The LTC3859ALIUHF#PBF 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 LTC3859ALIUHF#PBF 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 LTC3859ALIUHF#PBF can operate from an input supply as low as 2.5V after start-up.
The 28μA 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 LTC3859ALIUHF#PBF features a precision 0.8V reference for the bucks, 1.2V reference for the boost and a power good output indicator. The PLLIN/MODE pin selects among Burst Mode operation, pulse-skipping mode, or continuous inductor current mode at light loads.
Compared to the LTC3859 and the LTC3859A, the LTC3859ALIUHF#PBF is fully pin-compatible, but with lower Burst Mode operation IQ (28μA with one channel on).
Quiescent Current (Burst Mode)NotesLTC3859AL28μA-One channel on, Buck38μA-All three channels onInternal clamp on the INTVCC pinLTC3859A55μA-One channel on, Buck80μA-All three channels onInternal clamp on the INTVCC pin. For new designs, we recommend LTC3859ALLTC385955μA-One channel on, Buck80μA-All three channels onFor new designs, we recommend LTC3859ALFeature
- Low Operating IQ: 28μA (One Channel On)
- Dual Buck Plus Single Boost Synchronous Controllers
- Outputs Remain in Regulation Through Cold Crank Down to 2.5V
- 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 Even in Burst Mode® Operation
- 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: 10μA
- Small 38-Lead 5mm × 7mm QFN and TSSOP Packages
Applications
- Automotive Always-On and Start-Stop Systems
- Battery Operated Digital Devices
- Distributed DC Power Systems
- Multioutput Buck-Boost Applications
