LTC3869 - Dual, 2-Phase Synchronous Step-Down DC/DC Controllers
Features
- Dual, 180° Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
- Accurate Multiphase Current Matching
- RSENSE or DCR Current Sensing
- ±0.75% 0.6V Output Voltage Accuracy
- Phase-Lockable Fixed Frequency 250kHz to 780kHz
- High Efficiency: Up to 95%
- Dual N-channel MOSFET Synchronous Drive
- Wide VIN Range: 4V to 38V (40V Max) Operation
- Wide VOUT Range: 0.6V to 12.5V Operation
- Adjustable Soft-Start Current Ramping or Tracking
- Foldback Output Current Limiting
- Output Overvoltage Protection
- Power Good Output Voltage Monitor
- 5V Low Dropout Regulator
- Small 28-Lead QFN and Narrow SSOP Packages
AEC-Q100 data available for specific packages
Typical Application
Description
The LTC®3869 is a high performance dual synchronous step-down switching regulator controller that drives all N-channel synchronous power MOSFET stages. A constant frequency current mode architecture allows a phaselockable frequency of up to 780kHz. Power loss and noise due to the ESR of the input capacitors are minimized by operating the two controller output stages out-of-phase.
OPTI-LOOP® compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. A wide 4V to 38V input supply range encompasses most battery chemistries. Independent TK/ SS pins for each controller ramp the output voltage during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The MODE/PLLIN pin selects among Burst Mode® operation, pulse-skipping mode, or continuous inductor current mode and allows the IC to be synchronized to an external clock.
The LTC3869 is available in low profile 4mm × 4mm and 4mm × 5mm QFN packages. The LTC3869-2 is available in an SSOP-28 package. The LTC3869 is pin-compatible with the LTC3850.
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 |
|---|---|---|---|---|---|
| LTC3869EUF#PBF | 4x4 QFN-28 | UF | E | 05-08-1721 | Yes |
| LTC3869EUF#TRPBF | 4x4 QFN-28 | UF | E | 05-08-1721 | Yes |
| LTC3869EUFD#PBF | 4x5 QFN-28 | UFD | E | 05-08-1712 | Yes |
| LTC3869EUFD#TRPBF | 4x5 QFN-28 | UFD | E | 05-08-1712 | Yes |
| LTC3869IGN-2#PBF | SSOP-28 | GN | I | 05-08-1641 (GN28) | Yes |
| LTC3869IGN-2#TRPBF | SSOP-28 | GN | I | 05-08-1641 (GN28) | Yes |
| LTC3869IUF#PBF | 4x4 QFN-28 | UF | I | 05-08-1721 | Yes |
| LTC3869IUF#TRPBF | 4x4 QFN-28 | UF | I | 05-08-1721 | Yes |
| LTC3869IUFD#PBF | 4x5 QFN-28 | UFD | I | 05-08-1712 | Yes |
| LTC3869IUFD#TRPBF | 4x5 QFN-28 | UFD | I | 05-08-1712 | 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 | |
|---|---|---|---|---|---|---|
| LTC3869EUF#PBF | 4x4 QFN-28 | E | $3.79 | $2.65 | Yes | |
| LTC3869EUF#TRPBF | 4x4 QFN-28 | E | $2.71 | Yes | ||
| LTC3869EUFD#PBF | 4x5 QFN-28 | E | $3.79 | $2.65 | Yes | |
| LTC3869EUFD#TRPBF | 4x5 QFN-28 | E | $2.71 | Yes | ||
| LTC3869IGN-2#PBF | SSOP-28 | I | $4.11 | $2.88 | Yes | |
| LTC3869IGN-2#TRPBF | SSOP-28 | I | $2.94 | Yes | ||
| LTC3869IUF#PBF | 4x4 QFN-28 | I | $4.11 | $2.88 | Yes | |
| LTC3869IUF#TRPBF | 4x4 QFN-28 | I | $2.94 | Yes | ||
| LTC3869IUFD#PBF | 4x5 QFN-28 | I | $4.11 | $2.88 | Yes | |
| LTC3869IUFD#TRPBF | 4x5 QFN-28 | I | $2.94 | 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 |
|---|---|---|---|
| DC1798A-A | LTC3869IGN-2 Demo Board | VIN = 4.5V to 26V, VOUT1= 3.3V @ 5A, VOUT2 = 2.5V @ 5A, with RSENSE | $150.00 | |
| DC1798A-B | LTC3869IGN-2 Demo Board | VIN = 4.5V to 26V, VOUT1= 3.3V @ 5A, VOUT2 = 2.5V @ 5A, with DCR Sense | $150.00 | |
| DC1807A-A | LTC3869EUFD Demo Board | VIN = 4.5V to 14V, VOUT1 = 1.5V @15A, VOUT2 = 1.2V @ 15A, with RSENSE | $150.00 | |
| DC1807A-B | LTC3869EUFD Demo Board | VIN = 4.5V to 14V, VOUT1 = 1.5V @15A, VOUT2 = 1.2V @ 15A, with DCR Sense | $150.00 | |
| 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 | |
|---|---|---|---|---|---|---|
| LTC3869IGN-2#PBF | SSOP-28 | I | $4.11 | $2.88 | Yes | |
| LTC3869IGN-2#TRPBF | SSOP-28 | I | $2.94 | Yes | ||
| Buy Now • Request Samples | ||||||
Applications
- Server Systems
- Telecom Systems
- Industrial and Medical Instruments
- High Power Battery-Operated Devices
- 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
- LTC3869-2 Demo Circuit - High Efficiency Dual 3.3V/2.5V Buck Converter using Rsense Current Sensing (4.5-26V to 3.3V & 2.5V @ 5A)
- LTC3869-2 Demo Circuit - High Efficiency Dual 3.3V/2.5V Buck Converter using Inductor DCR Current Sensing (4.5-26V to 3.3V & 2.5V @ 5A)
- LTC3869 Demo Circuit - High Efficiency Dual 1.5V/1.2V Buck Converter using Rsense Current Sensing (4.5-14V to 1.5V & 1.2V @ 15A)
- LTC3869 Demo Circuit - High Efficiency Dual 1.5V/1.2V Buck Converter using Inductor DCR Current Sensing (4.5-14V to 1.5V & 1.2V @ 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:
LTC3869
LTC3869-2
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
- 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:
LTC3869
LTC3869 Parallel
LTC3869-2
LTC3869-2 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.
