Datasheet LTC7818 (Analog Devices)
| 制造商 | Analog Devices |
| 描述 | 40V, Low IQ, 3MHz, Triple Output Buck/Buck/Boost Synchronous Controller |
| 页数 / 页 | 44 / 1 — FEATURES. DESCRIPTION. Dual Buck Plus Single Boost Synchronous … |
| 文件格式/大小 | PDF / 3.1 Mb |
| 文件语言 | 英语 |
FEATURES. DESCRIPTION. Dual Buck Plus Single Boost Synchronous Controllers. Low Operating I. 14μA (14V to 3.3V, Channel 1 On)
文件文字版本
LTC7818 40V, Low IQ, 3MHz, Triple Output Buck/Buck/Boost Synchronous Controller
FEATURES DESCRIPTION
n
Dual Buck Plus Single Boost Synchronous Controllers
The LTC®7818 is a high performance triple output (buck/ n
Low Operating I
buck/boost) synchronous DC/DC switching regulator con-
Q: 14μA (14V to 3.3V, Channel 1 On)
troller that drives all N-channel power MOSFET stages. n
Outputs Remain in Regulation Through Cold Crank
Its constant frequency current mode architecture allows a phase-lockable switching frequency of up to 3MHz.
Down to 1V Input Supply Voltage
n The LTC7818 operates from a wide 4.5V to 40V input
Wide Bias Input Voltage Range: 4.5V to 40V
n supply range. When biased from the output of the boost
Buck and Boost Output Voltages up to 40V
n converter or another auxiliary supply, the LTC7818 can
Spread Spectrum Operation
operate from an input supply as low as 1V after start-up. n
RSENSE or DCR Current Sensing
n
100% Duty Cycle for Boost Synchronous MOSFET
The very low no-load quiescent current extends operating n
Programmable Fixed Frequency (100kHz to 3MHz)
run time in battery powered systems. OPTI-LOOP® com- n Phase-Lockable Frequency (100kHz to 3MHz) pensation allows the transient response to be optimized n over a wide range of output capacitance and ESR values. Selectable Continuous, Pulse-Skipping, or Low The LTC7818 features a precision 0.8V reference for the Ripple Burst Mode Operation at Light Loads n bucks, 1.2V reference for the boost and a power good Boost Channel Current Monitor Output n output indicator. Low Shutdown IQ: 1.5μA n Small 40-Lead 6mm × 6mm QFN Package The LTC7818 additionally features spread spectrum oper- ation which significantly reduces the peak radiated and conducted noise on both the input and output supplies,
APPLICATIONS
making it easier to comply with electromagnetic interfer- n Automotive and Transportation ence (EMI) standards. n All registered trademarks and trademarks are the property of their respective owners. Protected Industrial by U.S. Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258. n Military/Avionics
TYPICAL APPLICATION
VOUT3
LTC7818 Response to a Cold LTC7818 Response to a Cold Crank
REGULATED TO 10V WHEN VIN < 10V VBIAS
Crank Automotive Waveform
150µF 22µF VFB3
Automotive Waveform
FOLLOWS VIN WHEN V TG3 TG1 IN >10V BOOST3 BOOST1 0.1µF 1.5mΩ 1.4µH 0.1µF 0.9µH 2mΩ VOUT1 VIN SW3 3.3V SW1 V 1V TO 38V 12A BATT 22µF 330µF STARTUP 150µF VOUT3 ABOVE 5V BG3 BG1 LTC7818 210k SENSE3– SENSE1+ SENSE3+ SENSE1– VOLTAGE VOUT3 RUN1,2,3 VFB1 VOUT3 68.1k 2V/DIV ITH1,2,3 TRACK/SS1,2,3 VOUT2 TG2 INTVCC BOOST2 VPRG3 0.1µF V 1.8µH 3mΩ V OUT1 0.1µF 4.7µF OUT2 5V SW2 10A BG2 10µF 330µF BOOST1,2,3 MODE SENSE2+ 357k PLLIN/SPREAD 0V SENSE2– TIME (10ms/DIV) 7818 TA01b FREQ VFB2 EXTV GND CC VOUT2 68.1k 7818 TA01a Rev 0 Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts
FEATURES DESCRIPTION
n
Dual Buck Plus Single Boost Synchronous Controllers
The LTC®7818 is a high performance triple output (buck/ n
Low Operating I
buck/boost) synchronous DC/DC switching regulator con-
Q: 14μA (14V to 3.3V, Channel 1 On)
troller that drives all N-channel power MOSFET stages. n
Outputs Remain in Regulation Through Cold Crank
Its constant frequency current mode architecture allows a phase-lockable switching frequency of up to 3MHz.
Down to 1V Input Supply Voltage
n The LTC7818 operates from a wide 4.5V to 40V input
Wide Bias Input Voltage Range: 4.5V to 40V
n supply range. When biased from the output of the boost
Buck and Boost Output Voltages up to 40V
n converter or another auxiliary supply, the LTC7818 can
Spread Spectrum Operation
operate from an input supply as low as 1V after start-up. n
RSENSE or DCR Current Sensing
n
100% Duty Cycle for Boost Synchronous MOSFET
The very low no-load quiescent current extends operating n
Programmable Fixed Frequency (100kHz to 3MHz)
run time in battery powered systems. OPTI-LOOP® com- n Phase-Lockable Frequency (100kHz to 3MHz) pensation allows the transient response to be optimized n over a wide range of output capacitance and ESR values. Selectable Continuous, Pulse-Skipping, or Low The LTC7818 features a precision 0.8V reference for the Ripple Burst Mode Operation at Light Loads n bucks, 1.2V reference for the boost and a power good Boost Channel Current Monitor Output n output indicator. Low Shutdown IQ: 1.5μA n Small 40-Lead 6mm × 6mm QFN Package The LTC7818 additionally features spread spectrum oper- ation which significantly reduces the peak radiated and conducted noise on both the input and output supplies,
APPLICATIONS
making it easier to comply with electromagnetic interfer- n Automotive and Transportation ence (EMI) standards. n All registered trademarks and trademarks are the property of their respective owners. Protected Industrial by U.S. Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258. n Military/Avionics
TYPICAL APPLICATION
VOUT3
LTC7818 Response to a Cold LTC7818 Response to a Cold Crank
REGULATED TO 10V WHEN VIN < 10V VBIAS
Crank Automotive Waveform
150µF 22µF VFB3
Automotive Waveform
FOLLOWS VIN WHEN V TG3 TG1 IN >10V BOOST3 BOOST1 0.1µF 1.5mΩ 1.4µH 0.1µF 0.9µH 2mΩ VOUT1 VIN SW3 3.3V SW1 V 1V TO 38V 12A BATT 22µF 330µF STARTUP 150µF VOUT3 ABOVE 5V BG3 BG1 LTC7818 210k SENSE3– SENSE1+ SENSE3+ SENSE1– VOLTAGE VOUT3 RUN1,2,3 VFB1 VOUT3 68.1k 2V/DIV ITH1,2,3 TRACK/SS1,2,3 VOUT2 TG2 INTVCC BOOST2 VPRG3 0.1µF V 1.8µH 3mΩ V OUT1 0.1µF 4.7µF OUT2 5V SW2 10A BG2 10µF 330µF BOOST1,2,3 MODE SENSE2+ 357k PLLIN/SPREAD 0V SENSE2– TIME (10ms/DIV) 7818 TA01b FREQ VFB2 EXTV GND CC VOUT2 68.1k 7818 TA01a Rev 0 Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts