DocumentationDatasheet
Design Note
Reliability Data
LT Journal
Press Release
- Low Start-up Current Wide VIN Range Current Mode Flyback DC/DC Controller
- Wide VIN Range Flyback Controllers Feature 150°C Maximum Junction Temperature
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Features
- VIN and VOUT Limited Only by External Components
- Adjustable Slope Compensation
- Adjustable Overcurrent Protection with Automatic Restart
- Adjustable Operating Frequency (70kHz to 700kHz) with One External Resistor
- Synchronizable to an External Clock
- ±1.5% Reference Accuracy
- Current Mode Operation for Excellent Line and Load Transient Response
- RUN Pin with Precision Threshold and Adjustable Hysteresis
- Programmable Soft-Start with One External Capacitor
- Low Quiescent Current: 360μA
- Small 10-Lead MSOP and 3mm × 3mm DFN
Typical Application
Description
The LTC3805 is a current mode controller for flyback DC/DC converters designed to drive an N-channel MOSFET in high input and output voltage converter applications. Operating frequency and slope compensation can be programmed by external resistors. Programmable overcurrent sensing protects the converter from short-circuits. Softstart can be programmed using an external capacitor and the soft-start capacitor also programs an automatic restart feature.
The LTC3805 provides ±1.5% output voltage accuracy and consumes only 360μA of quiescent current during normal operation and only 40μA during micropower startup. Using a 9.5V internal shunt regulator, the LTC3805 can be powered from a high VIN through a resistor or it can be powered directly from a low impedance DC voltage of 9V or less.
The LTC3805 is available in the 10-lead MSOP package and the 3mm × 3mm DFN package.
| Turn On Voltage |
|
| LTC3805 | 8.4V |
| LTC3805-5 | 4.5V |
3x3 DFN-10,MS-10E
Package Variations and Pricing
| Part Number | Package | Pins | Temp | Price (1-99) |
Price (1k)* |
|---|---|---|---|---|---|
| LTC3805EDD#PBF | DFN | 10 | E | $2.01 | $1.39 |
| LTC3805EDD#TRPBF | DFN | 10 | E | $1.45 | |
| LTC3805EDD-5#PBF | DFN | 10 | E | $1.99 | $1.39 |
| LTC3805EDD-5#TRPBF | DFN | 10 | E | $1.45 | |
| LTC3805EMSE#PBF | MSOP | 10 | E | $2.01 | $1.39 |
| LTC3805EMSE#TRPBF | MSOP | 10 | E | $1.45 | |
| LTC3805EMSE-5#PBF | MSOP | 10 | E | $1.99 | $1.39 |
| LTC3805EMSE-5#TRPBF | MSOP | 10 | E | $1.45 | |
| LTC3805HMSE#PBF | MSOP | 10 | H | $2.51 | $1.76 |
| LTC3805HMSE#TRPBF | MSOP | 10 | H | $1.82 | |
| LTC3805HMSE-5#PBF | MSOP | 10 | H | $2.51 | $1.76 |
| LTC3805HMSE-5#TRPBF | MSOP | 10 | H | $1.82 | |
| LTC3805IDD#PBF | DFN | 10 | I | $2.10 | $1.47 |
| LTC3805IDD#TRPBF | DFN | 10 | I | $1.53 | |
| LTC3805IDD-5#PBF | DFN | 10 | I | $2.10 | $1.47 |
| LTC3805IDD-5#TRPBF | DFN | 10 | I | $1.53 | |
| LTC3805IMSE#PBF | MSOP | 10 | I | $2.10 | $1.47 |
| LTC3805IMSE#TRPBF | MSOP | 10 | I | $1.53 | |
| LTC3805IMSE-5#PBF | MSOP | 10 | I | $2.10 | $1.47 |
| LTC3805IMSE-5#TRPBF | MSOP | 10 | I | $1.53 | |
| LTC3805MPMSE#PBF | MSOP | 10 | MP | $6.80 | $4.76 |
| LTC3805MPMSE#TRPBF | MSOP | 10 | MP | $4.82 | |
| LTC3805MPMSE-5#PBF | MSOP | 10 | MP | $6.80 | $4.76 |
| LTC3805MPMSE-5#TRPBF | MSOP | 10 | MP | $4.82 | |
| LTC3805HMSE#TR | MSOP | 10 | H | $3.64 |
Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.
| Part Number | Description | Price | Documentation |
|---|---|---|---|
| DC1045A | LTC3805EMSE Isolated Demo Board | 36V ≤ Vin ≤ 72V, Vout = 3.3V/3A | $75.00 | |
| DC1311A-A | LTC3805 Isolated Demo Board | Flyback Controller, 18V ≤ VIN ≤ 72V, Vout = 3.3V @ 3A | $75.00 |