LT3973 - 42V, 750mA Step-Down Regulator with 2.5μA Quiescent Current and Integrated Diodes
Features
- Ultralow Quiescent Current
2.5μA IQ at 12VIN to 3.3VOUT - Low Ripple Burst Mode® Operation
Output Ripple < 10mVP-P - Wide Input Voltage Range: 4.2V to 42V Operating
- Adjustable Switching Frequency: 200kHz to 2.2MHz
- Integrated Boost and Catch Diodes
- 750mA Output Current
- Excellent Start-Up and Dropout Performance
- Fixed Output Voltages: 3.3V, 5V
1.9μA IQ at 12VIN - Accurate Programmable Undervoltage Lockout
- Low Shutdown Current: IQ = 0.75μA
- Internal Catch Diode Current Limit
- Power Good Flag
- Thermal Shutdown
- Small, Thermally Enhanced 10-Lead MSOP and (3mm × 3mm) DFN Packages
AEC-Q100 data available for specific packages
Typical Application
Description
The LT®3973 is an adjustable frequency monolithic buck switching regulator that accepts a wide input voltage range up to 42V, and consumes only 2.5μA of quiescent current. A high efficiency switch is included on the die along with the catch diode, boost diode, and the necessary oscillator, control and logic circuitry. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping the output ripple below 10mV in a typical application. A minimum dropout voltage of 530mV is maintained when the input voltage drops below the programmed output voltage, such as during automotive cold crank. Current mode topology is used for fast transient response and good loop stability. A catch diode current limit provides protection against shorted outputs and overvoltage conditions, with thermal shutdown providing additional fault protection. An accurate programmable undervoltage lockout feature is available, producing a low shutdown current of 0.75μA. A power good flag signals when VOUT reaches 90% of the programmed output voltage. The LT3973 is available in small, thermally enhanced 10-lead MSOP and 3mm × 3mm DFN packages.
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 |
|---|---|---|---|---|---|
| LT3973EDD-3.3#PBF | 3x3 DFN-10 | DD | E | 05-08-1699 | Yes |
| LT3973EDD-3.3#TRPBF | 3x3 DFN-10 | DD | E | 05-08-1699 | Yes |
| LT3973EDD-5#PBF | 3x3 DFN-10 | DD | E | 05-08-1699 | Yes |
| LT3973EDD-5#TRPBF | 3x3 DFN-10 | DD | E | 05-08-1699 | Yes |
| LT3973EDD#PBF | 3x3 DFN-10 | DD | E | 05-08-1699 | Yes |
| LT3973EDD#TRPBF | 3x3 DFN-10 | DD | E | 05-08-1699 | Yes |
| LT3973EMSE-3.3#PBF | MS-10E | MSE | E | 05-08-1664 | Yes |
| LT3973EMSE-3.3#TRPBF | MS-10E | MSE | E | 05-08-1664 | Yes |
| LT3973EMSE-5#PBF | MS-10E | MSE | E | 05-08-1664 | Yes |
| LT3973EMSE-5#TRPBF | MS-10E | MSE | E | 05-08-1664 | Yes |
| LT3973EMSE#PBF | MS-10E | MSE | E | 05-08-1664 | Yes |
| LT3973EMSE#TRPBF | MS-10E | MSE | E | 05-08-1664 | Yes |
| LT3973HDD-3.3#PBF | 3x3 DFN-10 | DD | H | 05-08-1699 | Yes |
| LT3973HDD-3.3#TRPBF | 3x3 DFN-10 | DD | H | 05-08-1699 | Yes |
| LT3973HDD-5#PBF | 3x3 DFN-10 | DD | H | 05-08-1699 | Yes |
| LT3973HDD-5#TRPBF | 3x3 DFN-10 | DD | H | 05-08-1699 | Yes |
| LT3973HDD#PBF | 3x3 DFN-10 | DD | H | 05-08-1699 | Yes |
| LT3973HDD#TRPBF | 3x3 DFN-10 | DD | H | 05-08-1699 | Yes |
| LT3973HMSE-3.3#PBF | MS-10E | MSE | H | 05-08-1664 | Yes |
| LT3973HMSE-3.3#TRPBF | MS-10E | MSE | H | 05-08-1664 | Yes |
| LT3973HMSE-5#PBF | MS-10E | MSE | H | 05-08-1664 | Yes |
| LT3973HMSE-5#TRPBF | MS-10E | MSE | H | 05-08-1664 | Yes |
| LT3973HMSE#PBF | MS-10E | MSE | H | 05-08-1664 | Yes |
| LT3973HMSE#TRPBF | MS-10E | MSE | H | 05-08-1664 | Yes |
| LT3973IDD-3.3#PBF | 3x3 DFN-10 | DD | I | 05-08-1699 | Yes |
| LT3973IDD-3.3#TRPBF | 3x3 DFN-10 | DD | I | 05-08-1699 | Yes |
| LT3973IDD-5#PBF | 3x3 DFN-10 | DD | I | 05-08-1699 | Yes |
| LT3973IDD-5#TRPBF | 3x3 DFN-10 | DD | I | 05-08-1699 | Yes |
| LT3973IDD#PBF | 3x3 DFN-10 | DD | I | 05-08-1699 | Yes |
| LT3973IDD#TRPBF | 3x3 DFN-10 | DD | I | 05-08-1699 | Yes |
| LT3973IMSE-3.3#PBF | MS-10E | MSE | I | 05-08-1664 | Yes |
| LT3973IMSE-3.3#TRPBF | MS-10E | MSE | I | 05-08-1664 | Yes |
| LT3973IMSE-5#PBF | MS-10E | MSE | I | 05-08-1664 | Yes |
| LT3973IMSE-5#TRPBF | MS-10E | MSE | I | 05-08-1664 | Yes |
| LT3973IMSE#PBF | MS-10E | MSE | I | 05-08-1664 | Yes |
| LT3973IMSE#TRPBF | MS-10E | MSE | I | 05-08-1664 | 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
sales office or authorized distributor.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 |
|---|---|---|---|
| DC1730A | LT3973EMSE Demo Board I 42V, 750mA Step-Down Regulator with 2.5uA Quiescent Current | $100.00 | |
| 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 pagesales office or authorized distributor.
Applications
- Automotive Battery Regulation
- Power for Portable Products
- Industrial Supplies
- Gate Drive Bias
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Design Tools
LTspice
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Models for the following parts are available in LTspice:
LT3973
LTpowerCAD
The LTpowerCAD design tool is a complete power supply design tool program that can significantly ease the tasks of power supply design. It guides users to a solution, selects power stage components, provides detailed power efficiency, shows quick loop bode plot stability and load transient analysis, and can export a final design to LTspice for simulation. Click here to download LTpowerCAD
Design tools for the following parts are available in LTpowerCAD:
LT3973
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.
