LT3640 - Dual Monolithic Buck Regulator with Power-On Reset and Watchdog Timer
Features
- High Voltage Buck Regulator:
4V to 35V Operating Range
1.3A Output Current - OVLO Protects Input to 55V
- Low Voltage Synchronous Buck Regulator:
2.5V to 5.5V Input Voltage Range
1.1A Output Current - Synchronizable, Adjustable 350kHz to 2.5MHz Switching Frequency
- Programmable Power-On Reset Timer
- Programmable Window Mode Watchdog Timer
- Typical Quiescent Current: 290μA
- Short-Circuit Robust
- Programmable Soft-Start
- Low Shutdown Current: IQ < 1μA
- Available in Thermally Enhanced 28-Lead
(4mm × 5mm) QFN and 28-Lead TSSOP Packages
AEC-Q100 data available for specific packages
Typical Application
Description
The LT3640 is a dual channel, current mode monolithic buck switching regulator with a power-on reset and a watchdog timer. Both regulators are synchronized to a single oscillator with an adjustable frequency (350kHz to 2.5MHz). At light loads, both regulators operate in low ripple Burst Mode® to maintain high efficiency and low output ripple.
The high voltage channel is a nonsynchronous buck with an internal 2.4A top switch that operates from an input of 4V to 35V; a 36.5V OVLO protects the device to 55V. The low voltage channel operates from an input of 2.5V to 5.5V. Internal synchronous power switches provide high efficiency without the need of external Schottky diode. Both channels have cycle-by-cycle current limit, providing protection against shorted outputs.
The power-on reset and watchdog timeout periods are both adjustable using external capacitors. The window mode watchdog timer flags when the μP pulses group too close together or too far apart.
The LT3640 is available in a 28-pin 4mm × 5mm QFN package and 28-pin TSSOP package. Both packages have an exposed pad for low thermal resistance.
Packaging
CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.
For complete and up to date package information and drawings, please refer to our packaging page
| Part Number | Package | Code | Temp | Package Drawing |
RoHS |
|---|---|---|---|---|---|
| LT3640EFE#PBF | TSSOP-28 | FE | E | 05-08-1663 (EB) | Yes |
| LT3640EFE#TRPBF | TSSOP-28 | FE | E | 05-08-1663 (EB) | Yes |
| LT3640EUFD#PBF | 4x5 QFN-28 | UFD | E | 05-08-1712 | Yes |
| LT3640EUFD#TRPBF | 4x5 QFN-28 | UFD | E | 05-08-1712 | Yes |
| LT3640IFE#PBF | TSSOP-28 | FE | I | 05-08-1663 (EB) | Yes |
| LT3640IFE#TRPBF | TSSOP-28 | FE | I | 05-08-1663 (EB) | Yes |
| LT3640IUFD#PBF | 4x5 QFN-28 | UFD | I | 05-08-1712 | Yes |
| LT3640IUFD#TRPBF | 4x5 QFN-28 | UFD | I | 05-08-1712 | Yes |
Order Info
- Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
- Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
- Please refer to our general ordering information or the product datasheet for more details
Package Variations and Pricing
| Part Number | Package | Temp | Price (1-99) |
Price (1k)* |
RoHS | |
|---|---|---|---|---|---|---|
| LT3640EFE#PBF | TSSOP-28 | E | $5.23 | $3.65 | Yes | |
| LT3640EFE#TRPBF | TSSOP-28 | E | $3.71 | Yes | ||
| LT3640EUFD#PBF | 4x5 QFN-28 | E | $5.00 | $3.50 | Yes | |
| LT3640EUFD#TRPBF | 4x5 QFN-28 | E | $3.56 | Yes | ||
| LT3640IFE#PBF | TSSOP-28 | I | $5.80 | $4.06 | Yes | |
| LT3640IFE#TRPBF | TSSOP-28 | I | $4.12 | Yes | ||
| LT3640IUFD#PBF | 4x5 QFN-28 | I | $5.56 | $3.89 | Yes | |
| LT3640IUFD#TRPBF | 4x5 QFN-28 | I | $3.95 | Yes | ||
| Buy Now • Request Samples | ||||||
Demo Boards
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 |
|---|---|---|---|
| DC1359A | LT3640EFE Demo Board | 5V ≤ VIN ≤ 35V(55V Transients), Vout1 = 1.2V @ 1A, Vout2 = 3.3V @ 0.8A | $125.00 | |
| Buy Now | |||
Designed for Automotive and Transportation Applications
AEC-Q100 data is available for these specific part numbers. Please contact your local sales representative for more information regarding reliability reports or to inquire about parts that are not included. For more information, view our Automotive and Transportation page
| Part Number | Package | Temp | Price (1-99) |
Price (1k)* |
RoHS | |
|---|---|---|---|---|---|---|
| LT3640IFE#PBF | TSSOP-28 | I | $5.80 | $4.06 | Yes | |
| LT3640IFE#TRPBF | TSSOP-28 | I | $4.12 | Yes | ||
| LT3640IUFD#PBF | 4x5 QFN-28 | I | $5.56 | $3.89 | Yes | |
| LT3640IUFD#TRPBF | 4x5 QFN-28 | I | $3.95 | Yes | ||
| Buy Now • Request Samples | ||||||
Applications
- Industrial Power Supplies
- Automotive Electronic Control Units
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Design Tools
LTspice
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LT3640
Technical Support
- For immediate technical assistance, contact your local sales office or distributor or call 1-800-4-LINEAR (US customers only) or 408-432-1900.
- For less urgent requests, please complete our Technical Support Request Form. Please allow 2-3 business days for reply.
