LTC3838-1 - Dual, Fast, Accurate Step-Down DC/DC Controller with Dual Differential Output Sensing
Features
- Wide VIN Range: 4.5V to 38V, VOUT: 0.6V to 5.5V
- Two Independent Channels: Dual/Single Output
- Output Voltage Regulation Accuracy: ±0.67% (VOUT1) and ±0.75% (VOUT2) Over Temperature
- Differential Remote Output Sensing: Up to ±500mV (VOUT1) and ±200mV (VOUT2) Ground Deviations
- Controlled On-Time, Valley Current Mode Control
- Fast Load Transient Response Without Clock Delay
- Detect Transient Release (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 Package
Typical Application
Description
The LTC®3838-1 is a dual-channel, 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 not only fast response to transients without clock delay, but also constant frequency switching at steady load condition. Its proprietary loadrelease transient detection feature (DTR) significantly reduces overshoot at low output voltages.
A precision internal reference enables accurate differential output regulation. The dual channels can either provide two independent output voltages, or be combined into multiphase single-output configuration.
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.
See Table 1 for a comparison of LTC3838, LTC3838-1 and LTC3838-2.
| 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 |
|---|---|---|---|---|---|
| LTC3838EUHF-1#PBF | 5x7 QFN-38 | UHF | E | 05-08-1701 | Yes |
| LTC3838EUHF-1#TRPBF | 5x7 QFN-38 | UHF | E | 05-08-1701 | Yes |
| LTC3838IUHF-1#PBF | 5x7 QFN-38 | UHF | I | 05-08-1701 | Yes |
| LTC3838IUHF-1#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 | |
|---|---|---|---|---|---|---|
| LTC3838EUHF-1#PBF | 5x7 QFN-38 | E | $4.54 | $3.18 | Yes | |
| LTC3838EUHF-1#TRPBF | 5x7 QFN-38 | E | $3.24 | Yes | ||
| LTC3838IUHF-1#PBF | 5x7 QFN-38 | I | $5.13 | $3.59 | Yes | |
| LTC3838IUHF-1#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 |
|---|---|---|---|
| DC1997A-A | LTC3838EUHF-1 Demo Board | 4.5V ≤ VIN ≤ 14V; VOUT1 = 1.5V @ 20A, VOUT2 = 1.2V @ 20A | $150.00 | |
| Buy Now | |||
Applications
- Distributed Power Systems; Power Supply for ASIC
- Computing, Data Storage, Communication Systems
- Low Voltage, High Current, and/or High Step-Down Ratio Converters That Demand Tight Load Transient Regulation
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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
- 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
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.
