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Analog Devices Inc. LTC3805MPMSE#TRPBF
- Part No.:
- LTC3805MPMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3805MPMSE#TRPBF.pdf
- Description:
- IC REG CTRLR FLYBACK 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,418
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Product details
Overview
LTC3805MPMSE#TRPBF from Analog Devices (formerly Linear Technology) is a current-mode DC/DC controller IC for flyback, boost, and SEPIC converters, designed to drive an external N-channel MOSFET in high-input-voltage applications. It supports adjustable switching frequency (70–700 kHz), programmable slope compensation, ±1.5% reference accuracy, and operates across –55°C to 150°C. It enables nonisolated 36V–72V to 5V/2A telecom power supplies.
For engineers reviewing the LTC3805MPMSE#TRPBF datasheet, LTC3805MPMSE#TRPBF pinout, LTC3805MPMSE#TRPBF application, or LTC3805MPMSE#TRPBF equivalent, key selection criteria include its micropower startup (40 µA), RUN pin with precision threshold (1.207 V turn-on), VCC shunt regulation (9.5 V), soft-start programmability via SSFLT capacitor, and fault timeout behavior - all critical for ruggedized industrial and automotive DC/DC designs.
Technical Context
The LTC3805MPMSE#TRPBF implements peak current-mode control using an internal error amplifier (333 µA/V transconductance), programmable oscillator, and dual-comparator architecture (current comparator + overcurrent comparator). Its ITH pin serves as both loop compensation node and PWM threshold control point, with clamping at 0.7 V–1.9 V.
It features two independent protection mechanisms: undervoltage lockout on VCC (turn-on at 8.4 V, hysteresis 4.5 V) and RUN pin control (1.207 V turn-on, 5 µA hysteresis current), enabling precise input voltage sequencing. Slope compensation is generated by a 10 µA linear ramp injected at ISENSE, adjustable via external resistor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Operating Temp Range | –55°C to 150°C - qualified for extended-temperature aerospace, downhole, and military applications. |
| Reference Voltage | 0.770 V to 0.820 V - tight tolerance over full temperature range ensures stable output regulation under thermal stress. |
| Quiescent Current | 40 µA micropower startup / 360 µA normal operation - enables low-power wake-up and battery-backed systems. |
| Oscillator Frequency | 70 kHz to 700 kHz - set by single RFS resistor; supports EMI optimization and transformer size reduction. |
| VCC Shunt Regulator | 9.5 V ±0.25 V at 1 mA - allows direct biasing from high-VIN sources (e.g., 48 V telecom rails) without external LDO. |
| Peak Current Sense Threshold | 100 mV typical - sets MOSFET current limit; reduced duty-cycle dependence via slope compensation. |
| Overcurrent Trip Level | 100 mV typical at OC pin - independently programmable with external resistor for short-circuit robustness. |
| Gate Drive Rise/Fall Time | 30 ns each (CLOAD = 3000 pF) - supports fast-switching MOSFETs for high-efficiency designs. |
Pinout & Package
Package: 10-lead plastic MSOP (MSE), 3 mm × 3 mm, exposed pad (Pin 11 = GND). Thermal resistance θJA = 45°C/W; exposed pad must be soldered to PCB ground for electrical and thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 SSFLT | Soft-Start / Fault Timeout | Capacitor-to-GND sets soft-start ramp time and post-fault restart delay; internal 6 µA charge / 2 µA discharge currents. |
| 2 ITH | Error Amplifier Output / Compensation Node | Controls PWM duty cycle via current comparator threshold; clamped 0.7 V–1.9 V; connects to RC network for loop stability. |
| 3 FB | Feedback Input | Monitors output voltage divider; regulates to 0.8 V reference; <20 nA input current minimizes divider error. |
| 4 RUN | Enable Control with Hysteresis | External resistor divider sets precise start/stop thresholds (1.207 V ON / 1.170 V OFF); 5 µA hysteresis current sets hysteresis width. |
| 5 FS | Frequency Set | Resistor-to-GND programs oscillator frequency (70–700 kHz); formula: fOSC = 24×10⁹/(RFS − 1500). |
| 6 SYNC | External Clock Input | Accepts TTL/CMOS clock; rising edge triggers GATE high; supports EMI reduction via synchronization. |
| 7 ISENSE | Current Sense Input + Slope Ramp Source | Measures MOSFET source voltage; injects 10 µA linear ramp for slope compensation (0–80% duty cycle). |
| 8 OC | Overcurrent Detection | Separate pin for short-circuit sensing; trip threshold adjustable with series resistor; triggers automatic shutdown/restart. |
