LTC3521 - 1A Buck-Boost DC/DC and Dual 600mA Buck DC/DC Converters
Features
- Three High Efficiency DC/DC Converters:
Buck-Boost (VOUT: 1.8V to 5.25V, IOUT: 1A)
Dual Buck (VOUT: 0.6V to VIN, IOUT: 600mA) - 1.8V to 5.5V Input Voltage Range
- Pin-Selectable Burst Mode® Operation
- 30μA Total Quiescent Current in Burst Mode Operation
- Independent Power Good Indicator Outputs
- Integrated Soft-Start
- Thermal and Overcurrent Protection
- <2μA Current in Shutdown
- Small 4mm × 4mm QFN and Thermally Enhanced TSSOP Packages
AEC-Q100 data available for specific packages
Typical Application
Description
The LTC®3521 combines a 1A buck-boost DC/DC converter and dual 600mA synchronous buck DC/DC converters. The 1.1MHz switching frequency minimizes the solution footprint while maintaining high efficiency. All three converters feature soft-start and internal compensation to minimize the solution footprint and simplify the design process.
The buck converters are current mode controlled and utilize an internal synchronous rectifier to improve efficiency. The buck converters support 100% duty cycle operation to extend battery life. If the PWM pin is held low, the buck converters automatically transition from Burst Mode operation to PWM mode at high loads. With the PWM pin held high, the buck converters remain in low noise, 1.1MHz PWM mode.
The buck-boost converter features continuous conduction operation to maximize efficiency and minimize noise. At light loads, the buck-boost converter can be operated in Burst Mode operation to improve efficiency and reduce no-load standby current.
The LTC3521 provides a <2μA shutdown mode, overtemperature shutdown and current limit protection on all converters. The LTC3521 is available in a 24-pin 0.75mm × 4mm × 4mm QFN package, and a 20-pin thermally enhanced TSSOP package.
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 |
|---|---|---|---|---|---|
| LTC3521EFE#PBF | TSSOP-20 | FE | E | 05-08-1663 (CB) | Yes |
| LTC3521EFE#TRPBF | TSSOP-20 | FE | E | 05-08-1663 (CB) | Yes |
| LTC3521EUF#PBF | 4x4 QFN-24 | UF | E | 05-08-1697 | Yes |
| LTC3521EUF#TRPBF | 4x4 QFN-24 | UF | E | 05-08-1697 | Yes |
| LTC3521IFE#PBF | TSSOP-20 | FE | I | 05-08-1663 (CB) | Yes |
| LTC3521IFE#TRPBF | TSSOP-20 | FE | I | 05-08-1663 (CB) | Yes |
| LTC3521IUF#PBF | 4x4 QFN-24 | UF | I | 05-08-1697 | Yes |
| LTC3521IUF#TRPBF | 4x4 QFN-24 | UF | I | 05-08-1697 | 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 | |
|---|---|---|---|---|---|---|
| LTC3521EFE#PBF | TSSOP-20 | E | $4.93 | $3.45 | Yes | |
| LTC3521EFE#TRPBF | TSSOP-20 | E | $3.51 | Yes | ||
| LTC3521EUF#PBF | 4x4 QFN-24 | E | $4.64 | $3.25 | Yes | |
| LTC3521EUF#TRPBF | 4x4 QFN-24 | E | $3.31 | Yes | ||
| LTC3521IFE#PBF | TSSOP-20 | I | $5.67 | $3.97 | Yes | |
| LTC3521IFE#TRPBF | TSSOP-20 | I | $4.03 | Yes | ||
| LTC3521IUF#PBF | 4x4 QFN-24 | I | $5.34 | $3.74 | Yes | |
| LTC3521IUF#TRPBF | 4x4 QFN-24 | I | $3.80 | 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 |
|---|---|---|---|
| DC1389A | LTC3521EUF Demo Board | Buck-Boost Plus Dual Buck, 2.4V ≤ VIN ≤ 5V, Vout1 = 3.3V @ 0.8A, Vout2=1.2V @ 0.6A, Vout3 = 1.8V @ 0.6A | $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 | |
|---|---|---|---|---|---|---|
| LTC3521IFE#PBF | TSSOP-20 | I | $5.67 | $3.97 | Yes | |
| LTC3521IFE#TRPBF | TSSOP-20 | I | $4.03 | Yes | ||
| Buy Now • Request Samples | ||||||
Applications
- Bar Code Readers
- Medical Instruments
- Handy Terminals
- PDAs, Handheld PCs
- GPS Receivers
People Who Viewed This Product Also Viewed
- LTC3115-1 - 40V, 2A Synchronous Buck-Boost DC/DC Converter
- LTC3536 - 1A Low Noise, Buck-Boost DC/DC Converter
- LT8471 - Dual Multitopology DC/DC Converters with 2A Switches and Synchronization
- LT3080 - Adjustable 1.1A Single Resistor Low Dropout Regulator
- LTC3127 - 1A Buck-Boost DC/DC Converter with Programmable Input Current Limit
- LTC3520 - Synchronous 1A Buck-Boost and 600mA Buck Converters
- LT3652 - Power Tracking 2A Battery Charger for Solar Power
- LT8705 - 80V VIN and VOUT Synchronous 4-Switch Buck- Boost DC/DC Controller
- LT1763 - 500mA, Low Noise, LDO Micropower Regulators
- LTC3112 - 15V, 2.5A Synchronous Buck-Boost DC/DC Converter
Product Notifications
Please login to your MyLinear account for notifications of datasheet updates, new document releases and LTspice model announcements for your favorite products. If you do not have a MyLinear account you may Sign Up Now.
Forgot your password? Click here.
Need help? Email mylinear@linear.com with questions and comments.
Design Tools
LTspice
LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice
To launch a ready to run LTspice demonstration circuit for this part:
- Step 1: If you have not installed LTspice on this computer, download and install LTspice
- Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
- Step 3: If LTspice does not automatically open after clicking the link above, you can instead run the simulation by right clicking on the link and selecting "Save Target As." After saving the file to your computer, start LTspice and open the demonstration circuit by selecting 'Open' from the 'File' menu
To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.
Models for the following parts are available in LTspice:
LTC3521
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.
