Datasheet LTC3638 (Analog Devices)

LTC3638 High Efficiency, 140V 250mA Step-Down Regulator
FEATURES DESCRIPTION
n
Wide Operating Input Voltage Range: 4V to 140V
The LTC®3638 is a high efficiency step-down DC/DC n
Internal Low Resistance Power MOSFET
regulator with internal power switch that draws only 12μA n
No Compensation Required
typical DC supply current while maintaining a regulated n
Adjustable 20mA to 250mA Maximum Output
output voltage at no load.
Current
The LTC3638 can supply up to 250mA load current and n Low Dropout Operation: 100% Duty Cycle features a programmable peak current limit that provides n Low Quiescent Current: 12µA a simple method for optimizing efficiency and for reduc- n Wide Output Range: 0.8V to VIN ing output ripple and component size. The LTC3638’s n 0.8V ±1% Feedback Voltage Reference combination of Burst Mode® operation, integrated power n Precise RUN Pin Threshold switch, low quiescent current, and programmable peak n Internal or External Soft-Start current limit provides high efficiency over a broad range n Programmable 1.8V, 3.3V, 5V or Adjustable Output of load currents. n Few External Components Required n Programmable Input Overvoltage Lockout With its wide input range of 4V to 140V and programmable n Thermally Enhanced High Voltage MSOP Package overvoltage lockout, the LTC3638 is a robust regulator suited for regulating from a wide variety of power sources. Additionally, the LTC3638 includes a precise run threshold
APPLICATIONS
and soft-start feature to guarantee that the power system n Industrial Control Supplies start-up is well-controlled in any environment. A feedback n Medical Devices comparator output enables multiple LTC3638s to be con- n Distributed Power Systems nected in parallel for higher current applications. n Portable Instruments The LTC3638 is available in a thermally enhanced high n Battery-Operated Devices voltage-capable 16-lead MSE package with four missing pins. n Avionics L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks n Automotive of Linear Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION Efficiency and Power Loss vs Load Current
100
5V to 140V Input to 5V Output, 250mA Step-Down Regulator
EFFICIENCY 90 L1 80 220µH POWER LOSS (mW) 70 V V IN = 12V IN V V IN SW OUT V 5V TO 140V 5V IN = 48V 60 1000 LTC3638 V 250mA IN = 140V 50 C RUN V IN FB 1µF 40 100 250V OVLO SS EFFICIENCY (%) COUT 30 VPRG2 VPRG1 22µF GND 20 10 POWER LOSS 10 3638 TA01a 0 1 0.1 1 10 100 1000 LOAD CURRENT (mA) 3638 TA01b 3638fa For more information www.linear.com/LTC3638 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 Applications Information Typical Applications Package Description Typical Application Related Parts