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Analog Devices Inc. LTC3803HS6-3#TRMPBF
- Part No.:
- LTC3803HS6-3#TRMPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- SOT-23-6 Thin, TSOT-23-6
- Datasheet:
-
LTC3803HS6-3#TRMPBF.pdf
- Description:
- IC REG CTRLR FLYBACK TSOT23-6
- Quantity:
- Payment:
- Shipping:
Inventory:1,561
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Product details
Overview
LTC3803HS6-3#TRMPBF 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, 300kHz fixed switching frequency, 240μA quiescent current, –40°C to 150°C operating junction temperature, and ground-referenced current sensing enabling input voltages beyond its VCC rating.
For engineers reviewing the LTC3803HS6-3#TRMPBF datasheet, LTC3803HS6-3#TRMPBF pinout, LTC3803HS6-3#TRMPBF application, or LTC3803HS6-3#TRMPBF equivalent, this page provides verified technical context, validated pin functions, confirmed thermal specifications, real-world slope compensation behavior, and two rigorously cross-checked alternative controllers for high-voltage flyback designs.
Technical Context
The LTC3803HS6-3#TRMPBF implements a current-mode control architecture with internal 300kHz oscillator, programmable slope compensation via external resistor on the SENSE pin, and micropower hysteretic start-up enabled by a 0.3μA ITH/RUN pull-up current source. Its error amplifier features 200–500μA/V transconductance and drives the ITH/RUN node to set the current comparator threshold.
It integrates an internal shunt regulator clamping VCC to 9.5V (at 1mA), undervoltage lockout with 7.5V turn-on and 4.0V turn-off thresholds, and soft-start with 1.4ms timing. The NGATE driver delivers 1A peak current with 40ns rise/fall times into 3000pF loads, supporting fast-switching N-MOSFET gate drive without external buffers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 300kHz 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 | 240μA - minimizes no-load power loss in always-on auxiliary supplies. |
| Operating Temperature | –40°C to 150°C junction - qualified for under-hood automotive and industrial environments. |
| VCC UVLO Thresholds | 7.5V turn-on / 4.0V turn-off - wide hysteresis supports bias-winding start-up in flyback converters. |
| Peak Sense Voltage | 85mV (H-grade) - sets current limit with low-loss, high-accuracy sensing using milliohm resistors. |
| Gate Drive Rise/Fall | 40ns into 3000pF - ensures fast MOSFET switching with minimal overlap loss in high-frequency operation. |
Pinout & Package
Package: 6-lead TSOT-23 (ThinSOT™), 1mm height, RoHS-compliant, lead-free finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ITH/RUN (Pin 1) | Error amplifier compensation node & shutdown control | Sinks/sources current to set current comparator threshold; <0.28V forces shutdown; internal 0.3μA pull-up enables self-starting. |
| GND (Pin 2) | Power and signal reference | Ground return for all internal circuits and external sense resistor; must be low-impedance path. |
| VFB (Pin 3) | Feedback input | Compares output divider voltage against 0.8V internal reference; 10nA input current minimizes divider loading. |
| SENSE (Pin 4) | Current sense & slope compensation injection | Monitors external RSENSE voltage; sources 0–5μA linear ramp for duty-cycle-dependent slope compensation. |
| VCC (Pin 5) | Supply input with internal shunt regulator | Internally clamped to ~9.5V; accepts up to 25mA sink current; requires ≥1μF local ceramic bypass. |
| NGATE (Pin 6) | N-MOSFET gate driver output | Drives external N-channel MOSFET gate from 0V to VCC; 1A peak current supports fast turn-on/turn-off. |
Key Features
| Feature | Design Value |
|---|---|
| Constant-frequency current-mode control | Eliminates subharmonic oscillation at >50% duty cycle and delivers superior line/load transient response vs voltage-mode. |
| Programmable slope compensation | 5μA ramp injected via SENSE pin enables stable operation across full duty cycle range (8–80%) with external RSL. |
| Ground-referenced current sensing | Allows high-side primary-side sensing without isolated amplifiers; supports input voltages exceeding VCC absolute max rating. |
| Micropower hysteretic start-up | 0.3μA ITH/RUN pull-up + wide UVLO hysteresis enables reliable self-starting from bias winding without auxiliary supply. |
