Datasheet LTC7815 (Analog Devices)

ManufacturerAnalog Devices
DescriptionLow IQ, 2.25MHz, Triple Output, Buck/Buck/Boost Synchronous Controller
Pages / Page38 / 1 — FEATURES. DESCRIPTION. Dual Buck Plus Single Boost Synchronous …
File Format / SizePDF / 1.4 Mb
Document Languageenglish

FEATURES. DESCRIPTION. Dual Buck Plus Single Boost Synchronous Controllers. Wide Bias Input Voltage Range: 4.5V to 38V

Datasheet LTC7815 Analog Devices

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LTC7815 Low IQ, 2.25MHz, Triple Output, Buck/Buck/Boost Synchronous Controller
FEATURES DESCRIPTION
n
Dual Buck Plus Single Boost Synchronous Controllers
The LTC®7815 is a high performance triple output (buck/ n
Wide Bias Input Voltage Range: 4.5V to 38V
buck/boost) synchronous DC/DC switching regulator con- n
Outputs Remain in Regulation Through Cold Crank
troller that drives all N-channel power MOSFET stages.
Down to a 2.5V Input Supply Voltage
Constant frequency current mode architecture allows a n phase-lockable switching frequency of up to 2.25MHz.
Buck Output Voltage Range: 0.8V ≤ VOUT ≤ 24V
n The LTC7815 operates from a wide 4.5V to 38V input
Boost Output Voltage Up to 60V
n supply range. When biased from the output of the boost
Low Operating IQ: 28μA (One Channel On)
n converter or another auxiliary supply, the LTC7815 can
RSENSE or DCR Current Sensing
operate from an input supply as low as 2.5V after start-up. n
100% Duty Cycle for Boost Synchronous MOSFET Even in Burst Mode
®
Operation
The 28μA no-load quiescent current extends operating n
Phase-Lockable Frequency (320kHz to 2.25MHz)
runtime in battery powered systems. OPTI-LOOP com- n
Programmable Fixed Frequency (320kHz to 2.25MHz)
pensation allows the transient response to be optimized n over a wide range of output capacitance and ESR values. Very Low Buck Dropout Operation: 98% Duty Cycle n The LTC7815 features a precision 0.8V reference for the Small 38-Lead 5mm × 7mm QFN Package bucks, 1.2V reference for the boost and a power good output indicator. The PLLIN/MODE pin selects among
APPLICATIONS
Burst Mode operation, pulse-skipping mode, or continu- n Automotive Always-On and Start-Stop Systems ous inductor current mode at light loads. n Battery Operated Digital Devices All registered trademarks and trademarks are the property of their respective owners. Protected n Distributed DC Power Systems by U.S. Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258. n Multioutput Buck-Boost Applications
TYPICAL APPLICATION
VOUT3 REGULATED AT 10V WHEN VIN < 10V
Efficiency and Power Loss vs
FOLLOWS VIN WHEN VIN > 10V 10µF
Output Current
499k + 68µF ×5 V V BIAS FB3 100 10k VIN = 12V 68.1k TG1 90 VOUT1 = 5V 0.33µH 3mΩ VOUT1 5V 80 1k TG3 SW1 VIN 3mΩ 0.16µH 7A POWER LOSS (mW) 70 2.5V TO 28V SW3 LTC7815 BG1 (START-UP ABOVE 5V) 60 100 + 220µF BG3 50 SENSE1+ SENSE3– SENSE1– 40 10 EFFICIENCY (%) SENSE3+ VFB1 30 INTV 10µF CC 357k COUT1 f = 2.1MHz 68.1k 47µF 20 1 ×2 4.7µF ×2 Burst Mode OPERATION BOOST1, 2, 3 EXTVCC VOUT1 10 BURST LOSS 0.1µF 0 0.1 SW1, 2, 3 TG2 0.33µH 3mΩ V 0.0001 0.001 0.01 0.1 1 10 OUT2 ITH1, 2, 3 SW2 3.3V LOAD CURRENT (A) 7815 TA01b BG2 10A SENSE2+ TRACK/SS1, 2 SENSE2– 0.1µF SS3 VFB2 C 210k OUT2 68.1k 33µF RUN1 ×2 RUN2 100k RUN3 FREQ PGND SGND 7815 TA01a 7815f For more information www.linear.com/LTC7815 1 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL CHARACTERISTICS TYPICAL PERFORMANCE CHARACTERISTICS PIN FUNCTIONS FUNCTIONAL DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION TYPICAL APPLICATION RELATED PARTS
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