DocumentationDatasheet
Design Note
- DN1022 - Negative Buck Converter with Short-Circuit Protection and Shutdown
- DN458 - Buck Converter Eases the Task of Designing Auxiliary Low Voltage Negative Rails
Reliability Data
Press Release
- Wide VIN Range Flyback Controller is Specified over a -55°C to 150°C Junction Temperature Range
- Wide VIN Range Flyback Controllers Feature 150°C Maximum Junction Temperature
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Features
- VIN and VOUT Limited Only by External Components
- 4.5V Undervoltage Lockout Threshold
- 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
- Only 100mV Current Sense Voltage Drop
- 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 LTC3805-5 is a current mode DC/DC controller designed to drive an N-channel MOSFET in flyback, boost and SEPIC converter applications. Operating frequency and slope compensation can be programmed by external resistors. Programmable overcurrent sensing protects the converter from overload and short-circuit conditions. Soft-start can be programmed using an external capacitor and the soft-start capacitor also programs an automatic restart feature.
The LTC3805-5 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 LTC3805-5 can be powered from a high VIN through a resistor or it can be powered directly from a low impedance DC voltage from 4.7V to 8.8V.
The LTC3805-5 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 |
|---|---|---|---|
| DC1311A-B | LTC3805-5 Isolated Demo Board | Flyback Controller, 18V ≤ VIN ≤ 72V, Vout = 3.3V @ 3A | $75.00 | |
| DC1576A | LTC3805IMSE-5 Demo Board | SEPIC, 5V ≤ VIN ≤ 30V, Vout = 12V @ 3A | $75.00 |