LTC3838 - Dual, Fast, Accurate Step- Down DC/DC Controller with Differential Output Sensing
Features
- Wide VIN Range: 4.5V to 38V, VOUT: 0.6V to 5.5V
- ±0.67% Output Voltage Accuracy Over Temperature, Differential Output Voltage Sensing, Allowing Up to ±500mV Line Loss at Remote Ground on Channel 1
- ±1% Output on the Independent 2nd Channel
- Controlled On-Time, Valley Current Mode Control
- Fast Load Transient Response
- Detect Transient (DTR) Reduces VOUT Overshoot
- Frequency Programmable from 200kHz to 2MHz, Synchronizable to External Clock
- tON(MIN) = 30ns, tOFF(MIN) = 90ns
- RSENSE or Inductor DCR Current Sensing
- Overvoltage Protection and Current Limit Foldback
- Power Good Output Voltage Monitor
- Output Voltage Tracking and Adjustable Soft Start-Up
- Thermally Enhanced 38-Pin (5mm × 7mm) QFN and TSSOP packages
Typical Application
Description
The LTC®3838 is a dual, PolyPhase® synchronous step-down DC/DC switching regulator controller. Two independent channels drive all N-channel power MOSFETs. The controlled on-time, valley current mode control architecture allows for fast transient response and constant frequency switching in steady-state operation, independent of VIN, VOUT and load current. Its load-release transient detection feature significantly reduces overshoot at low output voltages.
Differential output voltage sensing, along with a precision internal reference, offers an accurate ±0.67% output regulation on Channel 1, even if the remote output ground deviates from local ground by ±500mV. The second channel can either provide an independent ±1% output, or together with the first channel of this controller, serve as one of the PolyPhase channels for a single-output voltage.
The switching frequency can be programmed from 200kHz to 2MHz with an external resistor, and can be synchronized to an external clock. Very low tON and tOFF times allow for near 0% and near 100% duty cycles, respectively. Voltage tracking soft start-up and multiple safety features are provided.
| Part Number | Description |
|---|---|
| LTC3838 | ±0.67% Differential Output Voltage Accuracy Over Temperature on Channel 1, ±1% Output Regulation on Channel 2, Separate Per Channel 30mV to 100mV Current Sense Range Controls |
| LTC3838-1 | ±0.67% Differential Output Voltage Accuracy Over Temperature on Both Channel 1 and Channel 2, Single Pin 30mV/60mV Current Sense Range Controls |
| LTC3838-2 | ±0.67% Differential Output Voltage Accuracy With Internal Reference on Channel 1, ±4mV Differential with External Reference Voltage on Channel 2, Fixed 30mV Current Sense Range |
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 |
|---|---|---|---|---|---|
| LTC3838EFE#PBF | TSSOP-38 | FE | E | 05-08-1772 | Yes |
| LTC3838EFE#TRPBF | TSSOP-38 | FE | E | 05-08-1772 | Yes |
| LTC3838EUHF#PBF | 5x7 QFN-38 | UHF | E | 05-08-1701 | Yes |
| LTC3838EUHF#TRPBF | 5x7 QFN-38 | UHF | E | 05-08-1701 | Yes |
| LTC3838IFE#PBF | TSSOP-38 | FE | I | 05-08-1772 | Yes |
| LTC3838IFE#TRPBF | TSSOP-38 | FE | I | 05-08-1772 | Yes |
| LTC3838IUHF#PBF | 5x7 QFN-38 | UHF | I | 05-08-1701 | Yes |
| LTC3838IUHF#TRPBF | 5x7 QFN-38 | UHF | I | 05-08-1701 | 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 | |
|---|---|---|---|---|---|---|
| LTC3838EFE#PBF | TSSOP-38 | E | $4.86 | $3.40 | Yes | |
| LTC3838EFE#TRPBF | TSSOP-38 | E | $3.46 | Yes | ||
| LTC3838EUHF#PBF | 5x7 QFN-38 | E | $4.54 | $3.18 | Yes | |
| LTC3838EUHF#TRPBF | 5x7 QFN-38 | E | $3.24 | Yes | ||
| LTC3838IFE#PBF | TSSOP-38 | I | $5.54 | $3.88 | Yes | |
| LTC3838IFE#TRPBF | TSSOP-38 | I | $3.94 | Yes | ||
| LTC3838IUHF#PBF | 5x7 QFN-38 | I | $5.13 | $3.59 | Yes | |
| LTC3838IUHF#TRPBF | 5x7 QFN-38 | I | $3.65 | 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 |
|---|---|---|---|
| DC1626A-A | LTC3838EFE Demo Board (DCR Sense) | 4.5V ≤ VIN ≤ 26V; VOUT1 = 1.2V @ 15A, VOUT2 = 1.5V @ 15A | $150.00 | |
| DC1626A-B | LTC3838EFE Demo Board (RSENSE) |4.5V ≤ VIN ≤ 26V; VOUT1 = 1.2V @ 15A, VOUT2 = 1.5V @ 15A | $150.00 | |
| DC1801A-A | LTC3838EUHF Demo Board (DCR Sense) | VIN = 4.5V to 14V, VOUT1 = 1.2V @ 20A, VOUT2 = 1.5V @ 20A | $150.00 | |
| DC1801A-B | LTC3838EUHF Demo Board (RSENSE) | VIN = 4.5V to 14V, VOUT1 = 1.2V @ 20A, VOUT2 = 1.5V @ 20A | $150.00 | |
| Buy Now | |||
Applications
- Distributed Power Systems
- Point-of-Load Converters
- Computing Systems
- Data Communication Systems
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Product Notifications
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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
- LTC3838 Demo Circuit - Wide Input Range, High Efficiency Step-Down DC/DC Converter with Inductor DCR Current Sensing (4.5-26V to 1.2V @ 15A & 1.5V & 15A)
- LTC3838 Demo Circuit - Wide Input Range, High Efficiency Step-Down DC/DC Converter with Rsense Current Sensing (4.5-26V to 1.2V @ 15A & 1.5V @ 15A)
- 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:
LTC3838
LTC3838-1
LTC3838-2
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
To open the project file for this circuit:
- Step 1: If you have not installed LTpowerCAD on this computer, download and install LTpowerCAD
- Step 2: Once LTpowerCAD is installed, click on the link(s) below to open the project file
- LTC3838 Project - Dual, Fast, Accrate Step-Down DC/DC Converter with Inductor DCR Current Sensing (4.5-14V to 1.2V @ 20A & 1.5V @ 20A)
- LTC3838 Project - Dual, Fast, Accrate Step-Down DC/DC Converter with Inductor DCR Current Sensing (4.5-26V to 1.2V @ 15A & 1.5V & 15A)
- LTC3838 Project - Dual, Fast, Accrate Step-Down DC/DC Converter with Rsense Current Sensing (4.5-14V to 1.2V @ 20A & 1.5V @ 20A)
- LTC3838 Project - Dual, Fast, Accrate Step-Down DC/DC Converter with Rsense Current Sensing (4.5-26V to 1.2V @ 15A & 1.5V & 15A)
- Step 3: If LTpowerCAD does not automatically open after clicking the link above, you can open the project file by right clicking on the link and selecting "Save Target As." After saving the file to your computer, start LTpowerCAD and open the project file by selecting 'Open Project' from the 'File' menu
Design tools for the following parts are available in LTpowerCAD:
LTC3838
LTC3838 Parallel
LTC3838-1
LTC3838-2
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.
