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Analog Devices Inc. LTC3805EMSE#TRPBF
- Part No.:
- LTC3805EMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3805EMSE#TRPBF.pdf
- Description:
- IC REG CTRLR FLYBACK 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,227
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Product details
Overview
LTC3805EMSE#TRPBF from Analog Devices (formerly Linear Technology) is a current-mode DC/DC controller IC designed to drive an external N-channel MOSFET in nonisolated flyback, boost, and SEPIC converters. It supports input/output voltages limited only by external components, offers adjustable 70–700 kHz switching frequency via one resistor, ±1.5% reference accuracy, and 360 µA quiescent current - enabling high-efficiency telecom and automotive power supplies delivering up to 5 V/2 A.
For engineers reviewing the LTC3805EMSE#TRPBF datasheet, LTC3805EMSE#TRPBF pinout, LTC3805EMSE#TRPBF application, or LTC3805EMSE#TRPBF equivalent, key selection considerations include programmable slope compensation, precision RUN pin with hysteresis, soft-start timing control via SSFLT capacitor, overcurrent protection with automatic restart, and compatibility with high-VIN bias schemes using the internal 9.5 V shunt regulator.
Technical Context
The LTC3805EMSE#TRPBF implements peak current-mode control with a voltage-controlled oscillator, error amplifier output at ITH pin, and dual-function ISENSE pin for current sensing and programmable slope compensation. Its current comparator compares sensed switch current against an ITH-derived threshold, while the SR latch enforces duty cycle limits (6–95%) and blanking logic prevents false triggering during switching transitions.
It integrates precision undervoltage lockout on both VCC (turn-on at 8.4 V, turn-off at 4.0 V) and RUN pins (1.207 V ON / 1.170 V OFF), with 5 µA hysteresis current enabling stable start-up control. The internal 9.5 V shunt regulator allows direct high-VIN biasing through a resistor, decoupling controller operation from input voltage constraints.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology Support | Flyback, boost, SEPIC - no internal power switch; requires external N-MOSFET and transformer/inductor. |
| Switching Frequency Range | 70 kHz to 700 kHz - set by single resistor on FS pin; synchronizable to external clock via SYNC pin. |
| Reference Voltage Accuracy | ±1.5% over –40°C to +85°C - ensures tight output regulation in telecom and automotive applications. |
| Quiescent Current | 360 µA normal operation; 40 µA micropower startup - enables low-noise, high-efficiency standby modes. |
| VCC Shunt Regulator | 9.5 V clamp (25 mA max sink) - permits direct high-VIN biasing without external LDO or auxiliary winding. |
| Overcurrent Protection | Adjustable 85–115 mV OC threshold with automatic restart - configurable via external resistor on OC pin. |
| Soft-Start Control | Programmable via capacitor on SSFLT pin - also defines fault timeout duration after overcurrent event. |
Pinout & Package
The LTC3805EMSE#TRPBF is housed in a 10-lead plastic MSOP package (3 mm × 3 mm footprint, exposed pad) rated for –40°C to +85°C operation. The exposed pad (Pin 11) is GND and must be soldered to PCB ground for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SSFLT (1) | Soft-Start & Fault Timeout | Capacitor to GND sets ramp time for output voltage rise and delay before auto-restart after fault. |
| ITH (2) | Error Amplifier Output | Compensation node; voltage (0.7–1.9 V) sets current comparator threshold and loop stability. |
| FB (3) | Feedback Input | Monitors output via resistor divider; regulates output to 0.8 V reference with ±1.5% accuracy. |
| RUN (4) | Enable Control | Precision UVLO input (1.207 V ON / 1.170 V OFF) with 5 µA hysteresis current for controlled start/stop. |
| FS (5) | Frequency Set | Resistor to GND programs oscillator frequency from 70 kHz to 700 kHz per fOSC = 24×10⁹/(RFS−1500). |
| SYNC (6) | External Clock Input | Rising edge triggers GATE high; enables synchronization to system clock or noise-sensitive timing domains. |
| ISENSE (7) | Current Sense & Slope Ramp | Senses MOSFET current; injects 10 µA linear ramp for slope compensation up to 80% duty cycle. |
| OC (8) | Overcurrent Detection | Secondary current sense input; trips shutdown if voltage exceeds programmed threshold (e.g., 100 mV). |
| VCC (9) | Supply Input | Powered via internal 9.5 V shunt regulator; accepts high VIN through series resistor or low-impedance ≤9 V source. |
| GATE (10) | MOSFET Driver Output | Push-pull gate driver (30 ns rise/fall) capable of driving N-channel MOSFETs in high-side flyback configurations. |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable Operating Frequency | 70–700 kHz via single RFS; eliminates EMI peaks and enables optimization for size vs. efficiency. |
| Programmable Slope Compensation | 10 µA linear ramp from ISENSE pin - prevents subharmonic oscillation in continuous conduction mode. |
| Automatic Restart After Fault | SSFLT capacitor defines both soft-start ramp and fault timeout - enables self-recovery without external circuitry. |
| Precision RUN Pin with Hysteresis | 1.207 V turn-on / 1.170 V turn-off with 5 µA hysteresis current - ensures clean, bounce-free enable/disable sequencing. |
| High-VIN Bias Capability | Internal 9.5 V shunt regulator sinks up to 25 mA - allows direct biasing from 36–72 V telecom rails without auxiliary winding. |
Applications
| Telecom Power Supplies | Automotive 12V/42V Systems |
|---|---|
Use Scenario: 36–72 V input telecom rectifier powering 5 V/2 A backplane interface cards. IC Role / Device Role / Timing Role: Primary-side flyback controller regulating isolated 5 V rail using external N-MOSFET and custom transformer. Use Value: Adjustable frequency avoids noise coupling into sensitive communication circuits; ±1.5% reference ensures compliance with GR-1089 immunity requirements. | Use Scenario: 12 V or 42 V battery-fed infotainment module requiring regulated 5 V supply with cold-crank tolerance. IC Role / Device Role / Timing Role: Nonisolated flyback controller driving high-side N-MOSFET to generate stable 5 V from wide-input automotive rail. Use Value: RUN pin hysteresis and VCC UVLO (8.4 V ON / 4.0 V OFF) support reliable start-up during cranking transients down to 6 V. |
