~9.5 V; accepts up to 25 mA sink current-enables simple resistor-fed operation from 36–72 V inputs. |
| NGATE (Pin 6) | N-channel MOSFET gate driver | Drives gate from 0 V to VCC; 40 ns rise/fall times support efficient switching at 300 kHz with minimal dead-time loss. |
Key Features
| Feature | Design Value |
|---|---|
| Constant-frequency current-mode control | 300 kHz operation maintained down to zero load - eliminates low-frequency beat notes in sensitive analog/RF subsystems. |
| Ground-referenced current sensing | SENSE pin referenced to GND - allows primary-side sensing without high-side current monitors or isolated amplifiers. |
| Internal VCC shunt regulator | Clamps VCC to ~9.5 V with up to 25 mA sink capability - eliminates need for external regulators when powering from 42 V+ rails. |
| Programmable slope compensation | 5 μA linear ramp injected via SENSE pin - stabilizes control loop across full duty-cycle range (8–80%) without extra components. |
| Micropower hysteretic start-up | 240 μA operating ICC + 40 μA start-up ICC - enables efficient bootstrapping from transformer bias windings in high-VIN flyback topologies. |
Applications
| Telecom Housekeeping Supply | Automotive Auxiliary Power |
|---|---|
|
Use Scenario: Nonisolated 5 V/2 A power rail for baseband processors and PHYs in 48 V telecom systems (36–72 V input range). IC Role / Device Role / Timing Role: Flyback controller managing primary-side switch timing, current limiting, and output regulation via VFB feedback loop. Use Value: Eliminates need for isolated DC/DC modules-reduces BOM cost and board area while maintaining ±1.5% output accuracy across temperature. |
Use Scenario: 12 V auxiliary supply for infotainment ECUs in 42 V stop-start automotive systems. IC Role / Device Role / Timing Role: Constant-frequency current-mode controller driving external N-MOSFET to regulate output despite wide input transients (up to 60 V load dump). Use Value: VCC UVLO hysteresis (7.5 V / 4.4 V) ensures robust start-up after cold cranking; –40°C to 125°C rating supports under-hood placement. |
| Power over Ethernet PD | Industrial Control Auxiliary Rail |
|
Use Scenario: 5 V/1 A auxiliary supply for PoE-powered devices using midspan or endspan PSEs (57 V nominal input). IC Role / Device Role / Timing Role: Primary-side flyback controller implementing IEEE 802.3af/at detection/classification handshaking via VCC sequencing. Use Value: Low 240 μA quiescent current meets PoE standby power budget; internal soft-start prevents inrush during classification phase. |
Use Scenario: 3.3 V/1.5 A isolated auxiliary supply for PLC I/O modules powered from 24 V DC industrial bus. IC Role / Device Role / Timing Role: Controller for flyback converter with optocoupler feedback, regulating secondary-side output via primary-side sensing. Use Value: Adjustable slope compensation ensures stability with variable transformer leakage; 6-pin ThinSOT™ eases layout in space-constrained DIN-rail enclosures. |
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; no internal VCC shunt regulator; requires external bias supply; 100 mV current sense threshold. | Designed for cost-sensitive industrial SMPS; lacks micropower start-up and wide UVLO hysteresis needed for telecom bias winding schemes. | Choose UCC28C43DR only if external bias is available and 300 kHz EMI targeting is not required. |
| MAX17595ATP+ | 4.5–60 V input range; integrated 1.2 A gate driver; 0.8 V reference; but larger 20-pin TQFN package and higher 1.5 mA quiescent current. | Targets higher-power (>10 W) isolated flyback; includes built-in soft-start timer and fault protection not present in LTC3803IS6-3#TRMPBF. | Select MAX17595ATP+ when >5 W output, enhanced protection, or tighter input voltage range (4.5–60 V) is prioritized over footprint and ultra-low IQ. |
Compared with UCC28C43DR and MAX17595ATP+, the LTC3803IS6-3#TRMPBF uniquely balances ultra-low quiescent current (240 μA), integrated VCC shunt regulation, and 6-pin ThinSOT™ compactness-making it optimal for space- and efficiency-constrained 1–5 W telecom and automotive auxiliary supplies where bias-winding start-up is essential.