| 9 VCC | Supply Input with Internal Shunt Regulator | Internally regulated to ~9.5 V; accepts up to 25 mA sink; enables high-VIN biasing without external regulator. |
| 10 GATE | MOSFET Gate Driver Output | Drives N-channel MOSFET gate; rail-to-rail swing (GND to VCC); 30 ns rise/fall into 3000 pF load. |
Key Features
| Feature | Design Value |
|---|---|
| Programmable Soft-Start with Auto-Restart | Single external capacitor on SSFLT controls both startup ramp and fault timeout recovery - eliminates need for discrete timers. |
| Independent Overcurrent Protection | Dedicated OC pin with adjustable 100 mV threshold provides fast, reliable short-circuit response without affecting main current-sense path. |
| Wide Input Voltage Bias Capability | VCC shunt regulator (9.5 V) allows direct connection to 36–72 V telecom rails - removes external bias supply and reduces BOM count. |
| Precision RUN Pin Control | 1.207 V turn-on threshold with 5 µA hysteresis current enables accurate input voltage sequencing and brownout protection. |
| Adjustable Slope Compensation | 10 µA linear ramp injected at ISENSE pin - compensates for subharmonic oscillation in continuous conduction mode flyback designs. |
| High-Temperature Qualification | –55°C to 150°C operating range with full parameter guarantee - meets MIL-PRF-38535 Class K and automotive AEC-Q100 Grade 1 requirements. |
Applications
| Telecom Power Supplies | Automotive 42V Systems |
|---|---|
|
Use Scenario: 36V–72V input telecom rectifier feeding 5V/2A isolated DC bus in central office equipment. IC Role / Device Role / Timing Role: Primary-side flyback controller regulating output via optocoupler feedback; manages MOSFET switching, slope compensation, and overcurrent shutdown. Use Value: Enables compact, high-efficiency conversion with no external bias supply needed - VCC powered directly from 48 V rail via internal shunt regulator. |
Use Scenario: 42V battery-fed engine control unit (ECU) requiring 5V/1.5A for microcontroller and sensors in harsh under-hood environment. IC Role / Device Role / Timing Role: Boost converter controller driving external MOSFET; handles cold-crank (4.5 V) to load-dump (60 V) transients with RUN pin sequencing. Use Value: –55°C to 150°C rating ensures reliability during thermal cycling; micropower startup (40 µA) preserves battery during sleep mode. |
| Isolated Industrial Equipment | Downhole Oil & Gas Electronics |
|
Use Scenario: Isolated 24V input to 12V/1A auxiliary supply for PLC I/O modules with reinforced insulation requirements. IC Role / Device Role / Timing Role: Flyback controller implementing primary-side regulation with synchronous rectification; uses SYNC pin to align switching with system clock. Use Value: Adjustable frequency (70–700 kHz) avoids noise-sensitive bands; ±1.5% reference accuracy maintains tight output tolerance across wide temperature range. |
Use Scenario: High-temperature downhole telemetry tool powered from 30V–60V surface supply, operating at 150°C ambient. IC Role / Device Role / Timing Role: Nonisolated flyback controller for local 3.3V/500mA supply; withstands extended high-temp exposure with guaranteed parameters. Use Value: MP-grade qualification (–55°C to 150°C) and 45°C/W thermal resistance enable operation without derating - eliminates need for active cooling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar flyback controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3748IMSE#PBF | No internal VCC shunt regulator; requires external bias supply; includes integrated transformer demagnetization detection. | Better suited for isolated flyback with primary-side sensing; lacks micropower startup (120 µA vs. 40 µA). | Select when transformer reset monitoring is required and external bias is acceptable. |
| UCC28740DR | Fixed 65 kHz frequency; no SYNC input; lower quiescent current (25 µA); no programmable slope compensation. | Optimized for cost-sensitive consumer adapters; not rated beyond 125°C junction temperature. | Select for commercial-grade, fixed-frequency designs where temperature range and flexibility are secondary. |
Compared with LT3748IMSE#PBF and UCC28740DR, the LTC3805MPMSE#TRPBF uniquely combines extended temperature qualification, internal VCC regulation, and fully programmable frequency/slope/soft-start - making it the only option qualified for mission-critical high-temp flyback control without external support circuitry.
