Datasheet LTC3859AL (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Triple Output, Buck/Buck/Boost Synchronous Controller with 28μA Burst Mode IQ |
| Pages / Page | 44 / 1 — FEATURES. DESCRIPTION. Low Operating IQ: 28μA (One Channel On). Dual Buck … |
| Revision | B |
| File Format / Size | PDF / 1.2 Mb |
| Document Language | English |
FEATURES. DESCRIPTION. Low Operating IQ: 28μA (One Channel On). Dual Buck Plus Single Boost Synchronous Controllers
Model Line for this Datasheet
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LTC3859AL Triple Output, Buck/Buck/Boost Synchronous Controller with 28µA Burst Mode IQ
FEATURES DESCRIPTION
n
Low Operating IQ: 28μA (One Channel On)
The LTC®3859AL is a high performance triple output (buck/ n
Dual Buck Plus Single Boost Synchronous Controllers
buck/boost) synchronous DC/DC switching regulator n
Outputs Remain in Regulation Through Cold Crank
controller that drives all N-channel power MOSFET stages.
Down to 2.5V
Constant frequency current mode architecture allows n a phase-lockable switching frequency of up to 850kHz.
Wide Bias Input Voltage Range: 4.5V to 38V
n The LTC3859AL operates from a wide 4.5V to 38V input
Buck Output Voltage Range: 0.8V ≤ VOUT ≤ 24V
n supply range. When biased from the output of the boost
Boost Output Voltage Up to 60V
n converter or another auxiliary supply, the LTC3859AL 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 (75kHz to 850kHz) runtime in battery powered systems. OPTI-LOOP com- n Programmable Fixed Frequency (50kHz to 900kHz) 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 Ripple The LTC3859AL features a precision 0.8V reference for Burst Mode Operation at Light Loads n the bucks, 1.2V reference for the boost and a power good Very Low Buck Dropout Operation: 99% Duty Cycle n output indicator. The PLLIN/MODE pin selects among Adjustable Output Voltage Soft-Start or Tracking Burst Mode operation, pulse-skipping mode, or continu- n Low Shutdown IQ: 10μA ous inductor current mode at light loads. n Small 38-Lead 5mm × 7mm QFN and TSSOP Packages Compared to the LTC3859 and the LTC3859A, the
APPLICATIONS
LTC3859AL is fully pin-compatible, but with lower Burst n Automotive Always-On and Start-Stop Systems Mode operation IQ (28µA with one channel on). n Battery Operated Digital Devices All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258. n Distributed DC Power Systems n Multioutput Buck-Boost Applications
TYPICAL APPLICATION
VOUT3 REGULATED AT 10V WHEN VIN < 10V 220µF 1µF FOLLOWS V
Efficiency and Power Loss vs
IN WHEN VIN > 10V 499k V VBIAS
Output Current
FB3 68.1k TG1 100 10000 4.9µH V 6mΩ V IN = 12V OUT1 90 V 2mΩ 1.2µH TG3 SW1 5V IN VOUT1 = BURST 2.5V TO 38V 5A 80 1000 SW3 EFFICIENCY LTC3859AL BG1 (START-UP ABOVE 5V) POWER LOSS (mW) 70 220µF BG3 60 100 SENSE1+ SENSE3– SENSE1– 50 SENSE3+ VFB1 40 10 INTV EFFICIENCY (%) CC 357k 68.1k 220µF 30 4.7µF RUN1, 2, 3 VOUT1 = BURST LOSS BOOST1, 2, 3 EXTV 20 1 CC VOUT1 0.1µF 10 SW1, 2, 3 TG2 6.5µH 8mΩ VOUT2 0 0.1 ITH1, 2, 3 SW2 8.5V 0.0001 0.001 0.01 0.1 1 10 BG2 3A OUTPUT CURRENT (A) 3859al TA01b SENSE2+ TRACK/SS1, 2 SENSE2– 0.1µF SS3 VFB2 PGND SGND 649k 68.1k 68µF 3859al TA01a Rev. B Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
FEATURES DESCRIPTION
n
Low Operating IQ: 28μA (One Channel On)
The LTC®3859AL is a high performance triple output (buck/ n
Dual Buck Plus Single Boost Synchronous Controllers
buck/boost) synchronous DC/DC switching regulator n
Outputs Remain in Regulation Through Cold Crank
controller that drives all N-channel power MOSFET stages.
Down to 2.5V
Constant frequency current mode architecture allows n a phase-lockable switching frequency of up to 850kHz.
Wide Bias Input Voltage Range: 4.5V to 38V
n The LTC3859AL operates from a wide 4.5V to 38V input
Buck Output Voltage Range: 0.8V ≤ VOUT ≤ 24V
n supply range. When biased from the output of the boost
Boost Output Voltage Up to 60V
n converter or another auxiliary supply, the LTC3859AL 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 (75kHz to 850kHz) runtime in battery powered systems. OPTI-LOOP com- n Programmable Fixed Frequency (50kHz to 900kHz) 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 Ripple The LTC3859AL features a precision 0.8V reference for Burst Mode Operation at Light Loads n the bucks, 1.2V reference for the boost and a power good Very Low Buck Dropout Operation: 99% Duty Cycle n output indicator. The PLLIN/MODE pin selects among Adjustable Output Voltage Soft-Start or Tracking Burst Mode operation, pulse-skipping mode, or continu- n Low Shutdown IQ: 10μA ous inductor current mode at light loads. n Small 38-Lead 5mm × 7mm QFN and TSSOP Packages Compared to the LTC3859 and the LTC3859A, the
APPLICATIONS
LTC3859AL is fully pin-compatible, but with lower Burst n Automotive Always-On and Start-Stop Systems Mode operation IQ (28µA with one channel on). n Battery Operated Digital Devices All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258. n Distributed DC Power Systems n Multioutput Buck-Boost Applications
TYPICAL APPLICATION
VOUT3 REGULATED AT 10V WHEN VIN < 10V 220µF 1µF FOLLOWS V
Efficiency and Power Loss vs
IN WHEN VIN > 10V 499k V VBIAS
Output Current
FB3 68.1k TG1 100 10000 4.9µH V 6mΩ V IN = 12V OUT1 90 V 2mΩ 1.2µH TG3 SW1 5V IN VOUT1 = BURST 2.5V TO 38V 5A 80 1000 SW3 EFFICIENCY LTC3859AL BG1 (START-UP ABOVE 5V) POWER LOSS (mW) 70 220µF BG3 60 100 SENSE1+ SENSE3– SENSE1– 50 SENSE3+ VFB1 40 10 INTV EFFICIENCY (%) CC 357k 68.1k 220µF 30 4.7µF RUN1, 2, 3 VOUT1 = BURST LOSS BOOST1, 2, 3 EXTV 20 1 CC VOUT1 0.1µF 10 SW1, 2, 3 TG2 6.5µH 8mΩ VOUT2 0 0.1 ITH1, 2, 3 SW2 8.5V 0.0001 0.001 0.01 0.1 1 10 BG2 3A OUTPUT CURRENT (A) 3859al TA01b SENSE2+ TRACK/SS1, 2 SENSE2– 0.1µF SS3 VFB2 PGND SGND 649k 68.1k 68µF 3859al TA01a Rev. B Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
