LTC7817
40V, Low I , 3MHz,
Q
Triple Output Buck/Buck/Boost Synchronous Controller
FEATURES
DESCRIPTION
The LTC®7817 is a high performance triple output (buck/
buck/boost) synchronous DC/DC switching regulator con-
troller that drives all N-channel power MOSFET stages.
Its constant frequency current mode architecture allows
a phase-lockable switching frequency of up to 3MHz.
The LTC7817 operates from a wide 4.5V to 40V input
supply range. When biased from the output of the boost
converter or another auxiliary supply, the LTC7817 can
operate from an input supply as low as 1V after start-up.
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Dual Buck Plus Single Boost Synchronous Controllers
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Low Operating I :
Q
14μA (14V to 3.3V, Channel 1 On)
Outputs Remain in Regulation Through Cold Crank
Down to 1V Input Supply Voltage
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Wide Bias Input Voltage Range: 4.5V to 40V
Buck and Boost Output Voltages up to 40V
R
or DCR Current Sensing
SENSE
Pass-Thru™ Operation: 100% Duty Cycle for
The very low no-load quiescent current extends operating
run time in battery powered systems. OPTI-LOOP® com-
pensation allows the transient response to be optimized
over a wide range of output capacitance and ESR values.
The LTC7817 features a precision 0.8V reference for the
bucks, 1.2V reference for the boost and a power good
output indicator.
Boost Synchronous MOSFET
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Programmable Fixed Frequency (100kHz to 3MHz)
Phase-Lockable Frequency (100kHz to 3MHz)
Selectable Continuous, Pulse-Skipping, or Low
Ripple Burst Mode Operation at Light Loads
Very Low Buck Dropout Operation: 99% Duty Cycle
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Low Shutdown I : 1.5μA
Q
Small 38-Lead 5mm × 7mm QFN Package
The LTC7817 synchronous boost Pass-Thru capability
minimizes losses in automotive start-stop applications.
All registered trademarks and trademarks are the property of their respective owners. Protected
by U.S. Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258.
AEC-Q100 Automotive Qualification in Process
APPLICATIONS
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Automotive and Transportation
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Industrial
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Military/Avionics
TYPICAL APPLICATION
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LTC7817 Response to a Cold
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Crank Automotive Waveform
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