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Analog Devices Inc. LTC3805IMSE#PBF
- Part No.:
- LTC3805IMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3805IMSE#PBF.pdf
- Description:
- IC REG CTRLR FLYBACK 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:532
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Product details
Overview
LTC3805IMSE#PBF from Analog Devices (formerly Linear Technology) is a current-mode DC/DC controller IC designed specifically for flyback, boost, and SEPIC converters, driving an external N-channel MOSFET in high-input-voltage applications up to 72V. It delivers ±1.5% output voltage accuracy, programmable switching frequency from 70kHz to 700kHz via a single resistor, and operates with only 360µA quiescent current. It enables nonisolated 36V–72V to 5V/2A telecom power supplies.
For engineers reviewing the LTC3805IMSE#PBF datasheet, LTC3805IMSE#PBF pinout, LTC3805IMSE#PBF application, or LTC3805IMSE#PBF equivalent, key selection considerations include its adjustable slope compensation, RUN pin with precision undervoltage lockout (1.207V turn-on), soft-start programmability via SSFLT capacitor, overcurrent protection with automatic restart, and compatibility with high-VIN biasing schemes using its internal 9.5V shunt regulator.
Technical Context
The LTC3805IMSE#PBF implements peak-current-mode control with a dedicated ITH compensation node, integrated 10µA linear current ramp for slope compensation on ISENSE, and dual-threshold RUN pin (1.207V ON / 1.170V OFF) with 5µA hysteresis current. Its oscillator supports both resistor-programmed operation (RFS) and external synchronization via SYNC pin.
It features fault management through SSFLT pin-used jointly for soft-start timing (charged by 6µA) and fault timeout (discharged by 2µA)-and overcurrent detection via OC pin with 100mV threshold (adjustable with external resistor). The GATE driver delivers fast rise/fall times (30ns into 3000pF) and swings rail-to-rail between GND and VCC.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology Support | Flyback, boost, SEPIC - no internal power switch; requires external N-MOSFET. |
| Switching Frequency Range | 70kHz to 700kHz - set by single RFS resistor; synchronizable to external clock. |
| Output Voltage Accuracy | ±1.5% - specified over –40°C to 125°C junction temperature for I-grade. |
| Quiescent Current | 360µA normal operation; 40µA micropower startup - enables low-noise, high-efficiency standby modes. |
| VCC Shunt Regulator | 9.5V clamp (8.9–9.9V range at 25mA) - allows direct high-VIN biasing without external LDO. |
| Overcurrent Threshold | 100mV (typical) on OC pin - adjustable with series resistor; triggers automatic restart after fault timeout. |
| Soft-Start Control | Programmable via capacitor on SSFLT - sets both startup ramp time and post-fault recovery delay. |
Pinout & Package
Package: 10-lead plastic MSOP (MSE), 3mm × 3mm footprint, exposed pad (Pin 11) connected to GND for thermal and electrical performance. Rated for –40°C to +125°C operating junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SSFLT (1) | Soft-Start / Fault Timeout | Capacitor-connected node controlling startup ramp rate and post-fault holdoff time; charged at 6µA, discharged at 2µA. |
| ITH (2) | Error Amplifier Output / Compensation Node | Clamped 0.7V–1.9V; sets current comparator threshold; connects to RC network for loop stability. |
| FB (3) | Feedback Input | Monitors resistive divider output; regulates to 0.800V reference (I-grade); ±1.5% accuracy over full temp range. |
| RUN (4) | Enable Control with UVLO | External resistor divider sets precise enable (1.207V) and disable (1.170V) thresholds; adds hysteresis via 5µA current source. |
| FS (5) | Frequency Set | Resistor-to-GND sets oscillator frequency per fOSC = 24×10⁹/(RFS − 1500). |
| SYNC (6) | External Clock Input | Accepts rising-edge-triggered external clock (2.9V min amplitude); overrides internal oscillator. |
| ISENSE (7) | Current Sense & Slope Compensation Source | Measures MOSFET source current; injects 10µA linear ramp for duty-cycle-dependent slope compensation. |
| OC (8) | Overcurrent Detection | Compares sensed current against adjustable threshold; trips shutdown if >100mV (typical). |
| VCC (9) | Supply Input | Bypassed with ≥1µF ceramic cap; internally clamped to ~9.5V; accepts 9V or less low-impedance supply or high-VIN via resistor. |
| GATE (10) | MOSFET Gate Driver Output | Drives N-channel MOSFET gate; rail-to-rail swing (GND to VCC); 30ns rise/fall into 3000pF load. |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable frequency (70–700kHz) | Enables EMI optimization and magnetics sizing flexibility with one external resistor (RFS). |
| Programmable slope compensation | 10µA linear current ramp on ISENSE pin eliminates subharmonic oscillation in continuous conduction mode. |
| Automatic restart after overcurrent fault | SSFLT capacitor defines both soft-start duration and fault timeout period - no external logic required. |
| Precision RUN pin with hysteresis | 1.207V turn-on / 1.170V turn-off thresholds + 5µA hysteresis current enable clean system-level power sequencing. |
| Low-quiescent-current micropower startup | 40µA supply current during startup allows reliable initiation from weak bias sources like trickle chargers. |
Applications
| Telecom Power Supplies | Automotive 42V Systems |
|---|---|
|
Use Scenario: 36V–72V input telecom rectifier supplying isolated 5V/2A for line card electronics. IC Role / Device Role / Timing Role: Flyback controller managing primary-side switching, feedback regulation, and fault recovery without optocoupler dependency. Use Value: Enables compact, high-efficiency nonisolated flyback design with ±1.5% output regulation across wide input range and temperature. |
Use Scenario: 42V battery-fed auxiliary power module delivering 5V for infotainment and ADAS sensors. IC Role / Device Role / Timing Role: High-VIN DC/DC controller supporting wide input transients (load dump, cold crank) while maintaining stable 5V output. Use Value: Internal 9.5V shunt regulator allows direct high-VIN biasing; RUN pin hysteresis ensures robust start/stop behavior during battery voltage sags. |
