Datasheet LTC3121 (Analog Devices)

LTC3121 15V, 1.5A Synchronous Step-Up DC/DC Converter with Output Disconnect
FeaTures DescripTion
n
VIN Range: 1.8V to 5.5V, 500mV After Start-Up
The LTC®3121 is a synchronous step-up DC/DC converter n
Output Voltage Range: 2.2V to 15V
with true output disconnect and inrush current limiting. The n
400mA Output Current for VIN = 5V and VOUT = 12V
1.5A current limit along with the ability to program output n
Output Disconnects from Input When Shut Down
voltages up to 15V makes the LTC3121 well suited for a n
Synchronous Rectification: Up to 95% Efficiency
variety of demanding applications. Once started, operation n
Inrush Current Limit
will continue with inputs down to 500mV, extending run n Up to 3MHz Adjustable Switching Frequency time in many applications. Synchronizable to External Clock The LTC3121 features output disconnect in shutdown, n Selectable Burst Mode® Operation: 25µA IQ dramatically reducing input power drain and enabling n Output Overvoltage Protection VOUT to completely discharge. Adjustable PWM switching n Soft-Start from 100kHz to 3MHz optimizes applications for highest n <1µA IQ in Shutdown efficiency or smallest solution footprint. The oscillator n 12-Lead, 3mm × 4mm Thermally Enhanced DFN can also be synchronized to an external clock for noise Package sensitive applications. Selectable Burst Mode operation reduces quiescent current to 25µA, ensuring high efficiency
applicaTions
across the entire load range. An internal soft-start limits n inrush current during start-up. PCI Express Cards/Systems n Piezo Actuators Other features include a <1µA shutdown current and robust n Small DC Motors protection under short-circuit, thermal overload, and output n 12V Analog Rail From Battery, 5V, or Backup Capacitor overvoltage conditions. The LTC3121 is offered in a low L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks profile 12-lead (3mm × 4mm × 0.75mm) DFN package. and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
Typical applicaTion 5V to 12V Synchronous Boost Converter with Output Disconnect Efficiency Curve
100 10 6.8µH VIN 90 Burst Mode 5V OPERATION 80 SW VOUT V POWER LOSS (W) IN VOUT 12V 70 PWM 1 LTC3121 400mA OFF SD 60 4.7µF ON 100nF 50 BURST PWM PWM/SYNC CAP 1.02M 40 RT FB 22µF EFFICIENCY (%) 0.1 30 PWM POWER LOSS VCC VC 113k 20 SGND PGND 210k 57.6k 10 10pF 0 0.01 4.7µF 390pF 0.01 0.1 1 10 100 600 LOAD CURRENT (mA) 3121 TA01b 3121 TA01a 3121fa For more information www.linear.com/LTC3121 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Package Description Typical Application Related Parts Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Low Voltage Operation Low Noise Fixed Frequency Operation Burst Mode Operation Applications Information PCB Layout Guidelines Schottky Diode Component Selection Operating Frequency Selection Typical Applications Package Description Revision History Typical Application Related Parts