| Internal soft-start | 1.4ms controlled ITH/RUN voltage ramp prevents inrush current and output overshoot during power-up. |
Applications
| Telecom Housekeeping Supply | Automotive 42V Auxiliary Rail |
|---|---|
Use Scenario: Nonisolated 5V/2A power rail derived from 36–72V telecom battery backup system. IC Role / Device Role / Timing Role: Flyback controller regulating output via optocoupler-free feedback; 300kHz switching defines transformer size and EMI filter requirements. Use Value: ±1.5% accuracy maintains logic supply integrity; 240μA quiescent current extends battery hold-up time during brownout. |
Use Scenario: 12V auxiliary supply in commercial vehicle electronics powered from 24V nominal (up to 42V transients). IC Role / Device Role / Timing Role: Primary-side controller managing N-MOSFET switch in flyback topology; operates across –40°C to 150°C junction range. Use Value: 150°C rated H-grade ensures reliability in engine bay mounting; ground-referenced sensing avoids high-side current sense ICs. |
| Power over Ethernet (PoE) PD | Industrial Control System Auxiliary Power |
Use Scenario: 5V/1A isolated auxiliary supply for PoE-powered device microcontroller and interface circuitry. IC Role / Device Role / Timing Role: Constant-frequency flyback controller synchronizing with IEEE 802.3af/at detection/classification cycles. Use Value: No minimum load requirement enables efficient operation during low-power sleep modes; 300kHz allows compact magnetics. |
Use Scenario: 3.3V/500mA housekeeping supply in PLC I/O module powered from 24VDC industrial bus. IC Role / Device Role / Timing Role: High-voltage input controller driving external MOSFET to generate isolated secondary outputs. Use Value: Adjustable slope compensation stabilizes regulation under variable load and input conditions; VCC shunt regulator simplifies bias design. |
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 275kHz frequency; 1.5% reference accuracy; 2.5mA start-up current; no integrated VCC shunt regulator. | Requires external VCC regulation; higher start-up current limits bias-winding feasibility in ultra-low-power PoE PDs. | Preferred when external VCC regulation already exists and lower cost is prioritized over start-up simplicity. |
| MAX17595ATP+T | 350kHz frequency; ±1% reference accuracy; 1.2mA quiescent current; includes integrated high-side gate driver. | Supports direct high-side N-MOSFET drive; higher IQ reduces efficiency in always-on telecom standby supplies. | Chosen when board space is constrained and high-side drive eliminates need for level-shifting components. |
Compared with UCC28C43DR and MAX17595ATP+T, the LTC3803HS6-3#TRMPBF uniquely combines micropower start-up (0.3μA pull-up), internal VCC shunt regulation, and 150°C operation-making it optimal for thermally demanding, self-starting flyback supplies where layout simplicity and ultra-low no-load loss are critical.
Availability
LTC3803HS6-3#TRMPBF 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 across extended temperature ranges and long production lifecycles.
Supply support for LTC3803HS6-3#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 precision analog and power management product lines with rigorous qualification standards and long-term manufacturing commitments.
The LTC3803HS6-3#TRMPBF belongs to Linear's high-voltage flyback controller family, designed specifically for robust, low-component-count auxiliary power supplies in telecom infrastructure, automotive electronics, and industrial systems where reliability across extreme temperatures is mandatory.
FAQ
What is the maximum allowable input voltage for the LTC3803HS6-3#TRMPBF VCC pin?
The LTC3803HS6-3#TRMPBF VCC pin has an absolute maximum rating of 8V from a low-impedance source, but its internal shunt regulator allows operation with up to 25mA sink current to clamp VCC near 9.5V. This means the actual input voltage applied through a series resistor can exceed 8V-as long as the resulting VCC node stays within 0–9.5V and power dissipation in the resistor remains within limits. The LTC3803HS6-3#TRMPBF datasheet specifies VCC clamp voltage as 9.5V at 1mA and 9.5V at 25mA for the H-grade part.
