LTC3875 - Dual, 2-Phase, Synchronous Controller with Low Value DCR Sensing and Temperature Compensation
Features
- Low Value DCR Current Sensing
- Programmable DCR Temperature Compensation
- ±0.5% 0.6V Output Voltage Accuracy
- Dual True Remote Sensing Differential Amplifiers
- Optional Fast Transient Operation
- Phase-Lockable Fixed Frequency 250kHz to 720kHz
- Dual, 180° Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
- Dual N-Channel MOSFET Synchronous Drive
- Wide VIN Range: 4.5V to 38V Operation
- Output Voltage Range with Low DCR: 0.6V to 3.5V, without Low DCR: 0.6V to 5V
- Adjustable Soft-Start Current Ramping or Tracking
- Foldback Output Current Limiting
- Clock Input and Output for Up to 12-Phase Operation
- Short-Circuit Soft Recovery
- Output Overvoltage Protection
- Power Good Output Voltage Monitor
- 40-Lead QFN Packages
AEC-Q100 data available for specific packages
Typical Application
Description
The LTC®3875 is a dual output current mode synchronous step-down DC/DC controller that drives all N-channel synchronous power MOSFET stages. It employs a unique architecture which enhances the signal-to-noise ratio of the current sense signal, allowing the use of very low DC resistance power inductors to maximize the efficiency in high current applications. This feature also reduces the switching jitter commonly found in low DCR applications.
The LTC3875 features two high speed remote sense differential amplifiers, programmable current sense limits from 10mV to 30mV and DCR temperature compensation to limit the maximum output current precisely over temperature.
A unique thermal balancing function adjusts per phase current in order to minimize the thermal stress for multichip single output applications. The LTC3875 also features a precise 0.6V reference with guaranteed accuracy of ±0.5% that provides an accurate output voltage from 0.6V to 3.5V. A 4.5V to 38V input voltage range allows it to support a wide variety of bus voltages. The LTC3875 is available in a low profile 40-lead 6mm × 6mm (0.5mm pitch) and 40-lead 5mm × 5mm (0.4mm pitch) QFN 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 |
|---|---|---|---|---|---|
| LTC3875EUH#PBF | 5x5 QFN-40 | UH | E | 05-08-1746 | Yes |
| LTC3875EUH#TRPBF | 5x5 QFN-40 | UH | E | 05-08-1746 | Yes |
| LTC3875EUJ#PBF | 6x6 QFN-40 | UJ | E | 05-08-1728 | Yes |
| LTC3875EUJ#TRPBF | 6x6 QFN-40 | UJ | E | 05-08-1728 | Yes |
| LTC3875IUH#PBF | 5x5 QFN-40 | UH | I | 05-08-1746 | Yes |
| LTC3875IUH#TRPBF | 5x5 QFN-40 | UH | I | 05-08-1746 | Yes |
| LTC3875IUJ#PBF | 6x6 QFN-40 | UJ | I | 05-08-1728 | Yes |
| LTC3875IUJ#TRPBF | 6x6 QFN-40 | UJ | I | 05-08-1728 | 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 | |
|---|---|---|---|---|---|---|
| LTC3875EUH#PBF | 5x5 QFN-40 | E | $4.96 | $3.47 | Yes | |
| LTC3875EUH#TRPBF | 5x5 QFN-40 | E | $3.53 | Yes | ||
| LTC3875EUJ#PBF | 6x6 QFN-40 | E | $4.96 | $3.47 | Yes | |
| LTC3875EUJ#TRPBF | 6x6 QFN-40 | E | $3.53 | Yes | ||
| LTC3875IUH#PBF | 5x5 QFN-40 | I | $5.22 | $3.65 | Yes | |
| LTC3875IUH#TRPBF | 5x5 QFN-40 | I | $3.71 | Yes | ||
| LTC3875IUJ#PBF | 6x6 QFN-40 | I | $5.22 | $3.65 | Yes | |
| LTC3875IUJ#TRPBF | 6x6 QFN-40 | I | $3.71 | 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 |
|---|---|---|---|
| DC2000A | LTC3875EUJ Demo Board | 4.5V ≤ VIN ≤ 14V; VOUT1 = 1.0V @ 30A, VOUT2 = 1.5V @ 30A | $150.00 | |
| DC2055A | LTC3875EUJ Demo Board | 4.5V ≤ VIN ≤ 14V; VOUT: 1V @ 120A | $200.00 | |
| DC2142A | LTC3875EUJ/LTC3874IUFD Demo Board | 4.5V ≤ VIN ≤ 14V; VOUT: 1V @ 120A | $225.00 | |
| DC2225A | LTC3875EUJ Demo Board | 4-Phase Sync Buck Solution, LTC3875 (x2), 4.5V ≤ VIN ≤ 14V; Vout = 1V @ 160A | $250.00 | |
| 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 | |
|---|---|---|---|---|---|---|
| LTC3875EUH#PBF | 5x5 QFN-40 | E | $4.96 | $3.47 | Yes | |
| LTC3875EUH#TRPBF | 5x5 QFN-40 | E | $3.53 | Yes | ||
| LTC3875EUJ#PBF | 6x6 QFN-40 | E | $4.96 | $3.47 | Yes | |
| LTC3875EUJ#TRPBF | 6x6 QFN-40 | E | $3.53 | Yes | ||
| LTC3875IUH#PBF | 5x5 QFN-40 | I | $5.22 | $3.65 | Yes | |
| LTC3875IUH#TRPBF | 5x5 QFN-40 | I | $3.71 | Yes | ||
| LTC3875IUJ#PBF | 6x6 QFN-40 | I | $5.22 | $3.65 | Yes | |
| LTC3875IUJ#TRPBF | 6x6 QFN-40 | I | $3.71 | Yes | ||
| Buy Now • Request Samples | ||||||
Applications
- Servers and Instruments
- Telecom Systems
- DC Power Distribution Systems
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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
- LTC3875 Demo Circuit - High Efficiency Dual Output Step-Down Converter with Ultralow Inductor DCR Sensing and Fast Transient (4.5-14V to 1V @ 30A & 1.5V @ 30A)
- LTC3875 Demo Circuit - Dual Phase 1.0V, 60A Power System with Ultralow Inductor DCR Sensing (4.5-14V to 1V @ 60A)
- LTC3875 Demo Circuit - Four-Phase 1.0V, 120A Buck Converter with Ultralow Inductor DCR Sensing (4.5-14V to 1V @ 120A)
- LTC3874/LTC3875 Demo Circuit - High Efficiency, 4-Phase Step-Down Supply with Sub-Milliohm Inductor DCR Sensing (4.5-14V to 1V @ 120A)
- 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:
LTC3875
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
- 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:
LTC3875
LTC3875 Parallel
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.
