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Analog Devices Inc. LTC3805EMSE-5#TRPBF
- Part No.:
- LTC3805EMSE-5#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3805EMSE-5#TRPBF.pdf
- Description:
- IC REG CTRLR MULT TOP 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,243
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Product details
Overview
LTC3805EMSE-5#TRPBF from Analog Devices (formerly Linear Technology) is a current-mode DC/DC controller IC designed to drive external N-channel MOSFETs in flyback, boost, and SEPIC topologies. It delivers ±1.5% output voltage accuracy, supports 70kHz–700kHz adjustable switching frequency via a single resistor, features programmable overcurrent protection with automatic restart, and operates from 4.7V–8.8V VCC or high-VIN bias through internal 9.5V shunt regulator - enabling use in automotive auxiliary power supplies.
For engineers reviewing the LTC3805EMSE-5#TRPBF datasheet, LTC3805EMSE-5#TRPBF pinout, LTC3805EMSE-5#TRPBF application, or LTC3805EMSE-5#TRPBF equivalent, key selection criteria include its 10-lead MSOP package, 360µA quiescent current, 100mV current sense threshold, RUN pin with precision undervoltage lockout (4.5V turn-on), and compatibility with isolated and non-isolated step-up/step-down converter designs requiring robust fault management.
Technical Context
The LTC3805EMSE-5#TRPBF implements peak current-mode control using an internal error amplifier (gm = 333 µA/V), programmable slope compensation (10 µA ramp), and dual-threshold RUN pin logic (1.207V ON / 1.170V OFF). Its oscillator frequency is set by RFS (70–700 kHz) and can be synchronized externally via the SYNC pin.
It integrates a 9.5V internal shunt regulator on VCC, supports micropower startup (40 µA), provides soft-start/fault timeout via SSFLT pin (programmable with capacitor), and enforces duty cycle limits (6–95%) to prevent subharmonic oscillation and ensure stable operation across wide input/output ranges.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology Support | Flyback, boost, SEPIC - enables isolated and non-isolated DC/DC conversion without transformer turns-ratio constraints. |
| Output Voltage Accuracy | ±1.5% - ensures tight regulation for sensitive loads like telecom housekeeping rails or PoE auxiliary supplies. |
| Switching Frequency Range | 70 kHz to 700 kHz - adjustable via single RFS resistor; higher frequencies reduce magnetics size, lower frequencies improve efficiency at light load. |
| Quiescent Current | 360 µA (normal), 40 µA (micropower start-up) - minimizes standby loss in always-on automotive or industrial systems. |
| VCC Operating Range | 4.7 V to 8.8 V direct supply, or high-VIN via internal 9.5 V shunt regulator - allows flexible biasing from battery, bus rail, or auxiliary winding. |
| Current Sense Threshold | 100 mV (typical) - low-loss sensing with minimal I²R dissipation in high-current boost converters. |
| Undervoltage Lockout | VTURNON = 4.5 V, VTURNOFF = 3.95 V - prevents erratic gate drive during brownout conditions in automotive 12 V systems. |
Pinout & Package
Package: 10-lead MSOP (3 mm × 3 mm), exposed pad (Pin 11) connected to GND for thermal and electrical performance. Rated θJA = 45°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SSFLT (1) | Soft-start & fault timeout timing node | Capacitor to GND sets soft-start ramp duration and post-fault restart delay; internal 6 µA charge / 2 µA discharge currents enable precise timing control. |
| ITH (2) | Error amplifier output / compensation point | Voltage (0.7–1.9 V clamped) sets peak current comparator threshold; RC network here defines loop stability and transient response. |
| FB (3) | Feedback input | Monitors resistive divider output; regulates VOUT to 0.800 V reference (±1.5%) - enables arbitrary output voltages (e.g., 5 V, 12 V, 24 V). |
| RUN (4) | Enable/disable control with hysteresis | 1.207 V turn-on / 1.170 V turn-off thresholds + 5 µA hysteresis current allow programmable VIN UVLO with external resistor divider. |
| FS (5) | Frequency set input | Resistor to GND programs fOSC = 24×10⁹/(RFS − 1500); enables optimization of EMI, efficiency, and component size. |
| SYNC (6) | External clock synchronization input | Accepts 70–700 kHz external clock; rising edge triggers GATE high - critical for noise-sensitive multi-rail systems. |
| ISENSE (7) | Current sense & slope compensation injection | Measures MOSFET source voltage; injects 10 µA linear ramp for slope compensation - prevents subharmonic instability in DCM/CCM boundary operation. |
| OC (8) | Overcurrent fault detection | Compares sensed current against programmable threshold (85–115 mV); triggers shutdown on overload/short-circuit with automatic restart. |