Availability
LTC3803IS6-3#TRMPBF is available at Aetrix Electronics and suitable for telecom housekeeping supplies, automotive auxiliary power rails, and Power over Ethernet powered devices requiring stable component supply, long-term lifecycle assurance, and extended temperature performance.
Supply support for LTC3803IS6-3#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 LTC3803 family is designed specifically for compact, high-efficiency flyback and boost controllers in high-input-voltage applications-including telecom, automotive, and industrial auxiliary power-where low IQ, small footprint, and bias-winding compatibility are critical.
FAQ
What is the operating temperature range of the LTC3803IS6-3#TRMPBF?
The LTC3803IS6-3#TRMPBF is rated for operation from –40°C to 125°C junction temperature. This grade (I-temp) is validated per manufacturer specifications and supports deployment in automotive under-hood environments and industrial telecom chassis without thermal derating. The device uses the same die as the LTC3803I-3 variant, packaged in a 6-lead TSOT-23 with specified thermal resistance θJA = 192°C/W.
How does the LTC3803IS6-3#TRMPBF achieve start-up from high input voltages like 48 V or 72 V?
The LTC3803IS6-3#TRMPBF achieves high-VIN start-up via its internal VCC shunt regulator (clamped to ~9.5 V) and micropower hysteretic start-up circuitry. A simple resistor from VIN to VCC supplies initial charge to the CVCC capacitor; once VCC reaches 7.5 V, the controller enables and begins switching. The internal 0.3 μA pull-up on ITH/RUN and wide UVLO hysteresis (7.5 V / 4.4 V) ensure reliable bootstrap from transformer bias windings or resistor-fed sources.
Can the LTC3803IS6-3#TRMPBF be used in isolated flyback topologies?
Yes, the LTC3803IS6-3#TRMPBF is commonly used in isolated flyback designs. Its ground-referenced SENSE pin enables primary-side current sensing, and VFB feedback can be implemented via optocoupler or auxiliary winding. The datasheet includes isolated application circuits with third-winding bias, and the device's 300 kHz fixed frequency simplifies transformer design and EMI filtering for safety-isolated 5 V or 12 V outputs.
What is the purpose of the SENSE pin on the LTC3803IS6-3#TRMPBF beyond current sensing?
Beyond measuring voltage across the external current-sense resistor, the SENSE pin on the LTC3803IS6-3#TRMPBF injects a programmable 5 μA linear current ramp (active from 8% to 80% duty cycle). When routed through an external resistor (RSL), this ramp generates a slope-compensation voltage that stabilizes the current-mode control loop against subharmonic oscillation-eliminating need for external ramp generators or complex compensation networks.
Does the LTC3803IS6-3#TRMPBF require an external soft-start capacitor?
No, the LTC3803IS6-3#TRMPBF includes internal soft-start with a fixed 1.4 ms ramp time. Upon exit from shutdown (whether via VCC UVLO recovery or ITH/RUN release), the ITH/RUN voltage is clamped and gradually released to prevent output voltage overshoot and MOSFET gate stress. No external capacitor or resistor is needed-soft-start behavior is fully integrated and factory-trimmed.
LTC3803IS6-3#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:
- 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#TRMPBF FAQ
1.How can I place an order for LTC3803IS6-3#TRMPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3803IS6-3#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 LTC3803IS6-3#TRMPBF reliable?
The price and inventory of LTC3803IS6-3#TRMPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3803IS6-3#TRMPBF is usually 5 days.
3.What payment methods are accepted for LTC3803IS6-3#TRMPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3803IS6-3#TRMPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3803IS6-3#TRMPBF?
LTC3803IS6-3#TRMPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3803IS6-3#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 LTC3803IS6-3#TRMPBF?
For technical support, including LTC3803IS6-3#TRMPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3803IS6-3#TRMPBF requirements.
6.How does Aetrix verify that LTC3803IS6-3#TRMPBF is sourced from the original manufacturer or authorized distributors?
All LTC3803IS6-3#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 LTC3803IS6-3#TRMPBF meets industry standards.
7.What is the process for return or replacement of LTC3803IS6-3#TRMPBF?
All LTC3803IS6-3#TRMPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3803IS6-3#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 LTC3803IS6-3#TRMPBF part is unused and in its original packaging.
Return procedure for LTC3803IS6-3#TRMPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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