LTC3868-1 - Low IQ, Dual 2-Phase Synchronous Step-Down Controller
Features
- Low Operating IQ: 170μA (One Channel On)
- Wide Output Voltage Range: 0.8V ≤ VOUT ≤ 14V
- Wide VIN Range: 4V to 24V
- RSENSE or DCR Current Sensing
- Out-of-Phase Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
- OPTI-LOOP® Compensation Minimizes COUT
- Phase-Lockable Frequency (75kHz to 850kHz)
- Programmable Fixed Frequency (50kHz to 900kHz)
- Selectable Continuous, Pulse-Skipping or Burst Mode® Operation at Light Loads
- Very Low Dropout Operation: 99% Duty Cycle
- Adjustable Output Voltage Soft-Start
- Power Good Output Voltage Monitor
- Output Overvoltage Protection
- Output Latchoff Protection During Short Circuit
- Low Shutdown IQ: 8μA
- Internal LDO Powers Gate Drive from VIN or EXTVCC
- No Current Foldback During Start-Up
- Small 4mm × 5mm QFN and Narrow SSOP Packages
Typical Application
Description
The LTC3868-1 is a high performance dual step-down switching regulator controller that drives all N-channel synchronous power MOSFET stages. A constant frequency current mode architecture allows a phase-lockable frequency of up to 850kHz. Power loss and noise due to the input capacitor ESR are minimized by operating the two controller outputs out of phase.
The 170μA no-load quiescent current extends operating life in battery powered systems. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3868-1 features a precision 0.8V reference and a power good output indicator. A wide 4V to 24V input supply range encompasses a wide range of intermediate bus voltages and battery chemistries.
Independent soft-start pins for each controller ramp the output voltages during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The output short-circuit latchoff feature further protects the circuit in short-circuit conditions.
For a leadless 32-pin QFN package with the additional features of adjustable current limit, clock out, phase modulation and two PGOOD outputs, see the LTC3868 data sheet.
| LTC3868 | LTC3868-1 | |
|---|---|---|
| Features | Adjustable Current Limit, Clock Out Pin, Phase Modulation, Two PGOOD | Fixed Current Limit, One PGOOD |
| Package | QFN-32 | SSOP-28 |
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 |
|---|---|---|---|---|---|
| LTC3868EGN-1#PBF | SSOP-28 | GN | E | 05-08-1641 (GN28) | Yes |
| LTC3868EGN-1#TRPBF | SSOP-28 | GN | E | 05-08-1641 (GN28) | Yes |
| LTC3868EUFD-1#PBF | 4x5 QFN-28 | UFD | E | 05-08-1712 | Yes |
| LTC3868EUFD-1#TRPBF | 4x5 QFN-28 | UFD | E | 05-08-1712 | Yes |
| LTC3868IGN-1#PBF | SSOP-28 | GN | I | 05-08-1641 (GN28) | Yes |
| LTC3868IGN-1#TRPBF | SSOP-28 | GN | I | 05-08-1641 (GN28) | Yes |
| LTC3868IUFD-1#PBF | 4x5 QFN-28 | UFD | I | 05-08-1712 | Yes |
| LTC3868IUFD-1#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 | |
|---|---|---|---|---|---|---|
| LTC3868EGN-1#PBF | SSOP-28 | E | $3.70 | $2.59 | Yes | |
| LTC3868EGN-1#TRPBF | SSOP-28 | E | $2.65 | Yes | ||
| LTC3868EUFD-1#PBF | 4x5 QFN-28 | E | $3.87 | $2.71 | Yes | |
| LTC3868EUFD-1#TRPBF | 4x5 QFN-28 | E | $2.77 | Yes | ||
| LTC3868IGN-1#PBF | SSOP-28 | I | $4.03 | $2.82 | Yes | |
| LTC3868IGN-1#TRPBF | SSOP-28 | I | $2.88 | Yes | ||
| LTC3868IUFD-1#PBF | 4x5 QFN-28 | I | $4.20 | $2.94 | Yes | |
| LTC3868IUFD-1#TRPBF | 4x5 QFN-28 | I | $3.00 | 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.Click here to view our complete list of demo boards
Applications
- Notebook and Palmtop Computers
- Portable Instruments
- Battery Operated Digital Devices
- Distributed DC Power 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
Models for the following parts are available in LTspice:
LTC3868
LTC3868-1
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:
LTC3868
LTC3868 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.