| VCC (9) | Supply input with internal shunt regulator | Internally clamped to ~9.5 V; accepts 4.7–8.8 V direct supply or high-VIN via series resistor - simplifies bias design in wide-input applications. |
| GATE (10) | N-MOSFET gate driver output | Drives external N-channel MOSFET gate with 30 ns rise/fall times; rated for capacitive loads up to 3000 pF. |
Key Features
| Feature | Design Value |
|---|---|
| Programmable soft-start with fault timeout | Single external capacitor on SSFLT pin controls both startup ramp time and post-fault holdoff - eliminates need for separate timers or microcontroller intervention. |
| Adjustable slope compensation | 10 µA internal current ramp injected at ISENSE pin - enables stable current-mode control across full duty cycle range without external op-amp circuitry. |
| Synchronizable oscillator | SYNC pin accepts external clock (70–700 kHz) - allows EMI reduction via frequency alignment in multi-converter systems (e.g., base station power modules). |
| Precision RUN pin with user-programmable hysteresis | 5 µA hysteresis current sourced during operation - permits custom VIN UVLO window (e.g., 9–16 V for 12 V automotive) using two resistors only. |
| Low 100 mV current sense threshold | Minimizes power loss in high-current paths - supports efficient 1 A+ boost converters using <10 mΩ sense resistors. |
Applications
| Automotive Auxiliary Power Supply | Telecom Housekeeping Rail |
|---|---|
Use Scenario: Generating isolated 5 V/1 A bias for infotainment MCU and CAN transceivers from 12 V battery with cold-crank tolerance. IC Role / Device Role / Timing Role: Flyback controller managing primary-side switching, feedback isolation via optocoupler, and fault recovery after load dump. Use Value: 4.5 V VCC UVLO and 40 µA micropower start-up ensure reliable boot during cranking; ±1.5% accuracy maintains MCU reset margin. |
Use Scenario: Providing regulated 3.3 V/500 mA auxiliary power for FPGA configuration and PHY management in telecom line cards. IC Role / Device Role / Timing Role: Boost controller driving external MOSFET to step up -48 V intermediate bus to positive rail; SYNC pin aligns switching with system clock. Use Value: 700 kHz max frequency enables compact 2.2 µH inductor; 100 mV sense threshold reduces heat in high-current path. |
| Power over Ethernet (PoE) PD Interface | Industrial Isolated Sensor Supply |
Use Scenario: Deriving 12 V/1 A isolated auxiliary power from PoE Class 4 input (57 V) for PD-side microcontroller and interface ICs. IC Role / Device Role / Timing Role: Flyback controller with primary-side regulation; RUN pin tied to PoE detection signature for controlled enable. Use Value: Adjustable OC threshold protects against shorted secondary windings; SSFLT capacitor ensures graceful restart after cable disconnect/reconnect. |
Use Scenario: Generating galvanically isolated ±15 V rails for analog front-end op-amps in high-voltage motor drives. IC Role / Device Role / Timing Role: SEPIC controller operating from 24 V industrial bus; ITH compensation network optimized for 100 kHz switching and low-noise output. Use Value: ±1.5% FB reference accuracy ensures stable sensor excitation; 360 µA quiescent current minimizes standby loss in always-on monitoring systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar current-mode DC/DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3751EMSE#TRPBF | Higher VCC rating (up to 100 V), integrated high-side gate driver, no SYNC pin - targets flyback controllers with direct high-VIN bias. | Designed for high-input-voltage flyback (e.g., 48 V telecom rectified bus), lacks programmable slope compensation and soft-start flexibility. | Select LT3751EMSE#TRPBF when input exceeds 12 V and integrated gate driver simplifies layout; avoid if slope compensation or SYNC is required. |
| UCC28083D | Fixed 100 kHz frequency, no programmable soft-start or RUN hysteresis, 2.5 V minimum VCC - TI's current-mode PWM controller with simpler feature set. | Targeted at cost-sensitive AC/DC PFC pre-regulators and fixed-frequency boost converters; lacks isolated topology support and precision UVLO. | Choose UCC28083D for basic boost applications where frequency stability and BOM cost outweigh programmability needs; not suitable for flyback or SEPIC. |
Compared with LT3751EMSE#TRPBF and UCC28083D, the LTC3805EMSE-5#TRPBF offers broader topology flexibility (flyback/boost/SEPIC), finer control over timing (soft-start, fault timeout, SYNC), and superior precision (±1.5% VREF, 4.5 V UVLO) - making it optimal for automotive and industrial isolated auxiliary supplies demanding reliability and configurability.
