Datasheet LTC3891 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Low IQ, 60V Synchronous Step-Down Controller |
| Pages / Page | 32 / 1 — FEATURES. DESCRIPTION. Wide VIN Range: 4V to 60V (65V Abs Max). Low … |
| File Format / Size | PDF / 691 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Wide VIN Range: 4V to 60V (65V Abs Max). Low Operating IQ: 50μA
Model Line for this Datasheet
Text Version of Document
LTC3891 Low IQ, 60V Synchronous Step-Down Controller
FEATURES DESCRIPTION
n
Wide VIN Range: 4V to 60V (65V Abs Max)
The LTC®3891 is a high performance step-down switching n
Low Operating IQ: 50μA
regulator DC/DC controller that drives an all N-channel n
Wide Output Voltage Range: 0.8V ≤ VOUT ≤ 24V
synchronous power MOSFET stage. A constant fre- n
RSENSE or DCR Current Sensing
quency current mode architecture allows a phase-lockable n Phase-Lockable Frequency (75kHz to 750kHz) frequency of up to 750kHz. n Programmable Fixed Frequency (50kHz to 900kHz) The 50μA no-load quiescent current extends operating run n Selectable Continuous, Pulse-Skipping or Low Ripple time in battery-powered systems. OPTI-LOOP® compensa- Burst Mode® Operation at Light Load tion allows the transient response to be optimized over n Selectable Current Limit a wide range of output capacitance and ESR values. The n Very Low Dropout Operation: 99% Duty Cycle LTC3891 features a precision 0.8V reference and power n Adjustable Output Voltage Soft-Start or Tracking good output indicator. A wide 4V to 60V input supply range n Power Good Output Voltage Monitor encompasses a wide range of intermediate bus voltages n Output Overvoltage Protection and battery chemistries. The output voltage of the LTC3891 n Low Shutdown IQ: < 14μA can be programmed between 0.8V to 24V. n Internal LDO Powers Gate Drive from VIN or EXTVCC n No Current Foldback During Start-Up The TRACK/SS pin ramps the output voltages during n Small 20-Pin 3mm × 4mm QFN and TSSOP Packages start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The PLLIN/MODE pin se- lects among Burst Mode operation, pulse-skipping mode,
APPLICATIONS
or continuous conduction mode at light loads. n Automotive Always-On Systems L, LT, LTC, LTM, OPTI-LOOP, Burst Mode, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their n Battery Powered Digital Devices respective owners. Patents, including 5481178, 5705919, 6611131, 6498466, 6580258, 7230497. n Distributed DC Power Systems
TYPICAL APPLICATION Efficiency and Power Loss vs High Efficiency 3.3V Step-Down Converter Output Current
VIN 4V TO 60V 100 10000 VIN = 12V 22µF 90 V V OUT = 3.3V IN INTVCC LTC3891 2.2µF 80 1000 POWER LOSS (mW) 70 41.2k TG 60 100 FREQ 0.1µF 2200pF BOOST 50 10k 4.7µH 8mΩ ITH V SW OUT 40 10 100pF 3.3V EFFICIENCY (%) 30 BG 150µF 5A 0.1µF 20 1 TRACK/SS SENSE+ 10 0 0.1 SENSE– 100k 0.0001 0.001 0.01 0.1 1 10 SGND OUTPUT CURRENT (A) VFB 3891 TA01b 100k PGOOD INTVCC 31.6k 3891 TA01a 3891fa 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions FUNCTIONAL Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts
FEATURES DESCRIPTION
n
Wide VIN Range: 4V to 60V (65V Abs Max)
The LTC®3891 is a high performance step-down switching n
Low Operating IQ: 50μA
regulator DC/DC controller that drives an all N-channel n
Wide Output Voltage Range: 0.8V ≤ VOUT ≤ 24V
synchronous power MOSFET stage. A constant fre- n
RSENSE or DCR Current Sensing
quency current mode architecture allows a phase-lockable n Phase-Lockable Frequency (75kHz to 750kHz) frequency of up to 750kHz. n Programmable Fixed Frequency (50kHz to 900kHz) The 50μA no-load quiescent current extends operating run n Selectable Continuous, Pulse-Skipping or Low Ripple time in battery-powered systems. OPTI-LOOP® compensa- Burst Mode® Operation at Light Load tion allows the transient response to be optimized over n Selectable Current Limit a wide range of output capacitance and ESR values. The n Very Low Dropout Operation: 99% Duty Cycle LTC3891 features a precision 0.8V reference and power n Adjustable Output Voltage Soft-Start or Tracking good output indicator. A wide 4V to 60V input supply range n Power Good Output Voltage Monitor encompasses a wide range of intermediate bus voltages n Output Overvoltage Protection and battery chemistries. The output voltage of the LTC3891 n Low Shutdown IQ: < 14μA can be programmed between 0.8V to 24V. n Internal LDO Powers Gate Drive from VIN or EXTVCC n No Current Foldback During Start-Up The TRACK/SS pin ramps the output voltages during n Small 20-Pin 3mm × 4mm QFN and TSSOP Packages start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The PLLIN/MODE pin se- lects among Burst Mode operation, pulse-skipping mode,
APPLICATIONS
or continuous conduction mode at light loads. n Automotive Always-On Systems L, LT, LTC, LTM, OPTI-LOOP, Burst Mode, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their n Battery Powered Digital Devices respective owners. Patents, including 5481178, 5705919, 6611131, 6498466, 6580258, 7230497. n Distributed DC Power Systems
TYPICAL APPLICATION Efficiency and Power Loss vs High Efficiency 3.3V Step-Down Converter Output Current
VIN 4V TO 60V 100 10000 VIN = 12V 22µF 90 V V OUT = 3.3V IN INTVCC LTC3891 2.2µF 80 1000 POWER LOSS (mW) 70 41.2k TG 60 100 FREQ 0.1µF 2200pF BOOST 50 10k 4.7µH 8mΩ ITH V SW OUT 40 10 100pF 3.3V EFFICIENCY (%) 30 BG 150µF 5A 0.1µF 20 1 TRACK/SS SENSE+ 10 0 0.1 SENSE– 100k 0.0001 0.001 0.01 0.1 1 10 SGND OUTPUT CURRENT (A) VFB 3891 TA01b 100k PGOOD INTVCC 31.6k 3891 TA01a 3891fa 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions FUNCTIONAL Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts
