LTC3859
RECOMMENDED FOR NEW DESIGNSLow IQ, Triple Output, Buck/Buck/Boost Synchronous Controller
- Part Models
- 8
- 1ku List Price
- Starting From $6.57
Overview
- Dual Buck Plus Single Boost Synchronous Controllers
- Outputs Remain in Regulation Through Cold Crank Down to 2.5V
- Low Operating IQ: 55μA (One Channel On)
- Wide Bias Input Voltage Range: 4.5V to 38V
- Buck Output Voltage Range: 0.8V ≤ VOUT ≤ 24V
- Boost Output Voltage Up to 60V
- RSENSE or DCR Current Sensing
- 100% Duty Cycle for Boost Synchronous MOSFET
- Phase-Lockable Frequency (75kHz to 850kHz)
- Programmable Fixed Frequency (50kHz to 900kHz)
- Selectable Continuous, Pulse-Skipping or Low Ripple Burst Mode® Operation at Light Loads
- Very Low Buck Dropout Operation: 99% Duty Cycle
- Adjustable Output Voltage Soft-Start or Tracking
- Low Shutdown IQ: 14μA
- Small 38-Pin 5mm × 7mm QFN and TSSOP Packages
The LTC3859 is a high performance triple output (buck/ buck/boost) synchronous DC/DC switching regulator controller that drives all N-channel power MOSFET stages. Constant frequency current mode architecture allows a phase-lockable switching frequency of up to 850kHz. The LTC3859 operates from a wide 4.5V to 38V input supply range. When biased from the output of the boost converter or another auxiliary supply, the LTC3859 can operate from an input supply as low as 2.5V after start-up.
The 55μA no-load quiescent current extends operating runtime 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 LTC3859 features a precision 0.8V reference for the bucks, 1.2V reference for the boost and a power good output indicator.
Independent TRACK/SS pins for each controller ramp the output voltages during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The PLLIN/ MODE pin selects among Burst Mode operation, pulse-skipping mode, or continuous inductor current mode at light loads.
| Quiescent Current (Burst Mode) | Notes | |
| LTC3859AL | 28μA-One channel on, Buck 38μA-All three channels on |
Internal clamp on the INTVCC pin |
| LTC3859A | 55μA-One channel on, Buck 80μA-All three channels on |
Internal clamp on the INTVCC pin. For new designs, we recommend LTC3859AL |
| LTC3859 | 55μA-One channel on, Buck 80μA-All three channels on |
For new designs, we recommend LTC3859AL |
Applications
- Automotive Always-On and Start-Stop Systems
- Battery Operated Digital Devices
- Distributed DC Power Systems
Documentation
Data Sheet 1
Technical Articles 1
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.
| Part Model | Pin/Package Drawing | Documentation | CAD Symbols, Footprints, and 3D Models |
|---|---|---|---|
| LTC3859EFE#PBF | 38-Lead TSSOP w/ EP | ||
| LTC3859EFE#TRPBF | 38-Lead TSSOP w/ EP | ||
| LTC3859EUHF#PBF | 38-Lead QFN (5mm x 7mm w/ EP) | ||
| LTC3859EUHF#TRPBF | 38-Lead QFN (5mm x 7mm w/ EP) | ||
| LTC3859IFE#PBF | 38-Lead TSSOP w/ EP | ||
| LTC3859IFE#TRPBF | 38-Lead TSSOP w/ EP | ||
| LTC3859IUHF#PBF | 38-Lead QFN (5mm x 7mm w/ EP) | ||
| LTC3859IUHF#TRPBF | 38-Lead QFN (5mm x 7mm w/ EP) |
| Part Models | Product Lifecycle | PCN |
|---|---|---|
|
May 18, 2026 - 26_0072 Epoxy Change for Select TSSOP Products |
||
| LTC3859EFE#PBF | PRODUCTION | |
| LTC3859EFE#TRPBF | PRODUCTION | |
| LTC3859IFE#PBF | PRODUCTION | |
| LTC3859IFE#TRPBF | PRODUCTION | |
|
Apr 17, 2025 - 25_0043 Change of Gold to Copper Wire and BOM (Automotive) |
||
| LTC3859EFE#PBF | PRODUCTION | |
| LTC3859EFE#TRPBF | PRODUCTION | |
| LTC3859EUHF#PBF | PRODUCTION | |
| LTC3859EUHF#TRPBF | PRODUCTION | |
| LTC3859IFE#PBF | PRODUCTION | |
| LTC3859IFE#TRPBF | PRODUCTION | |
| LTC3859IUHF#PBF | PRODUCTION | |
| LTC3859IUHF#TRPBF | PRODUCTION | |
|
Apr 6, 2022 - 22_0068 Laser Top Mark for ETSSOP and TSSOP Packages Assembled in ADPG [PNG] and UTL |
||
| LTC3859EFE#PBF | PRODUCTION | |
| LTC3859EFE#TRPBF | PRODUCTION | |
| LTC3859IFE#PBF | PRODUCTION | |
| LTC3859IFE#TRPBF | PRODUCTION | |
|
Jul 31, 2020 - 20_0245 Notification of Wafer Fab Location Change for 0.6µm BICMOS Process Devices from ADI Milpitas (Hillview) to Vanguard Int. (Taiwan) |
||
| LTC3859EFE#PBF | PRODUCTION | |
| LTC3859EFE#TRPBF | PRODUCTION | |
| LTC3859EUHF#PBF | PRODUCTION | |
| LTC3859EUHF#TRPBF | PRODUCTION | |
| LTC3859IFE#PBF | PRODUCTION | |
| LTC3859IFE#TRPBF | PRODUCTION | |
| LTC3859IUHF#PBF | PRODUCTION | |
| LTC3859IUHF#TRPBF | PRODUCTION | |
This is the most up-to-date revision of the Data Sheet.
Software Resources
Can't find the software or driver you need?
Request a Driver/SoftwareHardware Ecosystem
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| LTC3899 | RECOMMENDED FOR NEW DESIGNS | 60V Low IQ, Triple Output, Buck/Buck/Boost Synchronous Controller with PassThru |
| Parts | Product Life Cycle | Description |
|---|---|---|
| LTC3859AL | PRODUCTION | Triple Output, Buck/Buck/Boost Synchronous Controller with 28μA Burst Mode IQ |
Tools & Simulations
LTspice 1
Models for the following parts are available in LTspice:
- LTC3859
- LTC3859AL
LTpowerCAD
Design tools for the following parts are available in LTpowerCAD:
- LTC3859AL(BOOST)
- LTC3859AL(BUCK)
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.