Availability
LTC3805EMSE-5#TRPBF is available at Aetrix Electronics and suitable for automotive auxiliary power supplies, telecom housekeeping rails, Power over Ethernet (PoE) powered devices, and industrial isolated sensor interfaces requiring stable component supply across extended temperature ranges (–40°C to 85°C).
Supply support for LTC3805EMSE-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 analog and power management portfolio. Linear pioneered precision DC/DC control ICs with emphasis on efficiency, accuracy, and robustness in harsh environments.
The LTC3805-5 product line was engineered specifically for flexible, isolated and non-isolated DC/DC converter designs requiring programmable fault management, low quiescent current, and wide input voltage tolerance - targeting automotive, telecom, and industrial power subsystems.
FAQ
What is the maximum duty cycle limit of the LTC3805EMSE-5#TRPBF?
The LTC3805EMSE-5#TRPBF enforces a maximum switch-on duty cycle of 95% at 200 kHz. This limit prevents subharmonic oscillation in continuous conduction mode and ensures stable current-mode control across all operating conditions. Duty cycle is automatically reduced below this threshold when output voltage sags or overcurrent conditions occur - a behavior confirmed in the Electrical Characteristics table and Operation section of the datasheet.
Can the LTC3805EMSE-5#TRPBF operate with input voltages above 8.8 V?
Yes, the LTC3805EMSE-5#TRPBF can operate with input voltages well above 8.8 V when powered via the VCC pin through a series resistor. Its internal 9.5 V shunt regulator safely clamps VCC to approximately 9.5 V, allowing bias from 24 V, 48 V, or even higher rails - provided the shunt current remains ≤25 mA. This capability is explicitly documented in the Absolute Maximum Ratings and Applications Information sections.
Does the LTC3805EMSE-5#TRPBF support synchronous rectification?
No, the LTC3805EMSE-5#TRPBF does not support synchronous rectification. It provides a single N-channel MOSFET gate drive signal (GATE pin) and relies on external diodes for rectification in flyback and boost topologies. The datasheet makes no provision for secondary-side gate control or adaptive dead-time management - confirming it is intended for use with standard diode-based outputs.
What is the purpose of the exposed pad (Pin 11) on the LTC3805EMSE-5#TRPBF MSOP package?
The exposed pad (Pin 11) on the LTC3805EMSE-5#TRPBF is electrically and thermally connected to GND. It must be soldered directly to a PCB ground plane to achieve the specified θJA = 45°C/W thermal resistance and ensure reliable operation at full load. This requirement is explicitly stated in the Pin Configuration diagram and Absolute Maximum Ratings table of the datasheet.
How is overcurrent protection configured on the LTC3805EMSE-5#TRPBF?
Overcurrent protection on the LTC3805EMSE-5#TRPBF is configured using the OC pin, which senses voltage across the same external current-sense resistor used at ISENSE. An optional resistor between OC and GND adjusts the trip threshold from 85 mV to 115 mV - a method detailed in the Applications Information section under "Programmable Overcurrent." Fault detection triggers immediate shutdown and automatic restart after timeout.
LTC3805EMSE-5#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-Up/Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Boost, Flyback, SEPIC
- 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-5#TRPBF FAQ
1.How can I place an order for LTC3805EMSE-5#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3805EMSE-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 LTC3805EMSE-5#TRPBF reliable?
The price and inventory of LTC3805EMSE-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 LTC3805EMSE-5#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3805EMSE-5#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3805EMSE-5#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3805EMSE-5#TRPBF?
LTC3805EMSE-5#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3805EMSE-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 LTC3805EMSE-5#TRPBF?
For technical support, including LTC3805EMSE-5#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3805EMSE-5#TRPBF requirements.
6.How does Aetrix verify that LTC3805EMSE-5#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3805EMSE-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 LTC3805EMSE-5#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3805EMSE-5#TRPBF?
All LTC3805EMSE-5#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3805EMSE-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 LTC3805EMSE-5#TRPBF part is unused and in its original packaging.
Return procedure for LTC3805EMSE-5#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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