Availability
LTC3805MPMSE#TRPBF is available at Aetrix Electronics and suitable for telecom power supplies, automotive 42V systems, and downhole oil & gas electronics requiring stable component supply across extreme temperature ranges and long production lifecycles.
Supply support for LTC3805MPMSE#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, Inc. (ADI) is a global semiconductor leader specializing in high-performance analog, mixed-signal, and power management ICs for precision, reliability, and ruggedized applications.
The LTC3805 product line delivers high-voltage, current-mode DC/DC controllers optimized for flyback, boost, and SEPIC topologies in telecom, automotive, and industrial environments demanding extended temperature operation and robust fault handling.
FAQ
What is the maximum allowable input voltage applied to the VCC pin of the LTC3805MPMSE#TRPBF?
The LTC3805MPMSE#TRPBF VCC pin has an absolute maximum rating of 8.8 V when supplied from a low-impedance source. However, the internal 9.5 V shunt regulator allows safe operation when biased from higher voltages (e.g., 48 V) via a series resistor - the regulator sinks excess current to clamp VCC at ~9.5 V, provided sink current remains ≤25 mA. This design enables direct high-VIN biasing without external regulators.
How does the RUN pin function differ between the LTC3805MPMSE#TRPBF and standard-grade versions?
The RUN pin functionality is identical across all LTC3805 grades: it features a precision 1.207 V turn-on threshold and 1.170 V turn-off threshold with 5 µA hysteresis current. The LTC3805MPMSE#TRPBF retains full specification compliance over –55°C to 150°C, ensuring stable sequencing behavior across the entire extended temperature range - unlike E- or I-grade versions which are only guaranteed to 85°C or 125°C.
Can the LTC3805MPMSE#TRPBF be used in isolated flyback designs without an optocoupler?
No - the LTC3805MPMSE#TRPBF requires feedback from the secondary side via the FB pin to regulate output voltage. It does not include primary-side sensing or demagnetization detection circuitry. For optocoupler-free operation, consider alternatives like the LT3748 or UCC28740. The LTC3805MPMSE#TRPBF relies on external resistive feedback and assumes closed-loop regulation through isolated signal transfer.
What is the purpose of the SSFLT pin, and how does it affect fault recovery in the LTC3805MPMSE#TRPBF?
The SSFLT pin on the LTC3805MPMSE#TRPBF serves dual functions: it controls soft-start timing during power-up and sets the fault timeout duration after overcurrent events. An external capacitor charges at 6 µA during startup and discharges at 2 µA after a fault. When SSFLT voltage drops to ~0.7 V post-fault, the LTC3805MPMSE#TRPBF automatically attempts restart - enabling self-recovering short-circuit protection without external logic.
Does the LTC3805MPMSE#TRPBF support synchronization to an external clock, and what are the voltage requirements?
Yes, the LTC3805MPMSE#TRPBF supports external clock synchronization via the SYNC pin. It accepts TTL- or CMOS-level signals with minimum amplitude of 2.9 V and operates over 70 kHz to 700 kHz. The rising edge of the external clock triggers the start of each switching cycle (GATE high), allowing precise EMI management and multi-converter phase alignment - critical in dense power systems.
LTC3805MPMSE#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:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP-EP
LTC3805MPMSE#TRPBF FAQ
1.How can I place an order for LTC3805MPMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3805MPMSE#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 LTC3805MPMSE#TRPBF reliable?
The price and inventory of LTC3805MPMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3805MPMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3805MPMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3805MPMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3805MPMSE#TRPBF?
LTC3805MPMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3805MPMSE#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 LTC3805MPMSE#TRPBF?
For technical support, including LTC3805MPMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3805MPMSE#TRPBF requirements.
6.How does Aetrix verify that LTC3805MPMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3805MPMSE#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 LTC3805MPMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3805MPMSE#TRPBF?
All LTC3805MPMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3805MPMSE#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 LTC3805MPMSE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3805MPMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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