LTC3859AL - Triple Output, Buck/Buck/Boost Synchronous Controller with 28μA Burst Mode IQ

The LTC®3859AL 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 LTC3859AL 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 LTC3859AL 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 LTC3859AL 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 LTC3859AL is fully pin-compatible, but with lower Burst Mode operation IQ (28μA with one channel on).

Features

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

Typical Application

Applications

Automotive Always-On and Start-Stop Systems
Battery Operated Digital Devices
Distributed DC Power Systems
Multioutput Buck-Boost Applications

Packaging

**Order Information**
Part Number	Package	Temp	Price(1-99)	Price (1k)*
LTC3859ALEFE#PBF	TSSOP-38	E	$6.47	$4.53
LTC3859ALEFE#TRPBF	TSSOP-38	E		$4.59
LTC3859ALEUHF#PBF	5x7 QFN-38	E	$6.22	$4.35
LTC3859ALEUHF#TRPBF	5x7 QFN-38	E		$4.41
LTC3859ALHFE#PBF	TSSOP-38	H	$7.64	$5.35
LTC3859ALHFE#TRPBF	TSSOP-38	H		$5.41
LTC3859ALHUHF#PBF	5x7 QFN-38	H	$7.40	$5.18
LTC3859ALHUHF#TRPBF	5x7 QFN-38	H		$5.24
LTC3859ALIFE#PBF	TSSOP-38	I	$7.23	$5.06
LTC3859ALIFE#TRPBF	TSSOP-38	I		$5.12
LTC3859ALIUHF#PBF	5x7 QFN-38	I	$6.97	$4.88
LTC3859ALIUHF#TRPBF	5x7 QFN-38	I		$4.94
LTC3859ALMPFE#PBF	TSSOP-38	MP	$19.50	$13.65
LTC3859ALMPFE#TRPBF	TSSOP-38	MP	$19.56	$13.71
LTC3859ALMPUHF#PBF	5x7 QFN-38	MP	$18.83	$13.18
LTC3859ALMPUHF#TRPBF	5x7 QFN-38	MP	$18.89	$13.24

Demo Boards


Part Number	Description	Price
DC2122A	LTC3859ALEUHF Demo Board \| 4.5V ≤ VIN ≤ 36V; VOUT1: 5V @ 5A, VOUT2: 8.5V @ 3A, VOUT3: 10V @ 7A	$200.00