| Isolated Industrial Sensors | Industrial Programmable Logic Controllers |
Use Scenario: Isolated 24 V sensor node powered from 48 V field bus, delivering 5 V to microcontroller and analog front-end. IC Role / Device Role / Timing Role: Flyback controller implementing galvanic isolation via transformer; uses SSFLT capacitor for controlled inrush limiting. Use Value: Soft-start programmability prevents bus voltage sag during simultaneous sensor node power-up across distributed systems. | Use Scenario: DIN-rail mounted PLC power module converting 24 V DC input to isolated 5 V/3.3 V rails for logic and I/O stages. IC Role / Device Role / Timing Role: Dual-output flyback controller managing primary-side regulation and secondary-side synchronous rectification timing. Use Value: Synchronizable SYNC pin enables coordinated switching across multiple power modules to reduce total system ripple and EMI. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3748EMSE#TRPBF | Integrated high-side gate driver with transformer feedback sensing; no optocoupler required; higher 100 V VIN rating. | Designed for isolated flyback with primary-side regulation; eliminates optocoupler and TL431, reducing BOM count. | Choose LT3748EMSE#TRPBF when designing cost-sensitive isolated supplies without secondary-side feedback components. |
| UCC28740DR | PSR (primary-side regulation) controller with digital adaptive control; 700 V integrated HV start-up; lower 2.5 mW no-load power. | Optimized for ultra-low-power AC/DC adapters; includes built-in demagnetization detection and valley switching. | Choose UCC28740DR for universal-input offline flyback designs where efficiency at light load and regulatory compliance (DoE Level VI) are critical. |
Compared with LT3748EMSE#TRPBF and UCC28740DR, the LTC3805EMSE#TRPBF provides greater flexibility in topology selection (flyback/boost/SEPIC), precise analog control tuning via ITH compensation, and robust high-VIN bias capability - making it ideal for industrial and telecom DC/DC where external component selection and thermal management dominate design priorities.
Availability
LTC3805EMSE#TRPBF is available at Aetrix Electronics and suitable for telecom power supplies, automotive 12V/42V systems, and isolated industrial sensors requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC3805EMSE#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, documentation, and manufacturing continuity for all Linear parts including the LTC3805 family.
The LTC3805EMSE#TRPBF belongs to Linear's high-voltage DC/DC controller product line, engineered for rugged, high-efficiency flyback and boost conversion in telecom infrastructure, automotive electronics, and industrial power systems.
FAQ
What is the operating temperature range for the LTC3805EMSE#TRPBF?
The LTC3805EMSE#TRPBF is specified for operation from –40°C to +85°C ambient temperature. This E-grade version uses the MSOP package with exposed pad thermal connection and is validated across that full industrial temperature range per manufacturer datasheet specifications.
Can the LTC3805EMSE#TRPBF be used in isolated flyback topologies?
Yes, the LTC3805EMSE#TRPBF supports isolated flyback configurations. It drives an external N-channel MOSFET on the primary side and relies on secondary-side feedback via optocoupler or transformer-coupled sensing. Its ITH pin enables full loop compensation, and SSFLT pin allows programmable soft-start for inrush control in isolated systems.
How is the switching frequency set on the LTC3805EMSE#TRPBF?
The switching frequency of the LTC3805EMSE#TRPBF is set by connecting a resistor (RFS) from the FS pin to ground. Frequency ranges from 70 kHz to 700 kHz and follows the formula fOSC = 24×10⁹/(RFS − 1500). For example, a 36 kΩ resistor yields ~700 kHz, while 350 kΩ yields ~70 kHz.
Does the LTC3805EMSE#TRPBF require an external current sense resistor?
Yes, the LTC3805EMSE#TRPBF requires an external current sense resistor connected between the source of the external N-MOSFET and ground (or low-side configuration). This resistor feeds the ISENSE pin for current-mode control and the OC pin for overcurrent protection - both thresholds are adjustable via external resistors.
What is the purpose of the SSFLT pin on the LTC3805EMSE#TRPBF?
The SSFLT pin on the LTC3805EMSE#TRPBF serves dual functions: it controls soft-start timing via an external capacitor to limit inrush current during power-up, and it defines the fault timeout duration before automatic restart after overcurrent shutdown. A 0.1 µF capacitor yields ~10 ms soft-start and ~20 ms fault recovery.
LTC3805EMSE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- 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):
- 3.95V ~ 9.5V
- Frequency - Switching:
- 70kHz ~ 700kHz
- Duty Cycle (Max):
- 80%
- Synchronous Rectifier:
- No
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Enable, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP-EP
LTC3805EMSE#TRPBF FAQ
1.How can I place an order for LTC3805EMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3805EMSE#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 LTC3805EMSE#TRPBF reliable?
The price and inventory of LTC3805EMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3805EMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3805EMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3805EMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3805EMSE#TRPBF?
LTC3805EMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3805EMSE#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 LTC3805EMSE#TRPBF?
For technical support, including LTC3805EMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3805EMSE#TRPBF requirements.
6.How does Aetrix verify that LTC3805EMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3805EMSE#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 LTC3805EMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3805EMSE#TRPBF?
All LTC3805EMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3805EMSE#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 LTC3805EMSE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3805EMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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