LT3668 - 40V 400mA Step-Down Switching Regulator with Dual Fault Protected Tracking LDOs
Features
- Dual Low Dropout Linear Tracking Regulators
200mA Outputs with Programmable Current Limits
1.6V to 45V Input Range
Fault Protected to ±45V - Triple Output Supply from a Single Input Requires Only One Inductor
- IQ = 50μA at 12VIN to 6V and 5V with No Load
- Buck Regulator:
Low Ripple (<15mVP-P) Burst Mode Operation®
400mA Output with Internal Power Switch
4.3V to 40V Input Operation Range (60V Max) - Adjustable 250kHz to 2.2MHz Switching Frequency
- Power Good Indicator
- Available in a Thermally-Enhanced 16-Lead MSOP Package
Typical Application
Description
The LT®3668 is a monolithic triple power supply composed of a 400mA buck switching regulator and two 200mA low dropout linear tracking regulators (LDOs).This provides a complete and robust power solution for applications that require the power supply of a sensor to tightly track the power supply of a measurement ASIC.
Each tracking LDO supplies 200mA of output current with a typical dropout voltage of 340mV, and each LDO has an accurate resistor programmable current limit.
Internal protection circuitry includes reverse-battery protection, current limiting, thermal limiting and reverse current protection.
The buck regulator includes a high efficiency switch, a boost diode, and the necessary oscillator, control and logic circuitry. Current mode topology is used for fast transient response and good loop stability. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping output ripple below 15mV in a typical application.
The LT3668 is available in a thermally-enhanced 16-lead MSOP package with 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 |
|---|---|---|---|---|---|
| LT3668EMSE#PBF | MS-16E | MSE | E | 05-08-1667 | Yes |
| LT3668EMSE#TRPBF | MS-16E | MSE | E | 05-08-1667 | Yes |
| LT3668HMSE#PBF | MS-16E | MSE | H | 05-08-1667 | Yes |
| LT3668HMSE#TRPBF | MS-16E | MSE | H | 05-08-1667 | Yes |
| LT3668IMSE#PBF | MS-16E | MSE | I | 05-08-1667 | Yes |
| LT3668IMSE#TRPBF | MS-16E | MSE | I | 05-08-1667 | 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 | |
|---|---|---|---|---|---|---|
| LT3668EMSE#PBF | MS-16E | E | $3.64 | $2.55 | Yes | |
| LT3668EMSE#TRPBF | MS-16E | E | $2.61 | Yes | ||
| LT3668HMSE#PBF | MS-16E | H | $4.37 | $3.06 | Yes | |
| LT3668HMSE#TRPBF | MS-16E | H | $3.12 | Yes | ||
| LT3668IMSE#PBF | MS-16E | I | $4.02 | $2.81 | Yes | |
| LT3668IMSE#TRPBF | MS-16E | I | $2.87 | 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 |
|---|---|---|---|
| DC2243A | LT3668EMSE Demo Board | Buck Plus Dual Post-Regulator LDOs, 7V ≤ VIN ≤ 40V; VOUT1 = 6V @ 0.4A, VOUT2 = 5V @ 0.2A, VOUT3 = 5V @ 0.2A | Contact Factory | |
| Buy Now | |||
Applications
- Fault-Protected Sensor Supply
- Automotive and Industrial Supplies
- Power for Portable Instrumentation
People Who Viewed This Product Also Viewed
- LT8471 - Dual Multitopology DC/DC Converters with 2A Switches and Synchronization
- LT3667 - 40V 400mA Step-Down Switching Regulator with Dual Fault Protected LDOs
- LT8614 - 42V, 4A Synchronous Step-Down Silent Switcher with 2.5μA Quiescent Current
- LT3080 - Adjustable 1.1A Single Resistor Low Dropout Regulator
- LTC3630 - High Efficiency, 65V 500mA Synchronous Step-Down Converter
- LTC3639 - High Efficiency, 150V 100mA Synchronous Step-Down Regulator
- LT8640/LT8640-1 - 42V, 5A Synchronous Step-Down Silent Switcher with 2.5μA Quiescent Current
- LTC4364 - Surge Stopper with Ideal Diode
- LT3042 - 20V, 200mA, Ultralow Noise, Ultrahigh PSRR RF Linear Regulator
- LTC3115-1 - 40V, 2A 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
Models for the following parts are available in LTspice:
LT3668
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.