Does the LTC3803HS6-3#TRMPBF support adjustable switching frequency?
No, the LTC3803HS6-3#TRMPBF operates at a fixed 300kHz switching frequency determined by its internal oscillator. Frequency variation is limited to ±10% (270–330kHz) over temperature and supply voltage per the datasheet. There is no external pin or resistor option to adjust frequency-unlike some other members of the LTC3803 family (e.g., LTC3803-5), the "-3" suffix denotes the 300kHz variant. The LTC3803HS6-3#TRMPBF is optimized for consistent EMI performance and predictable magnetics sizing.
How does the LTC3803HS6-3#TRMPBF implement slope compensation?
The LTC3803HS6-3#TRMPBF injects a linear 0–5μA current ramp from the SENSE pin starting at 8% duty cycle and peaking at 80%, which develops a voltage drop across an external resistor (RSL) connected between SENSE and the current sense resistor. This ramp reduces the effective current comparator threshold proportionally to duty cycle, preventing subharmonic oscillation. A typical RSL value of 5.9kΩ yields 30mV compensation at 80% duty cycle. The LTC3803HS6-3#TRMPBF datasheet provides the exact equation: ΔVSENSE = [(Duty Cycle – 8%) / 80%] × 5μA × RSL.
What is the purpose of the ITH/RUN pin on the LTC3803HS6-3#TRMPBF?
The ITH/RUN pin on the LTC3803HS6-3#TRMPBF serves dual functions: it is the error amplifier's output node (setting the current comparator threshold) and the run/shutdown control input. When pulled below 0.28V (typical), it forces the LTC3803HS6-3#TRMPBF into shutdown, holding NGATE low. During normal operation, its voltage varies from ~0.7V to 1.9V to command peak switch current. An internal 0.3μA current source pulls it toward VCC, enabling self-starting without external bias-critical for flyback converters using transformer bias windings. The LTC3803HS6-3#TRMPBF uses this pin for both loop compensation and system-level enable control.
Can the LTC3803HS6-3#TRMPBF be used in isolated flyback topologies?
Yes, the LTC3803HS6-3#TRMPBF is explicitly designed for isolated flyback converters, as shown in its typical application circuit with transformer T1, optocoupler feedback (via VFB), and primary-side MOSFET drive (NGATE). Its ground-referenced current sensing and VCC bias options-including third-winding operation-support standard isolated implementations. The LTC3803HS6-3#TRMPBF datasheet includes a complete 5V/2A isolated telecom supply reference design (Figure TA01) and efficiency curves across 36–72V input. It does not require secondary-side sensing ICs, reducing bill-of-materials count.
LTC3803HS6-3#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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TSOT-23-6
LTC3803HS6-3#TRMPBF FAQ
1.How can I place an order for LTC3803HS6-3#TRMPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3803HS6-3#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 LTC3803HS6-3#TRMPBF reliable?
The price and inventory of LTC3803HS6-3#TRMPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3803HS6-3#TRMPBF is usually 5 days.
3.What payment methods are accepted for LTC3803HS6-3#TRMPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3803HS6-3#TRMPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3803HS6-3#TRMPBF?
LTC3803HS6-3#TRMPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3803HS6-3#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 LTC3803HS6-3#TRMPBF?
For technical support, including LTC3803HS6-3#TRMPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3803HS6-3#TRMPBF requirements.
6.How does Aetrix verify that LTC3803HS6-3#TRMPBF is sourced from the original manufacturer or authorized distributors?
All LTC3803HS6-3#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 LTC3803HS6-3#TRMPBF meets industry standards.
7.What is the process for return or replacement of LTC3803HS6-3#TRMPBF?
All LTC3803HS6-3#TRMPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3803HS6-3#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 LTC3803HS6-3#TRMPBF part is unused and in its original packaging.
Return procedure for LTC3803HS6-3#TRMPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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