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Analog Devices Inc. LTC3803IS6-5#TRPBF
- Part No.:
- LTC3803IS6-5#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- SOT-23-6 Thin, TSOT-23-6
- Datasheet:
-
LTC3803IS6-5#TRPBF.pdf
- Description:
- IC REG CTRLR FLYBACK TSOT23-6
- Quantity:
- Payment:
- Shipping:
Inventory:2,475
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Product details
Overview
LTC3803IS6-5#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 isolated power supplies. It operates from 5V to 50V input, delivers ±1.5% output voltage accuracy, maintains 200kHz fixed switching frequency down to light loads, and consumes only 240μA quiescent current. It enables compact auxiliary/housekeeping supplies in telecom and automotive systems.
For engineers reviewing the LTC3803IS6-5#TRPBF datasheet, LTC3803IS6-5#TRPBF pinout, LTC3803IS6-5#TRPBF application, or LTC3803IS6-5#TRPBF equivalent, key selection criteria include its 200kHz oscillator, ground-referenced current sensing, internal soft-start, adjustable slope compensation, and –40°C to 125°C operating junction temperature range.
Technical Context
The LTC3803IS6-5#TRPBF implements peak current-mode control with a 200kHz free-running oscillator, internal 800mV reference, and error amplifier transconductance of 200–500μA/V. Its ITH/RUN pin serves dual roles: feedback compensation node and run/shutdown control, with a nominal 0.28V shutdown threshold and 0.7V–1.9V active-range voltage.
It features an internal VCC shunt regulator clamping at ~8.1V (1mA–25mA), undervoltage lockout with 4.8V turn-on and 4.0V turn-off thresholds, and programmable slope compensation via SENSE-pin 5μA ramp into external RSL. Gate drive rise/fall times are 40ns into 3000pF load.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Oscillator Frequency | 200kHz typical; ensures predictable EMI profile and simplifies filter design across wide load range. |
| Output Voltage Accuracy | ±1.5% over temperature; enables stable regulation without post-production trimming in telecom housekeeping rails. |
| Quiescent Current | 240μA typical; supports low-power standby modes in PoE-powered devices and automotive always-on circuits. |
| VCC UVLO Threshold | 4.8V turn-on / 4.0V turn-off; prevents unreliable gate drive during brownout while allowing operation from 5V minimum input. |
| Peak Sense Voltage | 100mV typical; sets precise current limit with minimal power loss in sense resistor (e.g., 0.02Ω for 5A peak). |
| Operating Junction Temp | –40°C to 125°C; qualified for under-hood automotive auxiliary supplies and industrial telecom equipment. |
| Gate Drive Rise/Fall | 40ns into 3000pF; ensures fast MOSFET switching with low overlap loss in high-efficiency flyback designs. |
Pinout & Package
The LTC3803IS6-5#TRPBF is housed in a 6-lead low-profile (1mm height) TSOT-23 (ThinSOT™) package, JEDEC MO-193 compliant, with lead-free finish and tape-and-reel packaging (TRPBF).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ITH/RUN (Pin 1) | Error amplifier output & shutdown control | Sets current comparator threshold; pulled up internally by 0.3μA; <0.28V forces shutdown; 0.7–1.9V active range. |
| 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 voltage input | Compares divided output voltage against 800mV internal reference; 10nA max input bias enables high-resistor-divider networks. |
| SENSE (Pin 4) | Current sense & slope compensation injection | Monitors MOSFET source voltage; sources 5μA linear ramp for duty-cycle-dependent slope compensation. |
| VCC (Pin 5) | Supply input with internal shunt regulator | Internally clamped to ~8.1V; accepts 5–50V input via series resistor; requires local 10μF ceramic bypass. |
| NGATE (Pin 6) | N-channel MOSFET gate driver output | 0V to VCC swing; 1A peak sink/source capability; 40ns rise/fall into 3000pF; drives logic-level FETs directly. |
Key Features
| Feature | Design Value |
|---|---|
| Constant-frequency current mode control | 200kHz fixed switching eliminates subharmonic instability and enables deterministic EMI filtering. |
| Ground-referenced current sensing | Allows direct sensing on MOSFET source without high-side sense circuitry-reducing component count and layout complexity. |
| Internal soft-start | 0.7ms controlled ramp-up of ITH/RUN voltage prevents inrush current and transformer saturation at startup. |
| Adjustable slope compensation | 5μA programmable ramp into external RSL stabilizes control loop at >50% duty cycle without adding external op-amps. |
| VCC shunt regulator | Self-regulates VCC to ~8.1V from VIN up to 50V-enabling single-resistor biasing and eliminating need for external LDO. |
Applications
| Telecom Housekeeping Supply | Automotive Auxiliary Power |
|---|---|
|
Use Scenario: Isolated 12V/100mA auxiliary rail in 36–75V telecom rectifier modules. IC Role / Device Role / Timing Role: Flyback controller regulating secondary-side output via optocoupler feedback; 200kHz timing sets transformer size and EMI class compliance. Use Value: ±1.5% accuracy maintains stable bias for supervisory ICs and fans; 240μA IQ extends hold-up time during AC dropout. |
Use Scenario: 5V/1.2A isolated supply for infotainment microcontroller in 12V/24V vehicle electrical system. IC Role / Device Role / Timing Role: Primary-side flyback controller with ground-referenced sensing; 200kHz frequency avoids AM radio band interference. Use Value: –40°C to 125°C rating ensures reliability under hood; VCC shunt allows direct connection to battery via single dropping resistor. |
| Power over Ethernet (PoE) PD | Industrial Isolated Sensor Interface |
|
Use Scenario: 3.3V/3A isolated output from 37–57V PoE Class 3/4 input in powered device. IC Role / Device Role / Timing Role: Constant-frequency flyback controller with opto-isolated feedback; 200kHz enables small planar transformer integration. Use Value: No minimum load requirement supports low-power sleep states; 100mV current sense enables accurate current limiting at full load. |
Use Scenario: 15V/100mA isolated supply for analog front-end in hazardous-area 4–20mA loop-powered sensors. IC Role / Device Role / Timing Role: High-voltage flyback controller with primary-side regulation; 200kHz timing supports compact creepage/clearance-compliant layout. Use Value: Input voltage limited only by external components-supports 60V+ inputs with appropriate MOSFET and transformer; 4.8V UVLO rejects brownouts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3805IS6-5#TRPBF | Adjustable 100–500kHz frequency; higher 350μA IQ; no internal VCC shunt regulator. | Requires external bias supply; better suited for variable-frequency EMI spread-spectrum designs. | Select when frequency tuning or lower EMI peaks are required; avoid if single-resistor VCC bias is needed. |
| LTC3873IS6-5#TRPBF | No external current sense resistor required; uses valley-current sensing; 250μA IQ; same 200kHz default frequency. | Eliminates RSENSE power loss and PCB area; less sensitive to layout parasitics than ground-referenced sensing. | Select for higher efficiency at light loads or where sense resistor placement is challenging; verify transformer reset compatibility. |
Compared with LTC3803IS6-5#TRPBF, LTC3805IS6-5#TRPBF offers frequency flexibility at the cost of added bias complexity, while LTC3873IS6-5#TRPBF removes the sense resistor but changes control architecture-making LTC3803IS6-5#TRPBF optimal for cost-sensitive, fixed-frequency, ground-sense flyback designs requiring minimal external components.
Availability
LTC3803IS6-5#TRPBF 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 across extended temperature ranges.
Supply support for LTC3803IS6-5#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 power management portfolio with rigorous qualification standards for industrial and automotive applications.
The LTC3803-5 product line delivers compact, high-voltage flyback controllers for isolated DC/DC conversion where simplicity, low IQ, and robust thermal performance are critical-targeting telecom, automotive, and industrial auxiliary power.
FAQ
What is the operating input voltage range for the LTC3803IS6-5#TRPBF?
The LTC3803IS6-5#TRPBF operates from a minimum input of 5V up to 50V on the VIN side of the external MOSFET. Its VCC pin is internally regulated to ~8.1V via a shunt, enabling direct biasing from high-voltage rails through a single series resistor-no external regulator required. This makes the LTC3803IS6-5#TRPBF ideal for wide-input isolated converters.
Does the LTC3803IS6-5#TRPBF require an external current sense resistor?
Yes, the LTC3803IS6-5#TRPBF requires an external current sense resistor (RSENSE) connected between the MOSFET source and ground. It monitors this voltage on the SENSE pin to implement peak current-mode control. The typical peak sense voltage is 100mV, allowing precise current limiting-for example, a 0.02Ω resistor sets a 5A peak switch current. The LTC3803IS6-5#TRPBF does not support no-RSENSE architectures.
What is the purpose of the ITH/RUN pin on the LTC3803IS6-5#TRPBF?
The ITH/RUN pin on the LTC3803IS6-5#TRPBF serves two critical functions: it acts as the error amplifier output (setting the current comparator threshold) and as the run/shutdown control input. When pulled below 0.28V, it forces shutdown; above that threshold-and with sufficient VCC-it enables operation. During normal regulation, its voltage varies from 0.7V to 1.9V, directly commanding the PWM duty cycle. It also serves as the loop compensation node.
Can the LTC3803IS6-5#TRPBF be used in synchronous rectification designs?
The LTC3803IS6-5#TRPBF is designed for standard diode-rectified flyback topologies and does not provide dedicated synchronous rectifier drive signals. While external gate drivers can be added using NGATE timing, the controller lacks built-in SR control logic or adaptive dead-time management. For synchronous flyback, Analog Devices recommends alternatives like the LT3757 or LT3758, which integrate SR drive capability-so LTC3803IS6-5#TRPBF is best applied in cost-optimized, diode-based isolated supplies.
What is the maximum duty cycle supported by the LTC3803IS6-5#TRPBF?
The LTC3803IS6-5#TRPBF enforces a maximum on-time duty cycle of 80%, with a minimum of 6.5%. This constraint is hard-coded in the internal timing logic and applies regardless of external component values. The 80% limit prevents transformer saturation and ensures reliable operation across input and load variations. Slope compensation is programmable to maintain stability near this boundary, especially in high-duty-cycle flyback configurations.
LTC3803IS6-5#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):
- 4V ~ 8.1V
- 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
LTC3803IS6-5#TRPBF FAQ
1.How can I place an order for LTC3803IS6-5#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3803IS6-5#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 LTC3803IS6-5#TRPBF reliable?
The price and inventory of LTC3803IS6-5#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3803IS6-5#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3803IS6-5#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3803IS6-5#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3803IS6-5#TRPBF?
LTC3803IS6-5#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3803IS6-5#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 LTC3803IS6-5#TRPBF?
For technical support, including LTC3803IS6-5#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3803IS6-5#TRPBF requirements.
6.How does Aetrix verify that LTC3803IS6-5#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3803IS6-5#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 LTC3803IS6-5#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3803IS6-5#TRPBF?
All LTC3803IS6-5#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3803IS6-5#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 LTC3803IS6-5#TRPBF part is unused and in its original packaging.
Return procedure for LTC3803IS6-5#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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