| Industrial Isolated Equipment | High-Voltage Test & Measurement Supplies |
|
Use Scenario: Isolated 24V-to-15V/1A flyback converter powering analog front-end circuitry in PLC modules. IC Role / Device Role / Timing Role: Primary-side controller implementing current-mode regulation, slope compensation, and overcurrent protection without secondary-side sensing. Use Value: Adjustable OC threshold and programmable soft-start prevent inrush damage during hot-plug insertion of field modules. |
Use Scenario: Lab-grade 72V input flyback supply generating 12V/500mA for precision ADC reference circuits. IC Role / Device Role / Timing Role: Precision DC/DC controller ensuring low-noise, low-drift output via tight FB reference (±1.5%) and minimal quiescent current. Use Value: 360µA operating current minimizes self-heating drift; SYNC pin enables synchronized switching to reduce measurement noise coupling. |
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 1MHz frequency; no SYNC or slope compensation ramp; 1.5% FB reference; 2.5mA quiescent current. | Higher-frequency, lower-power designs where EMI filtering is prioritized over efficiency at light loads. | Choose UCC28C43DR when fixed frequency simplifies EMI compliance and board space is constrained - but expect higher no-load losses. |
| MAX17595ATP+ | Integrated high-side MOSFET driver; 4.5–60V input range; 0.8V FB reference; 1.25mA quiescent current. | Medium-power industrial supplies requiring integrated gate drive and wider VIN range than LTC3805IMSE#PBF supports directly. | Choose MAX17595ATP+ when combining controller and gate driver reduces BOM count - but verify external MOSFET compatibility is unnecessary. |
Compared with UCC28C43DR and MAX17595ATP+, the LTC3805IMSE#PBF offers uniquely programmable frequency, ultra-low quiescent current, and dedicated slope compensation - making it optimal for high-efficiency, thermally sensitive, or EMI-tuned flyback designs where external MOSFET selection is preferred.
Availability
LTC3805IMSE#PBF is available at Aetrix Electronics and suitable for telecom power supplies, automotive 42V systems, and industrial isolated equipment requiring stable component supply across extended temperature ranges.
Supply support for LTC3805IMSE#PBF 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 product lines with rigorous qualification and long-term support.
The LTC3805IMSE#PBF belongs to Linear's legacy high-voltage current-mode controller family, engineered for rugged flyback, boost, and SEPIC topologies in telecom, automotive, and industrial power conversion where reliability under wide input voltage and temperature extremes is critical.
FAQ
What is the operating temperature range for the LTC3805IMSE#PBF?
The LTC3805IMSE#PBF is rated for –40°C to +125°C junction temperature. This I-grade specification ensures guaranteed performance across automotive under-hood and industrial ambient conditions. Its 10-lead MSOP package includes an exposed pad thermally tied to GND, enabling effective heat dissipation when properly soldered to a PCB ground plane.
How does the LTC3805IMSE#PBF achieve ±1.5% output voltage accuracy?
The LTC3805IMSE#PBF achieves ±1.5% output voltage accuracy through a precision 0.800V internal reference (VFB) with low drift over temperature (±0.8mV from –40°C to 125°C), combined with high-impedance FB input (<20nA leakage) and tightly controlled error amplifier transconductance (333µA/V). This accuracy is maintained across the full I-grade temperature range without external calibration.
Can the LTC3805IMSE#PBF be powered directly from a 48V input?
Yes - the LTC3805IMSE#PBF can be powered directly from 48V using its internal 9.5V shunt regulator. Connect a current-limiting resistor from VIN to VCC, sized to keep shunt current ≤25mA (e.g., ≥1.9kΩ for 48V). The regulator clamps VCC to ~9.5V, protecting internal circuitry while enabling high-VIN biasing without external regulators.
What is the function of the SSFLT pin on the LTC3805IMSE#PBF?
The SSFLT pin on the LTC3805IMSE#PBF serves dual functions: (1) soft-start timing - charged by 6µA current to control output voltage ramp rate during startup; (2) fault timeout - discharged by 2µA current after overcurrent events to define automatic restart delay. A single external capacitor sets both intervals, simplifying fault-recovery design.
Does the LTC3805IMSE#PBF support synchronization to an external clock?
Yes - the LTC3805IMSE#PBF supports external clock synchronization via the SYNC pin. A rising edge on SYNC forces the beginning of a new switching cycle (GATE high), allowing precise timing alignment with system clocks or other converters. The external clock frequency must be between 70kHz and 700kHz and have ≥2.9V amplitude for reliable triggering.
LTC3805IMSE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tube
- 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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP-EP
LTC3805IMSE#PBF FAQ
1.How can I place an order for LTC3805IMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3805IMSE#PBF 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 LTC3805IMSE#PBF reliable?
The price and inventory of LTC3805IMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3805IMSE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3805IMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3805IMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3805IMSE#PBF?
LTC3805IMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3805IMSE#PBF 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 LTC3805IMSE#PBF?
For technical support, including LTC3805IMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3805IMSE#PBF requirements.
6.How does Aetrix verify that LTC3805IMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3805IMSE#PBF 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 LTC3805IMSE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3805IMSE#PBF?
All LTC3805IMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3805IMSE#PBF, 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 LTC3805IMSE#PBF part is unused and in its original packaging.
Return procedure for LTC3805IMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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